Introduce the Counter character device interface

Hi William,

I love your patch! Yet something to improve:

[auto build test ERROR on stm32/stm32-next]
[cannot apply to linus/master linux/master v5.7-rc3 next-20200429] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system. BTW, we also suggest to use '--base' option to specify the base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/William-Breathitt-Gray/Introduce-the-Counter-character-device-interface/20200430-051734
base:   https://git.kernel.org/pub/scm/linux/kernel/git/atorgue/stm32.git stm32-next
config: x86_64-allyesconfig (attached as .config)
compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate

Reported-by kbuild test robot <[email protected]>

All errors (new ones prefixed by >>):

Quoted 1 line

Quoted 1 line

drivers/counter/stm32-lptimer-cnt.c:387:2: error: initializer element is not constant

     stm32_lptim_l2c_actions_map[STM32_LPTIM_SYNAPSE_ACTION_RISING_EDGE],
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/counter/stm32-lptimer-cnt.c:387:2: note: (near initialization for 'stm32_lptim_cnt_synapse_actions[0]')
   drivers/counter/stm32-lptimer-cnt.c:388:2: error: initializer element is not constant
     stm32_lptim_l2c_actions_map[STM32_LPTIM_SYNAPSE_ACTION_FALLING_EDGE],
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/counter/stm32-lptimer-cnt.c:388:2: note: (near initialization for 'stm32_lptim_cnt_synapse_actions[1]')
   drivers/counter/stm32-lptimer-cnt.c:389:2: error: initializer element is not constant
     stm32_lptim_l2c_actions_map[STM32_LPTIM_SYNAPSE_ACTION_BOTH_EDGES],
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/counter/stm32-lptimer-cnt.c:389:2: note: (near initialization for 'stm32_lptim_cnt_synapse_actions[2]')
   drivers/counter/stm32-lptimer-cnt.c:390:2: error: initializer element is not constant
     stm32_lptim_l2c_actions_map[STM32_LPTIM_SYNAPSE_ACTION_NONE],
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~

drivers/counter/stm32-lptimer-cnt.c:390:2: note: (near initialization for 'stm32_lptim_cnt_synapse_actions[3]')

vim +387 drivers/counter/stm32-lptimer-cnt.c

   385	
   386	static const enum counter_synapse_action stm32_lptim_cnt_synapse_actions[] = {

Quoted 1 line

387 stm32_lptim_l2c_actions_map[STM32_LPTIM_SYNAPSE_ACTION_RISING_EDGE],

388 stm32_lptim_l2c_actions_map[STM32_LPTIM_SYNAPSE_ACTION_FALLING_EDGE],
389 stm32_lptim_l2c_actions_map[STM32_LPTIM_SYNAPSE_ACTION_BOTH_EDGES],
390 stm32_lptim_l2c_actions_map[STM32_LPTIM_SYNAPSE_ACTION_NONE],

   391	};
   392	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

This is a reimplementation of the Generic Counter driver interface. There are no modifications to the Counter subsystem userspace interface, so existing userspace applications should continue to run seamlessly.

Overview
========

The purpose of this patch is to internalize the sysfs interface code among the various counter drivers into a shared module. Counter drivers pass and take data natively (i.e. unsigned long, bool, size_t, etc.) and the shared counter module handles the translation between the sysfs interface. This gurantees a standard userspace interface for all counter drivers, and helps generalize the Generic Counter driver ABI in order to support the Generic Counter chardev interface (introduced in a subsequent patch) without changes to the existing counter drivers.

A high-level view of how a count value is passed down from a counter driver can be exemplified by the following:

                 ----------------------
                / Counter device       \
                +----------------------+
                | Count register: 0x28 |
                +----------------------+
                        |
                 -----------------
                / raw count data /
                -----------------
                        |
                        V
                +----------------------------+
                | Counter device driver      |----------+
                +----------------------------+          |
                | Processes data from device |   -------------------
                |----------------------------|  / driver callbacks /
                | Type: unsigned long        |  -------------------
                | Value: 42                  |          |
                +----------------------------+          |
                        |                               |
                 ----------------                       |
                / unsigned long /                       |
                ----------------                        |
                        |                               |
                        |                               V
                        |               +----------------------+
                        |               | Counter core         |
                        |               +----------------------+
                        |               | Routes device driver |
                        |               | callbacks to the     |
                        |               | userspace interfaces |
                        |               +----------------------+
                        |                       |
                        |                -------------------
                        |               / driver callbacks /
                        |               -------------------
                        |                       |
                +-------+                       |
                |                               |
                |               +---------------+
                |               |
                V               |
        +--------------------+  |
        | Counter sysfs      |<-+
        +--------------------+
        | Translates to the  |
        | standard Counter   |
        | sysfs output       |
        |--------------------|
        | Type: const char * |
        | Value: "42"        |
        +--------------------+
                |
         ---------------
        / const char * /
        ---------------
                |
                V
        +--------------------------------------------------+
        | `/sys/bus/counter/devices/counterX/countY/count` |
        +--------------------------------------------------+
        \ Count: "42"                                      /
         --------------------------------------------------

There are three primary components involved:

Counter device driver
---------------------
Communicates with the hardware device to read/write data; e.g. counter drivers for 104-quad-8, stm32-timer, etc.

Counter core
------------
Registers the counter device driver to the system so that the respective callbacks are called during userspace interaction

Counter sysfs
-------------
Translates counter data to the standard Counter sysfs interface format and vice versa

Driver ABI
==========

This reimplementation entails several changes to the driver ABI. In particular, the device driver callbacks are now expected to handle standard C datatypes rather than translating the sysfs I/O directly.

To that end, the struct counter_data structure is introduced to establish counter extensions for Signals, Synapses, and Counts:

struct counter_data {
	enum counter_data_type type;
	const char *name;
	void *read;

	void *write;
	void *priv;
};

The "type" member specifies the type of data (e.g. unsigned long, boolean, etc.) handled by this extension. The "read" and "write" members can then be set by the counter device driver with callbacks to handle that data.

Convenience macros such as COUNTER_DATA_UNSIGNED_LONG are provided for use by driver authors. In particular, driver authors are expected to use the provided macros for standard Counter subsystem attributes in order to maintain a consistent interface for userspace. For example, a counter device driver may define several standard attributes like so:

struct counter_data count_ext[] = {
COUNTER_DATA_DIRECTION(count_direction_read), COUNTER_DATA_ENABLE(count_enable_read, count_enable_write), COUNTER_DATA_CEILING(count_ceiling_read, count_ceiling_write),
};

This makes it intuitive to see, add, and modify the attributes that are supported by this driver ("direction", "enable", and "ceiling") and to maintain this code without getting lost in a web of struct braces.

Callbacks must match the function type expected for the respective component or extension. These types are defined in the drivers/counter/counter-function-types.h file.

The corresponding prototypes for the callbacks would be:

int count_direction_read(struct counter_device *counter,

			 struct counter_count *count,
			 enum counter_count_direction *direction);
int count_enable_read(struct counter_device *counter,
		      struct counter_count *count, bool *enable);
int count_enable_write(struct counter_device *counter,
		       struct counter_count *count, bool enable);
int count_ceiling_read(struct counter_device *counter,
		       struct counter_count *count,
		       unsigned long *ceiling);
int count_ceiling_write(struct counter_device *counter,
			struct counter_count *count,
			unsigned long ceiling);

In this way, driver authors no longer need to mess with sysfs strings and are instead able to focus on what they actually care about doing -- getting data to/from the devices -- while the Generic Counter interface handles the translation of that data for them between the various userspace interfaces (e.g. sysfs and chardev).

Architecture
============

Counter device registration is the same as before: drivers populate a struct counter_device with components and callbacks, then pass the structure to the devm_counter_register function. However, what's different now is how the Counter subsystem code handles this registration internally.

Whereas before callbacks would interact directly with sysfs data, this interaction is now abstracted and instead callbacks interact with native C data types. The counter_data structure forms the basis for Counter extentions.

The counter-sysfs.c file contains the code to parse through the counter_device structure and register the requested components and extensions. Attributes are created and populated based on type, with respective translation functions to handle the mapping between sysfs and the counter driver callbacks.

The counter-sysfs-callbacks.c file contains the code to map between the abstract read and write callbacks of the counter driver and the more specific show and store callbacks expected for sysfs. This mapping is represented by the counter_data_sysfs_show and counter_data_sysfs_store arrays, which point to the show and store translation functions for each attribute.

The translation performed for each attribute is straightforward: the attribute type and data is parsed from the counter_attribute structure, the respective counter driver read/write callback is cast, and sysfs I/O is handled before or after the driver read/write function is called.

The counter-function-types.h file contains the typedefs to simplify this casting code. The counter-strings.h file contains the standard Counter sysfs I/O string constants to maintain a consistent interface for userspace.

Cc Syed Nayyar Waris <[email protected]>

Cc Patrick Havelange <[email protected]>

Cc Fabrice Gasnier <[email protected]>

Cc Maxime Coquelin <[email protected]>

Cc Alexandre Torgue <[email protected]>

Cc David Lechner <[email protected]>

Signed-off-by William Breathitt Gray <[email protected]>

---
 MAINTAINERS                               |    2 +-
 drivers/counter/104-quad-8.c              |  437 +++---
 drivers/counter/Makefile                  |    1 +
 drivers/counter/counter-core.c            |  190 +++
 drivers/counter/counter-function-types.h  |   81 ++
 drivers/counter/counter-strings.h         |   46 +
 drivers/counter/counter-sysfs-callbacks.c |  566 ++++++++
 drivers/counter/counter-sysfs-callbacks.h |   28 +
 drivers/counter/counter-sysfs.c           |  524 ++++++++
 drivers/counter/counter-sysfs.h           |   14 +
 drivers/counter/counter.c                 | 1496 ---------------------
 drivers/counter/ftm-quaddec.c             |   46 +-
 drivers/counter/stm32-lptimer-cnt.c       |  159 +--
 drivers/counter/stm32-timer-cnt.c         |  132 +-
 drivers/counter/ti-eqep.c                 |  170 +--
 include/linux/counter.h                   |  545 +++-----
 include/linux/counter_enum.h              |   45 -
 include/uapi/linux/counter-types.h        |   67 +
 18 files changed, 2130 insertions(+), 2419 deletions(-)
 create mode 100644 drivers/counter/counter-core.c
 create mode 100644 drivers/counter/counter-function-types.h
 create mode 100644 drivers/counter/counter-strings.h
 create mode 100644 drivers/counter/counter-sysfs-callbacks.c
 create mode 100644 drivers/counter/counter-sysfs-callbacks.h
 create mode 100644 drivers/counter/counter-sysfs.c
 create mode 100644 drivers/counter/counter-sysfs.h
 delete mode 100644 drivers/counter/counter.c
 delete mode 100644 include/linux/counter_enum.h
 create mode 100644 include/uapi/linux/counter-types.h

MAINTAINERS +1 -1

index 10eb348c801c..89def3fe1c76 100644
@@ -4367,7 +4367,7 @@ F:	Documentation/ABI/testing/sysfs-bus-counter*
 F:	Documentation/driver-api/generic-counter.rst
 F:	drivers/counter/
 F:	include/linux/counter.h
-F:	include/linux/counter_enum.h
+F:	include/uapi/linux/counter-types.h
 
 CPMAC ETHERNET DRIVER
 M:	Florian Fainelli <[email protected]>

drivers/counter/104-quad-8.c +0 -0

index 9dab190c49b0..bc1801e1bce9 100644
@@ -651,21 +651,22 @@ static int quad8_count_write(struct counter_device *counter,
 }

drivers/counter/104-quad-8.c +195 -234

 };
 
-static enum counter_count_function quad8_count_functions_list[] = {
-	[QUAD8_COUNT_FUNCTION_PULSE_DIRECTION] = COUNTER_COUNT_FUNCTION_PULSE_DIRECTION,
-	[QUAD8_COUNT_FUNCTION_QUADRATURE_X1] = COUNTER_COUNT_FUNCTION_QUADRATURE_X1_A,
-	[QUAD8_COUNT_FUNCTION_QUADRATURE_X2] = COUNTER_COUNT_FUNCTION_QUADRATURE_X2_A,
-	[QUAD8_COUNT_FUNCTION_QUADRATURE_X4] = COUNTER_COUNT_FUNCTION_QUADRATURE_X4
+static const enum counter_count_function quad8_count_functions_list[] = {
+	QUAD8_COUNT_FUNCTION_PULSE_DIRECTION,
+	QUAD8_COUNT_FUNCTION_QUADRATURE_X1,
+	QUAD8_COUNT_FUNCTION_QUADRATURE_X2,
+	QUAD8_COUNT_FUNCTION_QUADRATURE_X4,
 };
 
-static int quad8_function_get(struct counter_device *counter,
-	struct counter_count *count, size_t *function)
+static int quad8_function_read(struct counter_device *counter,
+			       struct counter_count *count,
+			       enum counter_count_function *function)
 {
 	const struct quad8_iio *const priv = counter->priv;
 	const int id = count->id;

@@ -690,11 +691,13 @@ static int quad8_function_get(struct counter_device *counter,
 	return 0;
 }
 
-static int quad8_function_set(struct counter_device *counter,
-	struct counter_count *count, size_t function)
+static int quad8_function_write(struct counter_device *counter,
+				struct counter_count *count,
+				enum counter_count_function function)
 {
 	struct quad8_iio *const priv = counter->priv;
 	const int id = count->id;
+	const enum quad8_count_function cnt_function = function;
 	unsigned int *const quadrature_mode = priv->quadrature_mode + id;
 	unsigned int *const scale = priv->quadrature_scale + id;
 	unsigned int mode_cfg = priv->count_mode[id] << 1;

@@ -702,7 +705,7 @@ static int quad8_function_set(struct counter_device *counter,
 	const unsigned int idr_cfg = priv->index_polarity[id] << 1;
 	const int base_offset = priv->base + 2 * id + 1;
 
-	if (function == QUAD8_COUNT_FUNCTION_PULSE_DIRECTION) {
+	if (cnt_function == QUAD8_COUNT_FUNCTION_PULSE_DIRECTION) {
 		*quadrature_mode = 0;
 
 		/* Quadrature scaling only available in quadrature mode */

@@ -717,7 +720,7 @@ static int quad8_function_set(struct counter_device *counter,
 	} else {
 		*quadrature_mode = 1;
 
-		switch (function) {
+		switch (cnt_function) {
 		case QUAD8_COUNT_FUNCTION_QUADRATURE_X1:
 			*scale = 0;
 			mode_cfg |= QUAD8_CMR_QUADRATURE_X1;

@@ -730,6 +733,7 @@ static int quad8_function_set(struct counter_device *counter,
 			*scale = 2;
 			mode_cfg |= QUAD8_CMR_QUADRATURE_X4;
 			break;
+		default: return -EINVAL;
 		}
 	}
 

@@ -739,8 +743,9 @@ static int quad8_function_set(struct counter_device *counter,
 	return 0;
 }
 
-static void quad8_direction_get(struct counter_device *counter,
-	struct counter_count *count, enum counter_count_direction *direction)
+static int quad8_direction_read(struct counter_device *counter,
+				struct counter_count *count,
+				enum counter_count_direction *direction)
 {
 	const struct quad8_iio *const priv = counter->priv;
 	unsigned int ud_flag;

@@ -751,91 +756,81 @@ static void quad8_direction_get(struct counter_device *counter,
 
 	*direction = (ud_flag) ? COUNTER_COUNT_DIRECTION_FORWARD :
 		COUNTER_COUNT_DIRECTION_BACKWARD;
-}
 
-enum quad8_synapse_action {
-	QUAD8_SYNAPSE_ACTION_NONE = 0,
-	QUAD8_SYNAPSE_ACTION_RISING_EDGE,
-	QUAD8_SYNAPSE_ACTION_FALLING_EDGE,
-	QUAD8_SYNAPSE_ACTION_BOTH_EDGES
-};
+	return 0;
+}
 
-static enum counter_synapse_action quad8_index_actions_list[] = {
-	[QUAD8_SYNAPSE_ACTION_NONE] = COUNTER_SYNAPSE_ACTION_NONE,
-	[QUAD8_SYNAPSE_ACTION_RISING_EDGE] = COUNTER_SYNAPSE_ACTION_RISING_EDGE
+static const enum counter_synapse_action quad8_index_actions_list[] = {
+	COUNTER_SYNAPSE_ACTION_NONE,
+	COUNTER_SYNAPSE_ACTION_RISING_EDGE,
 };
 
-static enum counter_synapse_action quad8_synapse_actions_list[] = {
-	[QUAD8_SYNAPSE_ACTION_NONE] = COUNTER_SYNAPSE_ACTION_NONE,
-	[QUAD8_SYNAPSE_ACTION_RISING_EDGE] = COUNTER_SYNAPSE_ACTION_RISING_EDGE,
-	[QUAD8_SYNAPSE_ACTION_FALLING_EDGE] = COUNTER_SYNAPSE_ACTION_FALLING_EDGE,
-	[QUAD8_SYNAPSE_ACTION_BOTH_EDGES] = COUNTER_SYNAPSE_ACTION_BOTH_EDGES
+static const enum counter_synapse_action quad8_synapse_actions_list[] = {
+	COUNTER_SYNAPSE_ACTION_NONE,
+	COUNTER_SYNAPSE_ACTION_RISING_EDGE,
+	COUNTER_SYNAPSE_ACTION_FALLING_EDGE,
+	COUNTER_SYNAPSE_ACTION_BOTH_EDGES,
 };
 
-static int quad8_action_get(struct counter_device *counter,
-	struct counter_count *count, struct counter_synapse *synapse,
-	size_t *action)
+static int quad8_action_read(struct counter_device *counter,
+			     struct counter_count *count,
+			     struct counter_synapse *synapse,
+			     enum counter_synapse_action *action)
 {
 	struct quad8_iio *const priv = counter->priv;
 	int err;
-	size_t function = 0;
+	enum counter_count_function function = 0;
 	const size_t signal_a_id = count->synapses[0].signal->id;
 	enum counter_count_direction direction;
 
 	/* Handle Index signals */
 	if (synapse->signal->id >= 16) {
 		if (priv->preset_enable[count->id])
-			*action = QUAD8_SYNAPSE_ACTION_RISING_EDGE;
+			*action = COUNTER_SYNAPSE_ACTION_RISING_EDGE;
 		else
-			*action = QUAD8_SYNAPSE_ACTION_NONE;
+			*action = COUNTER_SYNAPSE_ACTION_NONE;
 
 		return 0;
 	}
 
-	err = quad8_function_get(counter, count, &function);
+	err = quad8_function_read(counter, count, &function);
 	if (err)
 		return err;
 
 	/* Default action mode */
-	*action = QUAD8_SYNAPSE_ACTION_NONE;
+	*action = COUNTER_SYNAPSE_ACTION_NONE;
 
 	/* Determine action mode based on current count function mode */
 	switch (function) {
 	case QUAD8_COUNT_FUNCTION_PULSE_DIRECTION:
 		if (synapse->signal->id == signal_a_id)
-			*action = QUAD8_SYNAPSE_ACTION_RISING_EDGE;
+			*action = COUNTER_SYNAPSE_ACTION_RISING_EDGE;
 		break;
 	case QUAD8_COUNT_FUNCTION_QUADRATURE_X1:
 		if (synapse->signal->id == signal_a_id) {
-			quad8_direction_get(counter, count, &direction);
+			err = quad8_direction_read(counter, count, &direction);
+			if (err)
+				return err;
 
 			if (direction == COUNTER_COUNT_DIRECTION_FORWARD)
-				*action = QUAD8_SYNAPSE_ACTION_RISING_EDGE;
+				*action = COUNTER_SYNAPSE_ACTION_RISING_EDGE;
 			else
-				*action = QUAD8_SYNAPSE_ACTION_FALLING_EDGE;
+				*action = COUNTER_SYNAPSE_ACTION_FALLING_EDGE;
 		}
 		break;
 	case QUAD8_COUNT_FUNCTION_QUADRATURE_X2:
 		if (synapse->signal->id == signal_a_id)
-			*action = QUAD8_SYNAPSE_ACTION_BOTH_EDGES;
+			*action = COUNTER_SYNAPSE_ACTION_BOTH_EDGES;
 		break;
 	case QUAD8_COUNT_FUNCTION_QUADRATURE_X4:
-		*action = QUAD8_SYNAPSE_ACTION_BOTH_EDGES;
+		*action = COUNTER_SYNAPSE_ACTION_BOTH_EDGES;
 		break;
+	default: return -EINVAL;
 	}
 
 	return 0;
 }
 
-static const struct counter_ops quad8_ops = {
-	.signal_read = quad8_signal_read,
-	.count_read = quad8_count_read,
-	.count_write = quad8_count_write,
-	.function_get = quad8_function_get,
-	.function_set = quad8_function_set,
-	.action_get = quad8_action_get
-};
-
 static int quad8_index_polarity_get(struct counter_device *counter,
 	struct counter_signal *signal, size_t *index_polarity)
 {

@@ -864,12 +859,7 @@ static int quad8_index_polarity_set(struct counter_device *counter,
 	return 0;
 }
 
-static struct counter_signal_enum_ext quad8_index_pol_enum = {
-	.items = quad8_index_polarity_modes,
-	.num_items = ARRAY_SIZE(quad8_index_polarity_modes),
-	.get = quad8_index_polarity_get,
-	.set = quad8_index_polarity_set
-};
+static DEFINE_COUNTER_ENUM(quad8_index_pol_enum, quad8_index_polarity_modes);
 
 static int quad8_synchronous_mode_get(struct counter_device *counter,
 	struct counter_signal *signal, size_t *synchronous_mode)

@@ -903,22 +893,21 @@ static int quad8_synchronous_mode_set(struct counter_device *counter,
 	return 0;
 }
 
-static struct counter_signal_enum_ext quad8_syn_mode_enum = {
-	.items = quad8_synchronous_modes,
-	.num_items = ARRAY_SIZE(quad8_synchronous_modes),
-	.get = quad8_synchronous_mode_get,
-	.set = quad8_synchronous_mode_set
-};
+static DEFINE_COUNTER_ENUM(quad8_syn_mode_enum, quad8_synchronous_modes);
 
-static ssize_t quad8_count_floor_read(struct counter_device *counter,
-	struct counter_count *count, void *private, char *buf)
+static int quad8_count_floor_read(struct counter_device *counter,
+				  struct counter_count *count,
+				  unsigned long *floor)
 {
 	/* Only a floor of 0 is supported */
-	return sprintf(buf, "0\n");
+	*floor = 0;
+
+	return 0;
 }
 
-static int quad8_count_mode_get(struct counter_device *counter,
-	struct counter_count *count, size_t *cnt_mode)
+static int quad8_count_mode_read(struct counter_device *counter,
+				 struct counter_count *count,
+				 enum counter_count_mode *cnt_mode)
 {
 	const struct quad8_iio *const priv = counter->priv;
 

@@ -941,33 +930,35 @@ static int quad8_count_mode_get(struct counter_device *counter,
 	return 0;
 }
 
-static int quad8_count_mode_set(struct counter_device *counter,
-	struct counter_count *count, size_t cnt_mode)
+static int quad8_count_mode_write(struct counter_device *counter,
+				  struct counter_count *count,
+				  enum counter_count_mode cnt_mode)
 {
 	struct quad8_iio *const priv = counter->priv;
+	unsigned int count_mode = 0;
 	unsigned int mode_cfg;
 	const int base_offset = priv->base + 2 * count->id + 1;
 
 	/* Map Generic Counter count mode to 104-QUAD-8 count mode */
 	switch (cnt_mode) {
 	case COUNTER_COUNT_MODE_NORMAL:
-		cnt_mode = 0;
+		count_mode = 0;
 		break;
 	case COUNTER_COUNT_MODE_RANGE_LIMIT:
-		cnt_mode = 1;
+		count_mode = 1;
 		break;
 	case COUNTER_COUNT_MODE_NON_RECYCLE:
-		cnt_mode = 2;
+		count_mode = 2;
 		break;
 	case COUNTER_COUNT_MODE_MODULO_N:
-		cnt_mode = 3;
+		count_mode = 3;
 		break;
 	}
 
-	priv->count_mode[count->id] = cnt_mode;
+	priv->count_mode[count->id] = count_mode;
 
 	/* Set count mode configuration value */
-	mode_cfg = cnt_mode << 1;
+	mode_cfg = count_mode << 1;
 
 	/* Add quadrature mode configuration */
 	if (priv->quadrature_mode[count->id])

@@ -979,92 +970,89 @@ static int quad8_count_mode_set(struct counter_device *counter,
 	return 0;
 }
 
-static struct counter_count_enum_ext quad8_cnt_mode_enum = {
-	.items = counter_count_mode_str,
-	.num_items = ARRAY_SIZE(counter_count_mode_str),
-	.get = quad8_count_mode_get,
-	.set = quad8_count_mode_set
+static enum counter_count_mode quad8_cnt_modes[] = {
+	COUNTER_COUNT_MODE_NORMAL,
+	COUNTER_COUNT_MODE_RANGE_LIMIT,
+	COUNTER_COUNT_MODE_NON_RECYCLE,
+	COUNTER_COUNT_MODE_MODULO_N,
 };
 
-static ssize_t quad8_count_direction_read(struct counter_device *counter,
-	struct counter_count *count, void *priv, char *buf)
-{
-	enum counter_count_direction dir;
-
-	quad8_direction_get(counter, count, &dir);
-
-	return sprintf(buf, "%s\n", counter_count_direction_str[dir]);
-}
+static DEFINE_COUNTER_AVAILABLE(quad8_count_mode_available, quad8_cnt_modes);
 
-static ssize_t quad8_count_enable_read(struct counter_device *counter,
-	struct counter_count *count, void *private, char *buf)
+static int quad8_count_enable_read(struct counter_device *counter,
+				   struct counter_count *count, bool *enable)
 {
 	const struct quad8_iio *const priv = counter->priv;
 
-	return sprintf(buf, "%u\n", priv->ab_enable[count->id]);
+	*enable = priv->ab_enable[count->id];
+
+	return 0;
 }
 
-static ssize_t quad8_count_enable_write(struct counter_device *counter,
-	struct counter_count *count, void *private, const char *buf, size_t len)
+static int quad8_count_enable_write(struct counter_device *counter,
+				    struct counter_count *count, bool enable)
 {
 	struct quad8_iio *const priv = counter->priv;
 	const int base_offset = priv->base + 2 * count->id;
-	int err;
-	bool ab_enable;
 	unsigned int ior_cfg;
 
-	err = kstrtobool(buf, &ab_enable);
-	if (err)
-		return err;
+	priv->ab_enable[count->id] = enable;
 
-	priv->ab_enable[count->id] = ab_enable;
-
-	ior_cfg = ab_enable | priv->preset_enable[count->id] << 1;
+	ior_cfg = enable | priv->preset_enable[count->id] << 1;
 
 	/* Load I/O control configuration */
 	outb(QUAD8_CTR_IOR | ior_cfg, base_offset + 1);
 
-	return len;
+	return 0;
 }
 
-static int quad8_error_noise_get(struct counter_device *counter,
-	struct counter_count *count, size_t *noise_error)
+static ssize_t quad8_error_noise_read(struct counter_device *counter,
+				      struct counter_count *count, char *buf,
+				      size_t size)
 {
 	const struct quad8_iio *const priv = counter->priv;
 	const int base_offset = priv->base + 2 * count->id + 1;
+	size_t noise_error;
 
-	*noise_error = !!(inb(base_offset) & QUAD8_FLAG_E);
+	noise_error = !!(inb(base_offset) & QUAD8_FLAG_E);
 
-	return 0;
+	return snprintf(buf, size, "%s\n",
+			quad8_noise_error_states[noise_error]);
 }
 
-static struct counter_count_enum_ext quad8_error_noise_enum = {
-	.items = quad8_noise_error_states,
-	.num_items = ARRAY_SIZE(quad8_noise_error_states),
-	.get = quad8_error_noise_get
-};
+static ssize_t quad8_error_noise_available_read(struct counter_device *counter,
+						struct counter_count *count,
+						char *buf, size_t size)
+{
+	size_t i;
+	size_t len = 0;
 
-static ssize_t quad8_count_preset_read(struct counter_device *counter,
-	struct counter_count *count, void *private, char *buf)
+	for (i = 0; i < ARRAY_SIZE(quad8_noise_error_states) && size > 1; i++)
+		len += scnprintf(buf + len, size - len, "%s\n",
+				 quad8_noise_error_states[i]);
+
+	return len;
+}
+
+static int quad8_count_preset_read(struct counter_device *counter,
+				   struct counter_count *count,
+				   unsigned long *preset)
 {
 	const struct quad8_iio *const priv = counter->priv;
 
-	return sprintf(buf, "%u\n", priv->preset[count->id]);
+	*preset = priv->preset[count->id];
+
+	return 0;
 }
 
-static ssize_t quad8_count_preset_write(struct counter_device *counter,
-	struct counter_count *count, void *private, const char *buf, size_t len)
+static int quad8_count_preset_write(struct counter_device *counter,
+				    struct counter_count *count,
+				    unsigned long preset)
 {
 	struct quad8_iio *const priv = counter->priv;
 	const int base_offset = priv->base + 2 * count->id;
-	unsigned int preset;
-	int ret;
 	int i;
 
-	ret = kstrtouint(buf, 0, &preset);
-	if (ret)
-		return ret;
-
 	/* Only 24-bit values are supported */
 	if (preset > 0xFFFFFF)
 		return -EINVAL;

@@ -1078,11 +1066,12 @@ static ssize_t quad8_count_preset_write(struct counter_device *counter,
 	for (i = 0; i < 3; i++)
 		outb(preset >> (8 * i), base_offset);
 
-	return len;
+	return 0;
 }
 
-static ssize_t quad8_count_ceiling_read(struct counter_device *counter,
-	struct counter_count *count, void *private, char *buf)
+static int quad8_count_ceiling_read(struct counter_device *counter,
+				    struct counter_count *count,
+				    unsigned long *ceiling)
 {
 	const struct quad8_iio *const priv = counter->priv;
 

@@ -1090,15 +1079,18 @@ static ssize_t quad8_count_ceiling_read(struct counter_device *counter,
 	switch (priv->count_mode[count->id]) {
 	case 1:
 	case 3:
-		return quad8_count_preset_read(counter, count, private, buf);
+		return quad8_count_preset_read(counter, count, ceiling);
 	}
 
 	/* By default 0x1FFFFFF (25 bits unsigned) is maximum count */
-	return sprintf(buf, "33554431\n");
+	*ceiling = 0x1FFFFFF;
+
+	return 0;
 }
 
-static ssize_t quad8_count_ceiling_write(struct counter_device *counter,
-	struct counter_count *count, void *private, const char *buf, size_t len)
+static int quad8_count_ceiling_write(struct counter_device *counter,
+				     struct counter_count *count,
+				     unsigned long ceiling)
 {
 	struct quad8_iio *const priv = counter->priv;
 

@@ -1106,34 +1098,31 @@ static ssize_t quad8_count_ceiling_write(struct counter_device *counter,
 	switch (priv->count_mode[count->id]) {
 	case 1:
 	case 3:
-		return quad8_count_preset_write(counter, count, private, buf,
-						len);
+		return quad8_count_preset_write(counter, count, ceiling);
 	}
 
-	return len;
+	return -EINVAL;
 }
 
-static ssize_t quad8_count_preset_enable_read(struct counter_device *counter,
-	struct counter_count *count, void *private, char *buf)
+static int quad8_count_preset_enable_read(struct counter_device *counter,
+					  struct counter_count *count,
+					  bool *preset_enable)
 {
 	const struct quad8_iio *const priv = counter->priv;
 
-	return sprintf(buf, "%u\n", !priv->preset_enable[count->id]);
+	*preset_enable = !priv->preset_enable[count->id];
+
+	return 0;
 }
 
-static ssize_t quad8_count_preset_enable_write(struct counter_device *counter,
-	struct counter_count *count, void *private, const char *buf, size_t len)
+static int quad8_count_preset_enable_write(struct counter_device *counter,
+					   struct counter_count *count,
+					   bool preset_enable)
 {
 	struct quad8_iio *const priv = counter->priv;
 	const int base_offset = priv->base + 2 * count->id + 1;
-	bool preset_enable;
-	int ret;
 	unsigned int ior_cfg;
 
-	ret = kstrtobool(buf, &preset_enable);
-	if (ret)
-		return ret;
-
 	/* Preset enable is active low in Input/Output Control register */
 	preset_enable = !preset_enable;
 

@@ -1144,18 +1133,16 @@ static ssize_t quad8_count_preset_enable_write(struct counter_device *counter,
 	/* Load I/O control configuration to Input / Output Control Register */
 	outb(QUAD8_CTR_IOR | ior_cfg, base_offset);
 
-	return len;
+	return 0;
 }
 
-static ssize_t quad8_signal_cable_fault_read(struct counter_device *counter,
-					     struct counter_signal *signal,
-					     void *private, char *buf)
+static int quad8_signal_cable_fault_read(struct counter_device *counter,
+	struct counter_signal *signal, bool *cable_fault)
 {
 	const struct quad8_iio *const priv = counter->priv;
 	const size_t channel_id = signal->id / 2;
 	const bool disabled = !(priv->cable_fault_enable & BIT(channel_id));
 	unsigned int status;
-	unsigned int fault;
 
 	if (disabled)
 		return -EINVAL;

@@ -1164,36 +1151,29 @@ static ssize_t quad8_signal_cable_fault_read(struct counter_device *counter,
 	status = inb(priv->base + QUAD8_DIFF_ENCODER_CABLE_STATUS);
 
 	/* Mask respective channel and invert logic */
-	fault = !(status & BIT(channel_id));
+	*cable_fault = !(status & BIT(channel_id));
 
-	return sprintf(buf, "%u\n", fault);
+	return 0;
 }
 
-static ssize_t quad8_signal_cable_fault_enable_read(
-	struct counter_device *counter, struct counter_signal *signal,
-	void *private, char *buf)
+static int quad8_signal_cable_fault_enable_read(struct counter_device *counter,
+	struct counter_signal *signal, bool *enable)
 {
 	const struct quad8_iio *const priv = counter->priv;
 	const size_t channel_id = signal->id / 2;
-	const unsigned int enb = !!(priv->cable_fault_enable & BIT(channel_id));
 
-	return sprintf(buf, "%u\n", enb);
+	*enable = !!(priv->cable_fault_enable & BIT(channel_id));
+
+	return 0;
 }
 
-static ssize_t quad8_signal_cable_fault_enable_write(
-	struct counter_device *counter, struct counter_signal *signal,
-	void *private, const char *buf, size_t len)
+static int quad8_signal_cable_fault_enable_write(struct counter_device *counter,
+	struct counter_signal *signal, bool enable)
 {
 	struct quad8_iio *const priv = counter->priv;
 	const size_t channel_id = signal->id / 2;
-	bool enable;
-	int ret;
 	unsigned int cable_fault_enable;
 
-	ret = kstrtobool(buf, &enable);
-	if (ret)
-		return ret;
-
 	if (enable)
 		priv->cable_fault_enable |= BIT(channel_id);
 	else

@@ -1204,31 +1184,29 @@ static ssize_t quad8_signal_cable_fault_enable_write(
 
 	outb(cable_fault_enable, priv->base + QUAD8_DIFF_ENCODER_CABLE_STATUS);
 
-	return len;
+	return 0;
 }
 
-static ssize_t quad8_signal_fck_prescaler_read(struct counter_device *counter,
-	struct counter_signal *signal, void *private, char *buf)
+static int quad8_signal_fck_prescaler_read(struct counter_device *counter,
+	struct counter_signal *signal, unsigned long *prescaler)
 {
 	const struct quad8_iio *const priv = counter->priv;
-	const size_t channel_id = signal->id / 2;
 
-	return sprintf(buf, "%u\n", priv->fck_prescaler[channel_id]);
+	*prescaler = priv->fck_prescaler[signal->id / 2];
+
+	return 0;
 }
 
-static ssize_t quad8_signal_fck_prescaler_write(struct counter_device *counter,
-	struct counter_signal *signal, void *private, const char *buf,
-	size_t len)
+static int quad8_signal_fck_prescaler_write(struct counter_device *counter,
+	struct counter_signal *signal, unsigned long prescaler)
 {
 	struct quad8_iio *const priv = counter->priv;
 	const size_t channel_id = signal->id / 2;
 	const int base_offset = priv->base + 2 * channel_id;
-	u8 prescaler;
-	int ret;
 
-	ret = kstrtou8(buf, 0, &prescaler);
-	if (ret)
-		return ret;
+	/* prescaler is an 8-bit value */
+	if (prescaler > 255)
+		return -ERANGE;
 
 	priv->fck_prescaler[channel_id] = prescaler;
 

@@ -1240,31 +1218,28 @@ static ssize_t quad8_signal_fck_prescaler_write(struct counter_device *counter,
 	outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP | QUAD8_RLD_PRESET_PSC,
 	     base_offset + 1);
 
-	return len;
+	return 0;
 }
 
-static const struct counter_signal_ext quad8_signal_ext[] = {
-	{
-		.name = "cable_fault",
-		.read = quad8_signal_cable_fault_read
-	},
-	{
-		.name = "cable_fault_enable",
-		.read = quad8_signal_cable_fault_enable_read,
-		.write = quad8_signal_cable_fault_enable_write
-	},
-	{
-		.name = "filter_clock_prescaler",
-		.read = quad8_signal_fck_prescaler_read,
-		.write = quad8_signal_fck_prescaler_write
-	}
+static struct counter_data quad8_signal_ext[] = {
+	COUNTER_DATA_BOOL("cable_fault", quad8_signal_cable_fault_read, NULL),
+	COUNTER_DATA_BOOL("cable_fault_enable",
+			  quad8_signal_cable_fault_enable_read,
+			  quad8_signal_cable_fault_enable_write),
+	COUNTER_DATA_UNSIGNED_LONG("filter_clock_prescaler",
+				   quad8_signal_fck_prescaler_read,
+				   quad8_signal_fck_prescaler_write)
 };
 
-static const struct counter_signal_ext quad8_index_ext[] = {
-	COUNTER_SIGNAL_ENUM("index_polarity", &quad8_index_pol_enum),
-	COUNTER_SIGNAL_ENUM_AVAILABLE("index_polarity",	&quad8_index_pol_enum),
-	COUNTER_SIGNAL_ENUM("synchronous_mode", &quad8_syn_mode_enum),
-	COUNTER_SIGNAL_ENUM_AVAILABLE("synchronous_mode", &quad8_syn_mode_enum)
+static struct counter_data quad8_index_ext[] = {
+	COUNTER_DATA_ENUM_AND_AVAILABLE("index_polarity",
+					quad8_index_polarity_get,
+					quad8_index_polarity_set,
+					quad8_index_pol_enum),
+	COUNTER_DATA_ENUM_AND_AVAILABLE("synchronous_mode",
+					quad8_synchronous_mode_get,
+					quad8_synchronous_mode_set,
+					quad8_syn_mode_enum),
 };
 
 #define QUAD8_QUAD_SIGNAL(_id, _name) {		\

@@ -1333,39 +1308,20 @@ static struct counter_synapse quad8_count_synapses[][3] = {
 	QUAD8_COUNT_SYNAPSES(6), QUAD8_COUNT_SYNAPSES(7)
 };
 
-static const struct counter_count_ext quad8_count_ext[] = {
-	{
-		.name = "ceiling",
-		.read = quad8_count_ceiling_read,
-		.write = quad8_count_ceiling_write
-	},
-	{
-		.name = "floor",
-		.read = quad8_count_floor_read
-	},
-	COUNTER_COUNT_ENUM("count_mode", &quad8_cnt_mode_enum),
-	COUNTER_COUNT_ENUM_AVAILABLE("count_mode", &quad8_cnt_mode_enum),
-	{
-		.name = "direction",
-		.read = quad8_count_direction_read
-	},
-	{
-		.name = "enable",
-		.read = quad8_count_enable_read,
-		.write = quad8_count_enable_write
-	},
-	COUNTER_COUNT_ENUM("error_noise", &quad8_error_noise_enum),
-	COUNTER_COUNT_ENUM_AVAILABLE("error_noise", &quad8_error_noise_enum),
-	{
-		.name = "preset",
-		.read = quad8_count_preset_read,
-		.write = quad8_count_preset_write
-	},
-	{
-		.name = "preset_enable",
-		.read = quad8_count_preset_enable_read,
-		.write = quad8_count_preset_enable_write
-	}
+static struct counter_data quad8_count_ext[] = {
+	COUNTER_DATA_CEILING(quad8_count_ceiling_read,
+			     quad8_count_ceiling_write),
+	COUNTER_DATA_FLOOR(quad8_count_floor_read, NULL),
+	COUNTER_DATA_COUNT_MODE_AND_AVAILABLE(quad8_count_mode_read,
+					      quad8_count_mode_write,
+					      quad8_count_mode_available),
+	COUNTER_DATA_DIRECTION(quad8_direction_read),
+	COUNTER_DATA_ENABLE(quad8_count_enable_read, quad8_count_enable_write),
+	COUNTER_DATA_ERROR_NOISE_AND_AVAILABLE(quad8_error_noise_read,
+					       quad8_error_noise_available_read),
+	COUNTER_DATA_PRESET(quad8_count_preset_read, quad8_count_preset_write),
+	COUNTER_DATA_PRESET_ENABLE(quad8_count_preset_enable_read,
+				   quad8_count_preset_enable_write),
 };
 
 #define QUAD8_COUNT(_id, _cntname) {					\

@@ -1421,7 +1377,12 @@ static int quad8_probe(struct device *dev, unsigned int id)
 	quad8iio = iio_priv(indio_dev);
 	quad8iio->counter.name = dev_name(dev);
 	quad8iio->counter.parent = dev;
-	quad8iio->counter.ops = &quad8_ops;
+	quad8iio->counter.signal_read = quad8_signal_read;
+	quad8iio->counter.count_read = quad8_count_read;
+	quad8iio->counter.count_write = quad8_count_write;
+	quad8iio->counter.function_read = quad8_function_read;
+	quad8iio->counter.function_write = quad8_function_write;
+	quad8iio->counter.action_read = quad8_action_read;
 	quad8iio->counter.counts = quad8_counts;
 	quad8iio->counter.num_counts = ARRAY_SIZE(quad8_counts);
 	quad8iio->counter.signals = quad8_signals;

drivers/counter/Makefile +1 -0

index 55142d1f4c43..2d2644bd7777 100644
@@ -4,6 +4,7 @@
 #
 
 obj-$(CONFIG_COUNTER) += counter.o
+counter-y := counter-core.o counter-sysfs.o counter-sysfs-callbacks.o
 
 obj-$(CONFIG_104_QUAD_8)	+= 104-quad-8.o
 obj-$(CONFIG_STM32_TIMER_CNT)	+= stm32-timer-cnt.o

drivers/counter/counter-core.c new file +148 -0

new file mode 100644
index 000000000000..008d51284a2c
@@ -0,0 +1,190 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Generic Counter interface
+ * Copyright (C) 2020 William Breathitt Gray
+ */
+#include <linux/counter.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/gfp.h>
+#include <linux/idr.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#include "counter-sysfs.h"
+
+/* Provides a unique ID for each counter device */
+static DEFINE_IDA(counter_ida);
+
+static void counter_device_release(struct device *dev)
+{
+	struct counter_device *const counter = dev_get_drvdata(dev);
+
+	counter_sysfs_free(counter);
+	kfree(&counter->dev);
+	ida_simple_remove(&counter_ida, counter->id);
+}
+
+static struct device_type counter_device_type = {
+	.name = "counter_device",
+	.release = counter_device_release
+};
+
+static struct bus_type counter_bus_type = {
+	.name = "counter"
+};
+
+/**
+ * counter_register - register Counter to the system
+ * @counter:	pointer to Counter to register
+ *
+ * This function registers a Counter to the system. A sysfs "counter" directory
+ * will be created and populated with sysfs attributes correlating with the
+ * Counter Signals, Synapses, and Counts respectively.
+ */
+int counter_register(struct counter_device *const counter)
+{
+	struct device *const dev = &counter->dev;
+	int err;
+
+	/* Acquire unique ID */
+	counter->id = ida_simple_get(&counter_ida, 0, 0, GFP_KERNEL);
+	if (counter->id < 0)
+		return counter->id;
+
+	/* Configure device structure for Counter */
+	dev->type = &counter_device_type;
+	dev->bus = &counter_bus_type;
+	if (counter->parent) {
+		dev->parent = counter->parent;
+		dev->of_node = counter->parent->of_node;
+	}
+	dev_set_name(dev, "counter%d", counter->id);
+	device_initialize(dev);
+	dev_set_drvdata(dev, counter);
+
+	/* Add Counter sysfs attributes */
+	err = counter_sysfs_add(counter);
+	if (err)
+		goto err_free_id;
+
+	/* Add device to system */
+	err = device_add(dev);
+	if (err)
+		goto err_free_sysfs;
+
+	return 0;
+
+err_free_sysfs:
+	counter_sysfs_free(counter);
+err_free_id:
+	ida_simple_remove(&counter_ida, counter->id);
+	return err;
+}
+EXPORT_SYMBOL_GPL(counter_register);
+
+/**
+ * counter_unregister - unregister Counter from the system
+ * @counter:	pointer to Counter to unregister
+ *
+ * The Counter is unregistered from the system; all allocated memory is freed.
+ */
+void counter_unregister(struct counter_device *const counter)
+{
+	if (counter) {
+		device_del(&counter->dev);
+		counter_sysfs_free(counter);
+	}
+}
+EXPORT_SYMBOL_GPL(counter_unregister);
+
+static void devm_counter_unreg(struct device *dev, void *res)
+{
+	counter_unregister(*(struct counter_device **)res);
+}
+
+/**
+ * devm_counter_register - Resource-managed counter_register
+ * @dev:	device to allocate counter_device for
+ * @counter:	pointer to Counter to register
+ *
+ * Managed counter_register. The Counter registered with this function is
+ * automatically unregistered on driver detach. This function calls
+ * counter_register internally. Refer to that function for more information.
+ *
+ * If an Counter registered with this function needs to be unregistered
+ * separately, devm_counter_unregister must be used.
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure.
+ */
+int devm_counter_register(struct device *dev,
+			  struct counter_device *const counter)
+{
+	struct counter_device **ptr;
+	int ret;
+
+	ptr = devres_alloc(devm_counter_unreg, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return -ENOMEM;
+
+	ret = counter_register(counter);
+	if (!ret) {
+		*ptr = counter;
+		devres_add(dev, ptr);
+	} else {
+		devres_free(ptr);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(devm_counter_register);
+
+static int devm_counter_match(struct device *dev, void *res, void *data)
+{
+	struct counter_device **r = res;
+

drivers/counter/counter-strings.h new file +46 -0

@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Generic Counter strings
+ * Copyright (C) 2020 William Breathitt Gray
+ */
+#ifndef _COUNTER_STRINGS_H_
+#define _COUNTER_STRINGS_H_
+
+#include <linux/counter.h>
+
+const char *const counter_count_direction_str[] = {
+	[COUNTER_COUNT_DIRECTION_FORWARD] = "forward",
+	[COUNTER_COUNT_DIRECTION_BACKWARD] = "backward"
+};
+
+const char *const counter_count_function_str[] = {
+	[COUNTER_COUNT_FUNCTION_INCREASE] = "increase",
+	[COUNTER_COUNT_FUNCTION_DECREASE] = "decrease",
+	[COUNTER_COUNT_FUNCTION_PULSE_DIRECTION] = "pulse-direction",
+	[COUNTER_COUNT_FUNCTION_QUADRATURE_X1_A] = "quadrature x1 a",
+	[COUNTER_COUNT_FUNCTION_QUADRATURE_X1_B] = "quadrature x1 b",
+	[COUNTER_COUNT_FUNCTION_QUADRATURE_X2_A] = "quadrature x2 a",
+	[COUNTER_COUNT_FUNCTION_QUADRATURE_X2_B] = "quadrature x2 b",
+	[COUNTER_COUNT_FUNCTION_QUADRATURE_X4] = "quadrature x4"
+};
+
+const char *const counter_count_mode_str[] = {
+	[COUNTER_COUNT_MODE_NORMAL] = "normal",
+	[COUNTER_COUNT_MODE_RANGE_LIMIT] = "range limit",
+	[COUNTER_COUNT_MODE_NON_RECYCLE] = "non-recycle",
+	[COUNTER_COUNT_MODE_MODULO_N] = "modulo-n"
+};
+
+const char *const counter_signal_value_str[] = {
+	[COUNTER_SIGNAL_LOW] = "low",
+	[COUNTER_SIGNAL_HIGH] = "high"
+};
+
+const char *const counter_synapse_action_str[] = {
+	[COUNTER_SYNAPSE_ACTION_NONE] = "none",
+	[COUNTER_SYNAPSE_ACTION_RISING_EDGE] = "rising edge",
+	[COUNTER_SYNAPSE_ACTION_FALLING_EDGE] = "falling edge",
+	[COUNTER_SYNAPSE_ACTION_BOTH_EDGES] = "both edges"
+};
+
+#endif /* _COUNTER_STRINGS_H_ */

drivers/counter/counter-sysfs-callbacks.c new file +17 -0

new file mode 100644
index 000000000000..5740d61e999b
@@ -0,0 +1,566 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Generic Counter sysfs callbacks
+ * Copyright (C) 2020 William Breathitt Gray
+ */
+#include <linux/counter.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/types.h>
+
+#include "counter-function-types.h"
+#include "counter-strings.h"
+#include "counter-sysfs-callbacks.h"
+

drivers/counter/counter-sysfs-callbacks.c new file +24 -0

+	}
+	if (err)
+		return err;
+
+	return sprintf(buf, "%u\n", (unsigned int)data);
+}
+
+static ssize_t counter_data_bool_store(struct device *dev,
+				       struct device_attribute *attr,
+				       const char *buf, size_t len)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	const counter_count_bool_write count_bool_write = a->data.write;
+	const counter_device_bool_write device_bool_write = a->data.write;
+	const counter_signal_bool_write signal_bool_write = a->data.write;
+	struct counter_device *const counter = dev_get_drvdata(dev);
+	void *const owner = a->owner;
+	int err;
+	bool data;
+
+	err = kstrtobool(buf, &data);
+	if (err)
+		return err;
+

drivers/counter/counter-sysfs-callbacks.c new file +490 -0

+	}
+	if (err)
+		return err;
+
+	return len;
+}
+
+static ssize_t counter_data_lu_show(struct device *dev,
+				    struct device_attribute *attr, char *buf)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	const counter_count_lu_read count_lu_read = a->data.read;
+	const counter_device_lu_read device_lu_read = a->data.read;
+	const counter_signal_lu_read signal_lu_read = a->data.read;
+	struct counter_device *const counter = dev_get_drvdata(dev);
+	void *const owner = a->owner;
+	int err = 0;
+	unsigned long data;
+
+	switch (a->type) {
+	case COUNTER_OWNER_TYPE_COUNT:
+		err = count_lu_read(counter, owner, &data);
+		break;
+	case COUNTER_OWNER_TYPE_DEVICE:
+		err = device_lu_read(counter, &data);
+		break;
+	case COUNTER_OWNER_TYPE_SIGNAL:
+		err = signal_lu_read(counter, owner, &data);
+		break;
+	}
+	if (err)
+		return err;
+
+	return sprintf(buf, "%lu\n", data);
+}
+
+static ssize_t counter_data_lu_store(struct device *dev,
+				     struct device_attribute *attr,
+				     const char *buf, size_t len)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	const counter_count_lu_write count_lu_write = a->data.write;
+	const counter_device_lu_write device_lu_write = a->data.write;
+	const counter_signal_lu_write signal_lu_write = a->data.write;
+	struct counter_device *const counter = dev_get_drvdata(dev);
+	void *const owner = a->owner;
+	int err;
+	unsigned long data;
+
+	err = kstrtoul(buf, 0, &data);
+	if (err)
+		return err;
+
+	switch (a->type) {
+	case COUNTER_OWNER_TYPE_COUNT:
+		err = count_lu_write(counter, owner, data);
+		break;
+	case COUNTER_OWNER_TYPE_DEVICE:
+		err = device_lu_write(counter, data);
+		break;
+	case COUNTER_OWNER_TYPE_SIGNAL:
+		err = signal_lu_write(counter, owner, data);
+		break;
+	}
+	if (err)
+		return err;
+
+	return len;
+}
+
+static ssize_t counter_data_zu_show(struct device *dev,
+				    struct device_attribute *attr, char *buf)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	const counter_device_zu_read zu_read = a->data.read;
+	struct counter_device *const counter = dev_get_drvdata(dev);
+	int err;
+	size_t data;
+
+	err = zu_read(counter, &data);
+	if (err)
+		return err;
+
+	return sprintf(buf, "%zu\n", data);
+}
+
+static ssize_t counter_data_s_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	const counter_count_s_read count_s_read = a->data.read;
+	const counter_device_s_read device_s_read = a->data.read;
+	const counter_signal_s_read signal_s_read = a->data.read;
+	struct counter_device *const counter = dev_get_drvdata(dev);
+	void *const owner = a->owner;
+
+	switch (a->type) {
+	case COUNTER_OWNER_TYPE_COUNT:
+		return count_s_read(counter, owner, buf, PAGE_SIZE);
+	case COUNTER_OWNER_TYPE_DEVICE:
+		return device_s_read(counter, buf, PAGE_SIZE);
+	case COUNTER_OWNER_TYPE_SIGNAL:
+		return signal_s_read(counter, owner, buf, PAGE_SIZE);
+	}
+
+	return -EINVAL;
+}
+
+static ssize_t counter_data_s_store(struct device *dev,
+				    struct device_attribute *attr,
+				    const char *buf, size_t len)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	const counter_count_s_write count_s_write = a->data.write;
+	const counter_device_s_write device_s_write = a->data.write;
+	const counter_signal_s_write signal_s_write = a->data.write;
+	struct counter_device *const counter = dev_get_drvdata(dev);
+	void *const owner = a->owner;
+
+	switch (a->type) {
+	case COUNTER_OWNER_TYPE_COUNT:
+		return count_s_write(counter, owner, buf, len);
+	case COUNTER_OWNER_TYPE_DEVICE:
+		return device_s_write(counter, buf, len);
+	case COUNTER_OWNER_TYPE_SIGNAL:
+		return signal_s_write(counter, owner, buf, len);
+	}
+
+	return -EINVAL;
+}
+
+static ssize_t counter_data_count_function_show(struct device *dev,
+						struct device_attribute *attr,
+						char *buf)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	const counter_count_function_read function_read = a->data.read;
+	struct counter_device *const counter = dev_get_drvdata(dev);
+	struct counter_count *const count = a->owner;
+	int err;
+	enum counter_count_function function;
+
+	err = function_read(counter, count, &function);
+	if (err)
+		return err;
+
+	return sprintf(buf, "%s\n", counter_count_function_str[function]);
+}
+
+static ssize_t counter_data_count_function_store(struct device *dev,
+						 struct device_attribute *attr,
+						 const char *buf, size_t len)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	const counter_count_function_write function_write = a->data.write;
+	struct counter_device *const counter = dev_get_drvdata(dev);
+	struct counter_count *const count = a->owner;
+	const size_t num_functions = count->num_functions;
+	int err;
+	size_t index;
+	enum counter_count_function function;
+
+	/* Find requested function mode */
+	for (index = 0; index < num_functions; index++) {
+		function = count->functions_list[index];
+		if (sysfs_streq(buf, counter_count_function_str[function]))
+			break;
+	}
+	/* If requested function mode not found */
+	if (index >= num_functions)
+		return -EINVAL;
+
+	err = function_write(counter, count, function);
+	if (err)
+		return err;
+
+	return len;
+}
+
+static ssize_t counter_data_count_function_available_show(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	const struct counter_count *const count = a->owner;
+	size_t i;
+	enum counter_count_function function;
+	ssize_t len = 0;
+
+	for (i = 0; i < count->num_functions; i++) {
+		function = count->functions_list[i];
+		len += sprintf(buf + len, "%s\n",
+			       counter_count_function_str[function]);
+	}
+
+	return len;
+}
+
+static ssize_t counter_data_signal_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	const counter_signal_signal_read signal_read = a->data.read;
+	struct counter_device *const counter = dev_get_drvdata(dev);
+	struct counter_signal *const signal = a->owner;
+	int err;
+	enum counter_signal_value value;
+
+	err = signal_read(counter, signal, &value);
+	if (err)
+		return err;
+
+	return sprintf(buf, "%s\n", counter_signal_value_str[value]);
+}
+
+static ssize_t counter_data_synapse_action_show(struct device *dev,
+						struct device_attribute *attr,
+						char *buf)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	const counter_synapse_action_read action_read = a->data.read;
+	struct counter_device *const counter = dev_get_drvdata(dev);
+	struct counter_count *const count = a->owner;
+	struct counter_synapse *const synapse = a->data.priv;
+	int err;
+	enum counter_synapse_action action;
+
+	err = action_read(counter, count, synapse, &action);
+	if (err)
+		return err;
+
+	return sprintf(buf, "%s\n", counter_synapse_action_str[action]);
+}
+
+static ssize_t counter_data_synapse_action_store(struct device *dev,
+						 struct device_attribute *attr,
+						 const char *buf, size_t len)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	const counter_synapse_action_write action_write = a->data.write;
+	struct counter_device *const counter = dev_get_drvdata(dev);
+	struct counter_count *const count = a->owner;
+	struct counter_synapse *const synapse = a->data.priv;
+	const size_t num_actions = synapse->num_actions;
+	int err;
+	size_t index;
+	enum counter_synapse_action action;
+
+	/* Find requested action mode */
+	for (index = 0; index < num_actions; index++) {
+		action = synapse->actions_list[index];
+		if (sysfs_streq(buf, counter_synapse_action_str[action]))
+			break;
+	}
+	/* If requested action mode not found */
+	if (index >= num_actions)
+		return -EINVAL;
+
+	err = action_write(counter, count, synapse, action);
+	if (err)
+		return err;
+
+	return len;
+}
+
+static ssize_t counter_data_synapse_action_available_show(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	const struct counter_synapse *const synapse = a->data.priv;
+	size_t i;
+	enum counter_synapse_action action;
+	ssize_t len = 0;
+
+	for (i = 0; i < synapse->num_actions; i++) {
+		action = synapse->actions_list[i];
+		len += sprintf(buf + len, "%s\n",
+			       counter_synapse_action_str[action]);
+	}
+
+	return len;
+}
+
+static ssize_t counter_data_enum_show(struct device *dev,
+				      struct device_attribute *attr, char *buf)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	const counter_count_zu_read count_enum_read = a->data.read;
+	const counter_device_zu_read device_enum_read = a->data.read;
+	const counter_signal_zu_read signal_enum_read = a->data.read;
+	struct counter_device *const counter = dev_get_drvdata(dev);
+	void *const owner = a->owner;
+	struct counter_enum *const cntr_enum = a->data.priv;
+	int err = 0;
+	size_t index;
+
+	switch (a->type) {
+	case COUNTER_OWNER_TYPE_COUNT:
+		err = count_enum_read(counter, owner, &index);
+		break;
+	case COUNTER_OWNER_TYPE_DEVICE:
+		err = device_enum_read(counter, &index);
+		break;
+	case COUNTER_OWNER_TYPE_SIGNAL:
+		err = signal_enum_read(counter, owner, &index);
+		break;
+	}
+	if (err)
+		return err;
+
+	if (index >= cntr_enum->num_items)
+		return -EINVAL;
+
+	return sprintf(buf, "%s\n", cntr_enum->items[index]);
+}
+
+static ssize_t counter_data_enum_store(struct device *dev,
+				       struct device_attribute *attr,
+				       const char *buf, size_t len)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	struct counter_enum *const cntr_enum = a->data.priv;
+	const size_t num_items = cntr_enum->num_items;
+	const counter_count_zu_write count_enum_write = a->data.write;
+	const counter_device_zu_write device_enum_write = a->data.write;
+	const counter_signal_zu_write signal_enum_write = a->data.write;
+	struct counter_device *const counter = dev_get_drvdata(dev);
+	void *const owner = a->owner;
+	ssize_t index;
+	int err = 0;
+
+	index = __sysfs_match_string(cntr_enum->items, num_items, buf);
+	if (index < 0)
+		return index;
+
+	switch (a->type) {
+	case COUNTER_OWNER_TYPE_COUNT:
+		err = count_enum_write(counter, owner, index);
+		break;
+	case COUNTER_OWNER_TYPE_DEVICE:
+		err = device_enum_write(counter, index);
+		break;
+	case COUNTER_OWNER_TYPE_SIGNAL:
+		err = signal_enum_write(counter, owner, index);
+		break;
+	}
+	if (err)
+		return err;
+
+	return len;
+}
+
+static ssize_t counter_data_enum_available_show(struct device *dev,
+						struct device_attribute *attr,
+						char *buf)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	struct counter_enum *const cntr_enum = a->data.priv;
+	size_t i;
+	size_t len = 0;
+
+	for (i = 0; i < cntr_enum->num_items; i++)
+		len += sprintf(buf + len, "%s\n", cntr_enum->items[i]);
+
+	return len;
+}
+
+static ssize_t counter_data_count_direction_show(struct device *dev,
+						 struct device_attribute *attr,
+						 char *buf)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	const counter_count_direction_read direction_read = a->data.read;
+	struct counter_device *const counter = dev_get_drvdata(dev);
+	struct counter_count *const count = a->owner;
+	int err;
+	enum counter_count_direction direction;
+
+	err = direction_read(counter, count, &direction);
+	if (err)
+		return err;
+
+	return sprintf(buf, "%s\n", counter_count_direction_str[direction]);
+}
+
+static ssize_t counter_data_count_mode_show(struct device *dev,
+					    struct device_attribute *attr,
+					    char *buf)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	const counter_count_mode_read count_mode_read = a->data.read;
+	struct counter_device *const counter = dev_get_drvdata(dev);
+	struct counter_count *const count = a->owner;
+	int err;
+	enum counter_count_mode count_mode;
+
+	err = count_mode_read(counter, count, &count_mode);
+	if (err)
+		return err;
+
+	return sprintf(buf, "%s\n", counter_count_mode_str[count_mode]);
+}
+
+static ssize_t counter_data_count_mode_store(struct device *dev,
+					     struct device_attribute *attr,
+					     const char *buf, size_t len)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	const counter_count_mode_write count_mode_write = a->data.write;
+	struct counter_device *const counter = dev_get_drvdata(dev);
+	struct counter_count *const count = a->owner;
+	const struct counter_available *const available = a->data.priv;
+	const enum counter_count_mode *const items = available->items;
+	const size_t num_count_modes = available->num_items;
+	int err;
+	size_t index;
+	enum counter_count_mode count_mode;
+
+	/* Find requested count mode */
+	for (index = 0; index < num_count_modes; index++) {
+		count_mode = items[index];
+		if (sysfs_streq(buf, counter_count_mode_str[count_mode]))
+			break;
+	}
+	/* If requested count mode not found */
+	if (index >= num_count_modes)
+		return -EINVAL;
+
+	err = count_mode_write(counter, count, count_mode);
+	if (err)
+		return err;
+
+	return len;
+}
+
+static ssize_t counter_data_count_mode_available_show(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	const struct counter_available *const available = a->data.priv;
+	const enum counter_count_mode *const items = available->items;
+	size_t i;
+	enum counter_count_mode count_mode;
+	ssize_t len = 0;
+
+	for (i = 0; i < available->num_items; i++) {
+		count_mode = items[i];
+		len += sprintf(buf + len, "%s\n",
+			       counter_count_mode_str[count_mode]);
+	}
+
+	return len;
+}
+
+ssize_t (*counter_data_sysfs_show[])(struct device *, struct device_attribute *,
+				     char *) = {
+	[COUNTER_DATA_TYPE_BOOL] = counter_data_bool_show,
+	[COUNTER_DATA_TYPE_UNSIGNED_LONG] = counter_data_lu_show,
+	[COUNTER_DATA_TYPE_SIZE] = counter_data_zu_show,
+	[COUNTER_DATA_TYPE_STRING] = counter_data_s_show,
+	[COUNTER_DATA_TYPE_COUNT_FUNCTION] = counter_data_count_function_show,
+	[COUNTER_DATA_TYPE_COUNT_FUNCTION_AVAILABLE] = counter_data_count_function_available_show,
+	[COUNTER_DATA_TYPE_SIGNAL] = counter_data_signal_show,
+	[COUNTER_DATA_TYPE_SYNAPSE_ACTION] = counter_data_synapse_action_show,
+	[COUNTER_DATA_TYPE_SYNAPSE_ACTION_AVAILABLE] = counter_data_synapse_action_available_show,
+	[COUNTER_DATA_TYPE_ENUM] = counter_data_enum_show,
+	[COUNTER_DATA_TYPE_ENUM_AVAILABLE] = counter_data_enum_available_show,
+	[COUNTER_DATA_TYPE_COUNT_DIRECTION] = counter_data_count_direction_show,
+	[COUNTER_DATA_TYPE_COUNT_MODE] = counter_data_count_mode_show,
+	[COUNTER_DATA_TYPE_COUNT_MODE_AVAILABLE] = counter_data_count_mode_available_show,
+};
+
+ssize_t (*counter_data_sysfs_store[])(struct device *,
+				      struct device_attribute *, const char *,
+				      size_t) = {
+	[COUNTER_DATA_TYPE_BOOL] = counter_data_bool_store,
+	[COUNTER_DATA_TYPE_UNSIGNED_LONG] = counter_data_lu_store,
+	[COUNTER_DATA_TYPE_SIZE] = NULL,
+	[COUNTER_DATA_TYPE_STRING] = counter_data_s_store,
+	[COUNTER_DATA_TYPE_COUNT_FUNCTION] = counter_data_count_function_store,
+	[COUNTER_DATA_TYPE_COUNT_FUNCTION_AVAILABLE] = NULL,
+	[COUNTER_DATA_TYPE_SIGNAL] = NULL,
+	[COUNTER_DATA_TYPE_SYNAPSE_ACTION] = counter_data_synapse_action_store,
+	[COUNTER_DATA_TYPE_SYNAPSE_ACTION_AVAILABLE] = NULL,
+	[COUNTER_DATA_TYPE_ENUM] = counter_data_enum_store,
+	[COUNTER_DATA_TYPE_ENUM_AVAILABLE] = NULL,
+	[COUNTER_DATA_TYPE_COUNT_DIRECTION] = NULL,
+	[COUNTER_DATA_TYPE_COUNT_MODE] = counter_data_count_mode_store,
+	[COUNTER_DATA_TYPE_COUNT_MODE_AVAILABLE] = NULL,
+};

drivers/counter/counter-sysfs-callbacks.h new file +28 -0

new file mode 100644
index 000000000000..cf44e7c6ed18
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Generic Counter sysfs callbacks
+ * Copyright (C) 2020 William Breathitt Gray
+ */
+#ifndef _COUNTER_SYSFS_CALLBACKS_H_
+#define _COUNTER_SYSFS_CALLBACKS_H_
+
+#include <linux/counter.h>
+#include <linux/types.h>
+
+struct counter_attribute {
+	struct device_attribute dev_attr;
+	struct list_head l;
+
+	struct counter_data data;
+	enum counter_owner_type type;
+	void *owner;
+};
+
+extern ssize_t (*counter_data_sysfs_show[])(struct device *,
+					    struct device_attribute *, char *);
+
+extern ssize_t (*counter_data_sysfs_store[])(struct device *,
+					     struct device_attribute *,
+					     const char *, size_t);
+
+#endif /* _COUNTER_SYSFS_CALLBACKS_H_ */

drivers/counter/counter-sysfs.c new file +423 -0

new file mode 100644
index 000000000000..ed56c6b52490
@@ -0,0 +1,524 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Generic Counter sysfs interface
+ * Copyright (C) 2020 William Breathitt Gray
+ */
+#include <linux/counter.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/gfp.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/types.h>
+
+#include "counter-sysfs-callbacks.h"
+
+static int counter_attribute_create(struct counter_attribute_group *const group,
+				    const struct counter_data *const data,
+				    const enum counter_owner_type type,
+				    void *const owner)
+{
+	struct counter_attribute *counter_attr;
+	struct device_attribute *dev_attr;
+
+	/* Allocate and initialize Counter attribute */
+	counter_attr = kzalloc(sizeof(*counter_attr), GFP_KERNEL);
+	if (!counter_attr)
+		return -ENOMEM;
+	counter_attr->data = *data;
+	counter_attr->type = type;
+	counter_attr->owner = owner;
+
+	/* Configure device attribute */
+	dev_attr = &counter_attr->dev_attr;
+	sysfs_attr_init(&dev_attr->attr);
+	dev_attr->attr.name = data->name;
+	if (data->read) {
+		dev_attr->attr.mode |= 0444;
+		dev_attr->show = counter_data_sysfs_show[data->type];
+	}
+	if (data->write) {
+		dev_attr->attr.mode |= 0200;
+		dev_attr->store = counter_data_sysfs_store[data->type];
+	}
+
+	/* Keep track of the attribute for later cleanup */
+	list_add(&counter_attr->l, &group->attr_list);
+	group->num_attr++;
+
+	return 0;
+}
+
+static struct counter_data counter_signal_data = {
+	.type = COUNTER_DATA_TYPE_SIGNAL,
+	.name = "signal",
+};
+
+static struct counter_data counter_name_data =
+	COUNTER_DATA_STRING("name", NULL, NULL);
+
+static ssize_t counter_signal_name_read(struct counter_device *counter,
+					struct counter_signal *signal,
+					char *buf, size_t size)
+{
+	return snprintf(buf, size, "%s\n", signal->name);
+}
+
+static int counter_signal_attributes_create(
+	struct counter_attribute_group *const group,
+	struct counter_signal *const signal, void *const signal_read)
+{
+	const enum counter_owner_type type = COUNTER_OWNER_TYPE_SIGNAL;
+	int err;
+	struct counter_data data;
+	size_t i;
+	const struct counter_data *ext;
+
+	/* Create main Signal attribute */
+	data = counter_signal_data;
+	data.read = signal_read;
+	err = counter_attribute_create(group, &data, type, signal);
+	if (err)
+		return err;
+
+	/* Create Signal name attribute */
+	data = counter_name_data;
+	data.read = counter_signal_name_read;
+	err = counter_attribute_create(group, &data, type, signal);
+	if (err)
+		return err;
+
+	/* Create an attribute for each extension */
+	for (i = 0; i < signal->num_ext; i++) {
+		ext = signal->ext + i;
+		err = counter_attribute_create(group, ext, type, signal);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int counter_signals_register(
+	struct counter_attribute_group *const groups_list,
+	const struct counter_device *const counter)
+{
+	void *const signal_read = counter->signal_read;
+	size_t i;
+	struct counter_signal *signal;
+	const char *name;
+	int err;
+
+	/* Register each Signal */
+	for (i = 0; i < counter->num_signals; i++) {
+		signal = counter->signals + i;
+
+		/* Generate Signal attribute directory name */
+		name = kasprintf(GFP_KERNEL, "signal%d", signal->id);
+		if (!name)
+			return -ENOMEM;
+		groups_list[i].attr_group.name = name;
+
+		/* Create all attributes associated with Signal */
+		err = counter_signal_attributes_create(groups_list + i, signal,
+						       signal_read);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+struct counter_synapse_name {
+	struct list_head l;
+	const char *name;
+};
+
+static int counter_synapses_register(
+	struct counter_attribute_group *const group,
+	struct counter_device *const counter, struct counter_count *const count)
+{
+	const enum counter_owner_type type = COUNTER_OWNER_TYPE_COUNT;
+	size_t i;
+	struct counter_synapse *synapse;
+	int id;
+	struct counter_synapse_name *name;
+	struct counter_data data;
+	int err;
+
+	/* Register each Synapse */
+	for (i = 0; i < count->num_synapses; i++) {
+		synapse = count->synapses + i;
+		id = synapse->signal->id;
+
+		/* Generate Synapse name list item */
+		name = kmalloc(sizeof(*name), GFP_KERNEL);
+		if (!name)
+			return -ENOMEM;
+		list_add(&name->l, &counter->synapse_names_list);
+
+		/* Generate Synapse action name */
+		name->name = kasprintf(GFP_KERNEL, "signal%d_action", id);
+		if (!name->name)
+			return -ENOMEM;
+
+		/* Create action attribute */
+		data.type = COUNTER_DATA_TYPE_SYNAPSE_ACTION;
+		data.name = name->name;
+		data.read = counter->action_read;
+		data.write = counter->action_write;
+		data.priv = synapse;
+		err = counter_attribute_create(group, &data, type, count);
+		if (err)
+			return err;
+
+		/* Generate Synapse action_available name */
+		name->name = kasprintf(GFP_KERNEL, "signal%d_action_available",
+				       id);
+		if (!name->name)
+			return -ENOMEM;
+
+		/* Create action_available attribute */
+		data.type = COUNTER_DATA_TYPE_SYNAPSE_ACTION_AVAILABLE;
+		data.name = name->name;
+		data.read = counter->action_read;
+		data.priv = synapse;
+		err = counter_attribute_create(group, &data, type, count);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static struct counter_data counter_count_data =
+	COUNTER_DATA_UNSIGNED_LONG("count", NULL, NULL);
+
+static ssize_t counter_count_name_read(struct counter_device *counter,
+				       struct counter_count *count, char *buf,
+				       size_t size)
+{
+	return snprintf(buf, size, "%s\n", count->name);
+}
+
+static struct counter_data counter_count_function_data = {
+	.type = COUNTER_DATA_TYPE_COUNT_FUNCTION,
+	.name = "function",
+};
+
+static struct counter_data counter_count_function_available_data = {
+	.type = COUNTER_DATA_TYPE_COUNT_FUNCTION_AVAILABLE,
+	.name = "function_available",
+};
+
+static int counter_count_attributes_create(
+	struct counter_attribute_group *const group,
+	const struct counter_device *const counter,
+	struct counter_count *const count)
+{
+	const enum counter_owner_type type = COUNTER_OWNER_TYPE_COUNT;
+	int err;
+	struct counter_data data;
+	size_t i;
+	const struct counter_data *ext;
+
+	/* Create main Count attribute */
+	data = counter_count_data;
+	data.read = counter->count_read;
+	data.write = counter->count_write;
+	err = counter_attribute_create(group, &data, type, count);
+	if (err)
+		return err;
+
+	/* Create Count name attribute */
+	data = counter_name_data;
+	data.read = counter_count_name_read;
+	err = counter_attribute_create(group, &data, type, count);
+	if (err)
+		return err;
+
+	/* Create Count function attribute */
+	data = counter_count_function_data;
+	data.read = counter->function_read;
+	data.write = counter->function_write;
+	err = counter_attribute_create(group, &data, type, count);
+	if (err)
+		return err;
+
+	/* Create Count function_available attribute */
+	data = counter_count_function_available_data;
+	data.read = counter->function_read;
+	err = counter_attribute_create(group, &data, type, count);
+	if (err)
+		return err;
+
+	/* Create an attribute for each extension */
+	for (i = 0; i < count->num_ext; i++) {
+		ext = count->ext + i;
+		err = counter_attribute_create(group, ext, type, count);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int counter_counts_register(
+	struct counter_attribute_group *const groups_list,
+	struct counter_device *const counter)
+{
+	size_t i;
+	struct counter_count *count;
+	const char *name;
+	int err;
+
+	/* Register each Count */
+	for (i = 0; i < counter->num_counts; i++) {
+		count = counter->counts + i;
+
+		/* Generate Count attribute directory name */
+		name = kasprintf(GFP_KERNEL, "count%d", count->id);
+		if (!name)
+			return -ENOMEM;
+		groups_list[i].attr_group.name = name;
+
+		/* Register the Synapses associated with each Count */
+		err = counter_synapses_register(groups_list + i, counter,
+						count);
+		if (err)
+			return err;
+
+		/* Create all attributes associated with Count */
+		err = counter_count_attributes_create(groups_list + i, counter,
+						      count);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static ssize_t counter_name_read(struct counter_device *counter, char *buf,
+				 size_t size)
+{
+	return snprintf(buf, size, "%s\n", counter->name);
+}
+
+static int counter_num_signals_read(struct counter_device *counter, size_t *val)
+{
+	*val = counter->num_signals;
+	return 0;
+}
+
+static int counter_num_counts_read(struct counter_device *counter, size_t *val)
+{
+	*val = counter->num_counts;
+	return 0;
+}
+
+#define COUNTER_DATA_SIZE(_name, _read) \
+{ \
+	.type = COUNTER_DATA_TYPE_SIZE, \
+	.name = (_name), \
+	.read = (_read), \
+}
+
+static struct counter_data counter_num_signals_data =
+	COUNTER_DATA_SIZE("num_signals", counter_num_signals_read);
+
+static struct counter_data counter_num_counts_data =
+	COUNTER_DATA_SIZE("num_counts", counter_num_counts_read);
+
+static void counter_groups_list_free(struct counter_device *const counter)
+{
+	struct counter_attribute_group *group;
+	struct counter_attribute *p, *n;
+
+	/* Loop through all attribute groups (signals, counts, device, etc.) */
+	while (counter->num_groups--) {
+		group = counter->groups_list + counter->num_groups;
+
+		/* Free all attribute group and associated attributes memory */
+		kfree(group->attr_group.name);
+		kfree(group->attr_group.attrs);
+
+		/* Free attribute list */
+		list_for_each_entry_safe(p, n, &group->attr_list, l)
+			kfree(p);
+	}
+
+	kfree(counter->groups_list);
+}
+
+static int counter_device_register(struct counter_attribute_group *group,
+				   struct counter_device *const counter)
+{
+	const enum counter_owner_type type = COUNTER_OWNER_TYPE_DEVICE;
+	struct counter_data data;
+	int err;
+	size_t i;
+	const struct counter_data *ext;
+
+	/* Register Signals */
+	err = counter_signals_register(group, counter);
+	if (err)
+		goto err_free_groups_list;
+	group += counter->num_signals;
+
+	/* Register Counts and respective Synapses */
+	err = counter_counts_register(group, counter);
+	if (err)
+		goto err_free_groups_list;
+	group += counter->num_counts;
+
+	/* Create name attribute */
+	data = counter_name_data;
+	data.read = counter_name_read;
+	err = counter_attribute_create(group, &data, type, NULL);
+	if (err)
+		goto err_free_groups_list;
+
+	/* Create num_signals attribute */
+	data = counter_num_signals_data;
+	err = counter_attribute_create(group, &data, type, NULL);
+	if (err)
+		goto err_free_groups_list;
+
+	/* Create num_counts attribute */
+	data = counter_num_counts_data;
+	err = counter_attribute_create(group, &data, type, NULL);
+	if (err)
+		goto err_free_groups_list;
+
+	/* Create an attribute for each extension */
+	for (i = 0; i < counter->num_ext; i++) {
+		ext = counter->ext + i;
+		err = counter_attribute_create(group, ext, type, NULL);
+		if (err)
+			goto err_free_groups_list;
+	}
+
+	return 0;
+
+err_free_groups_list:
+	counter_groups_list_free(counter);
+	return err;
+}
+
+static int counter_groups_list_prepare(struct counter_device *const counter)
+{
+	const size_t num_grps = counter->num_signals + counter->num_counts + 1;
+	struct counter_attribute_group *groups_list;
+	size_t i;
+	int err;
+
+	/* Allocate space for attribute groups (signals, counts, and ext) */
+	groups_list = kcalloc(num_grps, sizeof(*groups_list), GFP_KERNEL);
+	if (!groups_list)
+		return -ENOMEM;
+
+	/* Store groups_list in counter structure */
+	counter->groups_list = groups_list;

drivers/counter/counter-sysfs.c new file +91 -0

+
+	return 0;
+}
+
+static int counter_groups_prepare(struct counter_device *const counter)
+{
+	size_t i, j;
+	struct counter_attribute_group *group;
+	struct attribute **attrs;
+	int err;
+	struct counter_attribute *p;
+
+	/* Allocate attribute groups for association with device */
+	counter->groups = kcalloc(counter->num_groups + 1,
+				  sizeof(*counter->groups), GFP_KERNEL);
+	if (!counter->groups)
+		return -ENOMEM;
+
+	/* Prepare each group of attributes for association */
+	for (i = 0; i < counter->num_groups; i++) {
+		group = counter->groups_list + i;
+
+		/* Allocate space for attribute pointers */
+		attrs = kcalloc(group->num_attr + 1, sizeof(*attrs),
+				GFP_KERNEL);
+		if (!attrs) {
+			err = -ENOMEM;
+			goto err_free_groups;
+		}
+		group->attr_group.attrs = attrs;
+
+		/* Add attribute pointers to attribute group */
+		j = 0;
+		list_for_each_entry(p, &group->attr_list, l)
+			attrs[j++] = &p->dev_attr.attr;
+
+		/* Group attributes in attribute group */
+		counter->groups[i] = &group->attr_group;
+	}
+	/* Associate attributes with device */
+	counter->dev.groups = counter->groups;
+
+	return 0;
+
+err_free_groups:
+	kfree(counter->groups);
+	return err;
+}
+
+static void counter_synapse_names_free(struct list_head *const names_list)
+{
+	struct counter_synapse_name *p, *n;
+
+	list_for_each_entry_safe(p, n, names_list, l) {
+		kfree(p->name);
+		kfree(p);
+	}
+}
+
+int counter_sysfs_add(struct counter_device *const counter)
+{
+	int err;
+
+	/* Initialize Synapse names list */
+	INIT_LIST_HEAD(&counter->synapse_names_list);
+
+	/* Prepare device attributes */
+	err = counter_groups_list_prepare(counter);
+	if (err)
+		goto err_free_synapse_names;
+
+	/* Organize device attributes to groups and match to device */
+	err = counter_groups_prepare(counter);
+	if (err)
+		goto err_free_groups_list;
+
+	return 0;
+
+err_free_groups_list:
+	counter_groups_list_free(counter);
+err_free_synapse_names:
+	counter_synapse_names_free(&counter->synapse_names_list);
+	return err;
+}
+
+void counter_sysfs_free(struct counter_device *const counter)
+{
+	kfree(counter->groups);
+	counter_groups_list_free(counter);
+	counter_synapse_names_free(&counter->synapse_names_list);
+}

drivers/counter/counter-sysfs.h new file +14 -0

new file mode 100644
index 000000000000..00e7cd6ea083
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Counter sysfs interface
+ * Copyright (C) 2020 William Breathitt Gray
+ */
+#ifndef _COUNTER_SYSFS_H_
+#define _COUNTER_SYSFS_H_
+
+#include <linux/counter.h>
+
+int counter_sysfs_add(struct counter_device *const counter);
+void counter_sysfs_free(struct counter_device *const counter);
+
+#endif /* _COUNTER_SYSFS_H_ */

drivers/counter/counter.c deleted +0 -1496

deleted file mode 100644
index 6a683d086008..000000000000
@@ -1,1496 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Generic Counter interface
- * Copyright (C) 2018 William Breathitt Gray
- */
-#include <linux/counter.h>
-#include <linux/device.h>
-#include <linux/err.h>
-#include <linux/export.h>
-#include <linux/fs.h>
-#include <linux/gfp.h>
-#include <linux/idr.h>
-#include <linux/init.h>
-#include <linux/kernel.h>
-#include <linux/list.h>
-#include <linux/module.h>
-#include <linux/printk.h>
-#include <linux/slab.h>
-#include <linux/string.h>
-#include <linux/sysfs.h>
-#include <linux/types.h>
-
-const char *const counter_count_direction_str[2] = {
-	[COUNTER_COUNT_DIRECTION_FORWARD] = "forward",
-	[COUNTER_COUNT_DIRECTION_BACKWARD] = "backward"
-};
-EXPORT_SYMBOL_GPL(counter_count_direction_str);
-
-const char *const counter_count_mode_str[4] = {
-	[COUNTER_COUNT_MODE_NORMAL] = "normal",
-	[COUNTER_COUNT_MODE_RANGE_LIMIT] = "range limit",
-	[COUNTER_COUNT_MODE_NON_RECYCLE] = "non-recycle",
-	[COUNTER_COUNT_MODE_MODULO_N] = "modulo-n"
-};
-EXPORT_SYMBOL_GPL(counter_count_mode_str);
-
-ssize_t counter_signal_enum_read(struct counter_device *counter,
-				 struct counter_signal *signal, void *priv,
-				 char *buf)
-{
-	const struct counter_signal_enum_ext *const e = priv;
-	int err;
-	size_t index;
-
-	if (!e->get)
-		return -EINVAL;
-
-	err = e->get(counter, signal, &index);
-	if (err)
-		return err;
-
-	if (index >= e->num_items)
-		return -EINVAL;
-
-	return sprintf(buf, "%s\n", e->items[index]);
-}
-EXPORT_SYMBOL_GPL(counter_signal_enum_read);
-
-ssize_t counter_signal_enum_write(struct counter_device *counter,
-				  struct counter_signal *signal, void *priv,
-				  const char *buf, size_t len)
-{
-	const struct counter_signal_enum_ext *const e = priv;
-	ssize_t index;
-	int err;
-
-	if (!e->set)
-		return -EINVAL;
-
-	index = __sysfs_match_string(e->items, e->num_items, buf);
-	if (index < 0)
-		return index;
-
-	err = e->set(counter, signal, index);
-	if (err)
-		return err;
-
-	return len;
-}
-EXPORT_SYMBOL_GPL(counter_signal_enum_write);
-
-ssize_t counter_signal_enum_available_read(struct counter_device *counter,
-					   struct counter_signal *signal,
-					   void *priv, char *buf)
-{
-	const struct counter_signal_enum_ext *const e = priv;
-	size_t i;
-	size_t len = 0;
-
-	if (!e->num_items)
-		return 0;
-
-	for (i = 0; i < e->num_items; i++)
-		len += sprintf(buf + len, "%s\n", e->items[i]);
-
-	return len;
-}
-EXPORT_SYMBOL_GPL(counter_signal_enum_available_read);
-
-ssize_t counter_count_enum_read(struct counter_device *counter,
-				struct counter_count *count, void *priv,
-				char *buf)
-{
-	const struct counter_count_enum_ext *const e = priv;
-	int err;
-	size_t index;
-
-	if (!e->get)
-		return -EINVAL;
-
-	err = e->get(counter, count, &index);
-	if (err)
-		return err;
-
-	if (index >= e->num_items)
-		return -EINVAL;
-
-	return sprintf(buf, "%s\n", e->items[index]);
-}
-EXPORT_SYMBOL_GPL(counter_count_enum_read);
-
-ssize_t counter_count_enum_write(struct counter_device *counter,
-				 struct counter_count *count, void *priv,
-				 const char *buf, size_t len)
-{
-	const struct counter_count_enum_ext *const e = priv;
-	ssize_t index;
-	int err;
-
-	if (!e->set)
-		return -EINVAL;
-
-	index = __sysfs_match_string(e->items, e->num_items, buf);
-	if (index < 0)
-		return index;
-
-	err = e->set(counter, count, index);
-	if (err)
-		return err;
-
-	return len;
-}
-EXPORT_SYMBOL_GPL(counter_count_enum_write);
-
-ssize_t counter_count_enum_available_read(struct counter_device *counter,
-					  struct counter_count *count,
-					  void *priv, char *buf)
-{
-	const struct counter_count_enum_ext *const e = priv;
-	size_t i;
-	size_t len = 0;
-
-	if (!e->num_items)
-		return 0;
-
-	for (i = 0; i < e->num_items; i++)
-		len += sprintf(buf + len, "%s\n", e->items[i]);
-
-	return len;
-}
-EXPORT_SYMBOL_GPL(counter_count_enum_available_read);
-
-ssize_t counter_device_enum_read(struct counter_device *counter, void *priv,
-				 char *buf)
-{
-	const struct counter_device_enum_ext *const e = priv;
-	int err;
-	size_t index;
-
-	if (!e->get)
-		return -EINVAL;
-
-	err = e->get(counter, &index);
-	if (err)
-		return err;
-
-	if (index >= e->num_items)
-		return -EINVAL;
-
-	return sprintf(buf, "%s\n", e->items[index]);
-}
-EXPORT_SYMBOL_GPL(counter_device_enum_read);
-
-ssize_t counter_device_enum_write(struct counter_device *counter, void *priv,
-				  const char *buf, size_t len)
-{
-	const struct counter_device_enum_ext *const e = priv;
-	ssize_t index;
-	int err;
-
-	if (!e->set)
-		return -EINVAL;
-
-	index = __sysfs_match_string(e->items, e->num_items, buf);
-	if (index < 0)
-		return index;
-
-	err = e->set(counter, index);
-	if (err)
-		return err;
-
-	return len;
-}
-EXPORT_SYMBOL_GPL(counter_device_enum_write);
-
-ssize_t counter_device_enum_available_read(struct counter_device *counter,
-					   void *priv, char *buf)
-{
-	const struct counter_device_enum_ext *const e = priv;
-	size_t i;
-	size_t len = 0;
-
-	if (!e->num_items)
-		return 0;
-
-	for (i = 0; i < e->num_items; i++)
-		len += sprintf(buf + len, "%s\n", e->items[i]);
-
-	return len;
-}
-EXPORT_SYMBOL_GPL(counter_device_enum_available_read);
-
-struct counter_attr_parm {
-	struct counter_device_attr_group *group;
-	const char *prefix;
-	const char *name;
-	ssize_t (*show)(struct device *dev, struct device_attribute *attr,
-			char *buf);
-	ssize_t (*store)(struct device *dev, struct device_attribute *attr,
-			 const char *buf, size_t len);
-	void *component;
-};
-
-struct counter_device_attr {
-	struct device_attribute dev_attr;
-	struct list_head l;
-	void *component;
-};
-
-static int counter_attribute_create(const struct counter_attr_parm *const parm)
-{
-	struct counter_device_attr *counter_attr;
-	struct device_attribute *dev_attr;
-	int err;
-	struct list_head *const attr_list = &parm->group->attr_list;
-
-	/* Allocate a Counter device attribute */
-	counter_attr = kzalloc(sizeof(*counter_attr), GFP_KERNEL);
-	if (!counter_attr)
-		return -ENOMEM;
-	dev_attr = &counter_attr->dev_attr;
-
-	sysfs_attr_init(&dev_attr->attr);
-
-	/* Configure device attribute */
-	dev_attr->attr.name = kasprintf(GFP_KERNEL, "%s%s", parm->prefix,
-					parm->name);
-	if (!dev_attr->attr.name) {
-		err = -ENOMEM;
-		goto err_free_counter_attr;
-	}
-	if (parm->show) {
-		dev_attr->attr.mode |= 0444;
-		dev_attr->show = parm->show;
-	}
-	if (parm->store) {
-		dev_attr->attr.mode |= 0200;
-		dev_attr->store = parm->store;
-	}
-
-	/* Store associated Counter component with attribute */
-	counter_attr->component = parm->component;
-
-	/* Keep track of the attribute for later cleanup */
-	list_add(&counter_attr->l, attr_list);
-	parm->group->num_attr++;
-
-	return 0;
-
-err_free_counter_attr:
-	kfree(counter_attr);
-	return err;
-}
-
-#define to_counter_attr(_dev_attr) \
-	container_of(_dev_attr, struct counter_device_attr, dev_attr)
-
-struct counter_signal_unit {
-	struct counter_signal *signal;
-};
-
-static const char *const counter_signal_value_str[] = {
-	[COUNTER_SIGNAL_LOW] = "low",
-	[COUNTER_SIGNAL_HIGH] = "high"
-};
-
-static ssize_t counter_signal_show(struct device *dev,
-				   struct device_attribute *attr, char *buf)
-{
-	struct counter_device *const counter = dev_get_drvdata(dev);
-	const struct counter_device_attr *const devattr = to_counter_attr(attr);
-	const struct counter_signal_unit *const component = devattr->component;
-	struct counter_signal *const signal = component->signal;
-	int err;
-	enum counter_signal_value val;
-
-	err = counter->ops->signal_read(counter, signal, &val);
-	if (err)
-		return err;
-
-	return sprintf(buf, "%s\n", counter_signal_value_str[val]);
-}
-
-struct counter_name_unit {
-	const char *name;
-};
-
-static ssize_t counter_device_attr_name_show(struct device *dev,
-					     struct device_attribute *attr,
-					     char *buf)
-{
-	const struct counter_name_unit *const comp = to_counter_attr(attr)->component;
-
-	return sprintf(buf, "%s\n", comp->name);
-}
-
-static int counter_name_attribute_create(
-	struct counter_device_attr_group *const group,
-	const char *const name)
-{
-	struct counter_name_unit *name_comp;
-	struct counter_attr_parm parm;
-	int err;
-
-	/* Skip if no name */
-	if (!name)
-		return 0;
-
-	/* Allocate name attribute component */
-	name_comp = kmalloc(sizeof(*name_comp), GFP_KERNEL);
-	if (!name_comp)
-		return -ENOMEM;
-	name_comp->name = name;
-
-	/* Allocate Signal name attribute */
-	parm.group = group;
-	parm.prefix = "";
-	parm.name = "name";
-	parm.show = counter_device_attr_name_show;
-	parm.store = NULL;
-	parm.component = name_comp;
-	err = counter_attribute_create(&parm);
-	if (err)
-		goto err_free_name_comp;
-
-	return 0;
-
-err_free_name_comp:
-	kfree(name_comp);
-	return err;
-}
-
-struct counter_signal_ext_unit {
-	struct counter_signal *signal;
-	const struct counter_signal_ext *ext;
-};
-
-static ssize_t counter_signal_ext_show(struct device *dev,
-				       struct device_attribute *attr, char *buf)
-{
-	const struct counter_device_attr *const devattr = to_counter_attr(attr);
-	const struct counter_signal_ext_unit *const comp = devattr->component;
-	const struct counter_signal_ext *const ext = comp->ext;
-
-	return ext->read(dev_get_drvdata(dev), comp->signal, ext->priv, buf);
-}
-
-static ssize_t counter_signal_ext_store(struct device *dev,
-					struct device_attribute *attr,
-					const char *buf, size_t len)
-{
-	const struct counter_device_attr *const devattr = to_counter_attr(attr);
-	const struct counter_signal_ext_unit *const comp = devattr->component;
-	const struct counter_signal_ext *const ext = comp->ext;
-
-	return ext->write(dev_get_drvdata(dev), comp->signal, ext->priv, buf,
-		len);
-}
-
-static void counter_device_attr_list_free(struct list_head *attr_list)
-{
-	struct counter_device_attr *p, *n;
-
-	list_for_each_entry_safe(p, n, attr_list, l) {
-		/* free attribute name and associated component memory */
-		kfree(p->dev_attr.attr.name);
-		kfree(p->component);
-		list_del(&p->l);
-		kfree(p);
-	}
-}
-
-static int counter_signal_ext_register(
-	struct counter_device_attr_group *const group,
-	struct counter_signal *const signal)
-{
-	const size_t num_ext = signal->num_ext;
-	size_t i;
-	const struct counter_signal_ext *ext;
-	struct counter_signal_ext_unit *signal_ext_comp;
-	struct counter_attr_parm parm;
-	int err;
-
-	/* Create an attribute for each extension */
-	for (i = 0 ; i < num_ext; i++) {
-		ext = signal->ext + i;
-
-		/* Allocate signal_ext attribute component */
-		signal_ext_comp = kmalloc(sizeof(*signal_ext_comp), GFP_KERNEL);
-		if (!signal_ext_comp) {
-			err = -ENOMEM;
-			goto err_free_attr_list;
-		}
-		signal_ext_comp->signal = signal;
-		signal_ext_comp->ext = ext;
-
-		/* Allocate a Counter device attribute */
-		parm.group = group;
-		parm.prefix = "";
-		parm.name = ext->name;
-		parm.show = (ext->read) ? counter_signal_ext_show : NULL;
-		parm.store = (ext->write) ? counter_signal_ext_store : NULL;
-		parm.component = signal_ext_comp;
-		err = counter_attribute_create(&parm);
-		if (err) {
-			kfree(signal_ext_comp);
-			goto err_free_attr_list;
-		}
-	}
-
-	return 0;
-
-err_free_attr_list:
-	counter_device_attr_list_free(&group->attr_list);
-	return err;
-}
-
-static int counter_signal_attributes_create(
-	struct counter_device_attr_group *const group,
-	const struct counter_device *const counter,
-	struct counter_signal *const signal)
-{
-	struct counter_signal_unit *signal_comp;
-	struct counter_attr_parm parm;
-	int err;
-
-	/* Allocate Signal attribute component */
-	signal_comp = kmalloc(sizeof(*signal_comp), GFP_KERNEL);
-	if (!signal_comp)
-		return -ENOMEM;
-	signal_comp->signal = signal;
-
-	/* Create main Signal attribute */
-	parm.group = group;
-	parm.prefix = "";
-	parm.name = "signal";
-	parm.show = (counter->ops->signal_read) ? counter_signal_show : NULL;
-	parm.store = NULL;
-	parm.component = signal_comp;
-	err = counter_attribute_create(&parm);
-	if (err) {
-		kfree(signal_comp);
-		return err;
-	}
-
-	/* Create Signal name attribute */
-	err = counter_name_attribute_create(group, signal->name);
-	if (err)
-		goto err_free_attr_list;
-
-	/* Register Signal extension attributes */
-	err = counter_signal_ext_register(group, signal);
-	if (err)
-		goto err_free_attr_list;
-
-	return 0;
-
-err_free_attr_list:
-	counter_device_attr_list_free(&group->attr_list);
-	return err;
-}
-
-static int counter_signals_register(
-	struct counter_device_attr_group *const groups_list,
-	const struct counter_device *const counter)
-{
-	const size_t num_signals = counter->num_signals;
-	size_t i;
-	struct counter_signal *signal;
-	const char *name;
-	int err;
-
-	/* Register each Signal */
-	for (i = 0; i < num_signals; i++) {
-		signal = counter->signals + i;
-
-		/* Generate Signal attribute directory name */
-		name = kasprintf(GFP_KERNEL, "signal%d", signal->id);
-		if (!name) {
-			err = -ENOMEM;
-			goto err_free_attr_groups;
-		}
-		groups_list[i].attr_group.name = name;
-
-		/* Create all attributes associated with Signal */
-		err = counter_signal_attributes_create(groups_list + i, counter,
-						       signal);
-		if (err)
-			goto err_free_attr_groups;
-	}
-
-	return 0;
-
-err_free_attr_groups:
-	do {
-		kfree(groups_list[i].attr_group.name);
-		counter_device_attr_list_free(&groups_list[i].attr_list);
-	} while (i--);
-	return err;
-}
-
-static const char *const counter_synapse_action_str[] = {
-	[COUNTER_SYNAPSE_ACTION_NONE] = "none",
-	[COUNTER_SYNAPSE_ACTION_RISING_EDGE] = "rising edge",
-	[COUNTER_SYNAPSE_ACTION_FALLING_EDGE] = "falling edge",
-	[COUNTER_SYNAPSE_ACTION_BOTH_EDGES] = "both edges"
-};
-
-struct counter_action_unit {
-	struct counter_synapse *synapse;
-	struct counter_count *count;
-};
-
-static ssize_t counter_action_show(struct device *dev,
-				   struct device_attribute *attr, char *buf)
-{
-	const struct counter_device_attr *const devattr = to_counter_attr(attr);
-	int err;
-	struct counter_device *const counter = dev_get_drvdata(dev);
-	const struct counter_action_unit *const component = devattr->component;
-	struct counter_count *const count = component->count;
-	struct counter_synapse *const synapse = component->synapse;
-	size_t action_index;
-	enum counter_synapse_action action;
-
-	err = counter->ops->action_get(counter, count, synapse, &action_index);
-	if (err)
-		return err;
-
-	synapse->action = action_index;
-
-	action = synapse->actions_list[action_index];
-	return sprintf(buf, "%s\n", counter_synapse_action_str[action]);
-}
-
-static ssize_t counter_action_store(struct device *dev,
-				    struct device_attribute *attr,
-				    const char *buf, size_t len)
-{
-	const struct counter_device_attr *const devattr = to_counter_attr(attr);
-	const struct counter_action_unit *const component = devattr->component;
-	struct counter_synapse *const synapse = component->synapse;
-	size_t action_index;
-	const size_t num_actions = synapse->num_actions;
-	enum counter_synapse_action action;
-	int err;
-	struct counter_device *const counter = dev_get_drvdata(dev);
-	struct counter_count *const count = component->count;
-
-	/* Find requested action mode */
-	for (action_index = 0; action_index < num_actions; action_index++) {
-		action = synapse->actions_list[action_index];
-		if (sysfs_streq(buf, counter_synapse_action_str[action]))
-			break;
-	}
-	/* If requested action mode not found */
-	if (action_index >= num_actions)
-		return -EINVAL;
-
-	err = counter->ops->action_set(counter, count, synapse, action_index);
-	if (err)
-		return err;
-
-	synapse->action = action_index;
-
-	return len;
-}
-
-struct counter_action_avail_unit {
-	const enum counter_synapse_action *actions_list;
-	size_t num_actions;
-};
-
-static ssize_t counter_synapse_action_available_show(struct device *dev,
-	struct device_attribute *attr, char *buf)
-{
-	const struct counter_device_attr *const devattr = to_counter_attr(attr);
-	const struct counter_action_avail_unit *const component = devattr->component;
-	size_t i;
-	enum counter_synapse_action action;
-	ssize_t len = 0;
-
-	for (i = 0; i < component->num_actions; i++) {
-		action = component->actions_list[i];
-		len += sprintf(buf + len, "%s\n",
-			       counter_synapse_action_str[action]);
-	}
-
-	return len;
-}
-
-static int counter_synapses_register(
-	struct counter_device_attr_group *const group,
-	const struct counter_device *const counter,
-	struct counter_count *const count, const char *const count_attr_name)
-{
-	size_t i;
-	struct counter_synapse *synapse;
-	const char *prefix;
-	struct counter_action_unit *action_comp;
-	struct counter_attr_parm parm;
-	int err;
-	struct counter_action_avail_unit *avail_comp;
-
-	/* Register each Synapse */
-	for (i = 0; i < count->num_synapses; i++) {
-		synapse = count->synapses + i;
-
-		/* Generate attribute prefix */
-		prefix = kasprintf(GFP_KERNEL, "signal%d_",
-				   synapse->signal->id);
-		if (!prefix) {
-			err = -ENOMEM;
-			goto err_free_attr_list;
-		}
-
-		/* Allocate action attribute component */
-		action_comp = kmalloc(sizeof(*action_comp), GFP_KERNEL);
-		if (!action_comp) {
-			err = -ENOMEM;
-			goto err_free_prefix;
-		}
-		action_comp->synapse = synapse;
-		action_comp->count = count;
-
-		/* Create action attribute */
-		parm.group = group;
-		parm.prefix = prefix;
-		parm.name = "action";
-		parm.show = (counter->ops->action_get) ? counter_action_show : NULL;
-		parm.store = (counter->ops->action_set) ? counter_action_store : NULL;
-		parm.component = action_comp;
-		err = counter_attribute_create(&parm);
-		if (err) {
-			kfree(action_comp);
-			goto err_free_prefix;
-		}
-
-		/* Allocate action available attribute component */
-		avail_comp = kmalloc(sizeof(*avail_comp), GFP_KERNEL);
-		if (!avail_comp) {
-			err = -ENOMEM;
-			goto err_free_prefix;
-		}
-		avail_comp->actions_list = synapse->actions_list;
-		avail_comp->num_actions = synapse->num_actions;
-
-		/* Create action_available attribute */
-		parm.group = group;
-		parm.prefix = prefix;
-		parm.name = "action_available";
-		parm.show = counter_synapse_action_available_show;
-		parm.store = NULL;
-		parm.component = avail_comp;
-		err = counter_attribute_create(&parm);
-		if (err) {
-			kfree(avail_comp);
-			goto err_free_prefix;
-		}
-
-		kfree(prefix);
-	}
-
-	return 0;
-
-err_free_prefix:
-	kfree(prefix);
-err_free_attr_list:
-	counter_device_attr_list_free(&group->attr_list);
-	return err;
-}
-
-struct counter_count_unit {
-	struct counter_count *count;
-};
-
-static ssize_t counter_count_show(struct device *dev,
-				  struct device_attribute *attr,
-				  char *buf)
-{
-	struct counter_device *const counter = dev_get_drvdata(dev);
-	const struct counter_device_attr *const devattr = to_counter_attr(attr);
-	const struct counter_count_unit *const component = devattr->component;
-	struct counter_count *const count = component->count;
-	int err;
-	unsigned long val;
-
-	err = counter->ops->count_read(counter, count, &val);
-	if (err)
-		return err;
-
-	return sprintf(buf, "%lu\n", val);
-}
-
-static ssize_t counter_count_store(struct device *dev,
-				   struct device_attribute *attr,
-				   const char *buf, size_t len)
-{
-	struct counter_device *const counter = dev_get_drvdata(dev);
-	const struct counter_device_attr *const devattr = to_counter_attr(attr);
-	const struct counter_count_unit *const component = devattr->component;
-	struct counter_count *const count = component->count;
-	int err;
-	unsigned long val;
-
-	err = kstrtoul(buf, 0, &val);
-	if (err)
-		return err;
-
-	err = counter->ops->count_write(counter, count, val);
-	if (err)
-		return err;
-
-	return len;
-}
-
-static const char *const counter_count_function_str[] = {
-	[COUNTER_COUNT_FUNCTION_INCREASE] = "increase",
-	[COUNTER_COUNT_FUNCTION_DECREASE] = "decrease",
-	[COUNTER_COUNT_FUNCTION_PULSE_DIRECTION] = "pulse-direction",
-	[COUNTER_COUNT_FUNCTION_QUADRATURE_X1_A] = "quadrature x1 a",
-	[COUNTER_COUNT_FUNCTION_QUADRATURE_X1_B] = "quadrature x1 b",
-	[COUNTER_COUNT_FUNCTION_QUADRATURE_X2_A] = "quadrature x2 a",
-	[COUNTER_COUNT_FUNCTION_QUADRATURE_X2_B] = "quadrature x2 b",
-	[COUNTER_COUNT_FUNCTION_QUADRATURE_X4] = "quadrature x4"
-};
-
-static ssize_t counter_function_show(struct device *dev,
-				     struct device_attribute *attr, char *buf)
-{
-	int err;
-	struct counter_device *const counter = dev_get_drvdata(dev);
-	const struct counter_device_attr *const devattr = to_counter_attr(attr);
-	const struct counter_count_unit *const component = devattr->component;
-	struct counter_count *const count = component->count;
-	size_t func_index;
-	enum counter_count_function function;
-
-	err = counter->ops->function_get(counter, count, &func_index);
-	if (err)
-		return err;
-
-	count->function = func_index;
-
-	function = count->functions_list[func_index];
-	return sprintf(buf, "%s\n", counter_count_function_str[function]);
-}
-
-static ssize_t counter_function_store(struct device *dev,
-				      struct device_attribute *attr,
-				      const char *buf, size_t len)
-{
-	const struct counter_device_attr *const devattr = to_counter_attr(attr);
-	const struct counter_count_unit *const component = devattr->component;
-	struct counter_count *const count = component->count;
-	const size_t num_functions = count->num_functions;
-	size_t func_index;
-	enum counter_count_function function;
-	int err;
-	struct counter_device *const counter = dev_get_drvdata(dev);
-
-	/* Find requested Count function mode */
-	for (func_index = 0; func_index < num_functions; func_index++) {
-		function = count->functions_list[func_index];
-		if (sysfs_streq(buf, counter_count_function_str[function]))
-			break;
-	}
-	/* Return error if requested Count function mode not found */
-	if (func_index >= num_functions)
-		return -EINVAL;
-
-	err = counter->ops->function_set(counter, count, func_index);
-	if (err)
-		return err;
-
[… more lines in the raw message]

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drivers/counter/ftm-quaddec.c +17 -29

index c2b3fdfd8b77..450353f495a2 100644

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drivers/counter/stm32-lptimer-cnt.c +84 -75

index 8e276eb655f5..53ca88533831 100644

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drivers/counter/stm32-timer-cnt.c +51 -81

index ef2a974a2f10..09e87cf79ce9 100644

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drivers/counter/ti-eqep.c +70 -100

index 1ff07faef27f..b1fac22a0a4f 100644

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include/linux/counter.h +191 -354

index 9dbd5df4cd34..d628c7eaf754 100644

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include/linux/counter_enum.h deleted +0 -45

deleted file mode 100644
index 9f917298a88f..000000000000

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include/uapi/linux/counter-types.h new file +67 -0

new file mode 100644
index 000000000000..757256775949

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