gpiolib: add gpiod_get_array and gpiod_put_array functions

Introduce new functions for conveniently obtaining and disposing of an entire array of GPIOs with one function call.

Suggested-by Alexandre Courbot <[email protected]>

Signed-off-by Rojhalat Ibrahim <[email protected]>

---
Change log:
v3: - rebase on current linux-gpio devel branch
- fix ACPI GPIO counting
- allow for zero-sized arrays
- make the flags argument mandatory for the new functions
- clarify documentation
v2: change interface

 Documentation/gpio/consumer.txt |  33 +++++-
 drivers/gpio/gpiolib.c          | 231 ++++++++++++++++++++++++++++++++++++++++
 include/linux/gpio/consumer.h   |  46 ++++++++
 3 files changed, 307 insertions(+), 3 deletions(-)

Documentation/gpio/consumer.txt +2 -1

index d85fbae..85a7e30 100644
@@ -58,7 +58,6 @@ pattern where a GPIO is optional, the gpiod_get_optional() and
 gpiod_get_index_optional() functions can be used. These functions return NULL
 instead of -ENOENT if no GPIO has been assigned to the requested function:
 
-
        struct gpio_desc *gpiod_get_optional(struct device *dev,
                                             const char *con_id,
                                             enum gpiod_flags flags)

@@ -68,6 +67,27 @@ instead of -ENOENT if no GPIO has been assigned to the requested function:
                                                   unsigned int index,
                                                   enum gpiod_flags flags)
 
+For a function using multiple GPIOs all of those can be obtained with one call:
+

Documentation/gpio/consumer.txt +18 -2

+       }
+
+The following function returns NULL instead of -ENOENT if no GPIOs have been
+assigned to the requested function:
+
+       struct gpio_descs *gpiod_get_array_optional(struct device *dev,
+                                                   const char *con_id,
+                                                   enum gpiod_flags flags)
+
 Device-managed variants of these functions are also defined:
 
        struct gpio_desc *devm_gpiod_get(struct device *dev, const char *con_id,

@@ -91,8 +111,15 @@ A GPIO descriptor can be disposed of using the gpiod_put() function:
 
        void gpiod_put(struct gpio_desc *desc)
 
-It is strictly forbidden to use a descriptor after calling this function. The
-device-managed variant is, unsurprisingly:
+For an array of GPIOs this function can be used:
+
+       void gpiod_put_array(struct gpio_descs *descs)
+
+It is strictly forbidden to use a descriptor after calling these functions.
+It is also not allowed to individually release descriptors (using gpiod_put())
+from an array acquired with gpiod_get_array().
+
+The device-managed variant is, unsurprisingly:
 
        void devm_gpiod_put(struct device *dev, struct gpio_desc *desc)
 

drivers/gpio/gpiolib.c +89 -0

index ff2b80d..d4153e0 100644
@@ -1804,6 +1804,158 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
        return desc;
 }
 
+static int dt_gpio_count(struct device *dev, const char *con_id)
+{
+       int ret;
+       char propname[32];
+       unsigned int i;
+
+       for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
+               if (con_id)
+                       snprintf(propname, sizeof(propname), "%s-%s",
+                                con_id, gpio_suffixes[i]);
+               else
+                       snprintf(propname, sizeof(propname), "%s",
+                                gpio_suffixes[i]);
+
+               ret = of_gpio_named_count(dev->of_node, propname);
+               if (ret >= 0)
+                       break;
+       }
+       return ret;
+}
+
+#ifdef CONFIG_ACPI
+
+static unsigned int acpi_gpio_package_count(const union acpi_object *obj)
+{
+       const union acpi_object *element = obj->package.elements;
+       const union acpi_object *end = element + obj->package.count;
+       unsigned int count = 0;
+
+       while (element < end) {
+               if (element->type == ACPI_TYPE_LOCAL_REFERENCE)
+                       count++;
+
+               element++;
+       }
+       return count;
+}
+
+static int acpi_find_gpio_count(struct acpi_resource *ares, void *data)
+{
+       unsigned int *count = data;
+
+       if (ares->type == ACPI_RESOURCE_TYPE_GPIO)
+               *count += ares->data.gpio.pin_table_length;
+
+       return 1;
+}
+
+static int acpi_gpio_count(struct device *dev, const char *con_id)
+{
+       struct acpi_device *adev = ACPI_COMPANION(dev);
+       const union acpi_object *obj;
+       const struct acpi_gpio_mapping *gm;
+       int count = -ENOENT;
+       int ret;
+       char propname[32];
+       unsigned int i;
+
+       /* Try first from _DSD */
+       for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
+               if (con_id && strcmp(con_id, "gpios"))
+                       snprintf(propname, sizeof(propname), "%s-%s",
+                                con_id, gpio_suffixes[i]);
+               else
+                       snprintf(propname, sizeof(propname), "%s",
+                                gpio_suffixes[i]);
+
+               ret = acpi_dev_get_property(adev, propname, ACPI_TYPE_ANY,
+                                           &obj);
+               if (ret == 0) {
+                       if (obj->type == ACPI_TYPE_LOCAL_REFERENCE)
+                               count = 1;
+                       else if (obj->type == ACPI_TYPE_PACKAGE)
+                               count = acpi_gpio_package_count(obj);
+               } else if (adev->driver_gpios) {
+                       for (gm = adev->driver_gpios; gm->name; gm++)
+                               if (strcmp(propname, gm->name) == 0) {
+                                       count = gm->size;
+                                       break;
+                               }
+               }
+               if (count >= 0)
+                       break;
+       }
+
+       /* Then from plain _CRS GPIOs */
+       if (count < 0) {
+               struct list_head resource_list;
+               unsigned int crs_count = 0;

Introduce new functions for conveniently obtaining and disposing of an entire array of GPIOs with one function call.

Suggested-by Alexandre Courbot <[email protected]>

Signed-off-by Rojhalat Ibrahim <[email protected]>

---
Change log:
v3: - rebase on current linux-gpio devel branch
- fix ACPI GPIO counting
- allow for zero-sized arrays
- make the flags argument mandatory for the new functions
- clarify documentation
v2: change interface

 Documentation/gpio/consumer.txt |  33 +++++-
 drivers/gpio/gpiolib.c          | 231 ++++++++++++++++++++++++++++++++++++++++
 include/linux/gpio/consumer.h   |  46 ++++++++
 3 files changed, 307 insertions(+), 3 deletions(-)

Documentation/gpio/consumer.txt +30 -3

index d85fbae..85a7e30 100644
@@ -58,7 +58,6 @@ pattern where a GPIO is optional, the gpiod_get_optional() and
 gpiod_get_index_optional() functions can be used. These functions return NULL
 instead of -ENOENT if no GPIO has been assigned to the requested function:
 
-
 	struct gpio_desc *gpiod_get_optional(struct device *dev,
 					     const char *con_id,
 					     enum gpiod_flags flags)

@@ -68,6 +67,27 @@ instead of -ENOENT if no GPIO has been assigned to the requested function:
 						   unsigned int index,
 						   enum gpiod_flags flags)
 
+For a function using multiple GPIOs all of those can be obtained with one call:
+
+	struct gpio_descs *gpiod_get_array(struct device *dev,
+					   const char *con_id,
+					   enum gpiod_flags flags)
+
+This function returns a struct gpio_descs which contains an array of
+descriptors:
+
+	struct gpio_descs {
+		unsigned int array_size;
+		struct gpio_desc *desc_array[];
+	}
+
+The following function returns NULL instead of -ENOENT if no GPIOs have been
+assigned to the requested function:
+
+	struct gpio_descs *gpiod_get_array_optional(struct device *dev,
+						    const char *con_id,
+						    enum gpiod_flags flags)
+
 Device-managed variants of these functions are also defined:
 
 	struct gpio_desc *devm_gpiod_get(struct device *dev, const char *con_id,

@@ -91,8 +111,15 @@ A GPIO descriptor can be disposed of using the gpiod_put() function:
 
 	void gpiod_put(struct gpio_desc *desc)
 
-It is strictly forbidden to use a descriptor after calling this function. The
-device-managed variant is, unsurprisingly:
+For an array of GPIOs this function can be used:
+
+	void gpiod_put_array(struct gpio_descs *descs)
+
+It is strictly forbidden to use a descriptor after calling these functions.
+It is also not allowed to individually release descriptors (using gpiod_put())
+from an array acquired with gpiod_get_array().
+
+The device-managed variant is, unsurprisingly:
 
 	void devm_gpiod_put(struct device *dev, struct gpio_desc *desc)
 

drivers/gpio/gpiolib.c +41 -0

index ff2b80d..d4153e0 100644
@@ -1804,6 +1804,158 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
 	return desc;
 }
 
+static int dt_gpio_count(struct device *dev, const char *con_id)
+{
+	int ret;
+	char propname[32];
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
+		if (con_id)
+			snprintf(propname, sizeof(propname), "%s-%s",
+				 con_id, gpio_suffixes[i]);
+		else
+			snprintf(propname, sizeof(propname), "%s",
+				 gpio_suffixes[i]);
+
+		ret = of_gpio_named_count(dev->of_node, propname);
+		if (ret >= 0)
+			break;
+	}
+	return ret;
+}
+
+#ifdef CONFIG_ACPI
+
+static unsigned int acpi_gpio_package_count(const union acpi_object *obj)
+{
+	const union acpi_object *element = obj->package.elements;
+	const union acpi_object *end = element + obj->package.count;
+	unsigned int count = 0;
+
+	while (element < end) {
+		if (element->type == ACPI_TYPE_LOCAL_REFERENCE)
+			count++;
+
+		element++;
+	}
+	return count;
+}
+
+static int acpi_find_gpio_count(struct acpi_resource *ares, void *data)
+{
+	unsigned int *count = data;

drivers/gpio/gpiolib.c +26 -0

+		else
+			snprintf(propname, sizeof(propname), "%s",
+				 gpio_suffixes[i]);
+
+		ret = acpi_dev_get_property(adev, propname, ACPI_TYPE_ANY,
+					    &obj);
+		if (ret == 0) {
+			if (obj->type == ACPI_TYPE_LOCAL_REFERENCE)
+				count = 1;
+			else if (obj->type == ACPI_TYPE_PACKAGE)
+				count = acpi_gpio_package_count(obj);
+		} else if (adev->driver_gpios) {
+			for (gm = adev->driver_gpios; gm->name; gm++)
+				if (strcmp(propname, gm->name) == 0) {
+					count = gm->size;
+					break;
+				}
+		}
+		if (count >= 0)
+			break;
+	}
+
+	/* Then from plain _CRS GPIOs */
+	if (count < 0) {
+		struct list_head resource_list;
+		unsigned int crs_count = 0;

drivers/gpio/gpiolib.c +35 -0

+
+#else
+
+static int acpi_gpio_count(struct device *dev, const char *con_id)
+{
+	return -ENODEV;
+}
+
+#endif
+
+static int lut_gpio_count(struct device *dev, const char *con_id)
+{
+	struct gpiod_lookup_table *table;
+	struct gpiod_lookup *p;
+	unsigned int count = 0;
+
+	table = gpiod_find_lookup_table(dev);
+	if (!table)
+		return -ENOENT;
+
+	for (p = &table->table[0]; p->chip_label; p++) {
+		if ((con_id && p->con_id && !strcmp(con_id, p->con_id)) ||
+		    (!con_id && !p->con_id))
+			count++;
+	}
+	if (!count)
+		return -ENOENT;
+
+	return count;
+}
+
+/**
+ * gpiod_count - return the number of GPIOs associated with a device / function
+ *		or -ENOENT if no GPIO has been assigned to the requested function
+ * @dev:	GPIO consumer, can be NULL for system-global GPIOs

drivers/gpio/gpiolib.c +23 -0

+
+	if (count < 0)
+		count = lut_gpio_count(dev, con_id);
+
+	return count;
+}
+EXPORT_SYMBOL_GPL(gpiod_count);
+
 /**
  * gpiod_get - obtain a GPIO for a given GPIO function
  * @dev:	GPIO consumer, can be NULL for system-global GPIOs

@@ -2005,6 +2157,70 @@ struct gpio_desc *__must_check __gpiod_get_index_optional(struct device *dev,
 EXPORT_SYMBOL_GPL(__gpiod_get_index_optional);
 
 /**
+ * gpiod_get_array - obtain multiple GPIOs from a multi-index GPIO function
+ * @dev:	GPIO consumer, can be NULL for system-global GPIOs
+ * @con_id:	function within the GPIO consumer
+ * @flags:	optional GPIO initialization flags
+ *
+ * This function acquires all the GPIOs defined under a given function.
+ *
+ * Return a struct gpio_descs containing an array of descriptors, -ENOENT if
+ * no GPIO has been assigned to the requested function, or another IS_ERR()
+ * code if an error occurred while trying to acquire the GPIOs.
+ */
+struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
+						const char *con_id,
+						enum gpiod_flags flags)
+{

drivers/gpio/gpiolib.c +17 -0

+		}
+		descs->desc_array[descs->array_size] = desc;
+		descs->array_size++;
+	}
+	return descs;
+}
+EXPORT_SYMBOL_GPL(gpiod_get_array);
+
+/**
+ * gpiod_get_array_optional - obtain multiple GPIOs from a multi-index GPIO
+ *                            function
+ * @dev:	GPIO consumer, can be NULL for system-global GPIOs
+ * @con_id:	function within the GPIO consumer
+ * @flags:	optional GPIO initialization flags
+ *
+ * This is equivalent to gpiod_get_array(), except that when no GPIO was
+ * assigned to the requested function it will return NULL.

drivers/gpio/gpiolib.c +21 -0

+
+	return descs;
+}
+EXPORT_SYMBOL_GPL(gpiod_get_array_optional);
+
+/**
  * gpiod_put - dispose of a GPIO descriptor
  * @desc:	GPIO descriptor to dispose of
  *

@@ -2016,6 +2232,21 @@ void gpiod_put(struct gpio_desc *desc)
 }
 EXPORT_SYMBOL_GPL(gpiod_put);
 
+/**
+ * gpiod_put_array - dispose of multiple GPIO descriptors
+ * @descs:	struct gpio_descs containing an array of descriptors
+ */
+void gpiod_put_array(struct gpio_descs *descs)
+{
+	unsigned int i;
+
+	for (i = 0; i < descs->array_size; i++)
+		gpiod_put(descs->desc_array[i]);
+
+	kfree(descs);
+}
+EXPORT_SYMBOL_GPL(gpiod_put_array);
+
 #ifdef CONFIG_DEBUG_FS
 
 static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)

include/linux/gpio/consumer.h +24 -0

index 45afc2d..6b1c389 100644
@@ -16,6 +16,15 @@ struct device;
  */
 struct gpio_desc;
 
+/**
+ * Struct containing an array of descriptors that can be obtained using
+ * gpiod_get_array().
+ */
+struct gpio_descs {
+	unsigned int array_size;
+	struct gpio_desc *desc_array[];
+};
+
 #define GPIOD_FLAGS_BIT_DIR_SET		BIT(0)
 #define GPIOD_FLAGS_BIT_DIR_OUT		BIT(1)
 #define GPIOD_FLAGS_BIT_DIR_VAL		BIT(2)

@@ -34,6 +43,9 @@ enum gpiod_flags {
 
 #ifdef CONFIG_GPIOLIB
 
+/* Return the number of GPIOs associated with a device / function */
+int gpiod_count(struct device *dev, const char *con_id);
+
 /* Acquire and dispose GPIOs */
 struct gpio_desc *__must_check __gpiod_get(struct device *dev,
 					 const char *con_id,

@@ -49,7 +61,14 @@ struct gpio_desc *__must_check __gpiod_get_index_optional(struct device *dev,
 							const char *con_id,
 							unsigned int index,
 							enum gpiod_flags flags);
+struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
+						const char *con_id,
+						enum gpiod_flags flags);
+struct gpio_descs *__must_check gpiod_get_array_optional(struct device *dev,
+							const char *con_id,
+							enum gpiod_flags flags);
 void gpiod_put(struct gpio_desc *desc);
+void gpiod_put_array(struct gpio_descs *descs);
 
 struct gpio_desc *__must_check __devm_gpiod_get(struct device *dev,
 					      const char *con_id,

@@ -113,6 +132,11 @@ struct gpio_desc *devm_get_gpiod_from_child(struct device *dev,
 					    struct fwnode_handle *child);
 #else /* CONFIG_GPIOLIB */
 
+static inline int gpiod_count(struct device *dev, const char *con_id)
+{
+	return 0;
+}
+
 static inline struct gpio_desc *__must_check __gpiod_get(struct device *dev,
 						const char *con_id,
 						enum gpiod_flags flags)

include/linux/gpio/consumer.h +10 -0

+}
+
 static inline void gpiod_put(struct gpio_desc *desc)
 {
 	might_sleep();

@@ -150,6 +188,14 @@ static inline void gpiod_put(struct gpio_desc *desc)
 	WARN_ON(1);
 }
 
+static inline void gpiod_put_array(struct gpio_descs *descs)
+{
+	might_sleep();
+
+	/* GPIO can never have been requested */
+	WARN_ON(1);
+}
+
 static inline struct gpio_desc *__must_check
 __devm_gpiod_get(struct device *dev,
 		 const char *con_id,

Signature · 1 line

2.0.5

[+Rafael]

Quoted 5 lines · Rojhalat Ibrahim

Introduce new functions for conveniently obtaining and disposing of an entire array of GPIOs with one function call.

Suggested-by Alexandre Courbot <[email protected]>

Signed-off-by Rojhalat Ibrahim <[email protected]>

Can you please next time CC me the whole series? Now it fails with:

drivers/gpio/gpiolib.c: In function ‘dt_gpio_count’:
drivers/gpio/gpiolib.c:1812:29: error: ‘gpio_suffixes’ undeclared (first use in this function)

  for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
                             ^

include/linux/kernel.h:54:33: note: in definition of macro ‘ARRAY_SIZE’
#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) +
__must_be_array(arr))

and so on.

Quoted 121 lines

---
Change log:
v3: - rebase on current linux-gpio devel branch
- fix ACPI GPIO counting
- allow for zero-sized arrays
- make the flags argument mandatory for the new functions
- clarify documentation
v2: change interface

 Documentation/gpio/consumer.txt |  33 +++++-
 drivers/gpio/gpiolib.c          | 231 ++++++++++++++++++++++++++++++++++++++++
 include/linux/gpio/consumer.h   |  46 ++++++++
 3 files changed, 307 insertions(+), 3 deletions(-)

Documentation/gpio/consumer.txt +30 -3

index d85fbae..85a7e30 100644
@@ -58,7 +58,6 @@ pattern where a GPIO is optional, the gpiod_get_optional() and
 gpiod_get_index_optional() functions can be used. These functions return NULL
 instead of -ENOENT if no GPIO has been assigned to the requested function:
 
-
 	struct gpio_desc *gpiod_get_optional(struct device *dev,
 					     const char *con_id,
 					     enum gpiod_flags flags)

@@ -68,6 +67,27 @@ instead of -ENOENT if no GPIO has been assigned to the requested function:
 						   unsigned int index,
 						   enum gpiod_flags flags)
 
+For a function using multiple GPIOs all of those can be obtained with one call:
+
+	struct gpio_descs *gpiod_get_array(struct device *dev,
+					   const char *con_id,
+					   enum gpiod_flags flags)
+
+This function returns a struct gpio_descs which contains an array of
+descriptors:
+
+	struct gpio_descs {
+		unsigned int array_size;
+		struct gpio_desc *desc_array[];
+	}
+
+The following function returns NULL instead of -ENOENT if no GPIOs have been
+assigned to the requested function:
+
+	struct gpio_descs *gpiod_get_array_optional(struct device *dev,
+						    const char *con_id,
+						    enum gpiod_flags flags)
+
 Device-managed variants of these functions are also defined:
 
 	struct gpio_desc *devm_gpiod_get(struct device *dev, const char *con_id,

@@ -91,8 +111,15 @@ A GPIO descriptor can be disposed of using the gpiod_put() function:
 
 	void gpiod_put(struct gpio_desc *desc)
 
-It is strictly forbidden to use a descriptor after calling this function. The
-device-managed variant is, unsurprisingly:
+For an array of GPIOs this function can be used:
+
+	void gpiod_put_array(struct gpio_descs *descs)
+
+It is strictly forbidden to use a descriptor after calling these functions.
+It is also not allowed to individually release descriptors (using gpiod_put())
+from an array acquired with gpiod_get_array().
+
+The device-managed variant is, unsurprisingly:
 
 	void devm_gpiod_put(struct device *dev, struct gpio_desc *desc)
 

drivers/gpio/gpiolib.c +41 -0

index ff2b80d..d4153e0 100644
@@ -1804,6 +1804,158 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
 	return desc;
 }
 
+static int dt_gpio_count(struct device *dev, const char *con_id)
+{
+	int ret;
+	char propname[32];
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
+		if (con_id)
+			snprintf(propname, sizeof(propname), "%s-%s",
+				 con_id, gpio_suffixes[i]);
+		else
+			snprintf(propname, sizeof(propname), "%s",
+				 gpio_suffixes[i]);
+
+		ret = of_gpio_named_count(dev->of_node, propname);
+		if (ret >= 0)
+			break;
+	}
+	return ret;
+}
+
+#ifdef CONFIG_ACPI
+
+static unsigned int acpi_gpio_package_count(const union acpi_object *obj)
+{
+	const union acpi_object *element = obj->package.elements;
+	const union acpi_object *end = element + obj->package.count;
+	unsigned int count = 0;
+
+	while (element < end) {
+		if (element->type == ACPI_TYPE_LOCAL_REFERENCE)
+			count++;
+
+		element++;
+	}
+	return count;
+}
+
+static int acpi_find_gpio_count(struct acpi_resource *ares, void *data)
+{
+	unsigned int *count = data;

drivers/gpio/gpiolib.c static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id, · line 1857

Quoted 10 lines

drivers/gpio/gpiolib.c +10 -0

+
+	if (ares->type == ACPI_RESOURCE_TYPE_GPIO)
+		*count += ares->data.gpio.pin_table_length;
+
+	return 1;
+}
+
+static int acpi_gpio_count(struct device *dev, const char *con_id)
+{
+	struct acpi_device *adev = ACPI_COMPANION(dev);

Should you check that the ACPI companion device actually exists here or is it checked somewhere before already?

drivers/gpio/gpiolib.c static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id, · line 1869

Quoted 12 lines

drivers/gpio/gpiolib.c +12 -0

+	const union acpi_object *obj;
+	const struct acpi_gpio_mapping *gm;
+	int count = -ENOENT;
+	int ret;
+	char propname[32];
+	unsigned int i;
+
+	/* Try first from _DSD */
+	for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
+		if (con_id && strcmp(con_id, "gpios"))
+			snprintf(propname, sizeof(propname), "%s-%s",
+				 con_id, gpio_suffixes[i]);

I'm assuming some previous patch added gpio_suffixes[].

Quoted 31 lines

drivers/gpio/gpiolib.c +31 -0

+		else
+			snprintf(propname, sizeof(propname), "%s",
+				 gpio_suffixes[i]);
+
+		ret = acpi_dev_get_property(adev, propname, ACPI_TYPE_ANY,
+					    &obj);
+		if (ret == 0) {
+			if (obj->type == ACPI_TYPE_LOCAL_REFERENCE)
+				count = 1;
+			else if (obj->type == ACPI_TYPE_PACKAGE)
+				count = acpi_gpio_package_count(obj);
+		} else if (adev->driver_gpios) {
+			for (gm = adev->driver_gpios; gm->name; gm++)
+				if (strcmp(propname, gm->name) == 0) {
+					count = gm->size;
+					break;
+				}
+		}
+		if (count >= 0)
+			break;
+	}
+
+	/* Then from plain _CRS GPIOs */
+	if (count < 0) {
+		struct list_head resource_list;
+		unsigned int crs_count = 0;
+
+		INIT_LIST_HEAD(&resource_list);
+		acpi_dev_get_resources(adev, &resource_list,
+				       acpi_find_gpio_count, &crs_count);
+		acpi_dev_free_resource_list(&resource_list);

drivers/gpio/gpiolib.c static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id, · line 1905

Quoted 5 lines

drivers/gpio/gpiolib.c +5 -0

+		if (crs_count > 0)
+			count = crs_count;
+	}
+	return count;
+}

Otherwise the ACPI parts look good to me. I still want to test this, though.

Quoted 35 lines

drivers/gpio/gpiolib.c +35 -0

+
+#else
+
+static int acpi_gpio_count(struct device *dev, const char *con_id)
+{
+	return -ENODEV;
+}
+
+#endif
+
+static int lut_gpio_count(struct device *dev, const char *con_id)
+{
+	struct gpiod_lookup_table *table;
+	struct gpiod_lookup *p;
+	unsigned int count = 0;
+
+	table = gpiod_find_lookup_table(dev);
+	if (!table)
+		return -ENOENT;
+
+	for (p = &table->table[0]; p->chip_label; p++) {
+		if ((con_id && p->con_id && !strcmp(con_id, p->con_id)) ||
+		    (!con_id && !p->con_id))
+			count++;
+	}
+	if (!count)
+		return -ENOENT;
+
+	return count;
+}
+
+/**
+ * gpiod_count - return the number of GPIOs associated with a device / function
+ *		or -ENOENT if no GPIO has been assigned to the requested function
+ * @dev:	GPIO consumer, can be NULL for system-global GPIOs

drivers/gpio/gpiolib.c static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id, · line 1950

Quoted 10 lines

drivers/gpio/gpiolib.c +10 -0

+ * @con_id:	function within the GPIO consumer
+ */
+int gpiod_count(struct device *dev, const char *con_id)
+{
+	int count = -ENOENT;
+
+	if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node)
+		count = dt_gpio_count(dev, con_id);
+	else if (IS_ENABLED(CONFIG_ACPI) && dev && ACPI_HANDLE(dev))
+		count = acpi_gpio_count(dev, con_id);

Aha, so you here you checked for the ACPI compation, all right then.

Quoted 34 lines

drivers/gpio/gpiolib.c +27 -0

+
+	if (count < 0)
+		count = lut_gpio_count(dev, con_id);
+
+	return count;
+}
+EXPORT_SYMBOL_GPL(gpiod_count);
+
 /**
  * gpiod_get - obtain a GPIO for a given GPIO function
  * @dev:	GPIO consumer, can be NULL for system-global GPIOs

@@ -2005,6 +2157,70 @@ struct gpio_desc *__must_check __gpiod_get_index_optional(struct device *dev,
 EXPORT_SYMBOL_GPL(__gpiod_get_index_optional);
 
 /**
+ * gpiod_get_array - obtain multiple GPIOs from a multi-index GPIO function
+ * @dev:	GPIO consumer, can be NULL for system-global GPIOs
+ * @con_id:	function within the GPIO consumer
+ * @flags:	optional GPIO initialization flags
+ *
+ * This function acquires all the GPIOs defined under a given function.
+ *
+ * Return a struct gpio_descs containing an array of descriptors, -ENOENT if
+ * no GPIO has been assigned to the requested function, or another IS_ERR()
+ * code if an error occurred while trying to acquire the GPIOs.
+ */
+struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
+						const char *con_id,
+						enum gpiod_flags flags)
+{
+	struct gpio_desc *desc;
+	struct gpio_descs *descs;
+	int count;
+

drivers/gpio/gpiolib.c struct gpio_desc *__must_check __gpiod_get_index_optional(struct device *dev, · line 2184

Quoted 6 lines

drivers/gpio/gpiolib.c +6 -0

+	count = gpiod_count(dev, con_id);
+	if (count < 0)
+		return ERR_PTR(count);
+
+	descs = kzalloc(sizeof(*descs) + sizeof(descs->desc_array[0]) * count,
+			GFP_KERNEL);

Should you return ERR_PTR(-ENOMEM) here if the allocation fails?

drivers/gpio/gpiolib.c struct gpio_desc *__must_check __gpiod_get_index_optional(struct device *dev, · line 2186

Quoted 2 lines

drivers/gpio/gpiolib.c +2 -0

+
+	for (descs->array_size = 0; descs->array_size < count; ) {

                                                              ^
                                                              |
                                                              +-- extra whitespace

drivers/gpio/gpiolib.c struct gpio_desc *__must_check __gpiod_get_index_optional(struct device *dev, · line 2190

Quoted 4 lines

drivers/gpio/gpiolib.c +4 -0

+		desc = gpiod_get_index(dev, con_id, descs->array_size, flags);
+		if (IS_ERR(desc)) {
+			gpiod_put_array(descs);
+			return ERR_PTR(PTR_ERR(desc));

Uh, why not

return desc

?

Quoted 23 lines

drivers/gpio/gpiolib.c +22 -0

+		}
+		descs->desc_array[descs->array_size] = desc;
+		descs->array_size++;
+	}
+	return descs;
+}
+EXPORT_SYMBOL_GPL(gpiod_get_array);
+
+/**
+ * gpiod_get_array_optional - obtain multiple GPIOs from a multi-index GPIO
+ *                            function
+ * @dev:	GPIO consumer, can be NULL for system-global GPIOs
+ * @con_id:	function within the GPIO consumer
+ * @flags:	optional GPIO initialization flags
+ *
+ * This is equivalent to gpiod_get_array(), except that when no GPIO was
+ * assigned to the requested function it will return NULL.
+ */
+struct gpio_descs *__must_check gpiod_get_array_optional(struct device *dev,
+							const char *con_id,
+							enum gpiod_flags flags)
+{

drivers/gpio/gpiolib.c struct gpio_desc *__must_check __gpiod_get_index_optional(struct device *dev, · line 2217

Quoted 5 lines

drivers/gpio/gpiolib.c +5 -0

+	struct gpio_descs *descs;
+
+	descs = gpiod_get_array(dev, con_id, flags);
+	if (IS_ERR(descs) && (PTR_ERR(descs) == -ENOENT))
+		return NULL;

The caller still needs to handle other error codes (than -ENOENT), so would it be better to just have only gpiod_get_array()?

Quoted 92 lines

drivers/gpio/gpiolib.c +21 -0

+
+	return descs;
+}
+EXPORT_SYMBOL_GPL(gpiod_get_array_optional);
+
+/**
  * gpiod_put - dispose of a GPIO descriptor
  * @desc:	GPIO descriptor to dispose of
  *

@@ -2016,6 +2232,21 @@ void gpiod_put(struct gpio_desc *desc)
 }
 EXPORT_SYMBOL_GPL(gpiod_put);
 
+/**
+ * gpiod_put_array - dispose of multiple GPIO descriptors
+ * @descs:	struct gpio_descs containing an array of descriptors
+ */
+void gpiod_put_array(struct gpio_descs *descs)
+{
+	unsigned int i;
+
+	for (i = 0; i < descs->array_size; i++)
+		gpiod_put(descs->desc_array[i]);
+
+	kfree(descs);
+}
+EXPORT_SYMBOL_GPL(gpiod_put_array);
+
 #ifdef CONFIG_DEBUG_FS
 
 static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)

include/linux/gpio/consumer.h +24 -0

index 45afc2d..6b1c389 100644
@@ -16,6 +16,15 @@ struct device;
  */
 struct gpio_desc;
 
+/**
+ * Struct containing an array of descriptors that can be obtained using
+ * gpiod_get_array().
+ */
+struct gpio_descs {
+	unsigned int array_size;
+	struct gpio_desc *desc_array[];
+};
+
 #define GPIOD_FLAGS_BIT_DIR_SET		BIT(0)
 #define GPIOD_FLAGS_BIT_DIR_OUT		BIT(1)
 #define GPIOD_FLAGS_BIT_DIR_VAL		BIT(2)

@@ -34,6 +43,9 @@ enum gpiod_flags {
 
 #ifdef CONFIG_GPIOLIB
 
+/* Return the number of GPIOs associated with a device / function */
+int gpiod_count(struct device *dev, const char *con_id);
+
 /* Acquire and dispose GPIOs */
 struct gpio_desc *__must_check __gpiod_get(struct device *dev,
 					 const char *con_id,

@@ -49,7 +61,14 @@ struct gpio_desc *__must_check __gpiod_get_index_optional(struct device *dev,
 							const char *con_id,
 							unsigned int index,
 							enum gpiod_flags flags);
+struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
+						const char *con_id,
+						enum gpiod_flags flags);
+struct gpio_descs *__must_check gpiod_get_array_optional(struct device *dev,
+							const char *con_id,
+							enum gpiod_flags flags);
 void gpiod_put(struct gpio_desc *desc);
+void gpiod_put_array(struct gpio_descs *descs);
 
 struct gpio_desc *__must_check __devm_gpiod_get(struct device *dev,
 					      const char *con_id,

@@ -113,6 +132,11 @@ struct gpio_desc *devm_get_gpiod_from_child(struct device *dev,
 					    struct fwnode_handle *child);
 #else /* CONFIG_GPIOLIB */
 
+static inline int gpiod_count(struct device *dev, const char *con_id)
+{
+	return 0;
+}
+
 static inline struct gpio_desc *__must_check __gpiod_get(struct device *dev,
 						const char *con_id,
 						enum gpiod_flags flags)

@@ -142,6 +166,20 @@ __gpiod_get_index_optional(struct device *dev, const char *con_id,
 	return ERR_PTR(-ENOSYS);
 }
 

include/linux/gpio/consumer.h __gpiod_get_index_optional(struct device *dev, const char *con_id, · line 173

Quoted 5 lines

include/linux/gpio/consumer.h +5 -0

+static inline struct gpio_descs *__must_check
+gpiod_get_array(struct device *dev, const char *con_id,
+		enum gpiod_flags flags)
+{
+	return ERR_PTR(-ENOSYS);

That should be -ENXIO.

include/linux/gpio/consumer.h __gpiod_get_index_optional(struct device *dev, const char *con_id, · line 180

Quoted 7 lines

include/linux/gpio/consumer.h +7 -0

+}
+
+static inline struct gpio_descs *__must_check
+gpiod_get_array_optional(struct device *dev, const char *con_id,
+			 enum gpiod_flags flags)
+{
+	return ERR_PTR(-ENOSYS);

Ditto.

Quoted 9 lines

include/linux/gpio/consumer.h +2 -0

+}
+
 static inline void gpiod_put(struct gpio_desc *desc)
 {
 	might_sleep();

@@ -150,6 +188,14 @@ static inline void gpiod_put(struct gpio_desc *desc)
 	WARN_ON(1);
 }
 

include/linux/gpio/consumer.h static inline void gpiod_put(struct gpio_desc *desc) · line 201

Quoted 11 lines

include/linux/gpio/consumer.h +8 -0

+static inline void gpiod_put_array(struct gpio_descs *descs)
+{
+	might_sleep();
+
+	/* GPIO can never have been requested */
+	WARN_ON(1);
+}
+
 static inline struct gpio_desc *__must_check
 __devm_gpiod_get(struct device *dev,
 		 const char *con_id,

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Quoted 11 lines · On Tuesday 10 February 2015 12:40:34 Mika Westerberg wrote:

[+Rafael]

Quoted 5 lines · Rojhalat Ibrahim

Introduce new functions for conveniently obtaining and disposing of an entire array of GPIOs with one function call.

Suggested-by Alexandre Courbot <[email protected]>

Signed-off-by Rojhalat Ibrahim <[email protected]>

Can you please next time CC me the whole series? Now it fails with:

Sure. Sorry about that.

Quoted 192 lines

drivers/gpio/gpiolib.c: In function ‘dt_gpio_count’:
drivers/gpio/gpiolib.c:1812:29: error: ‘gpio_suffixes’ undeclared (first use in this function)

  for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
                             ^

include/linux/kernel.h:54:33: note: in definition of macro ‘ARRAY_SIZE’
#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) +
__must_be_array(arr))

and so on.

Quoted 121 lines

---
Change log:
v3: - rebase on current linux-gpio devel branch
- fix ACPI GPIO counting
- allow for zero-sized arrays
- make the flags argument mandatory for the new functions
- clarify documentation
v2: change interface

 Documentation/gpio/consumer.txt |  33 +++++-
 drivers/gpio/gpiolib.c          | 231 ++++++++++++++++++++++++++++++++++++++++
 include/linux/gpio/consumer.h   |  46 ++++++++
 3 files changed, 307 insertions(+), 3 deletions(-)

Documentation/gpio/consumer.txt +30 -3

index d85fbae..85a7e30 100644
@@ -58,7 +58,6 @@ pattern where a GPIO is optional, the gpiod_get_optional() and
 gpiod_get_index_optional() functions can be used. These functions return NULL
 instead of -ENOENT if no GPIO has been assigned to the requested function:
 
-
 	struct gpio_desc *gpiod_get_optional(struct device *dev,
 					     const char *con_id,
 					     enum gpiod_flags flags)

@@ -68,6 +67,27 @@ instead of -ENOENT if no GPIO has been assigned to the requested function:
 						   unsigned int index,
 						   enum gpiod_flags flags)
 
+For a function using multiple GPIOs all of those can be obtained with one call:
+
+	struct gpio_descs *gpiod_get_array(struct device *dev,
+					   const char *con_id,
+					   enum gpiod_flags flags)
+
+This function returns a struct gpio_descs which contains an array of
+descriptors:
+
+	struct gpio_descs {
+		unsigned int array_size;
+		struct gpio_desc *desc_array[];
+	}
+
+The following function returns NULL instead of -ENOENT if no GPIOs have been
+assigned to the requested function:
+
+	struct gpio_descs *gpiod_get_array_optional(struct device *dev,
+						    const char *con_id,
+						    enum gpiod_flags flags)
+
 Device-managed variants of these functions are also defined:
 
 	struct gpio_desc *devm_gpiod_get(struct device *dev, const char *con_id,

@@ -91,8 +111,15 @@ A GPIO descriptor can be disposed of using the gpiod_put() function:
 
 	void gpiod_put(struct gpio_desc *desc)
 
-It is strictly forbidden to use a descriptor after calling this function. The
-device-managed variant is, unsurprisingly:
+For an array of GPIOs this function can be used:
+
+	void gpiod_put_array(struct gpio_descs *descs)
+
+It is strictly forbidden to use a descriptor after calling these functions.
+It is also not allowed to individually release descriptors (using gpiod_put())
+from an array acquired with gpiod_get_array().
+
+The device-managed variant is, unsurprisingly:
 
 	void devm_gpiod_put(struct device *dev, struct gpio_desc *desc)
 

drivers/gpio/gpiolib.c +41 -0

index ff2b80d..d4153e0 100644
@@ -1804,6 +1804,158 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
 	return desc;
 }
 
+static int dt_gpio_count(struct device *dev, const char *con_id)
+{
+	int ret;
+	char propname[32];
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
+		if (con_id)
+			snprintf(propname, sizeof(propname), "%s-%s",
+				 con_id, gpio_suffixes[i]);
+		else
+			snprintf(propname, sizeof(propname), "%s",
+				 gpio_suffixes[i]);
+
+		ret = of_gpio_named_count(dev->of_node, propname);
+		if (ret >= 0)
+			break;
+	}
+	return ret;
+}
+
+#ifdef CONFIG_ACPI
+
+static unsigned int acpi_gpio_package_count(const union acpi_object *obj)
+{
+	const union acpi_object *element = obj->package.elements;
+	const union acpi_object *end = element + obj->package.count;
+	unsigned int count = 0;
+
+	while (element < end) {
+		if (element->type == ACPI_TYPE_LOCAL_REFERENCE)
+			count++;
+
+		element++;
+	}
+	return count;
+}
+
+static int acpi_find_gpio_count(struct acpi_resource *ares, void *data)
+{
+	unsigned int *count = data;

drivers/gpio/gpiolib.c static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id, · line 1857

Quoted 10 lines

drivers/gpio/gpiolib.c +10 -0

+
+	if (ares->type == ACPI_RESOURCE_TYPE_GPIO)
+		*count += ares->data.gpio.pin_table_length;
+
+	return 1;
+}
+
+static int acpi_gpio_count(struct device *dev, const char *con_id)
+{
+	struct acpi_device *adev = ACPI_COMPANION(dev);

Should you check that the ACPI companion device actually exists here or is it checked somewhere before already?

drivers/gpio/gpiolib.c static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id, · line 1869

Quoted 12 lines

drivers/gpio/gpiolib.c +12 -0

+	const union acpi_object *obj;
+	const struct acpi_gpio_mapping *gm;
+	int count = -ENOENT;
+	int ret;
+	char propname[32];
+	unsigned int i;
+
+	/* Try first from _DSD */
+	for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
+		if (con_id && strcmp(con_id, "gpios"))
+			snprintf(propname, sizeof(propname), "%s-%s",
+				 con_id, gpio_suffixes[i]);

I'm assuming some previous patch added gpio_suffixes[].

Quoted 31 lines

drivers/gpio/gpiolib.c +31 -0

+		else
+			snprintf(propname, sizeof(propname), "%s",
+				 gpio_suffixes[i]);
+
+		ret = acpi_dev_get_property(adev, propname, ACPI_TYPE_ANY,
+					    &obj);
+		if (ret == 0) {
+			if (obj->type == ACPI_TYPE_LOCAL_REFERENCE)
+				count = 1;
+			else if (obj->type == ACPI_TYPE_PACKAGE)
+				count = acpi_gpio_package_count(obj);
+		} else if (adev->driver_gpios) {
+			for (gm = adev->driver_gpios; gm->name; gm++)
+				if (strcmp(propname, gm->name) == 0) {
+					count = gm->size;
+					break;
+				}
+		}
+		if (count >= 0)
+			break;
+	}
+
+	/* Then from plain _CRS GPIOs */
+	if (count < 0) {
+		struct list_head resource_list;
+		unsigned int crs_count = 0;
+
+		INIT_LIST_HEAD(&resource_list);
+		acpi_dev_get_resources(adev, &resource_list,
+				       acpi_find_gpio_count, &crs_count);
+		acpi_dev_free_resource_list(&resource_list);

Quoted 9 lines

drivers/gpio/gpiolib.c static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id, · line 1905

Quoted 5 lines

drivers/gpio/gpiolib.c +5 -0

+		if (crs_count > 0)
+			count = crs_count;
+	}
+	return count;
+}

Otherwise the ACPI parts look good to me. I still want to test this, though.

Great.

Quoted 82 lines

Quoted 35 lines

drivers/gpio/gpiolib.c +35 -0

+
+#else
+
+static int acpi_gpio_count(struct device *dev, const char *con_id)
+{
+	return -ENODEV;
+}
+
+#endif
+
+static int lut_gpio_count(struct device *dev, const char *con_id)
+{
+	struct gpiod_lookup_table *table;
+	struct gpiod_lookup *p;
+	unsigned int count = 0;
+
+	table = gpiod_find_lookup_table(dev);
+	if (!table)
+		return -ENOENT;
+
+	for (p = &table->table[0]; p->chip_label; p++) {
+		if ((con_id && p->con_id && !strcmp(con_id, p->con_id)) ||
+		    (!con_id && !p->con_id))
+			count++;
+	}
+	if (!count)
+		return -ENOENT;
+
+	return count;
+}
+
+/**
+ * gpiod_count - return the number of GPIOs associated with a device / function
+ *		or -ENOENT if no GPIO has been assigned to the requested function
+ * @dev:	GPIO consumer, can be NULL for system-global GPIOs

drivers/gpio/gpiolib.c static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id, · line 1950

Quoted 10 lines

drivers/gpio/gpiolib.c +10 -0

+ * @con_id:	function within the GPIO consumer
+ */
+int gpiod_count(struct device *dev, const char *con_id)
+{
+	int count = -ENOENT;
+
+	if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node)
+		count = dt_gpio_count(dev, con_id);
+	else if (IS_ENABLED(CONFIG_ACPI) && dev && ACPI_HANDLE(dev))
+		count = acpi_gpio_count(dev, con_id);

Aha, so you here you checked for the ACPI compation, all right then.

Quoted 34 lines

drivers/gpio/gpiolib.c +27 -0

+
+	if (count < 0)
+		count = lut_gpio_count(dev, con_id);
+
+	return count;
+}
+EXPORT_SYMBOL_GPL(gpiod_count);
+
 /**
  * gpiod_get - obtain a GPIO for a given GPIO function
  * @dev:	GPIO consumer, can be NULL for system-global GPIOs

@@ -2005,6 +2157,70 @@ struct gpio_desc *__must_check __gpiod_get_index_optional(struct device *dev,
 EXPORT_SYMBOL_GPL(__gpiod_get_index_optional);
 
 /**
+ * gpiod_get_array - obtain multiple GPIOs from a multi-index GPIO function
+ * @dev:	GPIO consumer, can be NULL for system-global GPIOs
+ * @con_id:	function within the GPIO consumer
+ * @flags:	optional GPIO initialization flags
+ *
+ * This function acquires all the GPIOs defined under a given function.
+ *
+ * Return a struct gpio_descs containing an array of descriptors, -ENOENT if
+ * no GPIO has been assigned to the requested function, or another IS_ERR()
+ * code if an error occurred while trying to acquire the GPIOs.
+ */
+struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
+						const char *con_id,
+						enum gpiod_flags flags)
+{
+	struct gpio_desc *desc;
+	struct gpio_descs *descs;
+	int count;
+

Quoted 9 lines

drivers/gpio/gpiolib.c struct gpio_desc *__must_check __gpiod_get_index_optional(struct device *dev, · line 2184

Quoted 6 lines

drivers/gpio/gpiolib.c +6 -0

+	count = gpiod_count(dev, con_id);
+	if (count < 0)
+		return ERR_PTR(count);
+
+	descs = kzalloc(sizeof(*descs) + sizeof(descs->desc_array[0]) * count,
+			GFP_KERNEL);

Should you return ERR_PTR(-ENOMEM) here if the allocation fails?

Of course. I'll put it in the next revision.

Quoted 13 lines

drivers/gpio/gpiolib.c struct gpio_desc *__must_check __gpiod_get_index_optional(struct device *dev, · line 2186

Quoted 2 lines

drivers/gpio/gpiolib.c +2 -0

+
+	for (descs->array_size = 0; descs->array_size < count; ) {

                                                              ^
                                                              |
                                                              +-- extra whitespace

drivers/gpio/gpiolib.c struct gpio_desc *__must_check __gpiod_get_index_optional(struct device *dev, · line 2190

Quoted 4 lines

drivers/gpio/gpiolib.c +4 -0

+		desc = gpiod_get_index(dev, con_id, descs->array_size, flags);
+		if (IS_ERR(desc)) {
+			gpiod_put_array(descs);
+			return ERR_PTR(PTR_ERR(desc));

Uh, why not

Quoted 3 lines

return desc

?

Because of the different pointer type. desc is a pointer to a GPIO descriptor whereas the return type of the function is a pointer to struct gpio_descs.

Quoted 24 lines

Quoted 24 lines

drivers/gpio/gpiolib.c +22 -0

+		}
+		descs->desc_array[descs->array_size] = desc;
+		descs->array_size++;
+	}
+	return descs;
+}
+EXPORT_SYMBOL_GPL(gpiod_get_array);
+
+/**
+ * gpiod_get_array_optional - obtain multiple GPIOs from a multi-index GPIO
+ *                            function
+ * @dev:	GPIO consumer, can be NULL for system-global GPIOs
+ * @con_id:	function within the GPIO consumer
+ * @flags:	optional GPIO initialization flags
+ *
+ * This is equivalent to gpiod_get_array(), except that when no GPIO was
+ * assigned to the requested function it will return NULL.
+ */
+struct gpio_descs *__must_check gpiod_get_array_optional(struct device *dev,
+							const char *con_id,
+							enum gpiod_flags flags)
+{

Quoted 9 lines

drivers/gpio/gpiolib.c struct gpio_desc *__must_check __gpiod_get_index_optional(struct device *dev, · line 2217

Quoted 5 lines

drivers/gpio/gpiolib.c +5 -0

+	struct gpio_descs *descs;
+
+	descs = gpiod_get_array(dev, con_id, flags);
+	if (IS_ERR(descs) && (PTR_ERR(descs) == -ENOENT))
+		return NULL;

The caller still needs to handle other error codes (than -ENOENT), so would it be better to just have only gpiod_get_array()?

This follows the same pattern as gpiod_get_optional() and gpiod_get_index_optional()

Quoted 1 line

From Documentation/gpio/consumer.txt:

This is useful to discriminate between mere
errors and an absence of GPIO for optional GPIO parameters. For the common pattern where a GPIO is optional, the gpiod_get_optional() and gpiod_get_index_optional() functions can be used. These functions return NULL instead of -ENOENT if no GPIO has been assigned to the requested function

Quoted 92 lines

Quoted 92 lines

drivers/gpio/gpiolib.c +21 -0

+
+	return descs;
+}
+EXPORT_SYMBOL_GPL(gpiod_get_array_optional);
+
+/**
  * gpiod_put - dispose of a GPIO descriptor
  * @desc:	GPIO descriptor to dispose of
  *

@@ -2016,6 +2232,21 @@ void gpiod_put(struct gpio_desc *desc)
 }
 EXPORT_SYMBOL_GPL(gpiod_put);
 
+/**
+ * gpiod_put_array - dispose of multiple GPIO descriptors
+ * @descs:	struct gpio_descs containing an array of descriptors
+ */
+void gpiod_put_array(struct gpio_descs *descs)
+{
+	unsigned int i;
+
+	for (i = 0; i < descs->array_size; i++)
+		gpiod_put(descs->desc_array[i]);
+
+	kfree(descs);
+}
+EXPORT_SYMBOL_GPL(gpiod_put_array);
+
 #ifdef CONFIG_DEBUG_FS
 
 static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)

include/linux/gpio/consumer.h +24 -0

index 45afc2d..6b1c389 100644
@@ -16,6 +16,15 @@ struct device;
  */
 struct gpio_desc;
 
+/**
+ * Struct containing an array of descriptors that can be obtained using
+ * gpiod_get_array().
+ */
+struct gpio_descs {
+	unsigned int array_size;
+	struct gpio_desc *desc_array[];
+};
+
 #define GPIOD_FLAGS_BIT_DIR_SET		BIT(0)
 #define GPIOD_FLAGS_BIT_DIR_OUT		BIT(1)
 #define GPIOD_FLAGS_BIT_DIR_VAL		BIT(2)

@@ -34,6 +43,9 @@ enum gpiod_flags {
 
 #ifdef CONFIG_GPIOLIB
 
+/* Return the number of GPIOs associated with a device / function */
+int gpiod_count(struct device *dev, const char *con_id);
+
 /* Acquire and dispose GPIOs */
 struct gpio_desc *__must_check __gpiod_get(struct device *dev,
 					 const char *con_id,

@@ -49,7 +61,14 @@ struct gpio_desc *__must_check __gpiod_get_index_optional(struct device *dev,
 							const char *con_id,
 							unsigned int index,
 							enum gpiod_flags flags);
+struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
+						const char *con_id,
+						enum gpiod_flags flags);
+struct gpio_descs *__must_check gpiod_get_array_optional(struct device *dev,
+							const char *con_id,
+							enum gpiod_flags flags);
 void gpiod_put(struct gpio_desc *desc);
+void gpiod_put_array(struct gpio_descs *descs);
 
 struct gpio_desc *__must_check __devm_gpiod_get(struct device *dev,
 					      const char *con_id,

@@ -113,6 +132,11 @@ struct gpio_desc *devm_get_gpiod_from_child(struct device *dev,
 					    struct fwnode_handle *child);
 #else /* CONFIG_GPIOLIB */
 
+static inline int gpiod_count(struct device *dev, const char *con_id)
+{
+	return 0;
+}
+
 static inline struct gpio_desc *__must_check __gpiod_get(struct device *dev,
 						const char *con_id,
 						enum gpiod_flags flags)

@@ -142,6 +166,20 @@ __gpiod_get_index_optional(struct device *dev, const char *con_id,
 	return ERR_PTR(-ENOSYS);
 }
 

Quoted 8 lines

include/linux/gpio/consumer.h __gpiod_get_index_optional(struct device *dev, const char *con_id, · line 173

Quoted 5 lines

include/linux/gpio/consumer.h +5 -0

+static inline struct gpio_descs *__must_check
+gpiod_get_array(struct device *dev, const char *con_id,
+		enum gpiod_flags flags)
+{
+	return ERR_PTR(-ENOSYS);

That should be -ENXIO.

Why? All the other functions in this section return -ENOSYS.

According to include/uapi/asm-generic/errno.h ENOSYS means "Function not implemented"
and in include/uapi/asm-generic/errno-base.h it says ENXIO stands for "No such device or address".

If ENXIO is more correct here (and I don't see why),

then it should at least be consistent for all functions, right?

Quoted 19 lines

include/linux/gpio/consumer.h __gpiod_get_index_optional(struct device *dev, const char *con_id, · line 180

Quoted 7 lines

include/linux/gpio/consumer.h +7 -0

+}
+
+static inline struct gpio_descs *__must_check
+gpiod_get_array_optional(struct device *dev, const char *con_id,
+			 enum gpiod_flags flags)
+{
+	return ERR_PTR(-ENOSYS);

Ditto.

Quoted 9 lines

include/linux/gpio/consumer.h +2 -0

+}
+
 static inline void gpiod_put(struct gpio_desc *desc)
 {
 	might_sleep();

@@ -150,6 +188,14 @@ static inline void gpiod_put(struct gpio_desc *desc)
 	WARN_ON(1);
 }
 

Quoted 7 lines

Quoted 7 lines

include/linux/gpio/consumer.h +7 -0

+static inline void gpiod_put_array(struct gpio_descs *descs)
+{
+	might_sleep();
+
+	/* GPIO can never have been requested */
+	WARN_ON(1);
+}

Quoted 9 lines

include/linux/gpio/consumer.h static inline void gpiod_put(struct gpio_desc *desc) · line 201

Quoted 4 lines

include/linux/gpio/consumer.h +1 -0

+
 static inline struct gpio_desc *__must_check
 __devm_gpiod_get(struct device *dev,
 		 const char *con_id,

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Quoted 15 lines · Rojhalat Ibrahim

Quoted 13 lines · On Tuesday 10 February 2015 12:40:34 Mika Westerberg wrote:

drivers/gpio/gpiolib.c struct gpio_desc *__must_check __gpiod_get_index_optional(struct device *dev, · line 2186

Quoted 2 lines

drivers/gpio/gpiolib.c +2 -0

+
+	for (descs->array_size = 0; descs->array_size < count; ) {

                                                              ^
                                                              |
                                                              +-- extra whitespace

drivers/gpio/gpiolib.c struct gpio_desc *__must_check __gpiod_get_index_optional(struct device *dev, · line 2190

Quoted 4 lines

drivers/gpio/gpiolib.c +4 -0

+		desc = gpiod_get_index(dev, con_id, descs->array_size, flags);
+		if (IS_ERR(desc)) {
+			gpiod_put_array(descs);
+			return ERR_PTR(PTR_ERR(desc));

Uh, why not

Quoted 6 lines

Quoted 3 lines

return desc

?

Because of the different pointer type. desc is a pointer to a GPIO descriptor whereas the return type of the function is a pointer to struct gpio_descs.

Right. I wonder if ERR_CAST() may be used here.