Add support for SAMA5D2 touchscreen

Add MAINTAINERS entry for generic resistive touchscreen adc

Signed-off-by Eugen Hristev <[email protected]>

---
Changes in v3:
- Changed source file name

 MAINTAINERS | 6 ++++++
 1 file changed, 6 insertions(+)

MAINTAINERS +6 -0

index 3bdc260..ce9720f 100644
@@ -5943,6 +5943,12 @@ F:	drivers/base/power/domain*.c
 F:	include/linux/pm_domain.h
 F:	Documentation/devicetree/bindings/power/power_domain.txt
 
+GENERIC RESISTIVE TOUCHSCREEN ADC DRIVER
+M:	Eugen Hristev <[email protected]>
+L:	linux-input at vger.kernel.org
+S:	Maintained
+F:	drivers/input/touchscreen/resistive-adc-touch.c
+
 GENERIC UIO DRIVER FOR PCI DEVICES
 M:	"Michael S. Tsirkin" <[email protected]>
 L:	kvm at vger.kernel.org

Add new channel type for relative position on a pad.

These type of analog sensor offers the position of a pen
on a touchpad, and is represented as a voltage, which can be converted to a position on X and Y axis on the pad.
The channel will hand the relative position on the pad in both directions.

The channel can then be consumed by a touchscreen driver or read as-is for a raw indication of the touchpen on a touchpad.

Signed-off-by Eugen Hristev <[email protected]>

---
Changes in v2:
- modified channel name to relative position as suggested.
- modified kernel version to 4.18 (presumable)

 Documentation/ABI/testing/sysfs-bus-iio | 12 ++++++++++++
 drivers/iio/industrialio-core.c         |  1 +
 include/uapi/linux/iio/types.h          |  1 +
 tools/iio/iio_event_monitor.c           |  2 ++
 4 files changed, 16 insertions(+)

Documentation/ABI/testing/sysfs-bus-iio +12 -0

index 6a5f34b..42a9287 100644
@@ -190,6 +190,18 @@ Description:
 		but should match other such assignments on device).
 		Units after application of scale and offset are m/s^2.
 
+What:		/sys/bus/iio/devices/iio:deviceX/in_positionrelative_x_raw
+What:		/sys/bus/iio/devices/iio:deviceX/in_positionrelative_y_raw
+KernelVersion:	4.18
+Contact:	linux-iio at vger.kernel.org
+Description:
+		Relative position in direction x or y on a pad (may be
+		arbitrarily assigned but should match other such assignments on
+		device).
+		Units after application of scale and offset are milli percents
+		from the pad's size in both directions. Should be calibrated by
+		the consumer.
+
 What:		/sys/bus/iio/devices/iio:deviceX/in_anglvel_x_raw
 What:		/sys/bus/iio/devices/iio:deviceX/in_anglvel_y_raw
 What:		/sys/bus/iio/devices/iio:deviceX/in_anglvel_z_raw

drivers/iio/industrialio-core.c +1 -0

index 19bdf3d..14bf3d24 100644
@@ -85,6 +85,7 @@ static const char * const iio_chan_type_name_spec[] = {
 	[IIO_COUNT] = "count",
 	[IIO_INDEX] = "index",
 	[IIO_GRAVITY]  = "gravity",
+	[IIO_POSITIONRELATIVE]  = "positionrelative",
 };
 
 static const char * const iio_modifier_names[] = {

include/uapi/linux/iio/types.h +1 -0

index 4213cdf..033c7d2 100644
@@ -44,6 +44,7 @@ enum iio_chan_type {
 	IIO_COUNT,
 	IIO_INDEX,
 	IIO_GRAVITY,
+	IIO_POSITIONRELATIVE,
 };
 
 enum iio_modifier {

tools/iio/iio_event_monitor.c +2 -0

index b61245e..148f69d 100644
@@ -58,6 +58,7 @@ static const char * const iio_chan_type_name_spec[] = {
 	[IIO_PH] = "ph",
 	[IIO_UVINDEX] = "uvindex",
 	[IIO_GRAVITY] = "gravity",
+	[IIO_POSITIONRELATIVE] = "positionrelative",
 };
 
 static const char * const iio_ev_type_text[] = {

@@ -151,6 +152,7 @@ static bool event_is_known(struct iio_event_data *event)
 	case IIO_PH:
 	case IIO_UVINDEX:
 	case IIO_GRAVITY:
+	case IIO_POSITIONRELATIVE:
 		break;
 	default:
 		return false;

Add a common touchscreen optional property that will specify the minimum pressure applied to the screen that is needed such that the driver will report the touch event.

Signed-off-by Eugen Hristev <[email protected]>

Reviewed-by Rob Herring <[email protected]>

---
Changes in v5:
- Modified property name to touchscreen-min-pressure from
touchscreen-threshold-property

 Documentation/devicetree/bindings/input/touchscreen/touchscreen.txt | 3 +++
 1 file changed, 3 insertions(+)

Documentation/devicetree/bindings/input/touchscreen/touchscreen.txt +3 -0

index 537643e..d092d5d 100644
@@ -7,6 +7,9 @@ Optional properties for Touchscreens:
 				  (in pixels)
  - touchscreen-max-pressure	: maximum reported pressure (arbitrary range
 				  dependent on the controller)
+ - touchscreen-min-pressure	: minimum pressure on the touchscreen to be
+				  achieved in order for the touchscreen
+				  driver to report a touch event.
  - touchscreen-fuzz-x		: horizontal noise value of the absolute input
 				  device (in pixels)
  - touchscreen-fuzz-y		: vertical noise value of the absolute input

Added bindings for generic resistive touchscreen ADC.

Signed-off-by Eugen Hristev <[email protected]>

Reviewed-by Rob Herring <[email protected]>

---
Changes in v5:
- changed property name touchscreen-threshold-pressure to
touchscreen-min-pressure

Changes in v3:
- renamed file and compatible to exclude "generic" keyword
- removed the pressure threshold property, added it as a common
touchscreen property in the touchscreen common bindings in a separate commit.

Changes in v2:
- modified bindings to have a generic resistive touchscreen adc driver
instead of specific architecture one.

 .../input/touchscreen/resistive-adc-touch.txt      | 30 ++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.txt

Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.txt new file +30 -0

new file mode 100644
index 0000000..51456c0
@@ -0,0 +1,30 @@
+Generic resistive touchscreen ADC
+
+Required properties:
+
+ - compatible: must be "resistive-adc-touch"
+The device must be connected to an ADC device that provides channels for
+position measurement and optional pressure.
+Refer to ../iio/iio-bindings.txt for details
+ - iio-channels: must have at least two channels connected to an ADC device.
+These should correspond to the channels exposed by the ADC device and should
+have the right index as the ADC device registers them. These channels
+represent the relative position on the "x" and "y" axes.
+ - iio-channel-names: must have all the channels' names. Mandatory channels
+are "x" and "y".
+
+Optional properties:
+ - iio-channels: The third channel named "pressure" is optional and can be
+used if the ADC device also measures pressure besides position.
+If this channel is missing, pressure will be ignored and the touchscreen
+will only report position.
+ - iio-channel-names: optional channel named "pressure".
+
+Example:
+
+	resistive_touch: resistive_touch {
+		compatible = "resistive-adc-touch";
+		touchscreen-min-pressure = <50000>;
+		io-channels = <&adc 24>, <&adc 25>, <&adc 26>;
+		io-channel-names = "x", "y", "pressure";
+	};

This implements the support for position and pressure for the included touchscreen support in the SAMA5D2 SOC ADC block.
Two position channels are added and one for pressure.
They can be read in raw format, or through a buffer.
A normal use case is for a consumer driver to register a callback buffer for these channels.
When the touchscreen channels are in the active scan mask, the driver will start the touchscreen sampling and push the data to the buffer.

Some parts of this patch are based on initial original work by Mohamed Jamsheeth Hajanajubudeen and Bandaru Venkateswara Swamy

Signed-off-by Eugen Hristev <[email protected]>

---
Changes in v6:
- fixed a crash when issuing buffer enable from sysfs, if no trigger was
previously configured. This is because now the driver can work in software buffer mode (to connect the callback buffer). So, when trying to enable the buffer, check if we are going indeed to a triggered mode or not. If not, do not allow buffer to be started (we do not have the right trigger). It's in buffer_postenable and predisable.

Changes in v4:
- use return value of at91_adc_configure_touch
- rewrote some part of the read_info_raw according to Jonathan's
suggestion

Changes in v3:
- prefix macros with AT91_SAMA5D2
- reworked the x_pos and y_pos functions into a single one with two
additional wrappers
- reworked pressure report to have it grow naturally and not top down
- fixed some checks regarding IIO_VOLTAGE as suggested
- added a comment explaining some code in trigger handling
- reworked the frequency get handler to use the saved value instead of
reading it from the hardware.
- added comment on deffered work queueing
- pulled out INFO_RAW function into a separate utility function as suggested
- added iio_dev ops structure at all times . The functions are needed in
case we do not have a hardware trigger attached, but we want to use the consumer touchscreen driver, thus a callback buffer is attached. Then we still need to have buffer preenable and postdisable to configure the touch IRQs (etc.)

Changes in v2:
- the support is now based on callback buffer.

 drivers/iio/adc/at91-sama5d2_adc.c | 609 +++++++++++++++++++++++++++++++++----
 1 file changed, 551 insertions(+), 58 deletions(-)

drivers/iio/adc/at91-sama5d2_adc.c +551 -58

index 8729d65..58c4c2b 100644
@@ -102,14 +102,26 @@
 #define AT91_SAMA5D2_LCDR	0x20
 /* Interrupt Enable Register */
 #define AT91_SAMA5D2_IER	0x24
+/* Interrupt Enable Register - TS X measurement ready */
+#define AT91_SAMA5D2_IER_XRDY   BIT(20)
+/* Interrupt Enable Register - TS Y measurement ready */
+#define AT91_SAMA5D2_IER_YRDY   BIT(21)
+/* Interrupt Enable Register - TS pressure measurement ready */
+#define AT91_SAMA5D2_IER_PRDY   BIT(22)
 /* Interrupt Enable Register - general overrun error */
 #define AT91_SAMA5D2_IER_GOVRE BIT(25)
+/* Interrupt Enable Register - Pen detect */
+#define AT91_SAMA5D2_IER_PEN    BIT(29)
+/* Interrupt Enable Register - No pen detect */
+#define AT91_SAMA5D2_IER_NOPEN  BIT(30)
 /* Interrupt Disable Register */
 #define AT91_SAMA5D2_IDR	0x28
 /* Interrupt Mask Register */
 #define AT91_SAMA5D2_IMR	0x2c
 /* Interrupt Status Register */
 #define AT91_SAMA5D2_ISR	0x30
+/* Interrupt Status Register - Pen touching sense status */
+#define AT91_SAMA5D2_ISR_PENS   BIT(31)
 /* Last Channel Trigger Mode Register */
 #define AT91_SAMA5D2_LCTMR	0x34
 /* Last Channel Compare Window Register */

@@ -131,8 +143,38 @@
 #define AT91_SAMA5D2_CDR0	0x50
 /* Analog Control Register */
 #define AT91_SAMA5D2_ACR	0x94
+/* Analog Control Register - Pen detect sensitivity mask */
+#define AT91_SAMA5D2_ACR_PENDETSENS_MASK        GENMASK(1, 0)
+
 /* Touchscreen Mode Register */
 #define AT91_SAMA5D2_TSMR	0xb0
+/* Touchscreen Mode Register - No touch mode */
+#define AT91_SAMA5D2_TSMR_TSMODE_NONE           0
+/* Touchscreen Mode Register - 4 wire screen, no pressure measurement */
+#define AT91_SAMA5D2_TSMR_TSMODE_4WIRE_NO_PRESS 1
+/* Touchscreen Mode Register - 4 wire screen, pressure measurement */
+#define AT91_SAMA5D2_TSMR_TSMODE_4WIRE_PRESS    2
+/* Touchscreen Mode Register - 5 wire screen */
+#define AT91_SAMA5D2_TSMR_TSMODE_5WIRE          3
+/* Touchscreen Mode Register - Average samples mask */
+#define AT91_SAMA5D2_TSMR_TSAV_MASK             GENMASK(5, 4)
+/* Touchscreen Mode Register - Average samples */
+#define AT91_SAMA5D2_TSMR_TSAV(x)               ((x) << 4)
+/* Touchscreen Mode Register - Touch/trigger frequency ratio mask */
+#define AT91_SAMA5D2_TSMR_TSFREQ_MASK           GENMASK(11, 8)
+/* Touchscreen Mode Register - Touch/trigger frequency ratio */
+#define AT91_SAMA5D2_TSMR_TSFREQ(x)             ((x) << 8)
+/* Touchscreen Mode Register - Pen Debounce Time mask */
+#define AT91_SAMA5D2_TSMR_PENDBC_MASK           GENMASK(31, 28)
+/* Touchscreen Mode Register - Pen Debounce Time */
+#define AT91_SAMA5D2_TSMR_PENDBC(x)            ((x) << 28)
+/* Touchscreen Mode Register - No DMA for touch measurements */
+#define AT91_SAMA5D2_TSMR_NOTSDMA               BIT(22)
+/* Touchscreen Mode Register - Disable pen detection */
+#define AT91_SAMA5D2_TSMR_PENDET_DIS            (0 << 24)
+/* Touchscreen Mode Register - Enable pen detection */
+#define AT91_SAMA5D2_TSMR_PENDET_ENA            BIT(24)
+
 /* Touchscreen X Position Register */
 #define AT91_SAMA5D2_XPOSR	0xb4
 /* Touchscreen Y Position Register */

@@ -151,6 +193,12 @@
 #define AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_FALL 2
 /* Trigger Mode external trigger any edge */
 #define AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_ANY 3
+/* Trigger Mode internal periodic */
+#define AT91_SAMA5D2_TRGR_TRGMOD_PERIODIC 5
+/* Trigger Mode - trigger period mask */
+#define AT91_SAMA5D2_TRGR_TRGPER_MASK           GENMASK(31, 16)
+/* Trigger Mode - trigger period */
+#define AT91_SAMA5D2_TRGR_TRGPER(x)             ((x) << 16)
 
 /* Correction Select Register */
 #define AT91_SAMA5D2_COSR	0xd0

@@ -169,6 +217,22 @@
 #define AT91_SAMA5D2_SINGLE_CHAN_CNT 12
 #define AT91_SAMA5D2_DIFF_CHAN_CNT 6
 
+#define AT91_SAMA5D2_TIMESTAMP_CHAN_IDX (AT91_SAMA5D2_SINGLE_CHAN_CNT + \
+					 AT91_SAMA5D2_DIFF_CHAN_CNT + 1)
+
+#define AT91_SAMA5D2_TOUCH_X_CHAN_IDX (AT91_SAMA5D2_SINGLE_CHAN_CNT + \
+					 AT91_SAMA5D2_DIFF_CHAN_CNT * 2)
+#define AT91_SAMA5D2_TOUCH_Y_CHAN_IDX   (AT91_SAMA5D2_TOUCH_X_CHAN_IDX + 1)
+#define AT91_SAMA5D2_TOUCH_P_CHAN_IDX   (AT91_SAMA5D2_TOUCH_Y_CHAN_IDX + 1)
+#define AT91_SAMA5D2_MAX_CHAN_IDX	AT91_SAMA5D2_TOUCH_P_CHAN_IDX
+
+#define AT91_SAMA5D2_TOUCH_SAMPLE_PERIOD_US          2000    /* 2ms */
+#define AT91_SAMA5D2_TOUCH_PEN_DETECT_DEBOUNCE_US    200
+
+#define AT91_SAMA5D2_XYZ_MASK		GENMASK(11, 0)
+
+#define AT91_SAMA5D2_MAX_POS_BITS			12
+
 /*
  * Maximum number of bytes to hold conversion from all channels
  * without the timestamp.

@@ -222,6 +286,37 @@
 		.indexed = 1,						\
 	}
 
+#define AT91_SAMA5D2_CHAN_TOUCH(num, name, mod)				\
+	{								\
+		.type = IIO_POSITIONRELATIVE,				\
+		.modified = 1,						\
+		.channel = num,						\
+		.channel2 = mod,					\
+		.scan_index = num,					\
+		.scan_type = {						\
+			.sign = 'u',					\
+			.realbits = 12,					\
+			.storagebits = 16,				\
+		},							\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),\
+		.datasheet_name = name,					\
+	}
+#define AT91_SAMA5D2_CHAN_PRESSURE(num, name)				\
+	{								\
+		.type = IIO_PRESSURE,					\
+		.channel = num,						\
+		.scan_index = num,					\
+		.scan_type = {						\
+			.sign = 'u',					\
+			.realbits = 12,					\
+			.storagebits = 16,				\
+		},							\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),\
+		.datasheet_name = name,					\
+	}
+
 #define at91_adc_readl(st, reg)		readl_relaxed(st->base + reg)
 #define at91_adc_writel(st, reg, val)	writel_relaxed(val, st->base + reg)
 

@@ -260,6 +355,22 @@ struct at91_adc_dma {
 	s64				dma_ts;
 };
 
+/**
+ * at91_adc_touch - at91-sama5d2 touchscreen information struct
+ * @sample_period_val:		the value for periodic trigger interval
+ * @touching:			is the pen touching the screen or not
+ * @x_pos:			temporary placeholder for pressure computation
+ * @channels_bitmask:		bitmask with the touchscreen channels enabled
+ * @workq:			workqueue for buffer data pushing
+ */
+struct at91_adc_touch {
+	u16				sample_period_val;
+	bool				touching;
+	u16				x_pos;
+	unsigned long			channels_bitmask;
+	struct work_struct		workq;
+};
+
 struct at91_adc_state {
 	void __iomem			*base;
 	int				irq;

@@ -267,6 +378,7 @@ struct at91_adc_state {
 	struct regulator		*reg;
 	struct regulator		*vref;
 	int				vref_uv;
+	unsigned int			current_sample_rate;
 	struct iio_trigger		*trig;
 	const struct at91_adc_trigger	*selected_trig;
 	const struct iio_chan_spec	*chan;

@@ -275,6 +387,7 @@ struct at91_adc_state {
 	struct at91_adc_soc_info	soc_info;
 	wait_queue_head_t		wq_data_available;
 	struct at91_adc_dma		dma_st;
+	struct at91_adc_touch		touch_st;
 	u16				buffer[AT91_BUFFER_MAX_HWORDS];
 	/*
 	 * lock to prevent concurrent 'single conversion' requests through

@@ -329,8 +442,10 @@ static const struct iio_chan_spec at91_adc_channels[] = {
 	AT91_SAMA5D2_CHAN_DIFF(6, 7, 0x68),
 	AT91_SAMA5D2_CHAN_DIFF(8, 9, 0x70),
 	AT91_SAMA5D2_CHAN_DIFF(10, 11, 0x78),
-	IIO_CHAN_SOFT_TIMESTAMP(AT91_SAMA5D2_SINGLE_CHAN_CNT
-				+ AT91_SAMA5D2_DIFF_CHAN_CNT + 1),
+	IIO_CHAN_SOFT_TIMESTAMP(AT91_SAMA5D2_TIMESTAMP_CHAN_IDX),
+	AT91_SAMA5D2_CHAN_TOUCH(AT91_SAMA5D2_TOUCH_X_CHAN_IDX, "x", IIO_MOD_X),
+	AT91_SAMA5D2_CHAN_TOUCH(AT91_SAMA5D2_TOUCH_Y_CHAN_IDX, "y", IIO_MOD_Y),
+	AT91_SAMA5D2_CHAN_PRESSURE(AT91_SAMA5D2_TOUCH_P_CHAN_IDX, "pressure"),
 };
 
 static int at91_adc_chan_xlate(struct iio_dev *indio_dev, int chan)

@@ -354,6 +469,160 @@ at91_adc_chan_get(struct iio_dev *indio_dev, int chan)
 	return indio_dev->channels + index;
 }
 
+static inline int at91_adc_of_xlate(struct iio_dev *indio_dev,
+				    const struct of_phandle_args *iiospec)
+{
+	return at91_adc_chan_xlate(indio_dev, iiospec->args[0]);
+}
+
+static int at91_adc_configure_touch(struct at91_adc_state *st, bool state)
+{
+	u32 clk_khz = st->current_sample_rate / 1000;
+	int i = 0;
+	u16 pendbc;
+	u32 tsmr, acr;
+
+	if (!state) {
+		/* disabling touch IRQs and setting mode to no touch enabled */
+		at91_adc_writel(st, AT91_SAMA5D2_IDR,
+				AT91_SAMA5D2_IER_PEN | AT91_SAMA5D2_IER_NOPEN);
+		at91_adc_writel(st, AT91_SAMA5D2_TSMR, 0);
+		return 0;
+	}
+	/*
+	 * debounce time is in microseconds, we need it in milliseconds to
+	 * multiply with kilohertz, so, divide by 1000, but after the multiply.
+	 * round up to make sure pendbc is at least 1
+	 */
+	pendbc = round_up(AT91_SAMA5D2_TOUCH_PEN_DETECT_DEBOUNCE_US *
+			  clk_khz / 1000, 1);
+
+	/* get the required exponent */
+	while (pendbc >> i++)
+		;
+
+	pendbc = i;
+
+	tsmr = AT91_SAMA5D2_TSMR_TSMODE_4WIRE_PRESS;
+
+	tsmr |= AT91_SAMA5D2_TSMR_TSAV(2) & AT91_SAMA5D2_TSMR_TSAV_MASK;
+	tsmr |= AT91_SAMA5D2_TSMR_PENDBC(pendbc) &
+		AT91_SAMA5D2_TSMR_PENDBC_MASK;
+	tsmr |= AT91_SAMA5D2_TSMR_NOTSDMA;
+	tsmr |= AT91_SAMA5D2_TSMR_PENDET_ENA;
+	tsmr |= AT91_SAMA5D2_TSMR_TSFREQ(2) & AT91_SAMA5D2_TSMR_TSFREQ_MASK;
+
+	at91_adc_writel(st, AT91_SAMA5D2_TSMR, tsmr);
+
+	acr =  at91_adc_readl(st, AT91_SAMA5D2_ACR);
+	acr &= ~AT91_SAMA5D2_ACR_PENDETSENS_MASK;
+	acr |= 0x02 & AT91_SAMA5D2_ACR_PENDETSENS_MASK;
+	at91_adc_writel(st, AT91_SAMA5D2_ACR, acr);
+
+	/* Sample Period Time = (TRGPER + 1) / ADCClock */
+	st->touch_st.sample_period_val =
+				 round_up((AT91_SAMA5D2_TOUCH_SAMPLE_PERIOD_US *
+				 clk_khz / 1000) - 1, 1);
+	/* enable pen detect IRQ */
+	at91_adc_writel(st, AT91_SAMA5D2_IER, AT91_SAMA5D2_IER_PEN);
+
+	return 0;
+}
+
+static u16 at91_adc_touch_pos(struct at91_adc_state *st, int reg)
+{
+	u32 val;
+	u32 scale, result, pos;
+
+	/*
+	 * to obtain the actual position we must divide by scale
+	 * and multiply with max, where
+	 * max = 2^AT91_SAMA5D2_MAX_POS_BITS - 1
+	 */
+	/* first half of register is the x or y, second half is the scale */
+	val = at91_adc_readl(st, reg);
+	if (!val)
+		dev_dbg(&iio_priv_to_dev(st)->dev, "pos is 0\n");
+
+	pos = val & AT91_SAMA5D2_XYZ_MASK;
+	result = (pos << AT91_SAMA5D2_MAX_POS_BITS) - pos;
+	scale = (val >> 16) & AT91_SAMA5D2_XYZ_MASK;
+	if (scale == 0) {
+		dev_err(&iio_priv_to_dev(st)->dev, "scale is 0\n");
+		return 0;
+	}
+	result /= scale;
+
+	return result;
+}
+
+static u16 at91_adc_touch_x_pos(struct at91_adc_state *st)
+{
+	st->touch_st.x_pos = at91_adc_touch_pos(st, AT91_SAMA5D2_XPOSR);
+	return st->touch_st.x_pos;
+}
+
+static u16 at91_adc_touch_y_pos(struct at91_adc_state *st)
+{
+	return at91_adc_touch_pos(st, AT91_SAMA5D2_YPOSR);
+}
+
+static u16 at91_adc_touch_pressure(struct at91_adc_state *st)
+{
+	u32 val;
+	u32 z1, z2;
+	u32 pres;
+	u32 rxp = 1;
+	u32 factor = 1000;
+
+	/* calculate the pressure */
+	val = at91_adc_readl(st, AT91_SAMA5D2_PRESSR);
+	z1 = val & AT91_SAMA5D2_XYZ_MASK;
+	z2 = (val >> 16) & AT91_SAMA5D2_XYZ_MASK;
+
+	if (z1 != 0)
+		pres = rxp * (st->touch_st.x_pos * factor / 1024) *
+			(z2 * factor / z1 - factor) /
+			factor;
+	else
+		pres = 0xFFFF;       /* no pen contact */
+
+	/*
+	 * The pressure from device grows down, minimum is 0xFFFF, maximum 0x0.
+	 * We compute it this way, but let's return it in the expected way,
+	 * growing from 0 to 0xFFFF.
+	 */
+	return 0xFFFF - pres;
+}
+
+static int at91_adc_read_position(struct at91_adc_state *st, int chan, u16 *val)
+{
+	*val = 0;
+	if (!st->touch_st.touching)
+		return -ENODATA;
+	if (chan == AT91_SAMA5D2_TOUCH_X_CHAN_IDX)
+		*val = at91_adc_touch_x_pos(st);
+	else if (chan == AT91_SAMA5D2_TOUCH_Y_CHAN_IDX)
+		*val = at91_adc_touch_y_pos(st);
+	else
+		return -ENODATA;
+
+	return IIO_VAL_INT;
+}
+
+static int at91_adc_read_pressure(struct at91_adc_state *st, int chan, u16 *val)
+{
+	*val = 0;
+	if (!st->touch_st.touching)
+		return -ENODATA;
+	if (chan == AT91_SAMA5D2_TOUCH_P_CHAN_IDX)
+		*val = at91_adc_touch_pressure(st);
+	else
+		return -ENODATA;
+
+	return IIO_VAL_INT;
+}
+
 static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
 {
 	struct iio_dev *indio = iio_trigger_get_drvdata(trig);

@@ -375,6 +644,11 @@ static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
 
 		if (!chan)
 			continue;
+		/* these channel types cannot be handled by this trigger */
+		if (chan->type == IIO_POSITIONRELATIVE ||
+		    chan->type == IIO_PRESSURE)
+			continue;
+
 		if (state) {
 			at91_adc_writel(st, AT91_SAMA5D2_CHER,
 					BIT(chan->channel));

@@ -520,7 +794,20 @@ static int at91_adc_dma_start(struct iio_dev *indio_dev)
 static int at91_adc_buffer_postenable(struct iio_dev *indio_dev)
 {
 	int ret;
+	struct at91_adc_state *st = iio_priv(indio_dev);
 
+	/* check if we are enabling triggered buffer or the touchscreen */
+	if (bitmap_subset(indio_dev->active_scan_mask,
+			  &st->touch_st.channels_bitmask,
+			  AT91_SAMA5D2_MAX_CHAN_IDX + 1)) {
+		/* touchscreen enabling */
+		return at91_adc_configure_touch(st, true);
+	}
+	/* if we are not in triggered mode, we cannot enable the buffer. */
+	if (!(indio_dev->currentmode & INDIO_ALL_TRIGGERED_MODES))
+		return -EINVAL;
+
+	/* we continue with the triggered buffer */
 	ret = at91_adc_dma_start(indio_dev);
 	if (ret) {
 		dev_err(&indio_dev->dev, "buffer postenable failed\n");

@@ -536,6 +823,18 @@ static int at91_adc_buffer_predisable(struct iio_dev *indio_dev)
 	int ret;
 	u8 bit;
 
+	/* check if we are disabling triggered buffer or the touchscreen */
+	if (bitmap_subset(indio_dev->active_scan_mask,
+			  &st->touch_st.channels_bitmask,
+			  AT91_SAMA5D2_MAX_CHAN_IDX + 1)) {
+		/* touchscreen disable */
+		return at91_adc_configure_touch(st, false);
+	}
+	/* if we are not in triggered mode, nothing to do here */
+	if (!(indio_dev->currentmode & INDIO_ALL_TRIGGERED_MODES))
+		return -EINVAL;
+
+	/* continue with the triggered buffer */
 	ret = iio_triggered_buffer_predisable(indio_dev);
 	if (ret < 0)
 		dev_err(&indio_dev->dev, "buffer predisable failed\n");

@@ -558,6 +857,10 @@ static int at91_adc_buffer_predisable(struct iio_dev *indio_dev)
 
 		if (!chan)
 			continue;
+		/* these channel types are virtual, no need to do anything */
+		if (chan->type == IIO_POSITIONRELATIVE ||
+		    chan->type == IIO_PRESSURE)
+			continue;
 		if (st->dma_st.dma_chan)
 			at91_adc_readl(st, chan->address);
 	}

@@ -622,7 +925,22 @@ static void at91_adc_trigger_handler_nodma(struct iio_dev *indio_dev,
 
 		if (!chan)
 			continue;
-		st->buffer[i] = at91_adc_readl(st, chan->address);
+		/*
+		 * Our external trigger only supports the voltage channels.
+		 * In case someone requested a different type of channel
+		 * just put zeroes to buffer.
+		 * This should not happen because we check the scan mode
+		 * and scan mask when we enable the buffer, and we don't allow
+		 * the buffer to start with a mixed mask (voltage and something
+		 * else).
+		 * Thus, emit a warning.
+		 */
+		if (chan->type == IIO_VOLTAGE) {
+			st->buffer[i] = at91_adc_readl(st, chan->address);
+		} else {
+			st->buffer[i] = 0;
+			WARN(true, "This trigger cannot handle this type of channel");
+		}
 		i++;
 	}
 	iio_push_to_buffers_with_timestamp(indio_dev, st->buffer,

@@ -688,9 +1006,20 @@ static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
 
 static int at91_adc_buffer_init(struct iio_dev *indio)
 {
-	return devm_iio_triggered_buffer_setup(&indio->dev, indio,
+	struct at91_adc_state *st = iio_priv(indio);
+
+	if (st->selected_trig->hw_trig) {
+		return devm_iio_triggered_buffer_setup(&indio->dev, indio,
 			&iio_pollfunc_store_time,
 			&at91_adc_trigger_handler, &at91_buffer_setup_ops);
+	}
+	/*
+	 * we need to prepare the buffer ops in case we will get
+	 * another buffer attached (like a callback buffer for the touchscreen)
+	 */
+	indio->setup_ops = &at91_buffer_setup_ops;
+
+	return 0;
 }
 
 static unsigned at91_adc_startup_time(unsigned startup_time_min,

@@ -736,19 +1065,83 @@ static void at91_adc_setup_samp_freq(struct at91_adc_state *st, unsigned freq)
 
 	dev_dbg(&indio_dev->dev, "freq: %u, startup: %u, prescal: %u\n",
 		freq, startup, prescal);
+	st->current_sample_rate = freq;
 }
 
-static unsigned at91_adc_get_sample_freq(struct at91_adc_state *st)
+static inline unsigned at91_adc_get_sample_freq(struct at91_adc_state *st)
 {
-	unsigned f_adc, f_per = clk_get_rate(st->per_clk);
-	unsigned mr, prescal;
+	return st->current_sample_rate;
+}
 
-	mr = at91_adc_readl(st, AT91_SAMA5D2_MR);
-	prescal = (mr >> AT91_SAMA5D2_MR_PRESCAL_OFFSET)
-		  & AT91_SAMA5D2_MR_PRESCAL_MAX;
-	f_adc = f_per / (2 * (prescal + 1));
+static void at91_adc_touch_data_handler(struct iio_dev *indio_dev)
+{
+	struct at91_adc_state *st = iio_priv(indio_dev);
+	u8 bit;
+	u16 val;
+	int i = 0;
 
-	return f_adc;
+	for_each_set_bit(bit, indio_dev->active_scan_mask,
+			 AT91_SAMA5D2_MAX_CHAN_IDX + 1) {
+		struct iio_chan_spec const *chan =
+					 at91_adc_chan_get(indio_dev, bit);
+
+		if (chan->type == IIO_POSITIONRELATIVE)
+			at91_adc_read_position(st, chan->channel, &val);
+		else if (chan->type == IIO_PRESSURE)
+			at91_adc_read_pressure(st, chan->channel, &val);
+		else
+			continue;
+		st->buffer[i] = val;
+		i++;
+	}
+	/*
+	 * Schedule work to push to buffers.
+	 * This is intended to push to the callback buffer that another driver
+	 * registered. We are still in a handler from our IRQ. If we push
+	 * directly, it means the other driver has it's callback called
+	 * from our IRQ context. Which is something we better avoid.
+	 * Let's schedule it after our IRQ is completed.
+	 */
+	schedule_work(&st->touch_st.workq);
+}
+
+static void at91_adc_pen_detect_interrupt(struct at91_adc_state *st)
+{
+	at91_adc_writel(st, AT91_SAMA5D2_IDR, AT91_SAMA5D2_IER_PEN);
+	at91_adc_writel(st, AT91_SAMA5D2_IER, AT91_SAMA5D2_IER_NOPEN |
+			AT91_SAMA5D2_IER_XRDY | AT91_SAMA5D2_IER_YRDY |
+			AT91_SAMA5D2_IER_PRDY);
+	at91_adc_writel(st, AT91_SAMA5D2_TRGR,
+			AT91_SAMA5D2_TRGR_TRGMOD_PERIODIC |
+			AT91_SAMA5D2_TRGR_TRGPER(st->touch_st.sample_period_val));
+	st->touch_st.touching = true;
+}
+
+static void at91_adc_no_pen_detect_interrupt(struct at91_adc_state *st)
+{
+	struct iio_dev *indio_dev = iio_priv_to_dev(st);
+
+	at91_adc_writel(st, AT91_SAMA5D2_TRGR,
+			AT91_SAMA5D2_TRGR_TRGMOD_NO_TRIGGER);
+	at91_adc_writel(st, AT91_SAMA5D2_IDR, AT91_SAMA5D2_IER_NOPEN |
+			AT91_SAMA5D2_IER_XRDY | AT91_SAMA5D2_IER_YRDY |
+			AT91_SAMA5D2_IER_PRDY);
+	st->touch_st.touching = false;
+
+	at91_adc_touch_data_handler(indio_dev);
+
+	at91_adc_writel(st, AT91_SAMA5D2_IER, AT91_SAMA5D2_IER_PEN);
+}
+
+static void at91_adc_workq_handler(struct work_struct *workq)
+{
+	struct at91_adc_touch *touch_st = container_of(workq,
+					struct at91_adc_touch, workq);
+	struct at91_adc_state *st = container_of(touch_st,
+					struct at91_adc_state, touch_st);
+	struct iio_dev *indio_dev = iio_priv_to_dev(st);
+
+	iio_push_to_buffers(indio_dev, st->buffer);
 }
 
 static irqreturn_t at91_adc_interrupt(int irq, void *private)

@@ -757,17 +1150,39 @@ static irqreturn_t at91_adc_interrupt(int irq, void *private)
 	struct at91_adc_state *st = iio_priv(indio);
 	u32 status = at91_adc_readl(st, AT91_SAMA5D2_ISR);
 	u32 imr = at91_adc_readl(st, AT91_SAMA5D2_IMR);
+	u32 rdy_mask = AT91_SAMA5D2_IER_XRDY | AT91_SAMA5D2_IER_YRDY |
+			AT91_SAMA5D2_IER_PRDY;
 
 	if (!(status & imr))
 		return IRQ_NONE;
-
-	if (iio_buffer_enabled(indio) && !st->dma_st.dma_chan) {
+	if (status & AT91_SAMA5D2_IER_PEN) {
+		/* pen detected IRQ */
+		at91_adc_pen_detect_interrupt(st);
+	} else if ((status & AT91_SAMA5D2_IER_NOPEN)) {
+		/* nopen detected IRQ */
+		at91_adc_no_pen_detect_interrupt(st);
+	} else if ((status & AT91_SAMA5D2_ISR_PENS) &&
+		   ((status & rdy_mask) == rdy_mask)) {
+		/* periodic trigger IRQ - during pen sense */
+		at91_adc_touch_data_handler(indio);
+	} else if (status & AT91_SAMA5D2_ISR_PENS) {
+		/*
+		 * touching, but the measurements are not ready yet.
+		 * read and ignore.
+		 */
+		status = at91_adc_readl(st, AT91_SAMA5D2_XPOSR);
+		status = at91_adc_readl(st, AT91_SAMA5D2_YPOSR);
+		status = at91_adc_readl(st, AT91_SAMA5D2_PRESSR);
+	} else if (iio_buffer_enabled(indio) && !st->dma_st.dma_chan) {
+		/* triggered buffer without DMA */
 		disable_irq_nosync(irq);
 		iio_trigger_poll(indio->trig);
 	} else if (iio_buffer_enabled(indio) && st->dma_st.dma_chan) {
+		/* triggered buffer with DMA - should not happen */
 		disable_irq_nosync(irq);
 		WARN(true, "Unexpected irq occurred\n");
 	} else if (!iio_buffer_enabled(indio)) {
+		/* software requested conversion */
 		st->conversion_value = at91_adc_readl(st, st->chan->address);
 		st->conversion_done = true;
 		wake_up_interruptible(&st->wq_data_available);

@@ -775,58 +1190,97 @@ static irqreturn_t at91_adc_interrupt(int irq, void *private)
 	return IRQ_HANDLED;
 }
 
-static int at91_adc_read_raw(struct iio_dev *indio_dev,
-			     struct iio_chan_spec const *chan,
-			     int *val, int *val2, long mask)
+static int at91_adc_read_info_raw(struct iio_dev *indio_dev,
+				  struct iio_chan_spec const *chan, int *val)
 {
 	struct at91_adc_state *st = iio_priv(indio_dev);
 	u32 cor = 0;
 	int ret;
 
-	switch (mask) {
-	case IIO_CHAN_INFO_RAW:
-		/* we cannot use software trigger if hw trigger enabled */
+	/*
+	 * Keep in mind that we cannot use software trigger or touchscreen
+	 * if external trigger is enabled
+	 */
+	if (chan->type == IIO_POSITIONRELATIVE) {
 		ret = iio_device_claim_direct_mode(indio_dev);
 		if (ret)
 			return ret;
 		mutex_lock(&st->lock);
 
-		st->chan = chan;
+		ret = at91_adc_read_position(st, chan->channel,
+					     (u16 *)val);
+		mutex_unlock(&st->lock);
+		iio_device_release_direct_mode(indio_dev);
 
-		if (chan->differential)
-			cor = (BIT(chan->channel) | BIT(chan->channel2)) <<
-			      AT91_SAMA5D2_COR_DIFF_OFFSET;
-
-		at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
-		at91_adc_writel(st, AT91_SAMA5D2_CHER, BIT(chan->channel));
-		at91_adc_writel(st, AT91_SAMA5D2_IER, BIT(chan->channel));
-		at91_adc_writel(st, AT91_SAMA5D2_CR, AT91_SAMA5D2_CR_START);
-
-		ret = wait_event_interruptible_timeout(st->wq_data_available,
-						       st->conversion_done,
-						       msecs_to_jiffies(1000));
-		if (ret == 0)
-			ret = -ETIMEDOUT;
-
-		if (ret > 0) {
-			*val = st->conversion_value;
-			if (chan->scan_type.sign == 's')
-				*val = sign_extend32(*val, 11);
-			ret = IIO_VAL_INT;
-			st->conversion_done = false;
-		}
+		return ret;
+	}
+	if (chan->type == IIO_PRESSURE) {
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret)
+			return ret;
+		mutex_lock(&st->lock);
 
-		at91_adc_writel(st, AT91_SAMA5D2_IDR, BIT(chan->channel));
-		at91_adc_writel(st, AT91_SAMA5D2_CHDR, BIT(chan->channel));
+		ret = at91_adc_read_pressure(st, chan->channel,
+					     (u16 *)val);
+		mutex_unlock(&st->lock);
+		iio_device_release_direct_mode(indio_dev);
 
-		/* Needed to ACK the DRDY interruption */
-		at91_adc_readl(st, AT91_SAMA5D2_LCDR);
+		return ret;
+	}
 
-		mutex_unlock(&st->lock);
+	/* in this case we have a voltage channel */
 
-		iio_device_release_direct_mode(indio_dev);
+	ret = iio_device_claim_direct_mode(indio_dev);
+	if (ret)
 		return ret;
+	mutex_lock(&st->lock);
+
+	st->chan = chan;
+
+	if (chan->differential)
+		cor = (BIT(chan->channel) | BIT(chan->channel2)) <<
+		      AT91_SAMA5D2_COR_DIFF_OFFSET;
+
+	at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
+	at91_adc_writel(st, AT91_SAMA5D2_CHER, BIT(chan->channel));
+	at91_adc_writel(st, AT91_SAMA5D2_IER, BIT(chan->channel));
+	at91_adc_writel(st, AT91_SAMA5D2_CR, AT91_SAMA5D2_CR_START);
+
+	ret = wait_event_interruptible_timeout(st->wq_data_available,
+					       st->conversion_done,
+					       msecs_to_jiffies(1000));
+	if (ret == 0)
+		ret = -ETIMEDOUT;
+
+	if (ret > 0) {
+		*val = st->conversion_value;
+		if (chan->scan_type.sign == 's')
+			*val = sign_extend32(*val, 11);
+		ret = IIO_VAL_INT;
+		st->conversion_done = false;
+	}
+
+	at91_adc_writel(st, AT91_SAMA5D2_IDR, BIT(chan->channel));
+	at91_adc_writel(st, AT91_SAMA5D2_CHDR, BIT(chan->channel));
+
+	/* Needed to ACK the DRDY interruption */
+	at91_adc_readl(st, AT91_SAMA5D2_LCDR);
+
+	mutex_unlock(&st->lock);
+
+	iio_device_release_direct_mode(indio_dev);
+	return ret;
+}
+
+static int at91_adc_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int *val, int *val2, long mask)
+{
+	struct at91_adc_state *st = iio_priv(indio_dev);
 
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		return at91_adc_read_info_raw(indio_dev, chan, val);
 	case IIO_CHAN_INFO_SCALE:
 		*val = st->vref_uv / 1000;
 		if (chan->differential)

@@ -974,9 +1428,29 @@ static int at91_adc_set_watermark(struct iio_dev *indio_dev, unsigned int val)
 	return 0;
 }
 
+static int at91_adc_update_scan_mode(struct iio_dev *indio_dev,
+				     const unsigned long *scan_mask)
+{
+	struct at91_adc_state *st = iio_priv(indio_dev);
+
+	if (bitmap_subset(scan_mask, &st->touch_st.channels_bitmask,
+			  AT91_SAMA5D2_MAX_CHAN_IDX + 1))
+		return 0;
+	/*
+	 * if the new bitmap is a combination of touchscreen and regular
+	 * channels, then we are not fine
+	 */
+	if (bitmap_intersects(&st->touch_st.channels_bitmask, scan_mask,
+			      AT91_SAMA5D2_MAX_CHAN_IDX + 1))
+		return -EINVAL;
+	return 0;
+}
+
 static const struct iio_info at91_adc_info = {
 	.read_raw = &at91_adc_read_raw,
 	.write_raw = &at91_adc_write_raw,
+	.update_scan_mode = &at91_adc_update_scan_mode,
+	.of_xlate = &at91_adc_of_xlate,
 	.hwfifo_set_watermark = &at91_adc_set_watermark,
 };
 

@@ -1044,13 +1518,20 @@ static int at91_adc_probe(struct platform_device *pdev)
 
 	indio_dev->dev.parent = &pdev->dev;
 	indio_dev->name = dev_name(&pdev->dev);
-	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_SOFTWARE;
 	indio_dev->info = &at91_adc_info;
 	indio_dev->channels = at91_adc_channels;
 	indio_dev->num_channels = ARRAY_SIZE(at91_adc_channels);
 
 	st = iio_priv(indio_dev);
 
+	bitmap_set(&st->touch_st.channels_bitmask,
+		   AT91_SAMA5D2_TOUCH_X_CHAN_IDX, 1);
+	bitmap_set(&st->touch_st.channels_bitmask,
+		   AT91_SAMA5D2_TOUCH_Y_CHAN_IDX, 1);
+	bitmap_set(&st->touch_st.channels_bitmask,
+		   AT91_SAMA5D2_TOUCH_P_CHAN_IDX, 1);
+
 	ret = of_property_read_u32(pdev->dev.of_node,
 				   "atmel,min-sample-rate-hz",
 				   &st->soc_info.min_sample_rate);

@@ -1100,6 +1581,7 @@ static int at91_adc_probe(struct platform_device *pdev)
 
 	init_waitqueue_head(&st->wq_data_available);
 	mutex_init(&st->lock);
+	INIT_WORK(&st->touch_st.workq, at91_adc_workq_handler);
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!res)

@@ -1159,13 +1641,13 @@ static int at91_adc_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, indio_dev);
 
-	if (st->selected_trig->hw_trig) {
-		ret = at91_adc_buffer_init(indio_dev);
-		if (ret < 0) {
-			dev_err(&pdev->dev, "couldn't initialize the buffer.\n");
-			goto per_clk_disable_unprepare;
-		}
+	ret = at91_adc_buffer_init(indio_dev);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "couldn't initialize the buffer.\n");
+		goto per_clk_disable_unprepare;
+	}
 
+	if (st->selected_trig->hw_trig) {
 		ret = at91_adc_trigger_init(indio_dev);
 		if (ret < 0) {
 			dev_err(&pdev->dev, "couldn't setup the triggers.\n");

@@ -1272,9 +1754,20 @@ static __maybe_unused int at91_adc_resume(struct device *dev)
 	at91_adc_hw_init(st);
 
 	/* reconfiguring trigger hardware state */
-	if (iio_buffer_enabled(indio_dev))
-		at91_adc_configure_trigger(st->trig, true);
+	if (!iio_buffer_enabled(indio_dev))
+		return 0;
+
+	/* check if we are enabling triggered buffer or the touchscreen */
+	if (bitmap_subset(indio_dev->active_scan_mask,
+			  &st->touch_st.channels_bitmask,
+			  AT91_SAMA5D2_MAX_CHAN_IDX + 1)) {
+		/* touchscreen enabling */
+		return at91_adc_configure_touch(st, true);
+	} else {
+		return at91_adc_configure_trigger(st->trig, true);
+	}
 
+	/* not needed but more explicit */
 	return 0;
 
 vref_disable_resume:

Signature · 1 line

2.7.4

Quoted 10 lines · Eugen Hristev

This implements the support for position and pressure for the included touchscreen support in the SAMA5D2 SOC ADC block.
Two position channels are added and one for pressure.
They can be read in raw format, or through a buffer.
A normal use case is for a consumer driver to register a callback buffer for these channels.
When the touchscreen channels are in the active scan mask, the driver will start the touchscreen sampling and push the data to the buffer.

Quoted 4 lines

Some parts of this patch are based on initial original work by Mohamed Jamsheeth Hajanajubudeen and Bandaru Venkateswara Swamy

Signed-off-by Eugen Hristev <[email protected]>

Acked-by Ludovic Desroches <[email protected]>

Quoted 876 lines

---
Changes in v6:
- fixed a crash when issuing buffer enable from sysfs, if no trigger was
previously configured. This is because now the driver can work in software buffer mode (to connect the callback buffer). So, when trying to enable the buffer, check if we are going indeed to a triggered mode or not. If not, do not allow buffer to be started (we do not have the right trigger). It's in buffer_postenable and predisable.

Changes in v4:
- use return value of at91_adc_configure_touch
- rewrote some part of the read_info_raw according to Jonathan's
suggestion

Changes in v3:
- prefix macros with AT91_SAMA5D2
- reworked the x_pos and y_pos functions into a single one with two
additional wrappers
- reworked pressure report to have it grow naturally and not top down
- fixed some checks regarding IIO_VOLTAGE as suggested
- added a comment explaining some code in trigger handling
- reworked the frequency get handler to use the saved value instead of
reading it from the hardware.
- added comment on deffered work queueing
- pulled out INFO_RAW function into a separate utility function as suggested
- added iio_dev ops structure at all times . The functions are needed in
case we do not have a hardware trigger attached, but we want to use the consumer touchscreen driver, thus a callback buffer is attached. Then we still need to have buffer preenable and postdisable to configure the touch IRQs (etc.)

Changes in v2:
- the support is now based on callback buffer.

 drivers/iio/adc/at91-sama5d2_adc.c | 609 +++++++++++++++++++++++++++++++++----
 1 file changed, 551 insertions(+), 58 deletions(-)

drivers/iio/adc/at91-sama5d2_adc.c +551 -58

index 8729d65..58c4c2b 100644
@@ -102,14 +102,26 @@
 #define AT91_SAMA5D2_LCDR	0x20
 /* Interrupt Enable Register */
 #define AT91_SAMA5D2_IER	0x24
+/* Interrupt Enable Register - TS X measurement ready */
+#define AT91_SAMA5D2_IER_XRDY   BIT(20)
+/* Interrupt Enable Register - TS Y measurement ready */
+#define AT91_SAMA5D2_IER_YRDY   BIT(21)
+/* Interrupt Enable Register - TS pressure measurement ready */
+#define AT91_SAMA5D2_IER_PRDY   BIT(22)
 /* Interrupt Enable Register - general overrun error */
 #define AT91_SAMA5D2_IER_GOVRE BIT(25)
+/* Interrupt Enable Register - Pen detect */
+#define AT91_SAMA5D2_IER_PEN    BIT(29)
+/* Interrupt Enable Register - No pen detect */
+#define AT91_SAMA5D2_IER_NOPEN  BIT(30)
 /* Interrupt Disable Register */
 #define AT91_SAMA5D2_IDR	0x28
 /* Interrupt Mask Register */
 #define AT91_SAMA5D2_IMR	0x2c
 /* Interrupt Status Register */
 #define AT91_SAMA5D2_ISR	0x30
+/* Interrupt Status Register - Pen touching sense status */
+#define AT91_SAMA5D2_ISR_PENS   BIT(31)
 /* Last Channel Trigger Mode Register */
 #define AT91_SAMA5D2_LCTMR	0x34
 /* Last Channel Compare Window Register */

@@ -131,8 +143,38 @@
 #define AT91_SAMA5D2_CDR0	0x50
 /* Analog Control Register */
 #define AT91_SAMA5D2_ACR	0x94
+/* Analog Control Register - Pen detect sensitivity mask */
+#define AT91_SAMA5D2_ACR_PENDETSENS_MASK        GENMASK(1, 0)
+
 /* Touchscreen Mode Register */
 #define AT91_SAMA5D2_TSMR	0xb0
+/* Touchscreen Mode Register - No touch mode */
+#define AT91_SAMA5D2_TSMR_TSMODE_NONE           0
+/* Touchscreen Mode Register - 4 wire screen, no pressure measurement */
+#define AT91_SAMA5D2_TSMR_TSMODE_4WIRE_NO_PRESS 1
+/* Touchscreen Mode Register - 4 wire screen, pressure measurement */
+#define AT91_SAMA5D2_TSMR_TSMODE_4WIRE_PRESS    2
+/* Touchscreen Mode Register - 5 wire screen */
+#define AT91_SAMA5D2_TSMR_TSMODE_5WIRE          3
+/* Touchscreen Mode Register - Average samples mask */
+#define AT91_SAMA5D2_TSMR_TSAV_MASK             GENMASK(5, 4)
+/* Touchscreen Mode Register - Average samples */
+#define AT91_SAMA5D2_TSMR_TSAV(x)               ((x) << 4)
+/* Touchscreen Mode Register - Touch/trigger frequency ratio mask */
+#define AT91_SAMA5D2_TSMR_TSFREQ_MASK           GENMASK(11, 8)
+/* Touchscreen Mode Register - Touch/trigger frequency ratio */
+#define AT91_SAMA5D2_TSMR_TSFREQ(x)             ((x) << 8)
+/* Touchscreen Mode Register - Pen Debounce Time mask */
+#define AT91_SAMA5D2_TSMR_PENDBC_MASK           GENMASK(31, 28)
+/* Touchscreen Mode Register - Pen Debounce Time */
+#define AT91_SAMA5D2_TSMR_PENDBC(x)            ((x) << 28)
+/* Touchscreen Mode Register - No DMA for touch measurements */
+#define AT91_SAMA5D2_TSMR_NOTSDMA               BIT(22)
+/* Touchscreen Mode Register - Disable pen detection */
+#define AT91_SAMA5D2_TSMR_PENDET_DIS            (0 << 24)
+/* Touchscreen Mode Register - Enable pen detection */
+#define AT91_SAMA5D2_TSMR_PENDET_ENA            BIT(24)
+
 /* Touchscreen X Position Register */
 #define AT91_SAMA5D2_XPOSR	0xb4
 /* Touchscreen Y Position Register */

@@ -151,6 +193,12 @@
 #define AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_FALL 2
 /* Trigger Mode external trigger any edge */
 #define AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_ANY 3
+/* Trigger Mode internal periodic */
+#define AT91_SAMA5D2_TRGR_TRGMOD_PERIODIC 5
+/* Trigger Mode - trigger period mask */
+#define AT91_SAMA5D2_TRGR_TRGPER_MASK           GENMASK(31, 16)
+/* Trigger Mode - trigger period */
+#define AT91_SAMA5D2_TRGR_TRGPER(x)             ((x) << 16)
 
 /* Correction Select Register */
 #define AT91_SAMA5D2_COSR	0xd0

@@ -169,6 +217,22 @@
 #define AT91_SAMA5D2_SINGLE_CHAN_CNT 12
 #define AT91_SAMA5D2_DIFF_CHAN_CNT 6
 
+#define AT91_SAMA5D2_TIMESTAMP_CHAN_IDX (AT91_SAMA5D2_SINGLE_CHAN_CNT + \
+					 AT91_SAMA5D2_DIFF_CHAN_CNT + 1)
+
+#define AT91_SAMA5D2_TOUCH_X_CHAN_IDX (AT91_SAMA5D2_SINGLE_CHAN_CNT + \
+					 AT91_SAMA5D2_DIFF_CHAN_CNT * 2)
+#define AT91_SAMA5D2_TOUCH_Y_CHAN_IDX   (AT91_SAMA5D2_TOUCH_X_CHAN_IDX + 1)
+#define AT91_SAMA5D2_TOUCH_P_CHAN_IDX   (AT91_SAMA5D2_TOUCH_Y_CHAN_IDX + 1)
+#define AT91_SAMA5D2_MAX_CHAN_IDX	AT91_SAMA5D2_TOUCH_P_CHAN_IDX
+
+#define AT91_SAMA5D2_TOUCH_SAMPLE_PERIOD_US          2000    /* 2ms */
+#define AT91_SAMA5D2_TOUCH_PEN_DETECT_DEBOUNCE_US    200
+
+#define AT91_SAMA5D2_XYZ_MASK		GENMASK(11, 0)
+
+#define AT91_SAMA5D2_MAX_POS_BITS			12
+
 /*
  * Maximum number of bytes to hold conversion from all channels
  * without the timestamp.

@@ -222,6 +286,37 @@
 		.indexed = 1,						\
 	}
 
+#define AT91_SAMA5D2_CHAN_TOUCH(num, name, mod)				\
+	{								\
+		.type = IIO_POSITIONRELATIVE,				\
+		.modified = 1,						\
+		.channel = num,						\
+		.channel2 = mod,					\
+		.scan_index = num,					\
+		.scan_type = {						\
+			.sign = 'u',					\
+			.realbits = 12,					\
+			.storagebits = 16,				\
+		},							\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),\
+		.datasheet_name = name,					\
+	}
+#define AT91_SAMA5D2_CHAN_PRESSURE(num, name)				\
+	{								\
+		.type = IIO_PRESSURE,					\
+		.channel = num,						\
+		.scan_index = num,					\
+		.scan_type = {						\
+			.sign = 'u',					\
+			.realbits = 12,					\
+			.storagebits = 16,				\
+		},							\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),\
+		.datasheet_name = name,					\
+	}
+
 #define at91_adc_readl(st, reg)		readl_relaxed(st->base + reg)
 #define at91_adc_writel(st, reg, val)	writel_relaxed(val, st->base + reg)
 

@@ -260,6 +355,22 @@ struct at91_adc_dma {
 	s64				dma_ts;
 };
 
+/**
+ * at91_adc_touch - at91-sama5d2 touchscreen information struct
+ * @sample_period_val:		the value for periodic trigger interval
+ * @touching:			is the pen touching the screen or not
+ * @x_pos:			temporary placeholder for pressure computation
+ * @channels_bitmask:		bitmask with the touchscreen channels enabled
+ * @workq:			workqueue for buffer data pushing
+ */
+struct at91_adc_touch {
+	u16				sample_period_val;
+	bool				touching;
+	u16				x_pos;
+	unsigned long			channels_bitmask;
+	struct work_struct		workq;
+};
+
 struct at91_adc_state {
 	void __iomem			*base;
 	int				irq;

@@ -267,6 +378,7 @@ struct at91_adc_state {
 	struct regulator		*reg;
 	struct regulator		*vref;
 	int				vref_uv;
+	unsigned int			current_sample_rate;
 	struct iio_trigger		*trig;
 	const struct at91_adc_trigger	*selected_trig;
 	const struct iio_chan_spec	*chan;

@@ -275,6 +387,7 @@ struct at91_adc_state {
 	struct at91_adc_soc_info	soc_info;
 	wait_queue_head_t		wq_data_available;
 	struct at91_adc_dma		dma_st;
+	struct at91_adc_touch		touch_st;
 	u16				buffer[AT91_BUFFER_MAX_HWORDS];
 	/*
 	 * lock to prevent concurrent 'single conversion' requests through

@@ -329,8 +442,10 @@ static const struct iio_chan_spec at91_adc_channels[] = {
 	AT91_SAMA5D2_CHAN_DIFF(6, 7, 0x68),
 	AT91_SAMA5D2_CHAN_DIFF(8, 9, 0x70),
 	AT91_SAMA5D2_CHAN_DIFF(10, 11, 0x78),
-	IIO_CHAN_SOFT_TIMESTAMP(AT91_SAMA5D2_SINGLE_CHAN_CNT
-				+ AT91_SAMA5D2_DIFF_CHAN_CNT + 1),
+	IIO_CHAN_SOFT_TIMESTAMP(AT91_SAMA5D2_TIMESTAMP_CHAN_IDX),
+	AT91_SAMA5D2_CHAN_TOUCH(AT91_SAMA5D2_TOUCH_X_CHAN_IDX, "x", IIO_MOD_X),
+	AT91_SAMA5D2_CHAN_TOUCH(AT91_SAMA5D2_TOUCH_Y_CHAN_IDX, "y", IIO_MOD_Y),
+	AT91_SAMA5D2_CHAN_PRESSURE(AT91_SAMA5D2_TOUCH_P_CHAN_IDX, "pressure"),
 };
 
 static int at91_adc_chan_xlate(struct iio_dev *indio_dev, int chan)

@@ -354,6 +469,160 @@ at91_adc_chan_get(struct iio_dev *indio_dev, int chan)
 	return indio_dev->channels + index;
 }
 
+static inline int at91_adc_of_xlate(struct iio_dev *indio_dev,
+				    const struct of_phandle_args *iiospec)
+{
+	return at91_adc_chan_xlate(indio_dev, iiospec->args[0]);
+}
+
+static int at91_adc_configure_touch(struct at91_adc_state *st, bool state)
+{
+	u32 clk_khz = st->current_sample_rate / 1000;
+	int i = 0;
+	u16 pendbc;
+	u32 tsmr, acr;
+
+	if (!state) {
+		/* disabling touch IRQs and setting mode to no touch enabled */
+		at91_adc_writel(st, AT91_SAMA5D2_IDR,
+				AT91_SAMA5D2_IER_PEN | AT91_SAMA5D2_IER_NOPEN);
+		at91_adc_writel(st, AT91_SAMA5D2_TSMR, 0);
+		return 0;
+	}
+	/*
+	 * debounce time is in microseconds, we need it in milliseconds to
+	 * multiply with kilohertz, so, divide by 1000, but after the multiply.
+	 * round up to make sure pendbc is at least 1
+	 */
+	pendbc = round_up(AT91_SAMA5D2_TOUCH_PEN_DETECT_DEBOUNCE_US *
+			  clk_khz / 1000, 1);
+
+	/* get the required exponent */
+	while (pendbc >> i++)
+		;
+
+	pendbc = i;
+
+	tsmr = AT91_SAMA5D2_TSMR_TSMODE_4WIRE_PRESS;
+
+	tsmr |= AT91_SAMA5D2_TSMR_TSAV(2) & AT91_SAMA5D2_TSMR_TSAV_MASK;
+	tsmr |= AT91_SAMA5D2_TSMR_PENDBC(pendbc) &
+		AT91_SAMA5D2_TSMR_PENDBC_MASK;
+	tsmr |= AT91_SAMA5D2_TSMR_NOTSDMA;
+	tsmr |= AT91_SAMA5D2_TSMR_PENDET_ENA;
+	tsmr |= AT91_SAMA5D2_TSMR_TSFREQ(2) & AT91_SAMA5D2_TSMR_TSFREQ_MASK;
+
+	at91_adc_writel(st, AT91_SAMA5D2_TSMR, tsmr);
+
+	acr =  at91_adc_readl(st, AT91_SAMA5D2_ACR);
+	acr &= ~AT91_SAMA5D2_ACR_PENDETSENS_MASK;
+	acr |= 0x02 & AT91_SAMA5D2_ACR_PENDETSENS_MASK;
+	at91_adc_writel(st, AT91_SAMA5D2_ACR, acr);
+
+	/* Sample Period Time = (TRGPER + 1) / ADCClock */
+	st->touch_st.sample_period_val =
+				 round_up((AT91_SAMA5D2_TOUCH_SAMPLE_PERIOD_US *
+				 clk_khz / 1000) - 1, 1);
+	/* enable pen detect IRQ */
+	at91_adc_writel(st, AT91_SAMA5D2_IER, AT91_SAMA5D2_IER_PEN);
+
+	return 0;
+}
+
+static u16 at91_adc_touch_pos(struct at91_adc_state *st, int reg)
+{
+	u32 val;
+	u32 scale, result, pos;
+
+	/*
+	 * to obtain the actual position we must divide by scale
+	 * and multiply with max, where
+	 * max = 2^AT91_SAMA5D2_MAX_POS_BITS - 1
+	 */
+	/* first half of register is the x or y, second half is the scale */
+	val = at91_adc_readl(st, reg);
+	if (!val)
+		dev_dbg(&iio_priv_to_dev(st)->dev, "pos is 0\n");
+
+	pos = val & AT91_SAMA5D2_XYZ_MASK;
+	result = (pos << AT91_SAMA5D2_MAX_POS_BITS) - pos;
+	scale = (val >> 16) & AT91_SAMA5D2_XYZ_MASK;
+	if (scale == 0) {
+		dev_err(&iio_priv_to_dev(st)->dev, "scale is 0\n");
+		return 0;
+	}
+	result /= scale;
+
+	return result;
+}
+
+static u16 at91_adc_touch_x_pos(struct at91_adc_state *st)
+{
+	st->touch_st.x_pos = at91_adc_touch_pos(st, AT91_SAMA5D2_XPOSR);
+	return st->touch_st.x_pos;
+}
+
+static u16 at91_adc_touch_y_pos(struct at91_adc_state *st)
+{
+	return at91_adc_touch_pos(st, AT91_SAMA5D2_YPOSR);
+}
+
+static u16 at91_adc_touch_pressure(struct at91_adc_state *st)
+{
+	u32 val;
+	u32 z1, z2;
+	u32 pres;
+	u32 rxp = 1;
+	u32 factor = 1000;
+
+	/* calculate the pressure */
+	val = at91_adc_readl(st, AT91_SAMA5D2_PRESSR);
+	z1 = val & AT91_SAMA5D2_XYZ_MASK;
+	z2 = (val >> 16) & AT91_SAMA5D2_XYZ_MASK;
+
+	if (z1 != 0)
+		pres = rxp * (st->touch_st.x_pos * factor / 1024) *
+			(z2 * factor / z1 - factor) /
+			factor;
+	else
+		pres = 0xFFFF;       /* no pen contact */
+
+	/*
+	 * The pressure from device grows down, minimum is 0xFFFF, maximum 0x0.
+	 * We compute it this way, but let's return it in the expected way,
+	 * growing from 0 to 0xFFFF.
+	 */
+	return 0xFFFF - pres;
+}
+
+static int at91_adc_read_position(struct at91_adc_state *st, int chan, u16 *val)
+{
+	*val = 0;
+	if (!st->touch_st.touching)
+		return -ENODATA;
+	if (chan == AT91_SAMA5D2_TOUCH_X_CHAN_IDX)
+		*val = at91_adc_touch_x_pos(st);
+	else if (chan == AT91_SAMA5D2_TOUCH_Y_CHAN_IDX)
+		*val = at91_adc_touch_y_pos(st);
+	else
+		return -ENODATA;
+
+	return IIO_VAL_INT;
+}
+
+static int at91_adc_read_pressure(struct at91_adc_state *st, int chan, u16 *val)
+{
+	*val = 0;
+	if (!st->touch_st.touching)
+		return -ENODATA;
+	if (chan == AT91_SAMA5D2_TOUCH_P_CHAN_IDX)
+		*val = at91_adc_touch_pressure(st);
+	else
+		return -ENODATA;
+
+	return IIO_VAL_INT;
+}
+
 static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
 {
 	struct iio_dev *indio = iio_trigger_get_drvdata(trig);

@@ -375,6 +644,11 @@ static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
 
 		if (!chan)
 			continue;
+		/* these channel types cannot be handled by this trigger */
+		if (chan->type == IIO_POSITIONRELATIVE ||
+		    chan->type == IIO_PRESSURE)
+			continue;
+
 		if (state) {
 			at91_adc_writel(st, AT91_SAMA5D2_CHER,
 					BIT(chan->channel));

@@ -520,7 +794,20 @@ static int at91_adc_dma_start(struct iio_dev *indio_dev)
 static int at91_adc_buffer_postenable(struct iio_dev *indio_dev)
 {
 	int ret;
+	struct at91_adc_state *st = iio_priv(indio_dev);
 
+	/* check if we are enabling triggered buffer or the touchscreen */
+	if (bitmap_subset(indio_dev->active_scan_mask,
+			  &st->touch_st.channels_bitmask,
+			  AT91_SAMA5D2_MAX_CHAN_IDX + 1)) {
+		/* touchscreen enabling */
+		return at91_adc_configure_touch(st, true);
+	}
+	/* if we are not in triggered mode, we cannot enable the buffer. */
+	if (!(indio_dev->currentmode & INDIO_ALL_TRIGGERED_MODES))
+		return -EINVAL;
+
+	/* we continue with the triggered buffer */
 	ret = at91_adc_dma_start(indio_dev);
 	if (ret) {
 		dev_err(&indio_dev->dev, "buffer postenable failed\n");

@@ -536,6 +823,18 @@ static int at91_adc_buffer_predisable(struct iio_dev *indio_dev)
 	int ret;
 	u8 bit;
 
+	/* check if we are disabling triggered buffer or the touchscreen */
+	if (bitmap_subset(indio_dev->active_scan_mask,
+			  &st->touch_st.channels_bitmask,
+			  AT91_SAMA5D2_MAX_CHAN_IDX + 1)) {
+		/* touchscreen disable */
+		return at91_adc_configure_touch(st, false);
+	}
+	/* if we are not in triggered mode, nothing to do here */
+	if (!(indio_dev->currentmode & INDIO_ALL_TRIGGERED_MODES))
+		return -EINVAL;
+
+	/* continue with the triggered buffer */
 	ret = iio_triggered_buffer_predisable(indio_dev);
 	if (ret < 0)
 		dev_err(&indio_dev->dev, "buffer predisable failed\n");

@@ -558,6 +857,10 @@ static int at91_adc_buffer_predisable(struct iio_dev *indio_dev)
 
 		if (!chan)
 			continue;
+		/* these channel types are virtual, no need to do anything */
+		if (chan->type == IIO_POSITIONRELATIVE ||
+		    chan->type == IIO_PRESSURE)
+			continue;
 		if (st->dma_st.dma_chan)
 			at91_adc_readl(st, chan->address);
 	}

@@ -622,7 +925,22 @@ static void at91_adc_trigger_handler_nodma(struct iio_dev *indio_dev,
 
 		if (!chan)
 			continue;
-		st->buffer[i] = at91_adc_readl(st, chan->address);
+		/*
+		 * Our external trigger only supports the voltage channels.
+		 * In case someone requested a different type of channel
+		 * just put zeroes to buffer.
+		 * This should not happen because we check the scan mode
+		 * and scan mask when we enable the buffer, and we don't allow
+		 * the buffer to start with a mixed mask (voltage and something
+		 * else).
+		 * Thus, emit a warning.
+		 */
+		if (chan->type == IIO_VOLTAGE) {
+			st->buffer[i] = at91_adc_readl(st, chan->address);
+		} else {
+			st->buffer[i] = 0;
+			WARN(true, "This trigger cannot handle this type of channel");
+		}
 		i++;
 	}
 	iio_push_to_buffers_with_timestamp(indio_dev, st->buffer,

@@ -688,9 +1006,20 @@ static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
 
 static int at91_adc_buffer_init(struct iio_dev *indio)
 {
-	return devm_iio_triggered_buffer_setup(&indio->dev, indio,
+	struct at91_adc_state *st = iio_priv(indio);
+
+	if (st->selected_trig->hw_trig) {
+		return devm_iio_triggered_buffer_setup(&indio->dev, indio,
 			&iio_pollfunc_store_time,
 			&at91_adc_trigger_handler, &at91_buffer_setup_ops);
+	}
+	/*
+	 * we need to prepare the buffer ops in case we will get
+	 * another buffer attached (like a callback buffer for the touchscreen)
+	 */
+	indio->setup_ops = &at91_buffer_setup_ops;
+
+	return 0;
 }
 
 static unsigned at91_adc_startup_time(unsigned startup_time_min,

@@ -736,19 +1065,83 @@ static void at91_adc_setup_samp_freq(struct at91_adc_state *st, unsigned freq)
 
 	dev_dbg(&indio_dev->dev, "freq: %u, startup: %u, prescal: %u\n",
 		freq, startup, prescal);
+	st->current_sample_rate = freq;
 }
 
-static unsigned at91_adc_get_sample_freq(struct at91_adc_state *st)
+static inline unsigned at91_adc_get_sample_freq(struct at91_adc_state *st)
 {
-	unsigned f_adc, f_per = clk_get_rate(st->per_clk);
-	unsigned mr, prescal;
+	return st->current_sample_rate;
+}
 
-	mr = at91_adc_readl(st, AT91_SAMA5D2_MR);
-	prescal = (mr >> AT91_SAMA5D2_MR_PRESCAL_OFFSET)
-		  & AT91_SAMA5D2_MR_PRESCAL_MAX;
-	f_adc = f_per / (2 * (prescal + 1));
+static void at91_adc_touch_data_handler(struct iio_dev *indio_dev)
+{
+	struct at91_adc_state *st = iio_priv(indio_dev);
+	u8 bit;
+	u16 val;
+	int i = 0;
 
-	return f_adc;
+	for_each_set_bit(bit, indio_dev->active_scan_mask,
+			 AT91_SAMA5D2_MAX_CHAN_IDX + 1) {
+		struct iio_chan_spec const *chan =
+					 at91_adc_chan_get(indio_dev, bit);
+
+		if (chan->type == IIO_POSITIONRELATIVE)
+			at91_adc_read_position(st, chan->channel, &val);
+		else if (chan->type == IIO_PRESSURE)
+			at91_adc_read_pressure(st, chan->channel, &val);
+		else
+			continue;
+		st->buffer[i] = val;
+		i++;
+	}
+	/*
+	 * Schedule work to push to buffers.
+	 * This is intended to push to the callback buffer that another driver
+	 * registered. We are still in a handler from our IRQ. If we push
+	 * directly, it means the other driver has it's callback called
+	 * from our IRQ context. Which is something we better avoid.
+	 * Let's schedule it after our IRQ is completed.
+	 */
+	schedule_work(&st->touch_st.workq);
+}
+
+static void at91_adc_pen_detect_interrupt(struct at91_adc_state *st)
+{
+	at91_adc_writel(st, AT91_SAMA5D2_IDR, AT91_SAMA5D2_IER_PEN);
+	at91_adc_writel(st, AT91_SAMA5D2_IER, AT91_SAMA5D2_IER_NOPEN |
+			AT91_SAMA5D2_IER_XRDY | AT91_SAMA5D2_IER_YRDY |
+			AT91_SAMA5D2_IER_PRDY);
+	at91_adc_writel(st, AT91_SAMA5D2_TRGR,
+			AT91_SAMA5D2_TRGR_TRGMOD_PERIODIC |
+			AT91_SAMA5D2_TRGR_TRGPER(st->touch_st.sample_period_val));
+	st->touch_st.touching = true;
+}
+
+static void at91_adc_no_pen_detect_interrupt(struct at91_adc_state *st)
+{
+	struct iio_dev *indio_dev = iio_priv_to_dev(st);
+
+	at91_adc_writel(st, AT91_SAMA5D2_TRGR,
+			AT91_SAMA5D2_TRGR_TRGMOD_NO_TRIGGER);
+	at91_adc_writel(st, AT91_SAMA5D2_IDR, AT91_SAMA5D2_IER_NOPEN |
+			AT91_SAMA5D2_IER_XRDY | AT91_SAMA5D2_IER_YRDY |
+			AT91_SAMA5D2_IER_PRDY);
+	st->touch_st.touching = false;
+
+	at91_adc_touch_data_handler(indio_dev);
+
+	at91_adc_writel(st, AT91_SAMA5D2_IER, AT91_SAMA5D2_IER_PEN);
+}
+
+static void at91_adc_workq_handler(struct work_struct *workq)
+{
+	struct at91_adc_touch *touch_st = container_of(workq,
+					struct at91_adc_touch, workq);
+	struct at91_adc_state *st = container_of(touch_st,
+					struct at91_adc_state, touch_st);
+	struct iio_dev *indio_dev = iio_priv_to_dev(st);
+
+	iio_push_to_buffers(indio_dev, st->buffer);
 }
 
 static irqreturn_t at91_adc_interrupt(int irq, void *private)

@@ -757,17 +1150,39 @@ static irqreturn_t at91_adc_interrupt(int irq, void *private)
 	struct at91_adc_state *st = iio_priv(indio);
 	u32 status = at91_adc_readl(st, AT91_SAMA5D2_ISR);
 	u32 imr = at91_adc_readl(st, AT91_SAMA5D2_IMR);
+	u32 rdy_mask = AT91_SAMA5D2_IER_XRDY | AT91_SAMA5D2_IER_YRDY |
+			AT91_SAMA5D2_IER_PRDY;
 
 	if (!(status & imr))
 		return IRQ_NONE;
-
-	if (iio_buffer_enabled(indio) && !st->dma_st.dma_chan) {
+	if (status & AT91_SAMA5D2_IER_PEN) {
+		/* pen detected IRQ */
+		at91_adc_pen_detect_interrupt(st);
+	} else if ((status & AT91_SAMA5D2_IER_NOPEN)) {
+		/* nopen detected IRQ */
+		at91_adc_no_pen_detect_interrupt(st);
+	} else if ((status & AT91_SAMA5D2_ISR_PENS) &&
+		   ((status & rdy_mask) == rdy_mask)) {
+		/* periodic trigger IRQ - during pen sense */
+		at91_adc_touch_data_handler(indio);
+	} else if (status & AT91_SAMA5D2_ISR_PENS) {
+		/*
+		 * touching, but the measurements are not ready yet.
+		 * read and ignore.
+		 */
+		status = at91_adc_readl(st, AT91_SAMA5D2_XPOSR);
+		status = at91_adc_readl(st, AT91_SAMA5D2_YPOSR);
+		status = at91_adc_readl(st, AT91_SAMA5D2_PRESSR);
+	} else if (iio_buffer_enabled(indio) && !st->dma_st.dma_chan) {
+		/* triggered buffer without DMA */
 		disable_irq_nosync(irq);
 		iio_trigger_poll(indio->trig);
 	} else if (iio_buffer_enabled(indio) && st->dma_st.dma_chan) {
+		/* triggered buffer with DMA - should not happen */
 		disable_irq_nosync(irq);
 		WARN(true, "Unexpected irq occurred\n");
 	} else if (!iio_buffer_enabled(indio)) {
+		/* software requested conversion */
 		st->conversion_value = at91_adc_readl(st, st->chan->address);
 		st->conversion_done = true;
 		wake_up_interruptible(&st->wq_data_available);

@@ -775,58 +1190,97 @@ static irqreturn_t at91_adc_interrupt(int irq, void *private)
 	return IRQ_HANDLED;
 }
 
-static int at91_adc_read_raw(struct iio_dev *indio_dev,
-			     struct iio_chan_spec const *chan,
-			     int *val, int *val2, long mask)
+static int at91_adc_read_info_raw(struct iio_dev *indio_dev,
+				  struct iio_chan_spec const *chan, int *val)
 {
 	struct at91_adc_state *st = iio_priv(indio_dev);
 	u32 cor = 0;
 	int ret;
 
-	switch (mask) {
-	case IIO_CHAN_INFO_RAW:
-		/* we cannot use software trigger if hw trigger enabled */
+	/*
+	 * Keep in mind that we cannot use software trigger or touchscreen
+	 * if external trigger is enabled
+	 */
+	if (chan->type == IIO_POSITIONRELATIVE) {
 		ret = iio_device_claim_direct_mode(indio_dev);
 		if (ret)
 			return ret;
 		mutex_lock(&st->lock);
 
-		st->chan = chan;
+		ret = at91_adc_read_position(st, chan->channel,
+					     (u16 *)val);
+		mutex_unlock(&st->lock);
+		iio_device_release_direct_mode(indio_dev);
 
-		if (chan->differential)
-			cor = (BIT(chan->channel) | BIT(chan->channel2)) <<
-			      AT91_SAMA5D2_COR_DIFF_OFFSET;
-
-		at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
-		at91_adc_writel(st, AT91_SAMA5D2_CHER, BIT(chan->channel));
-		at91_adc_writel(st, AT91_SAMA5D2_IER, BIT(chan->channel));
-		at91_adc_writel(st, AT91_SAMA5D2_CR, AT91_SAMA5D2_CR_START);
-
-		ret = wait_event_interruptible_timeout(st->wq_data_available,
-						       st->conversion_done,
-						       msecs_to_jiffies(1000));
-		if (ret == 0)
-			ret = -ETIMEDOUT;
-
-		if (ret > 0) {
-			*val = st->conversion_value;
-			if (chan->scan_type.sign == 's')
-				*val = sign_extend32(*val, 11);
-			ret = IIO_VAL_INT;
-			st->conversion_done = false;
-		}
+		return ret;
+	}
+	if (chan->type == IIO_PRESSURE) {
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret)
+			return ret;
+		mutex_lock(&st->lock);
 
-		at91_adc_writel(st, AT91_SAMA5D2_IDR, BIT(chan->channel));
-		at91_adc_writel(st, AT91_SAMA5D2_CHDR, BIT(chan->channel));
+		ret = at91_adc_read_pressure(st, chan->channel,
+					     (u16 *)val);
+		mutex_unlock(&st->lock);
+		iio_device_release_direct_mode(indio_dev);
 
-		/* Needed to ACK the DRDY interruption */
-		at91_adc_readl(st, AT91_SAMA5D2_LCDR);
+		return ret;
+	}
 
-		mutex_unlock(&st->lock);
+	/* in this case we have a voltage channel */
 
-		iio_device_release_direct_mode(indio_dev);
+	ret = iio_device_claim_direct_mode(indio_dev);
+	if (ret)
 		return ret;
+	mutex_lock(&st->lock);
+
+	st->chan = chan;
+
+	if (chan->differential)
+		cor = (BIT(chan->channel) | BIT(chan->channel2)) <<
+		      AT91_SAMA5D2_COR_DIFF_OFFSET;
+
+	at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
+	at91_adc_writel(st, AT91_SAMA5D2_CHER, BIT(chan->channel));
+	at91_adc_writel(st, AT91_SAMA5D2_IER, BIT(chan->channel));
+	at91_adc_writel(st, AT91_SAMA5D2_CR, AT91_SAMA5D2_CR_START);
+
+	ret = wait_event_interruptible_timeout(st->wq_data_available,
+					       st->conversion_done,
+					       msecs_to_jiffies(1000));
+	if (ret == 0)
+		ret = -ETIMEDOUT;
+
+	if (ret > 0) {
+		*val = st->conversion_value;
+		if (chan->scan_type.sign == 's')
+			*val = sign_extend32(*val, 11);
+		ret = IIO_VAL_INT;
+		st->conversion_done = false;
+	}
+
+	at91_adc_writel(st, AT91_SAMA5D2_IDR, BIT(chan->channel));
+	at91_adc_writel(st, AT91_SAMA5D2_CHDR, BIT(chan->channel));
+
+	/* Needed to ACK the DRDY interruption */
+	at91_adc_readl(st, AT91_SAMA5D2_LCDR);
+
+	mutex_unlock(&st->lock);
+
+	iio_device_release_direct_mode(indio_dev);
+	return ret;
+}
+
+static int at91_adc_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int *val, int *val2, long mask)
+{
+	struct at91_adc_state *st = iio_priv(indio_dev);
 
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		return at91_adc_read_info_raw(indio_dev, chan, val);
 	case IIO_CHAN_INFO_SCALE:
 		*val = st->vref_uv / 1000;
 		if (chan->differential)

@@ -974,9 +1428,29 @@ static int at91_adc_set_watermark(struct iio_dev *indio_dev, unsigned int val)
 	return 0;
 }
 
+static int at91_adc_update_scan_mode(struct iio_dev *indio_dev,
+				     const unsigned long *scan_mask)
+{
+	struct at91_adc_state *st = iio_priv(indio_dev);
+
+	if (bitmap_subset(scan_mask, &st->touch_st.channels_bitmask,
+			  AT91_SAMA5D2_MAX_CHAN_IDX + 1))
+		return 0;
+	/*
+	 * if the new bitmap is a combination of touchscreen and regular
+	 * channels, then we are not fine
+	 */
+	if (bitmap_intersects(&st->touch_st.channels_bitmask, scan_mask,
+			      AT91_SAMA5D2_MAX_CHAN_IDX + 1))
+		return -EINVAL;
+	return 0;
+}
+
 static const struct iio_info at91_adc_info = {
 	.read_raw = &at91_adc_read_raw,
 	.write_raw = &at91_adc_write_raw,
+	.update_scan_mode = &at91_adc_update_scan_mode,
+	.of_xlate = &at91_adc_of_xlate,
 	.hwfifo_set_watermark = &at91_adc_set_watermark,
 };
 

@@ -1044,13 +1518,20 @@ static int at91_adc_probe(struct platform_device *pdev)
 
 	indio_dev->dev.parent = &pdev->dev;
 	indio_dev->name = dev_name(&pdev->dev);
-	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_SOFTWARE;
 	indio_dev->info = &at91_adc_info;
 	indio_dev->channels = at91_adc_channels;
 	indio_dev->num_channels = ARRAY_SIZE(at91_adc_channels);
 
 	st = iio_priv(indio_dev);
 
+	bitmap_set(&st->touch_st.channels_bitmask,
+		   AT91_SAMA5D2_TOUCH_X_CHAN_IDX, 1);
+	bitmap_set(&st->touch_st.channels_bitmask,
+		   AT91_SAMA5D2_TOUCH_Y_CHAN_IDX, 1);
+	bitmap_set(&st->touch_st.channels_bitmask,
+		   AT91_SAMA5D2_TOUCH_P_CHAN_IDX, 1);
+
 	ret = of_property_read_u32(pdev->dev.of_node,
 				   "atmel,min-sample-rate-hz",
 				   &st->soc_info.min_sample_rate);

@@ -1100,6 +1581,7 @@ static int at91_adc_probe(struct platform_device *pdev)
 
 	init_waitqueue_head(&st->wq_data_available);
 	mutex_init(&st->lock);
+	INIT_WORK(&st->touch_st.workq, at91_adc_workq_handler);
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!res)

@@ -1159,13 +1641,13 @@ static int at91_adc_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, indio_dev);
 
-	if (st->selected_trig->hw_trig) {
-		ret = at91_adc_buffer_init(indio_dev);
-		if (ret < 0) {
-			dev_err(&pdev->dev, "couldn't initialize the buffer.\n");
-			goto per_clk_disable_unprepare;
-		}
+	ret = at91_adc_buffer_init(indio_dev);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "couldn't initialize the buffer.\n");
+		goto per_clk_disable_unprepare;
+	}
 
+	if (st->selected_trig->hw_trig) {
 		ret = at91_adc_trigger_init(indio_dev);
 		if (ret < 0) {
 			dev_err(&pdev->dev, "couldn't setup the triggers.\n");

@@ -1272,9 +1754,20 @@ static __maybe_unused int at91_adc_resume(struct device *dev)
 	at91_adc_hw_init(st);
 
 	/* reconfiguring trigger hardware state */
-	if (iio_buffer_enabled(indio_dev))
-		at91_adc_configure_trigger(st->trig, true);
+	if (!iio_buffer_enabled(indio_dev))
+		return 0;
+
+	/* check if we are enabling triggered buffer or the touchscreen */
+	if (bitmap_subset(indio_dev->active_scan_mask,
+			  &st->touch_st.channels_bitmask,
+			  AT91_SAMA5D2_MAX_CHAN_IDX + 1)) {
+		/* touchscreen enabling */
+		return at91_adc_configure_touch(st, true);
+	} else {
+		return at91_adc_configure_trigger(st->trig, true);
+	}
 
+	/* not needed but more explicit */
 	return 0;
 
 vref_disable_resume:

Signature · 1 line

2.7.4

This adds a generic resistive touchscreen (GRTS) driver, which is based on an IIO device (an ADC). It must be connected to the channels of an ADC to receive touch data. Then it will feed the data into the input subsystem where it registers an input device.
It uses an IIO callback buffer to register to the IIO device

Some parts of this patch are based on initial original work by Mohamed Jamsheeth Hajanajubudeen and Bandaru Venkateswara Swamy

Signed-off-by Eugen Hristev <[email protected]>

Acked-by Dmitry Torokhov <[email protected]>

---
Changes in v7:
- cosmetic fixes as suggested by Dmitry: moved min pressure
property lookup below and only if pressure channel is available. used the error variable in probe at some point, removed it at different point.

Changes in v6:
- changed a dev_err to dev_dbg which was forgotten in v5.

Changes in v5:
- return error on probe if failed add_action_or_reset
- renamed property touchscreen-threshold-pressure to
touchscreen-min-pressure, changed variables accordingly

Changes in v4:
- added a small description in file header
- changed MAX_POS_MASK to GRTS_MAX_POS_MASK
- initialized press with 0, as this value means no touch.
press has to be initialized because compiler/checkpatch complains that can be used uninitialized.
- changed of_property_read_u32 to device_*
- set_abs_params for pressure will have range according to threshold
- changed evbit and keybit with set_capability call
- changed variable names to error instead of ret
- checked errors for add_action_or_reset
- cosmetic cleaning

Changes in v3:
- pressure now reported naturally growing down-up
- using helpers from touchscreen.h to parse DT properties
- added devm_add_action_or_reset to handle callback buffer clean on exit
- changed compatible and threshold property to adapt to changed bindings

Changes in v2:
- this is now a generic resistive adc touchscreen driver

 drivers/input/touchscreen/Kconfig               |  13 ++
 drivers/input/touchscreen/Makefile              |   1 +
 drivers/input/touchscreen/resistive-adc-touch.c | 204 ++++++++++++++++++++++++
 3 files changed, 218 insertions(+)
 create mode 100644 drivers/input/touchscreen/resistive-adc-touch.c

drivers/input/touchscreen/Kconfig +13 -0

index 4f15496..8f85d3a 100644
@@ -92,6 +92,19 @@ config TOUCHSCREEN_AD7879_SPI
 	  To compile this driver as a module, choose M here: the
 	  module will be called ad7879-spi.
 
+config TOUCHSCREEN_ADC
+	tristate "Generic ADC based resistive touchscreen"
+	depends on IIO
+	select IIO_BUFFER_CB
+	help
+	  Say Y here if you want to use the generic ADC
+	  resistive touchscreen driver.
+
+	  If unsure, say N (but it's safe to say "Y").
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called resistive-adc-touch.ko.
+
 config TOUCHSCREEN_AR1021_I2C
 	tristate "Microchip AR1020/1021 i2c touchscreen"
 	depends on I2C && OF

drivers/input/touchscreen/Makefile +1 -0

index dddae79..843c7f9 100644
@@ -13,6 +13,7 @@ obj-$(CONFIG_TOUCHSCREEN_AD7877)	+= ad7877.o
 obj-$(CONFIG_TOUCHSCREEN_AD7879)	+= ad7879.o
 obj-$(CONFIG_TOUCHSCREEN_AD7879_I2C)	+= ad7879-i2c.o
 obj-$(CONFIG_TOUCHSCREEN_AD7879_SPI)	+= ad7879-spi.o
+obj-$(CONFIG_TOUCHSCREEN_ADC)		+= resistive-adc-touch.o
 obj-$(CONFIG_TOUCHSCREEN_ADS7846)	+= ads7846.o
 obj-$(CONFIG_TOUCHSCREEN_AR1021_I2C)	+= ar1021_i2c.o
 obj-$(CONFIG_TOUCHSCREEN_ATMEL_MXT)	+= atmel_mxt_ts.o

drivers/input/touchscreen/resistive-adc-touch.c new file +204 -0

new file mode 100644
index 0000000..cfc8bb4
@@ -0,0 +1,204 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ADC generic resistive touchscreen (GRTS)
+ * This is a generic input driver that connects to an ADC
+ * given the channels in device tree, and reports events to the input
+ * subsystem.
+ *
+ * Copyright (C) 2017,2018 Microchip Technology,
+ * Author: Eugen Hristev <[email protected]>
+ *
+ */
+#include <linux/input.h>
+#include <linux/input/touchscreen.h>
+#include <linux/iio/consumer.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+
+#define DRIVER_NAME					"resistive-adc-touch"
+#define GRTS_DEFAULT_PRESSURE_MIN			50000
+#define GRTS_MAX_POS_MASK				GENMASK(11, 0)
+
+/**
+ * grts_state - generic resistive touch screen information struct
+ * @pressure_min:	number representing the minimum for the pressure
+ * @pressure:		are we getting pressure info or not
+ * @iio_chans:		list of channels acquired
+ * @iio_cb:		iio_callback buffer for the data
+ * @input:		the input device structure that we register
+ * @prop:		touchscreen properties struct
+ */
+struct grts_state {
+	u32				pressure_min;
+	bool				pressure;
+	struct iio_channel		*iio_chans;
+	struct iio_cb_buffer		*iio_cb;
+	struct input_dev		*input;
+	struct touchscreen_properties	prop;
+};
+
+static int grts_cb(const void *data, void *private)
+{
+	const u16 *touch_info = data;
+	struct grts_state *st = private;
+	unsigned int x, y, press = 0x0;
+
+	/* channel data coming in buffer in the order below */
+	x = touch_info[0];
+	y = touch_info[1];
+	if (st->pressure)
+		press = touch_info[2];
+
+	if ((!x && !y) || (st->pressure && (press < st->pressure_min))) {
+		/* report end of touch */
+		input_report_key(st->input, BTN_TOUCH, 0);
+		input_sync(st->input);
+		return 0;
+	}
+
+	/* report proper touch to subsystem*/
+	touchscreen_report_pos(st->input, &st->prop, x, y, false);
+	if (st->pressure)
+		input_report_abs(st->input, ABS_PRESSURE, press);
+	input_report_key(st->input, BTN_TOUCH, 1);
+	input_sync(st->input);
+
+	return 0;
+}
+
+static int grts_open(struct input_dev *dev)
+{
+	int error;
+	struct grts_state *st = input_get_drvdata(dev);
+
+	error = iio_channel_start_all_cb(st->iio_cb);
+	if (error) {
+		dev_err(dev->dev.parent, "failed to start callback buffer.\n");
+		return error;
+	}
+	return 0;
+}
+
+static void grts_close(struct input_dev *dev)
+{
+	struct grts_state *st = input_get_drvdata(dev);
+
+	iio_channel_stop_all_cb(st->iio_cb);
+}
+
+static void grts_disable(void *data)
+{
+	iio_channel_release_all_cb(data);
+}
+
+static int grts_probe(struct platform_device *pdev)
+{
+	struct grts_state *st;
+	struct input_dev *input;
+	struct device *dev = &pdev->dev;
+	struct iio_channel *chan;
+	int error;
+
+	st = devm_kzalloc(dev, sizeof(struct grts_state), GFP_KERNEL);
+	if (!st)
+		return -ENOMEM;
+
+	/* get the channels from IIO device */
+	st->iio_chans = devm_iio_channel_get_all(dev);
+	if (IS_ERR(st->iio_chans)) {
+		error = PTR_ERR(st->iio_chans);
+		if (error != -EPROBE_DEFER)
+			dev_err(dev, "can't get iio channels.\n");
+		return error;
+	}
+
+	chan = &st->iio_chans[0];
+	st->pressure = false;
+	while (chan && chan->indio_dev) {
+		if (!strcmp(chan->channel->datasheet_name, "pressure"))
+			st->pressure = true;
+		chan++;
+	}
+
+	if (st->pressure) {
+		error = device_property_read_u32(dev,
+						 "touchscreen-min-pressure",
+						 &st->pressure_min);
+		if (error) {
+			dev_dbg(dev, "can't get touchscreen-min-pressure property.\n");
+			st->pressure_min = GRTS_DEFAULT_PRESSURE_MIN;
+		}
+	}
+
+	input = devm_input_allocate_device(dev);
+	if (!input) {
+		dev_err(dev, "failed to allocate input device.\n");
+		return -ENOMEM;
+	}
+
+	input->name = DRIVER_NAME;
+	input->id.bustype = BUS_HOST;
+	input->open = grts_open;
+	input->close = grts_close;
+
+	input_set_abs_params(input, ABS_X, 0, GRTS_MAX_POS_MASK - 1, 0, 0);
+	input_set_abs_params(input, ABS_Y, 0, GRTS_MAX_POS_MASK - 1, 0, 0);
+	if (st->pressure)
+		input_set_abs_params(input, ABS_PRESSURE, st->pressure_min,
+				     0xffff, 0, 0);
+
+	input_set_capability(input, EV_KEY, BTN_TOUCH);
+
+	/* parse optional device tree properties */
+	touchscreen_parse_properties(input, false, &st->prop);
+
+	st->input = input;
+	input_set_drvdata(input, st);
+
+	error = input_register_device(input);
+	if (error) {
+		dev_err(dev, "failed to register input device.");
+		return error;
+	}
+
+	st->iio_cb = iio_channel_get_all_cb(dev, grts_cb, st);
+	if (IS_ERR(st->iio_cb)) {
+		dev_err(dev, "failed to allocate callback buffer.\n");
+		return PTR_ERR(st->iio_cb);
+	}
+
+	error = devm_add_action_or_reset(dev, grts_disable, st->iio_cb);
+	if (error) {
+		dev_err(dev, "failed to add disable action.\n");
+		return error;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id grts_of_match[] = {
+	{
+		.compatible = "resistive-adc-touch",
+	}, {
+		/* sentinel */
+	},
+};
+
+MODULE_DEVICE_TABLE(of, grts_of_match);
+
+static struct platform_driver grts_driver = {
+	.probe = grts_probe,
+	.driver = {
+		.name = DRIVER_NAME,
+		.of_match_table = of_match_ptr(grts_of_match),
+	},
+};
+
+module_platform_driver(grts_driver);
+
+MODULE_AUTHOR("Eugen Hristev <[email protected]>");
+MODULE_DESCRIPTION("Generic ADC Resistive Touch Driver");
+MODULE_LICENSE("GPL v2");

Added defines for channel consumer device-tree binding

Signed-off-by Eugen Hristev <[email protected]>

Reviewed-by Rob Herring <[email protected]>

---
 .../devicetree/bindings/iio/adc/at91-sama5d2_adc.txt     |  9 +++++++++
 include/dt-bindings/iio/adc/at91-sama5d2_adc.h           | 16 ++++++++++++++++
 2 files changed, 25 insertions(+)
 create mode 100644 include/dt-bindings/iio/adc/at91-sama5d2_adc.h

Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt +9 -0

index 6469a4c..4a3c1d4 100644
@@ -21,6 +21,14 @@ Optional properties:
   - dmas: Phandle to dma channel for the ADC.
   - dma-names: Must be "rx" when dmas property is being used.
   See ../../dma/dma.txt for details.
+  - #io-channel-cells: in case consumer drivers are attached, this must be 1.
+  See <Documentation/devicetree/bindings/iio/iio-bindings.txt> for details.
+
+Properties for consumer drivers:
+  - Consumer drivers can be connected to this producer device, as specified
+  in <Documentation/devicetree/bindings/iio/iio-bindings.txt>
+  - Channels exposed are specified in:
+  <dt-bindings/iio/adc/at91-sama5d2_adc.txt>
 
 Example:
 

@@ -38,4 +46,5 @@ adc: adc at fc030000 {
 	atmel,trigger-edge-type = <IRQ_TYPE_EDGE_BOTH>;
 	dmas = <&dma0 (AT91_XDMAC_DT_MEM_IF(0) | AT91_XDMAC_DT_PER_IF(1) | AT91_XDMAC_DT_PERID(25))>;
 	dma-names = "rx";
+	#io-channel-cells = <1>;
 }

include/dt-bindings/iio/adc/at91-sama5d2_adc.h new file +16 -0

new file mode 100644
index 0000000..70f99db
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * This header provides constants for configuring the AT91 SAMA5D2 ADC
+ */
+
+#ifndef _DT_BINDINGS_IIO_ADC_AT91_SAMA5D2_ADC_H
+#define _DT_BINDINGS_IIO_ADC_AT91_SAMA5D2_ADC_H
+
+/* X relative position channel index */
+#define AT91_SAMA5D2_ADC_X_CHANNEL		24
+/* Y relative position channel index */
+#define AT91_SAMA5D2_ADC_Y_CHANNEL		25
+/* pressure channel index */
+#define AT91_SAMA5D2_ADC_P_CHANNEL		26
+
+#endif

Signature · 1 line

2.7.4

Quoted 4 lines · Eugen Hristev

Added defines for channel consumer device-tree binding

Signed-off-by Eugen Hristev <[email protected]>

Reviewed-by Rob Herring <[email protected]>

Acked-by Ludovic Desroches <[email protected]>

Quoted 57 lines

---
 .../devicetree/bindings/iio/adc/at91-sama5d2_adc.txt     |  9 +++++++++
 include/dt-bindings/iio/adc/at91-sama5d2_adc.h           | 16 ++++++++++++++++
 2 files changed, 25 insertions(+)
 create mode 100644 include/dt-bindings/iio/adc/at91-sama5d2_adc.h

Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt +9 -0

index 6469a4c..4a3c1d4 100644
@@ -21,6 +21,14 @@ Optional properties:
   - dmas: Phandle to dma channel for the ADC.
   - dma-names: Must be "rx" when dmas property is being used.
   See ../../dma/dma.txt for details.
+  - #io-channel-cells: in case consumer drivers are attached, this must be 1.
+  See <Documentation/devicetree/bindings/iio/iio-bindings.txt> for details.
+
+Properties for consumer drivers:
+  - Consumer drivers can be connected to this producer device, as specified
+  in <Documentation/devicetree/bindings/iio/iio-bindings.txt>
+  - Channels exposed are specified in:
+  <dt-bindings/iio/adc/at91-sama5d2_adc.txt>
 
 Example:
 

@@ -38,4 +46,5 @@ adc: adc at fc030000 {
 	atmel,trigger-edge-type = <IRQ_TYPE_EDGE_BOTH>;
 	dmas = <&dma0 (AT91_XDMAC_DT_MEM_IF(0) | AT91_XDMAC_DT_PER_IF(1) | AT91_XDMAC_DT_PERID(25))>;
 	dma-names = "rx";
+	#io-channel-cells = <1>;
 }

include/dt-bindings/iio/adc/at91-sama5d2_adc.h new file +16 -0

new file mode 100644
index 0000000..70f99db
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * This header provides constants for configuring the AT91 SAMA5D2 ADC
+ */
+
+#ifndef _DT_BINDINGS_IIO_ADC_AT91_SAMA5D2_ADC_H
+#define _DT_BINDINGS_IIO_ADC_AT91_SAMA5D2_ADC_H
+
+/* X relative position channel index */
+#define AT91_SAMA5D2_ADC_X_CHANNEL		24
+/* Y relative position channel index */
+#define AT91_SAMA5D2_ADC_Y_CHANNEL		25
+/* pressure channel index */
+#define AT91_SAMA5D2_ADC_P_CHANNEL		26
+
+#endif

Signature · 1 line

2.7.4

Preparing the ADC device to connect channel consumer drivers

Signed-off-by Eugen Hristev <[email protected]>

---
 arch/arm/boot/dts/sama5d2.dtsi | 2 ++
 1 file changed, 2 insertions(+)

arch/arm/boot/dts/sama5d2.dtsi +2 -0

index 61f68e5..f06ba99 100644
@@ -47,6 +47,7 @@
 #include <dt-bindings/dma/at91.h>
 #include <dt-bindings/interrupt-controller/irq.h>
 #include <dt-bindings/clock/at91.h>
+#include <dt-bindings/iio/adc/at91-sama5d2_adc.h>
 
 / {
 	model = "Atmel SAMA5D2 family SoC";

@@ -1437,6 +1438,7 @@
 				atmel,max-sample-rate-hz = <20000000>;
 				atmel,startup-time-ms = <4>;
 				atmel,trigger-edge-type = <IRQ_TYPE_EDGE_RISING>;
+				#io-channel-cells = <1>;
 				status = "disabled";
 			};
 

Add generic resistive touch device which is connected to ADC block inside the SAMA5D2 SoC

Signed-off-by Eugen Hristev <[email protected]>

---
Changes in v5:
- renamed touchscreen-threshold-pressure to touchscreen-min-pressure

 arch/arm/boot/dts/sama5d2.dtsi | 10 ++++++++++
 1 file changed, 10 insertions(+)

arch/arm/boot/dts/sama5d2.dtsi +10 -0

index f06ba99..a44f325 100644
@@ -1442,6 +1442,16 @@
 				status = "disabled";
 			};
 
+			resistive_touch: resistive-touch {
+				compatible = "resistive-adc-touch";
+				io-channels = <&adc AT91_SAMA5D2_ADC_X_CHANNEL>,
+					      <&adc AT91_SAMA5D2_ADC_Y_CHANNEL>,
+					      <&adc AT91_SAMA5D2_ADC_P_CHANNEL>;
+				io-channel-names = "x", "y", "pressure";
+				touchscreen-min-pressure = <50000>;
+				status = "disabled";
+			};
+
 			pioA: pinctrl at fc038000 {
 				compatible = "atmel,sama5d2-pinctrl";
 				reg = <0xfc038000 0x600>;

Hello,

This patch series is a rework of my previous series named:
[PATCH 00/14] iio: triggers: add consumer support

This is the version 7 of the series, and addresses the received feedback on the v2 series named:
[PATCH v2 00/10] Add support for SAMA5D2 touchscreen
and the v3 series named
[PATCH v3 00/11] Add support for SAMA5D2 touchscreen
and the v4 series named
[PATCH v4 0/9] Add support for SAMA5D2 touchscreen
and fixes one bug found in series named
[PATCH v5 0/9] Add support for SAMA5D2 touchscreen
and addresses comments in series named
[PATCH v6 0/9] Add support for SAMA5D2 touchscreen

This series applies on top of fixes-togreg branch of iio.git, specifically on top of commit:
"f0c8d1f" : iio: adc: at91-sama5d2_adc:
fix channel configuration for differential channels

Jonathan, if you need me to rebase this on top of testing, let me know.

Changes in previous versions are presented at the end of the cover letter below. Thanks everyone for the feedback. Below is the original v2 cover letter:

In few words, this is the implementation of splitting the functionality of the IP block ADC device in SAMA5D2 SoC from ADC with touchscreen support. In order to avoid having a MFD device, two separate drivers that would work on same register base and split the IRQ,etc, as advised on the mailing list, I created a consumer driver for the channels, that will connect to the ADC as described in the device tree.

I have collected feedback from everyone and here is the result:
I have added a new generic resistive touchscreen driver, which acts as a iio consumer for the given channels and will create an input device and report the events. It uses a callback buffer to register to the IIO device and waits for data to be pushed.
Inside the IIO device, I have kept a similar approach with the first version of the series, except that now the driver can take multiple buffers, and will configure the touchscreen part of the hardware device if the specific channels are requested.

The SAMA5D2 ADC driver registers three new channels: two for the position on the X and Y axis, and one for the touch pressure. When channels are requested, it will check if the touchscreen channel mask includes the requested channels (it is possible that the consumer driver will not request pressure for example). If it's the case, it will work in touchscreen mode, and will refuse to do usual analog-digital conversion, because we have a single trigger and the touchscreen needs it. When the scan mask will include only old channels, the driver will function in the same way as before. If the scan mask somehow is a mix of the two (the masks intersect), the driver will refuse to work whatsoever (cannot have both in the same time).
The driver allows reading raw data for the new channels, if claim direct mode works: no touchscreen driver requested anything. The new channels can act like the old ones. However, when requesting these channels, the usual trigger will not work and will not be enabled. The touchscreen channels require special trigger and irq configuration: pen detect, no pen detect and a periodic trigger to sample the touchscreen position and pressure. If the user attempts to use another trigger while there is a buffer that already requested the touchscreen channels (thus the trigger), the driver will refuse to comply.

In order to have defines for the channel numbers, I added a bindings include file that goes on a separate commit :
dt-bindings: iio: adc: at91-sama5d2_adc: add channel specific consumer info This should go in the same tree with the following commits :
ARM: dts: at91: sama5d2: add channel cells for ADC device
ARM: dts: at91: sama5d2: Add resistive touch device

as build will break because these commits depend on the binding one which creates the included header file.
V5 update: After discussing with Alexandre Belloni on Mailing list, the two DTS patches are to be taken in the next version after bindings reach mainline.

Changes in v7:
- Addressed some feedback from Dmitry, explained in input driver patch
changelog.
- Added Acked-by Dmitry.

Changes in v6:
- Fixed a crash in ADC driver , explained in driver patch changelog.
- changed a dev_err to dev_dbg in input driver.
- added Reviewed-by Rob Herring.

Changes in v5:
- renamed property touchscreen-threshold-pressure to touchscreen-min-pressure
- added one return in touchscreen driver

Changes in v4:
- removed patch for inkern module get/set kref
- addressed feedback on both the ADC and the touchscreen driver. each
patch has a history inside the patch file for the specific changes.
- patch that fixes the channel fix
[PATCH v3 01/11] iio: adc: at91-sama5d2_adc:
fix channel configuration for differential channels
was accepted in fixes-togreg branch thus removed from this series.
- added Reviewed-by for the bindings by Rob Herring

Changes in v3:
- changed input driver name according to feedback and reworked in commits
to adapt to binding changes and new name.
- moved channel index fix in at91-sama5d2_adc at the beginning of the series
(PATCH 01/11)
- created a new optional binding for the touchscreen as a separate commit
and added it to the series :
[PATCH v3 04/11] dt-bindings: input: touchscreen: add pressure threshold touchscreen property
- changed at91-sama5d2_adc driver patch to address the comments. Exact changes
are in the patch file for the driver source file.

Eugen Hristev (9):
MAINTAINERS: add generic resistive touchscreen adc
iio: Add channel for Position Relative
dt-bindings: input: touchscreen: add minimum pressure touchscreen
property
dt-bindings: input: touchscreen: resistive-adc-touch: create bindings
iio: adc: at91-sama5d2_adc: add support for position and pressure
channels
input: touchscreen: resistive-adc-touch: add generic resistive ADC
touchscreen
dt-bindings: iio: adc: at91-sama5d2_adc: add channel specific consumer
info
ARM: dts: at91: sama5d2: add channel cells for ADC device
ARM: dts: at91: sama5d2: Add resistive touch device

 Documentation/ABI/testing/sysfs-bus-iio            |  12 +
 .../bindings/iio/adc/at91-sama5d2_adc.txt          |   9 +
 .../input/touchscreen/resistive-adc-touch.txt      |  30 +
 .../bindings/input/touchscreen/touchscreen.txt     |   3 +
 MAINTAINERS                                        |   6 +
 arch/arm/boot/dts/sama5d2.dtsi                     |  12 +
 drivers/iio/adc/at91-sama5d2_adc.c                 | 609 +++++++++++++++++++--
 drivers/iio/industrialio-core.c                    |   1 +
 drivers/input/touchscreen/Kconfig                  |  13 +
 drivers/input/touchscreen/Makefile                 |   1 +

 drivers/input/touchscreen/resistive-adc-touch.c    | 204 +++++++
 include/dt-bindings/iio/adc/at91-sama5d2_adc.h     |  16 +
 include/uapi/linux/iio/types.h                     |   1 +
 tools/iio/iio_event_monitor.c                      |   2 +
 14 files changed, 861 insertions(+), 58 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.txt
 create mode 100644 drivers/input/touchscreen/resistive-adc-touch.c
 create mode 100644 include/dt-bindings/iio/adc/at91-sama5d2_adc.h