[RFCv2] staging/iio/adc: change the MXS touchscreen driver implementation

[RFCv2] staging/iio/adc: change the MXS touchscreen driver implementation

[Juergen Beisert]

The following series replaces the current busy loop touchscreen implementation
for i.MX28/i.MX23 SoCs by a fully interrupt driven implementation.

Since i.MX23 and i.Mx28 silicon differs, the existing implementation can
be used for the i.MX28 SoC only.

So, the first two patches of this series move the i.MX28 specific definitions
out of the way. Then the i.MX23 specific definitions are added, also the code
to distinguish both SoCs at run-time.
Up to here the existing driver will now run on an i.MX23 Soc as well.

When the i.MX23 SoC is running from battery it seems not to be a good idea to
run a busy loop to detect touches and their location. The fourth patch adds a
fully interrupt driven implementation which makes use of the built-in delay
and multiple sample features of the touchscreen controller. This will reduce
the interrupt load to a minimum.

The last patch in this series just removes the existing busy loop
implementation.

Some restrictions:

- yet tested on i.MX23 SoC only
- touchscreen parametrisation ability is provided (with fixed values for now)
  but should be done via device tree. Some recommendations how to define the
  bindings would be helpful

Changes since v1:

- adding register access functions to make the existing code more readable
- adding some functions to distinguish the SoCs at run-time to avoid if-else
  contructs whenever differences in the register layout between i.MX23 and
  i.MX28 must be handled

Comments are welcome.

Juergen

[PATCH 1/5] Staging/iio/adc/touchscreen/MXS: distinguish i.MX23's and i.MX28's LRADC

[Juergen Beisert]

The LRADC units in i.MX23 and i.MX28 differ and we need to distinguish both
SoC variants in order to make the touchscreen work on i.MX23

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
CC: linux-arm-kernel at lists.infradead.org
CC: devel at driverdev.osuosl.org
CC: Marek Vasut <marex@denx.de>
CC: Fabio Estevam <fabio.estevam@freescale.com>
CC: Jonathan Cameron <jic23@cam.ac.uk>
---
 drivers/staging/iio/adc/mxs-lradc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/staging/iio/adc/mxs-lradc.c b/drivers/staging/iio/adc/mxs-lradc.c
index a08c173..dffca90 100644
--- a/drivers/staging/iio/adc/mxs-lradc.c
+++ b/drivers/staging/iio/adc/mxs-lradc.c
@@ -174,6 +174,8 @@ struct mxs_lradc {
 
 	struct input_dev	*ts_input;
 	struct work_struct	ts_work;
+
+	enum mxs_lradc_id	soc;
 };
 
 #define	LRADC_CTRL0				0x00
@@ -920,6 +922,7 @@ static int mxs_lradc_probe(struct platform_device *pdev)
 	}
 
 	lradc = iio_priv(iio);
+	lradc->soc = (enum mxs_lradc_id)of_id->data;
 
 	/* Grab the memory area */
 	iores = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-- 
1.8.4.rc3

[PATCH 2/5] Staging/iio/adc/touchscreen/MXS: separate i.MX28 specific register bits

[Juergen Beisert]

In order to support i.MX23 and i.MX28 within one driver we need to separate the
register definitions which differ in both SoC variants.

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
CC: linux-arm-kernel at lists.infradead.org
CC: devel at driverdev.osuosl.org
CC: Marek Vasut <marex@denx.de>
CC: Fabio Estevam <fabio.estevam@freescale.com>
CC: Jonathan Cameron <jic23@cam.ac.uk>
---
 drivers/staging/iio/adc/mxs-lradc.c | 61 ++++++++++++++++++++-----------------
 1 file changed, 33 insertions(+), 28 deletions(-)

diff --git a/drivers/staging/iio/adc/mxs-lradc.c b/drivers/staging/iio/adc/mxs-lradc.c
index dffca90..5535fed 100644
--- a/drivers/staging/iio/adc/mxs-lradc.c
+++ b/drivers/staging/iio/adc/mxs-lradc.c
@@ -179,24 +179,29 @@ struct mxs_lradc {
 };
 
 #define	LRADC_CTRL0				0x00
-#define	LRADC_CTRL0_TOUCH_DETECT_ENABLE		(1 << 23)
-#define	LRADC_CTRL0_TOUCH_SCREEN_TYPE		(1 << 22)
-#define	LRADC_CTRL0_YNNSW	/* YM */	(1 << 21)
-#define	LRADC_CTRL0_YPNSW	/* YP */	(1 << 20)
-#define	LRADC_CTRL0_YPPSW	/* YP */	(1 << 19)
-#define	LRADC_CTRL0_XNNSW	/* XM */	(1 << 18)
-#define	LRADC_CTRL0_XNPSW	/* XM */	(1 << 17)
-#define	LRADC_CTRL0_XPPSW	/* XP */	(1 << 16)
-#define	LRADC_CTRL0_PLATE_MASK			(0x3f << 16)
+# define LRADC_CTRL0_MX28_TOUCH_DETECT_ENABLE	(1 << 23)
+# define LRADC_CTRL0_MX28_TOUCH_SCREEN_TYPE	(1 << 22)
+# define LRADC_CTRL0_MX28_YNNSW	/* YM */	(1 << 21)
+# define LRADC_CTRL0_MX28_YPNSW	/* YP */	(1 << 20)
+# define LRADC_CTRL0_MX28_YPPSW	/* YP */	(1 << 19)
+# define LRADC_CTRL0_MX28_XNNSW	/* XM */	(1 << 18)
+# define LRADC_CTRL0_MX28_XNPSW	/* XM */	(1 << 17)
+# define LRADC_CTRL0_MX28_XPPSW	/* XP */	(1 << 16)
+
+# define LRADC_CTRL0_MX28_PLATE_MASK \
+		(LRADC_CTRL0_MX28_TOUCH_DETECT_ENABLE | \
+		LRADC_CTRL0_MX28_YNNSW | LRADC_CTRL0_MX28_YPNSW | \
+		LRADC_CTRL0_MX28_YPPSW | LRADC_CTRL0_MX28_XNNSW | \
+		LRADC_CTRL0_MX28_XNPSW | LRADC_CTRL0_MX28_XPPSW)
 
 #define	LRADC_CTRL1				0x10
 #define	LRADC_CTRL1_TOUCH_DETECT_IRQ_EN		(1 << 24)
 #define	LRADC_CTRL1_LRADC_IRQ_EN(n)		(1 << ((n) + 16))
-#define	LRADC_CTRL1_LRADC_IRQ_EN_MASK		(0x1fff << 16)
+#define	LRADC_CTRL1_MX28_LRADC_IRQ_EN_MASK	(0x1fff << 16)
 #define	LRADC_CTRL1_LRADC_IRQ_EN_OFFSET		16
 #define	LRADC_CTRL1_TOUCH_DETECT_IRQ		(1 << 8)
 #define	LRADC_CTRL1_LRADC_IRQ(n)		(1 << (n))
-#define	LRADC_CTRL1_LRADC_IRQ_MASK		0x1fff
+#define	LRADC_CTRL1_MX28_LRADC_IRQ_MASK		0x1fff
 #define	LRADC_CTRL1_LRADC_IRQ_OFFSET		0
 
 #define	LRADC_CTRL2				0x20
@@ -264,7 +269,7 @@ static int mxs_lradc_read_raw(struct iio_dev *iio_dev,
 	 * Virtual channel 0 is always used here as the others are always not
 	 * used if doing raw sampling.
 	 */
-	writel(LRADC_CTRL1_LRADC_IRQ_EN_MASK,
+	writel(LRADC_CTRL1_MX28_LRADC_IRQ_EN_MASK,
 		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
 	writel(0xff, lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
 
@@ -319,9 +324,9 @@ static int mxs_lradc_ts_touched(struct mxs_lradc *lradc)
 	uint32_t reg;
 
 	/* Enable touch detection. */
-	writel(LRADC_CTRL0_PLATE_MASK,
+	writel(LRADC_CTRL0_MX28_PLATE_MASK,
 		lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
-	writel(LRADC_CTRL0_TOUCH_DETECT_ENABLE,
+	writel(LRADC_CTRL0_MX28_TOUCH_DETECT_ENABLE,
 		lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_SET);
 
 	msleep(LRADC_TS_SAMPLE_DELAY_MS);
@@ -367,21 +372,21 @@ static int32_t mxs_lradc_ts_sample(struct mxs_lradc *lradc,
 	 */
 	switch (plate) {
 	case LRADC_SAMPLE_X:
-		ctrl0 = LRADC_CTRL0_XPPSW | LRADC_CTRL0_XNNSW;
+		ctrl0 = LRADC_CTRL0_MX28_XPPSW | LRADC_CTRL0_MX28_XNNSW;
 		chan = 3;
 		break;
 	case LRADC_SAMPLE_Y:
-		ctrl0 = LRADC_CTRL0_YPPSW | LRADC_CTRL0_YNNSW;
+		ctrl0 = LRADC_CTRL0_MX28_YPPSW | LRADC_CTRL0_MX28_YNNSW;
 		chan = 4;
 		break;
 	case LRADC_SAMPLE_PRESSURE:
-		ctrl0 = LRADC_CTRL0_YPPSW | LRADC_CTRL0_XNNSW;
+		ctrl0 = LRADC_CTRL0_MX28_YPPSW | LRADC_CTRL0_MX28_XNNSW;
 		chan = 5;
 		break;
 	}
 
 	if (change) {
-		writel(LRADC_CTRL0_PLATE_MASK,
+		writel(LRADC_CTRL0_MX28_PLATE_MASK,
 			lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
 		writel(ctrl0, lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_SET);
 
@@ -442,7 +447,7 @@ static void mxs_lradc_ts_work(struct work_struct *ts_work)
 
 	while (mxs_lradc_ts_touched(lradc)) {
 		/* Disable touch detector so we can sample the touchscreen. */
-		writel(LRADC_CTRL0_TOUCH_DETECT_ENABLE,
+		writel(LRADC_CTRL0_MX28_TOUCH_DETECT_ENABLE,
 			lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
 
 		if (likely(valid)) {
@@ -491,7 +496,7 @@ static int mxs_lradc_ts_open(struct input_dev *dev)
 	lradc->stop_touchscreen = false;
 
 	/* Enable the touch-detect circuitry. */
-	writel(LRADC_CTRL0_TOUCH_DETECT_ENABLE,
+	writel(LRADC_CTRL0_MX28_TOUCH_DETECT_ENABLE,
 		lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_SET);
 
 	/* Enable the touch-detect IRQ. */
@@ -517,7 +522,7 @@ static void mxs_lradc_ts_close(struct input_dev *dev)
 		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
 
 	/* Power-down touchscreen touch-detect circuitry. */
-	writel(LRADC_CTRL0_TOUCH_DETECT_ENABLE,
+	writel(LRADC_CTRL0_MX28_TOUCH_DETECT_ENABLE,
 		lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
 }
 
@@ -581,7 +586,7 @@ static irqreturn_t mxs_lradc_handle_irq(int irq, void *data)
 		LRADC_CTRL1_TOUCH_DETECT_IRQ_EN |
 		LRADC_CTRL1_TOUCH_DETECT_IRQ;
 
-	if (!(reg & LRADC_CTRL1_LRADC_IRQ_MASK))
+	if (!(reg & LRADC_CTRL1_MX28_LRADC_IRQ_MASK))
 		return IRQ_NONE;
 
 	/*
@@ -601,7 +606,7 @@ static irqreturn_t mxs_lradc_handle_irq(int irq, void *data)
 	else if (reg & LRADC_CTRL1_LRADC_IRQ(0))
 		complete(&lradc->completion);
 
-	writel(reg & LRADC_CTRL1_LRADC_IRQ_MASK,
+	writel(reg & LRADC_CTRL1_MX28_LRADC_IRQ_MASK,
 		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
 
 	return IRQ_HANDLED;
@@ -722,7 +727,7 @@ static int mxs_lradc_buffer_preenable(struct iio_dev *iio)
 	if (ret < 0)
 		goto err_buf;
 
-	writel(LRADC_CTRL1_LRADC_IRQ_EN_MASK,
+	writel(LRADC_CTRL1_MX28_LRADC_IRQ_EN_MASK,
 		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
 	writel(0xff, lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
 
@@ -763,7 +768,7 @@ static int mxs_lradc_buffer_postdisable(struct iio_dev *iio)
 		lradc->base + LRADC_DELAY(0) + STMP_OFFSET_REG_CLR);
 
 	writel(0xff, lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
-	writel(LRADC_CTRL1_LRADC_IRQ_EN_MASK,
+	writel(LRADC_CTRL1_MX28_LRADC_IRQ_EN_MASK,
 		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
 
 	kfree(lradc->buffer);
@@ -867,11 +872,11 @@ static int mxs_lradc_hw_init(struct mxs_lradc *lradc)
 	writel(0, lradc->base + LRADC_DELAY(3));
 
 	/* Configure the touchscreen type */
-	writel(LRADC_CTRL0_TOUCH_SCREEN_TYPE,
+	writel(LRADC_CTRL0_MX28_TOUCH_SCREEN_TYPE,
 		lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
 
 	if (lradc->use_touchscreen == MXS_LRADC_TOUCHSCREEN_5WIRE) {
-		writel(LRADC_CTRL0_TOUCH_SCREEN_TYPE,
+		writel(LRADC_CTRL0_MX28_TOUCH_SCREEN_TYPE,
 			lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_SET);
 	}
 
@@ -885,7 +890,7 @@ static void mxs_lradc_hw_stop(struct mxs_lradc *lradc)
 {
 	int i;
 
-	writel(LRADC_CTRL1_LRADC_IRQ_EN_MASK,
+	writel(LRADC_CTRL1_MX28_LRADC_IRQ_EN_MASK,
 		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
 
 	for (i = 0; i < LRADC_MAX_DELAY_CHANS; i++)
-- 
1.8.4.rc3

[PATCH 3/5] Staging/iio/adc/touchscreen/MXS: add i.MX23 support to the LRADC driver

[Juergen Beisert]

Distinguish i.MX23 and i.MX28 at runtime and do the same for both SoC at least
for the 4 wire touchscreen.

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
CC: linux-arm-kernel at lists.infradead.org
CC: devel at driverdev.osuosl.org
CC: Marek Vasut <marex@denx.de>
CC: Fabio Estevam <fabio.estevam@freescale.com>
CC: Jonathan Cameron <jic23@cam.ac.uk>
---
 drivers/staging/iio/adc/mxs-lradc.c | 243 +++++++++++++++++++++++-------------
 1 file changed, 158 insertions(+), 85 deletions(-)

diff --git a/drivers/staging/iio/adc/mxs-lradc.c b/drivers/staging/iio/adc/mxs-lradc.c
index 5535fed..177e3fe 100644
--- a/drivers/staging/iio/adc/mxs-lradc.c
+++ b/drivers/staging/iio/adc/mxs-lradc.c
@@ -188,20 +188,33 @@ struct mxs_lradc {
 # define LRADC_CTRL0_MX28_XNPSW	/* XM */	(1 << 17)
 # define LRADC_CTRL0_MX28_XPPSW	/* XP */	(1 << 16)
 
+# define LRADC_CTRL0_MX23_TOUCH_DETECT_ENABLE	(1 << 20)
+# define LRADC_CTRL0_MX23_YM			(1 << 19)
+# define LRADC_CTRL0_MX23_XM			(1 << 18)
+# define LRADC_CTRL0_MX23_YP			(1 << 17)
+# define LRADC_CTRL0_MX23_XP			(1 << 16)
+
 # define LRADC_CTRL0_MX28_PLATE_MASK \
 		(LRADC_CTRL0_MX28_TOUCH_DETECT_ENABLE | \
 		LRADC_CTRL0_MX28_YNNSW | LRADC_CTRL0_MX28_YPNSW | \
 		LRADC_CTRL0_MX28_YPPSW | LRADC_CTRL0_MX28_XNNSW | \
 		LRADC_CTRL0_MX28_XNPSW | LRADC_CTRL0_MX28_XPPSW)
 
+# define LRADC_CTRL0_MX23_PLATE_MASK \
+		(LRADC_CTRL0_MX23_TOUCH_DETECT_ENABLE | \
+		LRADC_CTRL0_MX23_YM | LRADC_CTRL0_MX23_XM | \
+		LRADC_CTRL0_MX23_YP | LRADC_CTRL0_MX23_XP)
+
 #define	LRADC_CTRL1				0x10
 #define	LRADC_CTRL1_TOUCH_DETECT_IRQ_EN		(1 << 24)
 #define	LRADC_CTRL1_LRADC_IRQ_EN(n)		(1 << ((n) + 16))
 #define	LRADC_CTRL1_MX28_LRADC_IRQ_EN_MASK	(0x1fff << 16)
+#define	LRADC_CTRL1_MX23_LRADC_IRQ_EN_MASK	(0x01ff << 16)
 #define	LRADC_CTRL1_LRADC_IRQ_EN_OFFSET		16
 #define	LRADC_CTRL1_TOUCH_DETECT_IRQ		(1 << 8)
 #define	LRADC_CTRL1_LRADC_IRQ(n)		(1 << (n))
 #define	LRADC_CTRL1_MX28_LRADC_IRQ_MASK		0x1fff
+#define	LRADC_CTRL1_MX23_LRADC_IRQ_MASK		0x01ff
 #define	LRADC_CTRL1_LRADC_IRQ_OFFSET		0
 
 #define	LRADC_CTRL2				0x20
@@ -235,6 +248,69 @@ struct mxs_lradc {
 #define LRADC_RESOLUTION			12
 #define LRADC_SINGLE_SAMPLE_MASK		((1 << LRADC_RESOLUTION) - 1)
 
+static void mxs_lradc_reg_set(struct mxs_lradc *lradc, u32 val, u32 reg)
+{
+	writel(val, lradc->base + reg + STMP_OFFSET_REG_SET);
+}
+
+static void mxs_lradc_reg_clear(struct mxs_lradc *lradc, u32 val, u32 reg)
+{
+	writel(val, lradc->base + reg + STMP_OFFSET_REG_CLR);
+}
+
+static void mxs_lradc_reg(struct mxs_lradc *lradc, u32 val, u32 reg)
+{
+	writel(val, lradc->base + reg);
+}
+
+static u32 mxs_lradc_plate_mask(struct mxs_lradc *lradc)
+{
+	if (lradc->soc == IMX28_LRADC)
+		return LRADC_CTRL0_MX28_PLATE_MASK;
+	return LRADC_CTRL0_MX23_PLATE_MASK;
+}
+
+static u32 mxs_lradc_irq_en_mask(struct mxs_lradc *lradc)
+{
+	if (lradc->soc == IMX28_LRADC)
+		return LRADC_CTRL1_MX28_LRADC_IRQ_EN_MASK;
+	return LRADC_CTRL1_MX23_LRADC_IRQ_EN_MASK;
+}
+
+static u32 mxs_lradc_irq_mask(struct mxs_lradc *lradc)
+{
+	if (lradc->soc == IMX28_LRADC)
+		return LRADC_CTRL1_MX28_LRADC_IRQ_MASK;
+	return LRADC_CTRL1_MX23_LRADC_IRQ_MASK;
+}
+
+static u32 mxs_lradc_touch_detect_bit(struct mxs_lradc *lradc)
+{
+	if (lradc->soc == IMX28_LRADC)
+		return LRADC_CTRL0_MX28_TOUCH_DETECT_ENABLE;
+	return LRADC_CTRL0_MX23_TOUCH_DETECT_ENABLE;
+}
+
+static u32 mxs_lradc_drive_x_plate(struct mxs_lradc *lradc)
+{
+	if (lradc->soc == IMX28_LRADC)
+		return LRADC_CTRL0_MX28_XPPSW | LRADC_CTRL0_MX28_XNNSW;
+	return LRADC_CTRL0_MX23_XP | LRADC_CTRL0_MX23_XM;
+}
+
+static u32 mxs_lradc_drive_y_plate(struct mxs_lradc *lradc)
+{
+	if (lradc->soc == IMX28_LRADC)
+		return LRADC_CTRL0_MX28_YPPSW | LRADC_CTRL0_MX28_YNNSW;
+	return LRADC_CTRL0_MX23_YP | LRADC_CTRL0_MX23_YM;
+}
+
+static u32 mxs_lradc_drive_pressure(struct mxs_lradc *lradc)
+{
+	if (lradc->soc == IMX28_LRADC)
+		return LRADC_CTRL0_MX28_YPPSW | LRADC_CTRL0_MX28_XNNSW;
+	return LRADC_CTRL0_MX23_YP | LRADC_CTRL0_MX23_XM;
+}
 /*
  * Raw I/O operations
  */
@@ -269,21 +345,20 @@ static int mxs_lradc_read_raw(struct iio_dev *iio_dev,
 	 * Virtual channel 0 is always used here as the others are always not
 	 * used if doing raw sampling.
 	 */
-	writel(LRADC_CTRL1_MX28_LRADC_IRQ_EN_MASK,
-		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
-	writel(0xff, lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
+	if (lradc->soc == IMX28_LRADC)
+		mxs_lradc_reg_clear(lradc, LRADC_CTRL1_MX28_LRADC_IRQ_EN_MASK,
+			LRADC_CTRL1);
+	mxs_lradc_reg_clear(lradc, 0xff, LRADC_CTRL0);
 
 	/* Clean the slot's previous content, then set new one. */
-	writel(LRADC_CTRL4_LRADCSELECT_MASK(0),
-		lradc->base + LRADC_CTRL4 + STMP_OFFSET_REG_CLR);
-	writel(chan->channel, lradc->base + LRADC_CTRL4 + STMP_OFFSET_REG_SET);
+	mxs_lradc_reg_clear(lradc, LRADC_CTRL4_LRADCSELECT_MASK(0), LRADC_CTRL4);
+	mxs_lradc_reg_set(lradc, chan->channel, LRADC_CTRL4);
 
-	writel(0, lradc->base + LRADC_CH(0));
+	mxs_lradc_reg(lradc, 0, LRADC_CH(0));
 
 	/* Enable the IRQ and start sampling the channel. */
-	writel(LRADC_CTRL1_LRADC_IRQ_EN(0),
-		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_SET);
-	writel(1 << 0, lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_SET);
+	mxs_lradc_reg_set(lradc, LRADC_CTRL1_LRADC_IRQ_EN(0), LRADC_CTRL1);
+	mxs_lradc_reg_set(lradc, 1 << 0, LRADC_CTRL0);
 
 	/* Wait for completion on the channel, 1 second max. */
 	ret = wait_for_completion_killable_timeout(&lradc->completion, HZ);
@@ -297,8 +372,7 @@ static int mxs_lradc_read_raw(struct iio_dev *iio_dev,
 	ret = IIO_VAL_INT;
 
 err:
-	writel(LRADC_CTRL1_LRADC_IRQ_EN(0),
-		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
+	mxs_lradc_reg_clear(lradc, LRADC_CTRL1_LRADC_IRQ_EN(0), LRADC_CTRL1);
 
 	mutex_unlock(&lradc->lock);
 
@@ -324,10 +398,9 @@ static int mxs_lradc_ts_touched(struct mxs_lradc *lradc)
 	uint32_t reg;
 
 	/* Enable touch detection. */
-	writel(LRADC_CTRL0_MX28_PLATE_MASK,
-		lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
-	writel(LRADC_CTRL0_MX28_TOUCH_DETECT_ENABLE,
-		lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_SET);
+	mxs_lradc_reg_clear(lradc, mxs_lradc_plate_mask(lradc), LRADC_CTRL0);
+	mxs_lradc_reg_set(lradc, mxs_lradc_touch_detect_bit(lradc),
+								LRADC_CTRL0);
 
 	msleep(LRADC_TS_SAMPLE_DELAY_MS);
 
@@ -372,32 +445,33 @@ static int32_t mxs_lradc_ts_sample(struct mxs_lradc *lradc,
 	 */
 	switch (plate) {
 	case LRADC_SAMPLE_X:
-		ctrl0 = LRADC_CTRL0_MX28_XPPSW | LRADC_CTRL0_MX28_XNNSW;
+		ctrl0 = mxs_lradc_drive_x_plate(lradc);
 		chan = 3;
 		break;
 	case LRADC_SAMPLE_Y:
-		ctrl0 = LRADC_CTRL0_MX28_YPPSW | LRADC_CTRL0_MX28_YNNSW;
+		ctrl0 = mxs_lradc_drive_y_plate(lradc);
 		chan = 4;
 		break;
 	case LRADC_SAMPLE_PRESSURE:
-		ctrl0 = LRADC_CTRL0_MX28_YPPSW | LRADC_CTRL0_MX28_XNNSW;
+		ctrl0 = mxs_lradc_drive_pressure(lradc);
 		chan = 5;
 		break;
 	}
 
 	if (change) {
-		writel(LRADC_CTRL0_MX28_PLATE_MASK,
-			lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
-		writel(ctrl0, lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_SET);
-
-		writel(LRADC_CTRL4_LRADCSELECT_MASK(slot),
-			lradc->base + LRADC_CTRL4 + STMP_OFFSET_REG_CLR);
-		writel(chan << LRADC_CTRL4_LRADCSELECT_OFFSET(slot),
-			lradc->base + LRADC_CTRL4 + STMP_OFFSET_REG_SET);
+		mxs_lradc_reg_clear(lradc, mxs_lradc_plate_mask(lradc),
+						LRADC_CTRL0);
+		mxs_lradc_reg_set(lradc, ctrl0, LRADC_CTRL0);
+
+		mxs_lradc_reg_clear(lradc, LRADC_CTRL4_LRADCSELECT_MASK(slot),
+						LRADC_CTRL4);
+		mxs_lradc_reg_set(lradc,
+				chan << LRADC_CTRL4_LRADCSELECT_OFFSET(slot),
+				LRADC_CTRL4);
 	}
 
-	writel(0xffffffff, lradc->base + LRADC_CH(slot) + STMP_OFFSET_REG_CLR);
-	writel(1 << slot, lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_SET);
+	mxs_lradc_reg_clear(lradc, 0xffffffff, LRADC_CH(slot));
+	mxs_lradc_reg_set(lradc, 1 << slot, LRADC_CTRL0);
 
 	delay = jiffies + msecs_to_jiffies(LRADC_TS_SAMPLE_DELAY_MS);
 	do {
@@ -407,8 +481,7 @@ static int32_t mxs_lradc_ts_sample(struct mxs_lradc *lradc,
 			break;
 	} while (time_before(jiff, delay));
 
-	writel(LRADC_CTRL1_LRADC_IRQ(slot),
-		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
+	mxs_lradc_reg_clear(lradc, LRADC_CTRL1_LRADC_IRQ(slot), LRADC_CTRL1);
 
 	if (time_after_eq(jiff, delay))
 		return -ETIMEDOUT;
@@ -447,8 +520,8 @@ static void mxs_lradc_ts_work(struct work_struct *ts_work)
 
 	while (mxs_lradc_ts_touched(lradc)) {
 		/* Disable touch detector so we can sample the touchscreen. */
-		writel(LRADC_CTRL0_MX28_TOUCH_DETECT_ENABLE,
-			lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
+		mxs_lradc_reg_clear(lradc, mxs_lradc_touch_detect_bit(lradc),
+						LRADC_CTRL0);
 
 		if (likely(valid)) {
 			input_report_abs(lradc->ts_input, ABS_X, val_x);
@@ -482,10 +555,8 @@ static void mxs_lradc_ts_work(struct work_struct *ts_work)
 		return;
 
 	/* Restart the touchscreen interrupts. */
-	writel(LRADC_CTRL1_TOUCH_DETECT_IRQ,
-		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
-	writel(LRADC_CTRL1_TOUCH_DETECT_IRQ_EN,
-		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_SET);
+	mxs_lradc_reg_clear(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ, LRADC_CTRL1);
+	mxs_lradc_reg_set(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ_EN, LRADC_CTRL1);
 }
 
 static int mxs_lradc_ts_open(struct input_dev *dev)
@@ -496,12 +567,11 @@ static int mxs_lradc_ts_open(struct input_dev *dev)
 	lradc->stop_touchscreen = false;
 
 	/* Enable the touch-detect circuitry. */
-	writel(LRADC_CTRL0_MX28_TOUCH_DETECT_ENABLE,
-		lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_SET);
+	mxs_lradc_reg_set(lradc, mxs_lradc_touch_detect_bit(lradc),
+						LRADC_CTRL0);
 
 	/* Enable the touch-detect IRQ. */
-	writel(LRADC_CTRL1_TOUCH_DETECT_IRQ_EN,
-		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_SET);
+	mxs_lradc_reg_set(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ_EN, LRADC_CTRL1);
 
 	return 0;
 }
@@ -518,12 +588,11 @@ static void mxs_lradc_ts_close(struct input_dev *dev)
 	cancel_work_sync(&lradc->ts_work);
 
 	/* Disable touchscreen touch-detect IRQ. */
-	writel(LRADC_CTRL1_TOUCH_DETECT_IRQ_EN,
-		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
+	mxs_lradc_reg_clear(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ_EN,
+						LRADC_CTRL1);
 
 	/* Power-down touchscreen touch-detect circuitry. */
-	writel(LRADC_CTRL0_MX28_TOUCH_DETECT_ENABLE,
-		lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
+	mxs_lradc_reg_clear(lradc, mxs_lradc_touch_detect_bit(lradc), LRADC_CTRL0);
 }
 
 static int mxs_lradc_ts_register(struct mxs_lradc *lradc)
@@ -586,7 +655,7 @@ static irqreturn_t mxs_lradc_handle_irq(int irq, void *data)
 		LRADC_CTRL1_TOUCH_DETECT_IRQ_EN |
 		LRADC_CTRL1_TOUCH_DETECT_IRQ;
 
-	if (!(reg & LRADC_CTRL1_MX28_LRADC_IRQ_MASK))
+	if (!(reg & mxs_lradc_irq_mask(lradc)))
 		return IRQ_NONE;
 
 	/*
@@ -595,8 +664,7 @@ static irqreturn_t mxs_lradc_handle_irq(int irq, void *data)
 	 * it ASAP
 	 */
 	if (reg & LRADC_CTRL1_TOUCH_DETECT_IRQ) {
-		writel(ts_irq_mask,
-			lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
+		mxs_lradc_reg_clear(lradc, ts_irq_mask, LRADC_CTRL1);
 		if (!lradc->stop_touchscreen)
 			schedule_work(&lradc->ts_work);
 	}
@@ -606,8 +674,7 @@ static irqreturn_t mxs_lradc_handle_irq(int irq, void *data)
 	else if (reg & LRADC_CTRL1_LRADC_IRQ(0))
 		complete(&lradc->completion);
 
-	writel(reg & LRADC_CTRL1_MX28_LRADC_IRQ_MASK,
-		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
+	mxs_lradc_reg_clear(lradc, reg & mxs_lradc_irq_mask(lradc), LRADC_CTRL1);
 
 	return IRQ_HANDLED;
 }
@@ -626,7 +693,7 @@ static irqreturn_t mxs_lradc_trigger_handler(int irq, void *p)
 
 	for_each_set_bit(i, iio->active_scan_mask, LRADC_MAX_TOTAL_CHANS) {
 		lradc->buffer[j] = readl(lradc->base + LRADC_CH(j));
-		writel(chan_value, lradc->base + LRADC_CH(j));
+		mxs_lradc_reg(lradc, chan_value, LRADC_CH(j));
 		lradc->buffer[j] &= LRADC_CH_VALUE_MASK;
 		lradc->buffer[j] /= LRADC_DELAY_TIMER_LOOP;
 		j++;
@@ -651,7 +718,7 @@ static int mxs_lradc_configure_trigger(struct iio_trigger *trig, bool state)
 	struct mxs_lradc *lradc = iio_priv(iio);
 	const uint32_t st = state ? STMP_OFFSET_REG_SET : STMP_OFFSET_REG_CLR;
 
-	writel(LRADC_DELAY_KICK, lradc->base + LRADC_DELAY(0) + st);
+	mxs_lradc_reg(lradc, LRADC_DELAY_KICK, LRADC_DELAY(0) + st);
 
 	return 0;
 }
@@ -727,29 +794,27 @@ static int mxs_lradc_buffer_preenable(struct iio_dev *iio)
 	if (ret < 0)
 		goto err_buf;
 
-	writel(LRADC_CTRL1_MX28_LRADC_IRQ_EN_MASK,
-		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
-	writel(0xff, lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
+	if (lradc->soc == IMX28_LRADC)
+		mxs_lradc_reg_clear(lradc, LRADC_CTRL1_MX28_LRADC_IRQ_EN_MASK,
+							LRADC_CTRL1);
+	mxs_lradc_reg_clear(lradc, 0xff, LRADC_CTRL0);
 
 	for_each_set_bit(chan, iio->active_scan_mask, LRADC_MAX_TOTAL_CHANS) {
 		ctrl4_set |= chan << LRADC_CTRL4_LRADCSELECT_OFFSET(ofs);
 		ctrl4_clr |= LRADC_CTRL4_LRADCSELECT_MASK(ofs);
 		ctrl1_irq |= LRADC_CTRL1_LRADC_IRQ_EN(ofs);
-		writel(chan_value, lradc->base + LRADC_CH(ofs));
+		mxs_lradc_reg(lradc, chan_value, LRADC_CH(ofs));
 		bitmap_set(&enable, ofs, 1);
 		ofs++;
 	}
 
-	writel(LRADC_DELAY_TRIGGER_LRADCS_MASK | LRADC_DELAY_KICK,
-		lradc->base + LRADC_DELAY(0) + STMP_OFFSET_REG_CLR);
-
-	writel(ctrl4_clr, lradc->base + LRADC_CTRL4 + STMP_OFFSET_REG_CLR);
-	writel(ctrl4_set, lradc->base + LRADC_CTRL4 + STMP_OFFSET_REG_SET);
-
-	writel(ctrl1_irq, lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_SET);
-
-	writel(enable << LRADC_DELAY_TRIGGER_LRADCS_OFFSET,
-		lradc->base + LRADC_DELAY(0) + STMP_OFFSET_REG_SET);
+	mxs_lradc_reg_clear(lradc, LRADC_DELAY_TRIGGER_LRADCS_MASK |
+					LRADC_DELAY_KICK, LRADC_DELAY(0));
+	mxs_lradc_reg_clear(lradc, ctrl4_clr, LRADC_CTRL4);
+	mxs_lradc_reg_set(lradc, ctrl4_set, LRADC_CTRL4);
+	mxs_lradc_reg_set(lradc, ctrl1_irq, LRADC_CTRL1);
+	mxs_lradc_reg_set(lradc, enable << LRADC_DELAY_TRIGGER_LRADCS_OFFSET,
+					LRADC_DELAY(0));
 
 	return 0;
 
@@ -764,12 +829,13 @@ static int mxs_lradc_buffer_postdisable(struct iio_dev *iio)
 {
 	struct mxs_lradc *lradc = iio_priv(iio);
 
-	writel(LRADC_DELAY_TRIGGER_LRADCS_MASK | LRADC_DELAY_KICK,
-		lradc->base + LRADC_DELAY(0) + STMP_OFFSET_REG_CLR);
+	mxs_lradc_reg_clear(lradc, LRADC_DELAY_TRIGGER_LRADCS_MASK |
+					LRADC_DELAY_KICK, LRADC_DELAY(0));
 
-	writel(0xff, lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
-	writel(LRADC_CTRL1_MX28_LRADC_IRQ_EN_MASK,
-		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
+	mxs_lradc_reg_clear(lradc, 0xff, LRADC_CTRL0);
+	if (lradc->soc == IMX28_LRADC)
+		mxs_lradc_reg_clear(lradc, LRADC_CTRL1_MX28_LRADC_IRQ_EN_MASK,
+					LRADC_CTRL1);
 
 	kfree(lradc->buffer);
 	mutex_unlock(&lradc->lock);
@@ -864,24 +930,26 @@ static int mxs_lradc_hw_init(struct mxs_lradc *lradc)
 		return ret;
 
 	/* Configure DELAY CHANNEL 0 for generic ADC sampling. */
-	writel(adc_cfg, lradc->base + LRADC_DELAY(0));
+	mxs_lradc_reg(lradc, adc_cfg, LRADC_DELAY(0));
 
 	/* Disable remaining DELAY CHANNELs */
-	writel(0, lradc->base + LRADC_DELAY(1));
-	writel(0, lradc->base + LRADC_DELAY(2));
-	writel(0, lradc->base + LRADC_DELAY(3));
+	mxs_lradc_reg(lradc, 0, LRADC_DELAY(1));
+	mxs_lradc_reg(lradc, 0, LRADC_DELAY(2));
+	mxs_lradc_reg(lradc, 0, LRADC_DELAY(3));
 
 	/* Configure the touchscreen type */
-	writel(LRADC_CTRL0_MX28_TOUCH_SCREEN_TYPE,
-		lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
-
-	if (lradc->use_touchscreen == MXS_LRADC_TOUCHSCREEN_5WIRE) {
-		writel(LRADC_CTRL0_MX28_TOUCH_SCREEN_TYPE,
-			lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_SET);
+	if (lradc->soc == IMX28_LRADC) {
+		mxs_lradc_reg_clear(lradc, LRADC_CTRL0_MX28_TOUCH_SCREEN_TYPE,
+							LRADC_CTRL0);
+
+		if (lradc->use_touchscreen == MXS_LRADC_TOUCHSCREEN_5WIRE)
+			mxs_lradc_reg_set(lradc,
+					LRADC_CTRL0_MX28_TOUCH_SCREEN_TYPE,
+					LRADC_CTRL0);
 	}
 
 	/* Start internal temperature sensing. */
-	writel(0, lradc->base + LRADC_CTRL2);
+	mxs_lradc_reg(lradc, 0, LRADC_CTRL2);
 
 	return 0;
 }
@@ -890,11 +958,10 @@ static void mxs_lradc_hw_stop(struct mxs_lradc *lradc)
 {
 	int i;
 
-	writel(LRADC_CTRL1_MX28_LRADC_IRQ_EN_MASK,
-		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
+	mxs_lradc_reg_clear(lradc, mxs_lradc_irq_en_mask(lradc), LRADC_CTRL1);
 
 	for (i = 0; i < LRADC_MAX_DELAY_CHANS; i++)
-		writel(0, lradc->base + LRADC_DELAY(i));
+		mxs_lradc_reg(lradc, 0, LRADC_DELAY(i));
 }
 
 static const struct of_device_id mxs_lradc_dt_ids[] = {
@@ -951,6 +1018,12 @@ static int mxs_lradc_probe(struct platform_device *pdev)
 		dev_warn(dev, "Unsupported number of touchscreen wires (%d)\n",
 				ts_wires);
 
+	if ((lradc->soc == IMX23_LRADC) && (ts_wires == 5)) {
+		dev_warn(dev, "No support for 5 wire touches on i.MX23\n");
+		dev_warn(dev, "Falling back to 4 wire\n");
+		ts_wires = 4;
+	}
+
 	/* Grab all IRQ sources */
 	for (i = 0; i < of_cfg->irq_count; i++) {
 		lradc->irq[i] = platform_get_irq(pdev, i);
-- 
1.8.4.rc3

[PATCH 4/5] Staging/iio/adc/touchscreen/MXS: add interrupt driven touch detection

[Juergen Beisert]

For battery driven systems it is a very bad idea to collect the touchscreen
data within a kernel busy loop.

This change uses the features of the hardware to delay and accumulate samples in
hardware to avoid a high interrupt and CPU load.

Note: this is only tested on a i.MX23 SoC yet.

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
CC: linux-arm-kernel at lists.infradead.org
CC: devel at driverdev.osuosl.org
CC: Marek Vasut <marex@denx.de>
CC: Fabio Estevam <fabio.estevam@freescale.com>
CC: Jonathan Cameron <jic23@cam.ac.uk>
---
 drivers/staging/iio/adc/mxs-lradc.c | 548 ++++++++++++++++++++++++++++++++----
 1 file changed, 494 insertions(+), 54 deletions(-)

diff --git a/drivers/staging/iio/adc/mxs-lradc.c b/drivers/staging/iio/adc/mxs-lradc.c
index 177e3fe..28b5ea4 100644
--- a/drivers/staging/iio/adc/mxs-lradc.c
+++ b/drivers/staging/iio/adc/mxs-lradc.c
@@ -129,6 +129,17 @@ enum mxs_lradc_ts {
 	MXS_LRADC_TOUCHSCREEN_5WIRE,
 };
 
+/*
+ * Touchscreen handling
+ */
+enum lradc_ts_plate {
+	LRADC_TOUCH = 0,
+	LRADC_SAMPLE_X,
+	LRADC_SAMPLE_Y,
+	LRADC_SAMPLE_PRESSURE,
+	LRADC_SAMPLE_VALID,
+};
+
 struct mxs_lradc {
 	struct device		*dev;
 	void __iomem		*base;
@@ -169,13 +180,25 @@ struct mxs_lradc {
 #define CHAN_MASK_TOUCHSCREEN_4WIRE	(0xf << 2)
 #define CHAN_MASK_TOUCHSCREEN_5WIRE	(0x1f << 2)
 	enum mxs_lradc_ts	use_touchscreen;
-	bool			stop_touchscreen;
 	bool			use_touchbutton;
 
 	struct input_dev	*ts_input;
 	struct work_struct	ts_work;
 
 	enum mxs_lradc_id	soc;
+	enum lradc_ts_plate	cur_plate; /* statemachine */
+	bool			ts_valid;
+	unsigned		ts_x_pos;
+	unsigned		ts_y_pos;
+	unsigned		ts_pressure;
+
+	/* handle touchscreen's physical behaviour */
+	/* samples per coordinate */
+	unsigned		over_sample_cnt;
+	/* time clocks between samples */
+	unsigned		over_sample_delay;
+	/* time in clocks to wait after the plates where switched */
+	unsigned		settling_delay;
 };
 
 #define	LRADC_CTRL0				0x00
@@ -227,19 +250,33 @@ struct mxs_lradc {
 #define	LRADC_CH_ACCUMULATE			(1 << 29)
 #define	LRADC_CH_NUM_SAMPLES_MASK		(0x1f << 24)
 #define	LRADC_CH_NUM_SAMPLES_OFFSET		24
+#define	LRADC_CH_NUM_SAMPLES(x) \
+				((x) << LRADC_CH_NUM_SAMPLES_OFFSET)
 #define	LRADC_CH_VALUE_MASK			0x3ffff
 #define	LRADC_CH_VALUE_OFFSET			0
 
 #define	LRADC_DELAY(n)				(0xd0 + (0x10 * (n)))
 #define	LRADC_DELAY_TRIGGER_LRADCS_MASK		(0xff << 24)
 #define	LRADC_DELAY_TRIGGER_LRADCS_OFFSET	24
+#define	LRADC_DELAY_TRIGGER(x) \
+				(((x) << LRADC_DELAY_TRIGGER_LRADCS_OFFSET) & \
+				LRADC_DELAY_TRIGGER_LRADCS_MASK)
 #define	LRADC_DELAY_KICK			(1 << 20)
 #define	LRADC_DELAY_TRIGGER_DELAYS_MASK		(0xf << 16)
 #define	LRADC_DELAY_TRIGGER_DELAYS_OFFSET	16
+#define	LRADC_DELAY_TRIGGER_DELAYS(x) \
+				(((x) << LRADC_DELAY_TRIGGER_DELAYS_OFFSET) & \
+				LRADC_DELAY_TRIGGER_DELAYS_MASK)
 #define	LRADC_DELAY_LOOP_COUNT_MASK		(0x1f << 11)
 #define	LRADC_DELAY_LOOP_COUNT_OFFSET		11
+#define	LRADC_DELAY_LOOP(x) \
+				(((x) << LRADC_DELAY_LOOP_COUNT_OFFSET) & \
+				LRADC_DELAY_LOOP_COUNT_MASK)
 #define	LRADC_DELAY_DELAY_MASK			0x7ff
 #define	LRADC_DELAY_DELAY_OFFSET		0
+#define	LRADC_DELAY_DELAY(x) \
+				(((x) << LRADC_DELAY_DELAY_OFFSET) & \
+				LRADC_DELAY_DELAY_MASK)
 
 #define	LRADC_CTRL4				0x140
 #define	LRADC_CTRL4_LRADCSELECT_MASK(n)		(0xf << ((n) * 4))
@@ -311,6 +348,422 @@ static u32 mxs_lradc_drive_pressure(struct mxs_lradc *lradc)
 		return LRADC_CTRL0_MX28_YPPSW | LRADC_CTRL0_MX28_XNNSW;
 	return LRADC_CTRL0_MX23_YP | LRADC_CTRL0_MX23_XM;
 }
+
+static bool mxs_lradc_check_touch_event(struct mxs_lradc *lradc)
+{
+	return !!(readl(lradc->base + LRADC_STATUS) &
+					LRADC_STATUS_TOUCH_DETECT_RAW);
+}
+
+static void mxs_lradc_setup_ts_channel(struct mxs_lradc *lradc, unsigned ch)
+{
+	/*
+	 * prepare for oversampling conversion
+	 *
+	 * from the datasheet:
+	 * "The ACCUMULATE bit in the appropriate channel register
+	 * HW_LRADC_CHn must be set to 1 if NUM_SAMPLES is greater then 0;
+	 * otherwise, the IRQs will not fire."
+	 */
+	mxs_lradc_reg(lradc, LRADC_CH_ACCUMULATE |
+			LRADC_CH_NUM_SAMPLES(lradc->over_sample_cnt - 1),
+			LRADC_CH(ch));
+
+	/* from the datasheet:
+	 * "Software must clear this register in preparation for a
+	 * multi-cycle accumulation.
+	 */
+	mxs_lradc_reg_clear(lradc, LRADC_CH_VALUE_MASK, LRADC_CH(ch));
+
+	/* prepare the delay/loop unit according to the oversampling count */
+	mxs_lradc_reg(lradc, LRADC_DELAY_TRIGGER(1 << ch) |
+		LRADC_DELAY_TRIGGER_DELAYS(0) |
+		LRADC_DELAY_LOOP(lradc->over_sample_cnt - 1) |
+		LRADC_DELAY_DELAY(lradc->over_sample_delay - 1),
+			LRADC_DELAY(3));
+
+	mxs_lradc_reg_clear(lradc, LRADC_CTRL1_LRADC_IRQ(2) |
+			LRADC_CTRL1_LRADC_IRQ(3) | LRADC_CTRL1_LRADC_IRQ(4) |
+			LRADC_CTRL1_LRADC_IRQ(5), LRADC_CTRL1);
+
+	/* wake us again, when the complete conversion is done */
+	mxs_lradc_reg_set(lradc, LRADC_CTRL1_LRADC_IRQ_EN(ch), LRADC_CTRL1);
+	/*
+	 * after changing the touchscreen plates setting
+	 * the signals need some initial time to settle. Start the
+	 * SoC's delay unit and start the conversion later
+	 * and automatically.
+	 */
+	mxs_lradc_reg(lradc, LRADC_DELAY_TRIGGER(0) | /* don't trigger ADC */
+		LRADC_DELAY_TRIGGER_DELAYS(1 << 3) | /* trigger DELAY unit#3 */
+		LRADC_DELAY_KICK |
+		LRADC_DELAY_DELAY(lradc->settling_delay),
+			LRADC_DELAY(2));
+}
+
+/*
+ * Pressure detection is special:
+ * We want to do both required measurements for the pressure detection in
+ * one turn. Use the hardware features to chain both conversions and let the
+ * hardware report one interrupt if both conversions are done
+ */
+static void mxs_lradc_setup_ts_pressure(struct mxs_lradc *lradc, unsigned ch1,
+							unsigned ch2)
+{
+	u32 reg;
+
+	/*
+	 * prepare for oversampling conversion
+	 *
+	 * from the datasheet:
+	 * "The ACCUMULATE bit in the appropriate channel register
+	 * HW_LRADC_CHn must be set to 1 if NUM_SAMPLES is greater then 0;
+	 * otherwise, the IRQs will not fire."
+	 */
+	reg = LRADC_CH_ACCUMULATE |
+		LRADC_CH_NUM_SAMPLES(lradc->over_sample_cnt - 1);
+	mxs_lradc_reg(lradc, reg, LRADC_CH(ch1));
+	mxs_lradc_reg(lradc, reg, LRADC_CH(ch2));
+
+	/* from the datasheet:
+	 * "Software must clear this register in preparation for a
+	 * multi-cycle accumulation.
+	 */
+	mxs_lradc_reg_clear(lradc, LRADC_CH_VALUE_MASK, LRADC_CH(ch1));
+	mxs_lradc_reg_clear(lradc, LRADC_CH_VALUE_MASK, LRADC_CH(ch2));
+
+	/* prepare the delay/loop unit according to the oversampling count */
+	mxs_lradc_reg(lradc, LRADC_DELAY_TRIGGER(1 << ch1) |
+		LRADC_DELAY_TRIGGER(1 << ch2) | /* start both channels */
+		LRADC_DELAY_TRIGGER_DELAYS(0) |
+		LRADC_DELAY_LOOP(lradc->over_sample_cnt - 1) |
+		LRADC_DELAY_DELAY(lradc->over_sample_delay - 1),
+					LRADC_DELAY(3));
+
+	mxs_lradc_reg_clear(lradc, LRADC_CTRL1_LRADC_IRQ(2) |
+			LRADC_CTRL1_LRADC_IRQ(3) | LRADC_CTRL1_LRADC_IRQ(4) |
+			LRADC_CTRL1_LRADC_IRQ(5), LRADC_CTRL1);
+
+	/* wake us again, when the conversions are done */
+	mxs_lradc_reg_set(lradc, LRADC_CTRL1_LRADC_IRQ_EN(ch2), LRADC_CTRL1);
+	/*
+	 * after changing the touchscreen plates setting
+	 * the signals need some initial time to settle. Start the
+	 * SoC's delay unit and start the conversion later
+	 * and automatically.
+	 */
+	mxs_lradc_reg(lradc, LRADC_DELAY_TRIGGER(0) | /* don't trigger ADC */
+		LRADC_DELAY_TRIGGER_DELAYS(1 << 3) | /* trigger DELAY unit#3 */
+		LRADC_DELAY_KICK |
+		LRADC_DELAY_DELAY(lradc->settling_delay), LRADC_DELAY(2));
+}
+
+static unsigned mxs_lradc_read_raw_channel(struct mxs_lradc *lradc,
+							unsigned channel)
+{
+	u32 reg;
+	unsigned num_samples, val;
+
+	reg = readl(lradc->base + LRADC_CH(channel));
+	if (reg & LRADC_CH_ACCUMULATE)
+		num_samples = lradc->over_sample_cnt;
+	else
+		num_samples = 1;
+
+	val = (reg & LRADC_CH_VALUE_MASK) >> LRADC_CH_VALUE_OFFSET;
+	return val / num_samples;
+}
+
+static unsigned mxs_lradc_read_ts_pressure(struct mxs_lradc *lradc,
+						unsigned ch1, unsigned ch2)
+{
+	u32 reg, mask;
+	unsigned pressure, m1, m2;
+
+	mask = LRADC_CTRL1_LRADC_IRQ(ch1) | LRADC_CTRL1_LRADC_IRQ(ch2);
+	reg = readl(lradc->base + LRADC_CTRL1) & mask;
+
+	while (reg != mask) {
+		reg = readl(lradc->base + LRADC_CTRL1) & mask;
+		dev_dbg(lradc->dev, "One channel is still busy: %X\n", reg);
+	}
+
+	m1 = mxs_lradc_read_raw_channel(lradc, ch1);
+	m2 = mxs_lradc_read_raw_channel(lradc, ch2);
+
+	if (m1 == 0) {
+		dev_warn(lradc->dev, "Cannot calculate pressure\n");
+		return 1 << (LRADC_RESOLUTION - 1);
+	}
+
+	/* simply scale the value from 0 ... max ADC resolution */
+	pressure = m1;
+	pressure *= (1 << LRADC_RESOLUTION);
+	pressure /= m2;
+
+	dev_dbg(lradc->dev, "Pressure = %u\n", pressure);
+	return pressure;
+}
+
+#define TS_CH_XP 2
+#define TS_CH_YP 3
+#define TS_CH_XM 4
+#define TS_CH_YM 5
+
+static int mxs_lradc_read_ts_channel(struct mxs_lradc *lradc)
+{
+	u32 reg;
+	int val;
+
+	reg = readl(lradc->base + LRADC_CTRL1);
+
+	/* only channels 3 to 5 are of interest here */
+	if (reg & LRADC_CTRL1_LRADC_IRQ(TS_CH_YP)) {
+		pr_devel("!3");
+		mxs_lradc_reg_clear(lradc, LRADC_CTRL1_LRADC_IRQ_EN(TS_CH_YP) |
+			LRADC_CTRL1_LRADC_IRQ(TS_CH_YP), LRADC_CTRL1);
+		val = mxs_lradc_read_raw_channel(lradc, TS_CH_YP);
+	} else if (reg & LRADC_CTRL1_LRADC_IRQ(TS_CH_XM)) {
+		pr_devel("!4");
+		mxs_lradc_reg_clear(lradc, LRADC_CTRL1_LRADC_IRQ_EN(TS_CH_XM) |
+			LRADC_CTRL1_LRADC_IRQ(TS_CH_XM), LRADC_CTRL1);
+		val = mxs_lradc_read_raw_channel(lradc, TS_CH_XM);
+	} else if (reg & LRADC_CTRL1_LRADC_IRQ(TS_CH_YM)) {
+		pr_devel("!5");
+		mxs_lradc_reg_clear(lradc, LRADC_CTRL1_LRADC_IRQ_EN(TS_CH_YM) |
+			LRADC_CTRL1_LRADC_IRQ(TS_CH_YM), LRADC_CTRL1);
+		val = mxs_lradc_read_raw_channel(lradc, TS_CH_YM);
+	} else {
+		pr_devel("!?");
+		return -EIO;
+	}
+
+	mxs_lradc_reg(lradc, 0, LRADC_DELAY(2));
+	mxs_lradc_reg(lradc, 0, LRADC_DELAY(3));
+
+	return val;
+}
+
+/*
+ * YP(open)--+-------------+
+ *           |             |--+
+ *           |             |  |
+ *    YM(-)--+-------------+  |
+ *             +--------------+
+ *             |              |
+ *         XP(weak+)        XM(open)
+ *
+ * "weak+" means 200k Ohm VDDIO
+ * (-) means GND
+ */
+static void mxs_lradc_setup_touch_detection(struct mxs_lradc *lradc)
+{
+	/*
+	 * In order to detect a touch event the 'touch detect enable' bit
+	 * enables:
+	 *  - a weak pullup to the X+ connector
+	 *  - a strong ground at the Y- connector
+	 */
+	mxs_lradc_reg_clear(lradc, mxs_lradc_plate_mask(lradc), LRADC_CTRL0);
+	mxs_lradc_reg_set(lradc, mxs_lradc_touch_detect_bit(lradc),
+				LRADC_CTRL0);
+	pr_devel(">T");
+}
+
+/*
+ * YP(meas)--+-------------+
+ *           |             |--+
+ *           |             |  |
+ * YM(open)--+-------------+  |
+ *             +--------------+
+ *             |              |
+ *           XP(+)          XM(-)
+ *
+ * (+) means here 1.85 V
+ * (-) means here GND
+ */
+static void mxs_lradc_prepare_x_pos(struct mxs_lradc *lradc)
+{
+	mxs_lradc_reg_clear(lradc, mxs_lradc_plate_mask(lradc), LRADC_CTRL0);
+	mxs_lradc_reg_set(lradc, mxs_lradc_drive_x_plate(lradc), LRADC_CTRL0);
+
+	lradc->cur_plate = LRADC_SAMPLE_X;
+	mxs_lradc_setup_ts_channel(lradc, TS_CH_YP);
+	pr_devel(">X");
+}
+
+/*
+ *   YP(+)--+-------------+
+ *          |             |--+
+ *          |             |  |
+ *   YM(-)--+-------------+  |
+ *            +--------------+
+ *            |              |
+ *         XP(open)        XM(meas)
+ *
+ * (+) means here 1.85 V
+ * (-) means here GND
+ */
+static void mxs_lradc_prepare_y_pos(struct mxs_lradc *lradc)
+{
+	mxs_lradc_reg_clear(lradc, mxs_lradc_plate_mask(lradc), LRADC_CTRL0);
+	mxs_lradc_reg_set(lradc, mxs_lradc_drive_y_plate(lradc), LRADC_CTRL0);
+
+	lradc->cur_plate = LRADC_SAMPLE_Y;
+	mxs_lradc_setup_ts_channel(lradc, TS_CH_XM);
+	pr_devel(">Y");
+}
+
+/*
+ *    YP(+)--+-------------+
+ *           |             |--+
+ *           |             |  |
+ * YM(meas)--+-------------+  |
+ *             +--------------+
+ *             |              |
+ *          XP(meas)        XM(-)
+ *
+ * (+) means here 1.85 V
+ * (-) means here GND
+ */
+static void mxs_lradc_prepare_pressure(struct mxs_lradc *lradc)
+{
+	mxs_lradc_reg_clear(lradc, mxs_lradc_plate_mask(lradc), LRADC_CTRL0);
+	mxs_lradc_reg_set(lradc, mxs_lradc_drive_pressure(lradc), LRADC_CTRL0);
+
+	lradc->cur_plate = LRADC_SAMPLE_PRESSURE;
+	mxs_lradc_setup_ts_pressure(lradc, TS_CH_XP, TS_CH_YM);
+	pr_devel(">P");
+}
+
+static void mxs_lradc_enable_touch_detection(struct mxs_lradc *lradc)
+{
+	mxs_lradc_setup_touch_detection(lradc);
+
+	lradc->cur_plate = LRADC_TOUCH;
+	mxs_lradc_reg_clear(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ |
+				LRADC_CTRL1_TOUCH_DETECT_IRQ_EN, LRADC_CTRL1);
+	mxs_lradc_reg_set(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ_EN, LRADC_CTRL1);
+}
+
+static void mxs_lradc_report_ts_event(struct mxs_lradc *lradc)
+{
+	input_report_abs(lradc->ts_input, ABS_X, lradc->ts_x_pos);
+	input_report_abs(lradc->ts_input, ABS_Y, lradc->ts_y_pos);
+	input_report_abs(lradc->ts_input, ABS_PRESSURE, lradc->ts_pressure);
+	input_report_key(lradc->ts_input, BTN_TOUCH, 1);
+	input_sync(lradc->ts_input);
+}
+
+static void mxs_lradc_complete_touch_event(struct mxs_lradc *lradc)
+{
+	mxs_lradc_setup_touch_detection(lradc);
+	lradc->cur_plate = LRADC_SAMPLE_VALID;
+	/*
+	 * start a dummy conversion to burn time to settle the signals
+	 * note: we are not interested in the conversion's value
+	 */
+	mxs_lradc_reg(lradc, 0, LRADC_CH(5));
+	mxs_lradc_reg_clear(lradc, LRADC_CTRL1_LRADC_IRQ(5), LRADC_CTRL1);
+	mxs_lradc_reg_set(lradc, LRADC_CTRL1_LRADC_IRQ_EN(5), LRADC_CTRL1);
+	mxs_lradc_reg(lradc, LRADC_DELAY_TRIGGER(1 << 5) |
+		LRADC_DELAY_KICK | LRADC_DELAY_DELAY(10), /* waste 5 ms */
+			LRADC_DELAY(2));
+}
+
+/*
+ * in order to avoid false measurements, report only samples where
+ * the surface is still touched after the position measurement
+ */
+static void mxs_lradc_finish_touch_event(struct mxs_lradc *lradc, bool valid)
+{
+	/* if it is still touched, report the sample */
+	if (valid && mxs_lradc_check_touch_event(lradc)) {
+		lradc->ts_valid = true;
+		mxs_lradc_report_ts_event(lradc);
+		pr_devel("**");
+	}
+
+	/* if it is even still touched, continue with the next measurement */
+	if (mxs_lradc_check_touch_event(lradc)) {
+		mxs_lradc_prepare_y_pos(lradc);
+		return;
+	}
+
+	if (lradc->ts_valid) {
+		/* signal the release */
+		lradc->ts_valid = false;
+		input_report_key(lradc->ts_input, BTN_TOUCH, 0);
+		input_sync(lradc->ts_input);
+	}
+
+	pr_devel("+P");
+	/* if it is released, wait for the next touch via IRQ */
+	mxs_lradc_reg_clear(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ, LRADC_CTRL1);
+	mxs_lradc_reg_set(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ_EN, LRADC_CTRL1);
+}
+
+/* touchscreen's state machine */
+static void mxs_lradc_handle_touch(struct mxs_lradc *lradc)
+{
+	int val;
+
+	pr_devel("#I");
+	switch (lradc->cur_plate) {
+	case LRADC_TOUCH:
+		pr_devel("#T");
+		/*
+		 * start with the Y-pos, because it uses nearly the same plate
+		 * settings like the touch detection
+		 */
+		if (mxs_lradc_check_touch_event(lradc)) {
+			pr_devel("-P");
+			mxs_lradc_reg_clear(lradc,
+					LRADC_CTRL1_TOUCH_DETECT_IRQ_EN,
+					LRADC_CTRL1);
+			mxs_lradc_prepare_y_pos(lradc);
+		}
+		mxs_lradc_reg_clear(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ,
+					LRADC_CTRL1);
+		return;
+
+	case LRADC_SAMPLE_Y:
+		pr_devel("#Y");
+		val = mxs_lradc_read_ts_channel(lradc);
+		if (val < 0) {
+			mxs_lradc_enable_touch_detection(lradc); /* re-start */
+			return;
+		}
+		lradc->ts_y_pos = val;
+		mxs_lradc_prepare_x_pos(lradc);
+		return;
+
+	case LRADC_SAMPLE_X:
+		pr_devel("#X");
+		val = mxs_lradc_read_ts_channel(lradc);
+		if (val < 0) {
+			mxs_lradc_enable_touch_detection(lradc); /* re-start */
+			return;
+		}
+		lradc->ts_x_pos = val;
+		mxs_lradc_prepare_pressure(lradc);
+		return;
+
+	case LRADC_SAMPLE_PRESSURE:
+		pr_devel("#P");
+		lradc->ts_pressure =
+			mxs_lradc_read_ts_pressure(lradc, TS_CH_XP, TS_CH_YM);
+		mxs_lradc_complete_touch_event(lradc);
+		return;
+
+	case LRADC_SAMPLE_VALID:
+		pr_devel("!C\n");
+		val = mxs_lradc_read_ts_channel(lradc); /* ignore the value */
+		mxs_lradc_finish_touch_event(lradc, 1);
+		break;
+	}
+}
+
 /*
  * Raw I/O operations
  */
@@ -384,15 +837,6 @@ static const struct iio_info mxs_lradc_iio_info = {
 	.read_raw		= mxs_lradc_read_raw,
 };
 
-/*
- * Touchscreen handling
- */
-enum lradc_ts_plate {
-	LRADC_SAMPLE_X,
-	LRADC_SAMPLE_Y,
-	LRADC_SAMPLE_PRESSURE,
-};
-
 static int mxs_lradc_ts_touched(struct mxs_lradc *lradc)
 {
 	uint32_t reg;
@@ -550,10 +994,6 @@ static void mxs_lradc_ts_work(struct work_struct *ts_work)
 	input_report_key(lradc->ts_input, BTN_TOUCH, 0);
 	input_sync(lradc->ts_input);
 
-	/* Do not restart the TS IRQ if the driver is shutting down. */
-	if (lradc->stop_touchscreen)
-		return;
-
 	/* Restart the touchscreen interrupts. */
 	mxs_lradc_reg_clear(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ, LRADC_CTRL1);
 	mxs_lradc_reg_set(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ_EN, LRADC_CTRL1);
@@ -563,36 +1003,29 @@ static int mxs_lradc_ts_open(struct input_dev *dev)
 {
 	struct mxs_lradc *lradc = input_get_drvdata(dev);
 
-	/* The touchscreen is starting. */
-	lradc->stop_touchscreen = false;
-
 	/* Enable the touch-detect circuitry. */
-	mxs_lradc_reg_set(lradc, mxs_lradc_touch_detect_bit(lradc),
-						LRADC_CTRL0);
-
-	/* Enable the touch-detect IRQ. */
-	mxs_lradc_reg_set(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ_EN, LRADC_CTRL1);
+	mxs_lradc_enable_touch_detection(lradc);
 
 	return 0;
 }
 
-static void mxs_lradc_ts_close(struct input_dev *dev)
+static void mxs_lradc_disable_ts(struct mxs_lradc *lradc)
 {
-	struct mxs_lradc *lradc = input_get_drvdata(dev);
-
-	/* Indicate the touchscreen is stopping. */
-	lradc->stop_touchscreen = true;
-	mb();
+	/* stop all interrupts from firing */
+	mxs_lradc_reg_clear(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ_EN |
+		LRADC_CTRL1_LRADC_IRQ_EN(2) | LRADC_CTRL1_LRADC_IRQ_EN(3) |
+		LRADC_CTRL1_LRADC_IRQ_EN(4) | LRADC_CTRL1_LRADC_IRQ_EN(5),
+		LRADC_CTRL1);
 
-	/* Wait until touchscreen thread finishes any possible remnants. */
-	cancel_work_sync(&lradc->ts_work);
+	/* Power-down touchscreen touch-detect circuitry. */
+	mxs_lradc_reg_clear(lradc, mxs_lradc_plate_mask(lradc), LRADC_CTRL0);
+}
 
-	/* Disable touchscreen touch-detect IRQ. */
-	mxs_lradc_reg_clear(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ_EN,
-						LRADC_CTRL1);
+static void mxs_lradc_ts_close(struct input_dev *dev)
+{
+	struct mxs_lradc *lradc = input_get_drvdata(dev);
 
-	/* Power-down touchscreen touch-detect circuitry. */
-	mxs_lradc_reg_clear(lradc, mxs_lradc_touch_detect_bit(lradc), LRADC_CTRL0);
+	mxs_lradc_disable_ts(lradc);
 }
 
 static int mxs_lradc_ts_register(struct mxs_lradc *lradc)
@@ -640,6 +1073,7 @@ static void mxs_lradc_ts_unregister(struct mxs_lradc *lradc)
 
 	cancel_work_sync(&lradc->ts_work);
 
+	mxs_lradc_disable_ts(lradc);
 	input_unregister_device(lradc->ts_input);
 }
 
@@ -652,30 +1086,23 @@ static irqreturn_t mxs_lradc_handle_irq(int irq, void *data)
 	struct mxs_lradc *lradc = iio_priv(iio);
 	unsigned long reg = readl(lradc->base + LRADC_CTRL1);
 	const uint32_t ts_irq_mask =
-		LRADC_CTRL1_TOUCH_DETECT_IRQ_EN |
-		LRADC_CTRL1_TOUCH_DETECT_IRQ;
+		LRADC_CTRL1_TOUCH_DETECT_IRQ |
+		LRADC_CTRL1_LRADC_IRQ(2) |
+		LRADC_CTRL1_LRADC_IRQ(3) |
+		LRADC_CTRL1_LRADC_IRQ(4) |
+		LRADC_CTRL1_LRADC_IRQ(5);
 
 	if (!(reg & mxs_lradc_irq_mask(lradc)))
 		return IRQ_NONE;
 
-	/*
-	 * Touchscreen IRQ handling code has priority and therefore
-	 * is placed here. In case touchscreen IRQ arrives, disable
-	 * it ASAP
-	 */
-	if (reg & LRADC_CTRL1_TOUCH_DETECT_IRQ) {
-		mxs_lradc_reg_clear(lradc, ts_irq_mask, LRADC_CTRL1);
-		if (!lradc->stop_touchscreen)
-			schedule_work(&lradc->ts_work);
-	}
+	if (lradc->use_touchscreen && (reg & ts_irq_mask))
+		mxs_lradc_handle_touch(lradc);
 
 	if (iio_buffer_enabled(iio))
 		iio_trigger_poll(iio->trig, iio_get_time_ns());
 	else if (reg & LRADC_CTRL1_LRADC_IRQ(0))
 		complete(&lradc->completion);
 
-	mxs_lradc_reg_clear(lradc, reg & mxs_lradc_irq_mask(lradc), LRADC_CTRL1);
-
 	return IRQ_HANDLED;
 }
 
@@ -971,6 +1398,17 @@ static const struct of_device_id mxs_lradc_dt_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, mxs_lradc_dt_ids);
 
+static int mxs_lradc_probe_touchscreen(struct mxs_lradc *lradc,
+						struct device_node *lradc_node)
+{
+	/* TODO retrieve from device tree */
+	lradc->over_sample_cnt = 4;
+	lradc->over_sample_delay = 2;
+	lradc->settling_delay = 10;
+
+	return 0;
+}
+
 static int mxs_lradc_probe(struct platform_device *pdev)
 {
 	const struct of_device_id *of_id =
@@ -983,7 +1421,7 @@ static int mxs_lradc_probe(struct platform_device *pdev)
 	struct iio_dev *iio;
 	struct resource *iores;
 	uint32_t ts_wires = 0;
-	int ret = 0;
+	int ret = 0, touch_ret;
 	int i;
 
 	/* Allocate the IIO device. */
@@ -1003,7 +1441,7 @@ static int mxs_lradc_probe(struct platform_device *pdev)
 	if (IS_ERR(lradc->base))
 		return PTR_ERR(lradc->base);
 
-	INIT_WORK(&lradc->ts_work, mxs_lradc_ts_work);
+	touch_ret = mxs_lradc_probe_touchscreen(lradc, node);
 
 	/* Check if touchscreen is enabled in DT. */
 	ret = of_property_read_u32(node, "fsl,lradc-touchscreen-wires",
@@ -1066,9 +1504,11 @@ static int mxs_lradc_probe(struct platform_device *pdev)
 		goto err_dev;
 
 	/* Register the touchscreen input device. */
-	ret = mxs_lradc_ts_register(lradc);
-	if (ret)
-		goto err_dev;
+	if (touch_ret == 0) {
+		ret = mxs_lradc_ts_register(lradc);
+		if (ret)
+			goto err_dev;
+	}
 
 	/* Register IIO device. */
 	ret = iio_device_register(iio);
-- 
1.8.4.rc3

[PATCH 5/5] Staging/iio/adc/touchscreen/MXS: Remove old touchscreen detection implementation

[Juergen Beisert]

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
CC: linux-arm-kernel at lists.infradead.org
CC: devel at driverdev.osuosl.org
CC: Marek Vasut <marex@denx.de>
CC: Fabio Estevam <fabio.estevam@freescale.com>
CC: Jonathan Cameron <jic23@cam.ac.uk>
---
 drivers/staging/iio/adc/mxs-lradc.c | 165 ------------------------------------
 1 file changed, 165 deletions(-)

diff --git a/drivers/staging/iio/adc/mxs-lradc.c b/drivers/staging/iio/adc/mxs-lradc.c
index 28b5ea4..638a228 100644
--- a/drivers/staging/iio/adc/mxs-lradc.c
+++ b/drivers/staging/iio/adc/mxs-lradc.c
@@ -183,7 +183,6 @@ struct mxs_lradc {
 	bool			use_touchbutton;
 
 	struct input_dev	*ts_input;
-	struct work_struct	ts_work;
 
 	enum mxs_lradc_id	soc;
 	enum lradc_ts_plate	cur_plate; /* statemachine */
@@ -837,168 +836,6 @@ static const struct iio_info mxs_lradc_iio_info = {
 	.read_raw		= mxs_lradc_read_raw,
 };
 
-static int mxs_lradc_ts_touched(struct mxs_lradc *lradc)
-{
-	uint32_t reg;
-
-	/* Enable touch detection. */
-	mxs_lradc_reg_clear(lradc, mxs_lradc_plate_mask(lradc), LRADC_CTRL0);
-	mxs_lradc_reg_set(lradc, mxs_lradc_touch_detect_bit(lradc),
-								LRADC_CTRL0);
-
-	msleep(LRADC_TS_SAMPLE_DELAY_MS);
-
-	reg = readl(lradc->base + LRADC_STATUS);
-
-	return reg & LRADC_STATUS_TOUCH_DETECT_RAW;
-}
-
-static int32_t mxs_lradc_ts_sample(struct mxs_lradc *lradc,
-				enum lradc_ts_plate plate, int change)
-{
-	unsigned long delay, jiff;
-	uint32_t reg, ctrl0 = 0, chan = 0;
-	/* The touchscreen always uses CTRL4 slot #7. */
-	const uint8_t slot = 7;
-	uint32_t val;
-
-	/*
-	 * There are three correct configurations of the controller sampling
-	 * the touchscreen, each of these configuration provides different
-	 * information from the touchscreen.
-	 *
-	 * The following table describes the sampling configurations:
-	 * +-------------+-------+-------+-------+
-	 * | Wire \ Axis |   X   |   Y   |   Z   |
-	 * +---------------------+-------+-------+
-	 * |   X+ (CH2)  |   HI  |   TS  |   TS  |
-	 * +-------------+-------+-------+-------+
-	 * |   X- (CH4)  |   LO  |   SH  |   HI  |
-	 * +-------------+-------+-------+-------+
-	 * |   Y+ (CH3)  |   SH  |   HI  |   HI  |
-	 * +-------------+-------+-------+-------+
-	 * |   Y- (CH5)  |   TS  |   LO  |   SH  |
-	 * +-------------+-------+-------+-------+
-	 *
-	 * HI ... strong '1'  ; LO ... strong '0'
-	 * SH ... sample here ; TS ... tri-state
-	 *
-	 * There are a few other ways of obtaining the Z coordinate
-	 * (aka. pressure), but the one in the table seems to be the
-	 * most reliable one.
-	 */
-	switch (plate) {
-	case LRADC_SAMPLE_X:
-		ctrl0 = mxs_lradc_drive_x_plate(lradc);
-		chan = 3;
-		break;
-	case LRADC_SAMPLE_Y:
-		ctrl0 = mxs_lradc_drive_y_plate(lradc);
-		chan = 4;
-		break;
-	case LRADC_SAMPLE_PRESSURE:
-		ctrl0 = mxs_lradc_drive_pressure(lradc);
-		chan = 5;
-		break;
-	}
-
-	if (change) {
-		mxs_lradc_reg_clear(lradc, mxs_lradc_plate_mask(lradc),
-						LRADC_CTRL0);
-		mxs_lradc_reg_set(lradc, ctrl0, LRADC_CTRL0);
-
-		mxs_lradc_reg_clear(lradc, LRADC_CTRL4_LRADCSELECT_MASK(slot),
-						LRADC_CTRL4);
-		mxs_lradc_reg_set(lradc,
-				chan << LRADC_CTRL4_LRADCSELECT_OFFSET(slot),
-				LRADC_CTRL4);
-	}
-
-	mxs_lradc_reg_clear(lradc, 0xffffffff, LRADC_CH(slot));
-	mxs_lradc_reg_set(lradc, 1 << slot, LRADC_CTRL0);
-
-	delay = jiffies + msecs_to_jiffies(LRADC_TS_SAMPLE_DELAY_MS);
-	do {
-		jiff = jiffies;
-		reg = readl_relaxed(lradc->base + LRADC_CTRL1);
-		if (reg & LRADC_CTRL1_LRADC_IRQ(slot))
-			break;
-	} while (time_before(jiff, delay));
-
-	mxs_lradc_reg_clear(lradc, LRADC_CTRL1_LRADC_IRQ(slot), LRADC_CTRL1);
-
-	if (time_after_eq(jiff, delay))
-		return -ETIMEDOUT;
-
-	val = readl(lradc->base + LRADC_CH(slot));
-	val &= LRADC_CH_VALUE_MASK;
-
-	return val;
-}
-
-static int32_t mxs_lradc_ts_sample_filter(struct mxs_lradc *lradc,
-				enum lradc_ts_plate plate)
-{
-	int32_t val, tot = 0;
-	int i;
-
-	val = mxs_lradc_ts_sample(lradc, plate, 1);
-
-	/* Delay a bit so the touchscreen is stable. */
-	mdelay(2);
-
-	for (i = 0; i < LRADC_TS_SAMPLE_AMOUNT; i++) {
-		val = mxs_lradc_ts_sample(lradc, plate, 0);
-		tot += val;
-	}
-
-	return tot / LRADC_TS_SAMPLE_AMOUNT;
-}
-
-static void mxs_lradc_ts_work(struct work_struct *ts_work)
-{
-	struct mxs_lradc *lradc = container_of(ts_work,
-				struct mxs_lradc, ts_work);
-	int val_x, val_y, val_p;
-	bool valid = false;
-
-	while (mxs_lradc_ts_touched(lradc)) {
-		/* Disable touch detector so we can sample the touchscreen. */
-		mxs_lradc_reg_clear(lradc, mxs_lradc_touch_detect_bit(lradc),
-						LRADC_CTRL0);
-
-		if (likely(valid)) {
-			input_report_abs(lradc->ts_input, ABS_X, val_x);
-			input_report_abs(lradc->ts_input, ABS_Y, val_y);
-			input_report_abs(lradc->ts_input, ABS_PRESSURE, val_p);
-			input_report_key(lradc->ts_input, BTN_TOUCH, 1);
-			input_sync(lradc->ts_input);
-		}
-
-		valid = false;
-
-		val_x = mxs_lradc_ts_sample_filter(lradc, LRADC_SAMPLE_X);
-		if (val_x < 0)
-			continue;
-		val_y = mxs_lradc_ts_sample_filter(lradc, LRADC_SAMPLE_Y);
-		if (val_y < 0)
-			continue;
-		val_p = mxs_lradc_ts_sample_filter(lradc, LRADC_SAMPLE_PRESSURE);
-		if (val_p < 0)
-			continue;
-
-		valid = true;
-	}
-
-	input_report_abs(lradc->ts_input, ABS_PRESSURE, 0);
-	input_report_key(lradc->ts_input, BTN_TOUCH, 0);
-	input_sync(lradc->ts_input);
-
-	/* Restart the touchscreen interrupts. */
-	mxs_lradc_reg_clear(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ, LRADC_CTRL1);
-	mxs_lradc_reg_set(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ_EN, LRADC_CTRL1);
-}
-
 static int mxs_lradc_ts_open(struct input_dev *dev)
 {
 	struct mxs_lradc *lradc = input_get_drvdata(dev);
@@ -1071,8 +908,6 @@ static void mxs_lradc_ts_unregister(struct mxs_lradc *lradc)
 	if (!lradc->use_touchscreen)
 		return;
 
-	cancel_work_sync(&lradc->ts_work);
-
 	mxs_lradc_disable_ts(lradc);
 	input_unregister_device(lradc->ts_input);
 }
-- 
1.8.4.rc3

[PATCH 4/5] Staging/iio/adc/touchscreen/MXS: add interrupt driven touch detection

[Dan Carpenter]

On Fri, Sep 06, 2013 at 12:08:42PM +0200, Juergen Beisert wrote:
> +static int mxs_lradc_read_ts_channel(struct mxs_lradc *lradc)
> +{
> +	u32 reg;
> +	int val;
> +
> +	reg = readl(lradc->base + LRADC_CTRL1);
> +
> +	/* only channels 3 to 5 are of interest here */
> +	if (reg & LRADC_CTRL1_LRADC_IRQ(TS_CH_YP)) {
> +		pr_devel("!3");

Gar.  I meant to comment on this the first time this patch was sent.

Please remove the pr_devel() calls.  They are nonsense.

regards,
dan carpenter

[PATCH 4/5] Staging/iio/adc/touchscreen/MXS: add interrupt driven touch detection

[Jürgen Beisert]

On Friday 06 September 2013 14:26:11 Dan Carpenter wrote:
> On Fri, Sep 06, 2013 at 12:08:42PM +0200, Juergen Beisert wrote:
> > +static int mxs_lradc_read_ts_channel(struct mxs_lradc *lradc)
> > +{
> > +	u32 reg;
> > +	int val;
> > +
> > +	reg = readl(lradc->base + LRADC_CTRL1);
> > +
> > +	/* only channels 3 to 5 are of interest here */
> > +	if (reg & LRADC_CTRL1_LRADC_IRQ(TS_CH_YP)) {
> > +		pr_devel("!3");
>
> Gar.  I meant to comment on this the first time this patch was sent.
>
> Please remove the pr_devel() calls.  They are nonsense.

They are very helpful for development to monitor the statemachine... :) But you 
are right, I will remove them.

Regards,
Juergen

-- 
Pengutronix e.K. ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| Juergen Beisert ? ? ? ? ? ? |
Linux Solutions for Science and Industry ? ? ?| http://www.pengutronix.de/  |

[PATCH 4/5] Staging/iio/adc/touchscreen/MXS: add interrupt driven touch detection

[Marek Vasut]

Dear J?rgen Beisert,

> On Friday 06 September 2013 14:26:11 Dan Carpenter wrote:
> > On Fri, Sep 06, 2013 at 12:08:42PM +0200, Juergen Beisert wrote:
> > > +static int mxs_lradc_read_ts_channel(struct mxs_lradc *lradc)
> > > +{
> > > +	u32 reg;
> > > +	int val;
> > > +
> > > +	reg = readl(lradc->base + LRADC_CTRL1);
> > > +
> > > +	/* only channels 3 to 5 are of interest here */
> > > +	if (reg & LRADC_CTRL1_LRADC_IRQ(TS_CH_YP)) {
> > > +		pr_devel("!3");
> > 
> > Gar.  I meant to comment on this the first time this patch was sent.
> > 
> > Please remove the pr_devel() calls.  They are nonsense.
> 
> They are very helpful for development to monitor the statemachine... :) But
> you are right, I will remove them.

You can put them into a separate patch which can be NAK'd separatelly :)

Best regards,
Marek Vasut