Re: [PATCH 04/15] iio: adc: at91_adc: Add support for touchscreens without TSMR

From: Jonathan Cameron
Date: Sun Mar 16 2014 - 14:16:05 EST

On 05/03/14 17:35, Alexandre Belloni wrote:
Old ADCs, as present on the sam9rl and the sam9g45 don't have a TSMR register
and the touchscreen support should be handled differently.

Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
One comment inline about handling of devices where the platform data doesn't
include the touchscreen type. I'd expect zero to be the current default
rather than NONE...
---
arch/arm/mach-at91/include/mach/at91_adc.h | 13 ++
drivers/iio/adc/at91_adc.c | 199 ++++++++++++++++++++++-------
include/linux/platform_data/at91_adc.h | 8 ++
3 files changed, 172 insertions(+), 48 deletions(-)

diff --git a/arch/arm/mach-at91/include/mach/at91_adc.h b/arch/arm/mach-at91/include/mach/at91_adc.h
index c287307b9a3b..7d80396346b2 100644
--- a/arch/arm/mach-at91/include/mach/at91_adc.h
+++ b/arch/arm/mach-at91/include/mach/at91_adc.h
@@ -20,6 +20,9 @@
#define AT91_ADC_START (1 << 1) /* Start Conversion */

#define AT91_ADC_MR 0x04 /* Mode Register */
+#define AT91_ADC_TSAMOD (3 << 0) /* ADC mode */
+#define AT91_ADC_TSAMOD_ADC_ONLY_MODE (0 << 0) /* ADC Mode */
+#define AT91_ADC_TSAMOD_TS_ONLY_MODE (1 << 0) /* Touch Screen Only Mode */
#define AT91_ADC_TRGEN (1 << 0) /* Trigger Enable */
#define AT91_ADC_TRGSEL (7 << 1) /* Trigger Selection */
#define AT91_ADC_TRGSEL_TC0 (0 << 1)
@@ -28,6 +31,7 @@
#define AT91_ADC_TRGSEL_EXTERNAL (6 << 1)
#define AT91_ADC_LOWRES (1 << 4) /* Low Resolution */
#define AT91_ADC_SLEEP (1 << 5) /* Sleep Mode */
+#define AT91_ADC_PENDET (1 << 6) /* Pen contact detection enable */
#define AT91_ADC_PRESCAL_9260 (0x3f << 8) /* Prescalar Rate Selection */
#define AT91_ADC_PRESCAL_9G45 (0xff << 8)
#define AT91_ADC_PRESCAL_(x) ((x) << 8)
@@ -37,6 +41,12 @@
#define AT91_ADC_STARTUP_(x) ((x) << 16)
#define AT91_ADC_SHTIM (0xf << 24) /* Sample & Hold Time */
#define AT91_ADC_SHTIM_(x) ((x) << 24)
+#define AT91_ADC_PENDBC (0x0f << 28) /* Pen Debounce time */
+#define AT91_ADC_PENDBC_(x) ((x) << 28)
+
+#define AT91_ADC_TSR 0x0C
+#define AT91_ADC_TSR_SHTIM (0xf << 24) /* Sample & Hold Time */
+#define AT91_ADC_TSR_SHTIM_(x) ((x) << 24)

#define AT91_ADC_CHER 0x10 /* Channel Enable Register */
#define AT91_ADC_CHDR 0x14 /* Channel Disable Register */
@@ -60,6 +70,8 @@
#define AT91_ADC_IER 0x24 /* Interrupt Enable Register */
#define AT91_ADC_IDR 0x28 /* Interrupt Disable Register */
#define AT91_ADC_IMR 0x2C /* Interrupt Mask Register */
+#define AT91RL_ADC_IER_PEN (1 << 20)
+#define AT91RL_ADC_IER_NOPEN (1 << 21)
#define AT91_ADC_IER_PEN (1 << 29)
#define AT91_ADC_IER_NOPEN (1 << 30)
#define AT91_ADC_IER_XRDY (1 << 20)
@@ -102,6 +114,7 @@
#define AT91_ADC_TRGR_TRGPER (0xffff << 16)
#define AT91_ADC_TRGR_TRGPER_(x) ((x) << 16)
#define AT91_ADC_TRGR_TRGMOD (0x7 << 0)
+#define AT91_ADC_TRGR_NONE (0 << 0)
#define AT91_ADC_TRGR_MOD_PERIOD_TRIG (5 << 0)

#endif
diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
index 1beae65aef2c..3e92b16e9301 100644
--- a/drivers/iio/adc/at91_adc.c
+++ b/drivers/iio/adc/at91_adc.c
@@ -46,6 +46,10 @@
#define TOUCH_SAMPLE_PERIOD_US 2000 /* 2ms */
#define TOUCH_PEN_DETECT_DEBOUNCE_US 200

+#define MAX_RLPOS_BITS 10
+#define TOUCH_SAMPLE_PERIOD_US_RL 10000 /* 10ms, the SoC can't keep up with 2ms */
+#define TOUCH_SHTIM 0xa
+
/**
* struct at91_adc_reg_desc - Various informations relative to registers
* @channel_base: Base offset for the channel data registers
@@ -83,12 +87,6 @@ struct at91_adc_caps {
struct at91_adc_reg_desc registers;
};

-enum atmel_adc_ts_type {
- ATMEL_ADC_TOUCHSCREEN_NONE = 0,
- ATMEL_ADC_TOUCHSCREEN_4WIRE = 4,
- ATMEL_ADC_TOUCHSCREEN_5WIRE = 5,
-};
-
struct at91_adc_state {
struct clk *adc_clk;
u16 *buffer;
@@ -133,6 +131,11 @@ struct at91_adc_state {

u16 ts_sample_period_val;
u32 ts_pressure_threshold;
+ u16 ts_pendbc;
+
+ u8 ts_bufferedmeasure;
+ u32 ts_prev_absx;
+ u32 ts_prev_absy;
};

static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
@@ -239,19 +242,68 @@ static int at91_ts_sample(struct at91_adc_state *st)
return 0;
}

-static irqreturn_t at91_adc_interrupt(int irq, void *private)
+void handle_adc_rl_ts_irq(int irq, struct at91_adc_state *st, u32 status)
+{
+ unsigned int reg;
+
+ status &= at91_adc_readl(st, AT91_ADC_IMR);
+ if (status & AT91RL_ADC_IER_PEN) {
+ /* Disabling pen debounce is required to get a NOPEN irq */
+ reg = at91_adc_readl(st, AT91_ADC_MR);
+ reg &= ~AT91_ADC_PENDBC;
+ at91_adc_writel(st, AT91_ADC_MR, reg);
+
+ at91_adc_writel(st, AT91_ADC_IDR, AT91RL_ADC_IER_PEN);
+ at91_adc_writel(st, AT91_ADC_IER, AT91RL_ADC_IER_NOPEN
+ | AT91_ADC_EOC(3));
+ /* Set up period trigger for sampling */
+ at91_adc_writel(st, st->registers->trigger_register,
+ AT91_ADC_TRGR_MOD_PERIOD_TRIG |
+ AT91_ADC_TRGR_TRGPER_(st->ts_sample_period_val));
+ } else if (status & AT91RL_ADC_IER_NOPEN) {
+ reg = at91_adc_readl(st, AT91_ADC_MR);
+ reg |= AT91_ADC_PENDBC_(st->ts_pendbc) & AT91_ADC_PENDBC;
+ at91_adc_writel(st, AT91_ADC_MR, reg);
+ at91_adc_writel(st, st->registers->trigger_register,
+ AT91_ADC_TRGR_NONE);
+
+ at91_adc_writel(st, AT91_ADC_IDR, AT91RL_ADC_IER_NOPEN
+ | AT91_ADC_EOC(3));
+ at91_adc_writel(st, AT91_ADC_IER, AT91RL_ADC_IER_PEN);
+ st->ts_bufferedmeasure = 0;
+ input_report_key(st->ts_input, BTN_TOUCH, 0);
+ input_sync(st->ts_input);
+ } else if (status & AT91_ADC_EOC(3)) {
+ /* Conversion finished */
+ if (st->ts_bufferedmeasure) {
+ /* Last measurement is always discarded, since it can
+ * be erroneous.
+ * Always report previous measurement */
+ input_report_abs(st->ts_input, ABS_X, st->ts_prev_absx);
+ input_report_abs(st->ts_input, ABS_Y, st->ts_prev_absy);
+ input_report_key(st->ts_input, BTN_TOUCH, 1);
+ input_sync(st->ts_input);
+ } else
+ st->ts_bufferedmeasure = 1;
+
+ /* Now make new measurement */
+ st->ts_prev_absx = at91_adc_readl(st, AT91_ADC_CHAN(st, 3))
+ << MAX_RLPOS_BITS;
+ st->ts_prev_absx /= at91_adc_readl(st, AT91_ADC_CHAN(st, 2));
+
+ st->ts_prev_absy = at91_adc_readl(st, AT91_ADC_CHAN(st, 1))
+ << MAX_RLPOS_BITS;
+ st->ts_prev_absy /= at91_adc_readl(st, AT91_ADC_CHAN(st, 0));
+ }
+}
+
+void handle_adc_9x5_ts_irq(int irq, struct at91_adc_state *st, u32 status)
{
- struct iio_dev *idev = private;
- struct at91_adc_state *st = iio_priv(idev);
- u32 status = at91_adc_readl(st, st->registers->status_register);
const uint32_t ts_data_irq_mask =
AT91_ADC_IER_XRDY |
AT91_ADC_IER_YRDY |
AT91_ADC_IER_PRDY;

- if (status & st->registers->drdy_mask)
- handle_adc_eoc_trigger(irq, idev);
-
if (status & AT91_ADC_IER_PEN) {
at91_adc_writel(st, AT91_ADC_IDR, AT91_ADC_IER_PEN);
at91_adc_writel(st, AT91_ADC_IER, AT91_ADC_IER_NOPEN |
@@ -283,6 +335,21 @@ static irqreturn_t at91_adc_interrupt(int irq, void *private)
at91_adc_readl(st, AT91_ADC_TSPRESSR);
}
}
+}
+
+static irqreturn_t at91_adc_interrupt(int irq, void *private)
+{
+ struct iio_dev *idev = private;
+ struct at91_adc_state *st = iio_priv(idev);
+ u32 status = at91_adc_readl(st, st->registers->status_register);
+
+ if (status & st->registers->drdy_mask)
+ handle_adc_eoc_trigger(irq, idev);
+
+ if (st->caps->has_tsmr)
+ handle_adc_9x5_ts_irq(irq, st, status);
+ else
+ handle_adc_rl_ts_irq(irq, st, status);

return IRQ_HANDLED;
}
@@ -672,6 +739,8 @@ static int at91_adc_probe_dt_ts(struct device_node *node,
return -EINVAL;
}

+ if (!st->caps->has_tsmr)
+ return 0;
prop = 0;
of_property_read_u32(node, "atmel,adc-ts-pressure-threshold", &prop);
st->ts_pressure_threshold = prop;
@@ -795,6 +864,7 @@ static int at91_adc_probe_pdata(struct at91_adc_state *st,
st->trigger_number = pdata->trigger_number;
st->trigger_list = pdata->trigger_list;
st->registers = &st->caps->registers;
+ st->touchscreen_type = pdata->touchscreen_type;

return 0;
}
@@ -809,7 +879,10 @@ static int atmel_ts_open(struct input_dev *dev)
{
struct at91_adc_state *st = input_get_drvdata(dev);

- at91_adc_writel(st, AT91_ADC_IER, AT91_ADC_IER_PEN);
+ if (st->caps->has_tsmr)
+ at91_adc_writel(st, AT91_ADC_IER, AT91_ADC_IER_PEN);
+ else
+ at91_adc_writel(st, AT91_ADC_IER, AT91RL_ADC_IER_PEN);
return 0;
}

@@ -817,45 +890,61 @@ static void atmel_ts_close(struct input_dev *dev)
{
struct at91_adc_state *st = input_get_drvdata(dev);

- at91_adc_writel(st, AT91_ADC_IDR, AT91_ADC_IER_PEN);
+ if (st->caps->has_tsmr)
+ at91_adc_writel(st, AT91_ADC_IDR, AT91_ADC_IER_PEN);
+ else
+ at91_adc_writel(st, AT91_ADC_IDR, AT91RL_ADC_IER_PEN);
}

static int at91_ts_hw_init(struct at91_adc_state *st, u32 adc_clk_khz)
{
- u32 reg = 0, pendbc;
+ u32 reg = 0;
int i = 0;

- if (st->touchscreen_type == ATMEL_ADC_TOUCHSCREEN_4WIRE)
- reg = AT91_ADC_TSMR_TSMODE_4WIRE_PRESS;
- else
- reg = AT91_ADC_TSMR_TSMODE_5WIRE;
-
/* a Pen Detect Debounce Time is necessary for the ADC Touch to avoid
* pen detect noise.
* The formula is : Pen Detect Debounce Time = (2 ^ pendbc) / ADCClock
*/
- pendbc = round_up(TOUCH_PEN_DETECT_DEBOUNCE_US * adc_clk_khz / 1000, 1);
+ st->ts_pendbc = round_up(TOUCH_PEN_DETECT_DEBOUNCE_US * adc_clk_khz /
+ 1000, 1);

- while (pendbc >> ++i)
+ while (st->ts_pendbc >> ++i)
; /* Empty! Find the shift offset */
- if (abs(pendbc - (1 << i)) < abs(pendbc - (1 << (i - 1))))
- pendbc = i;
+ if (abs(st->ts_pendbc - (1 << i)) < abs(st->ts_pendbc - (1 << (i - 1))))
+ st->ts_pendbc = i;
else
- pendbc = i - 1;
+ st->ts_pendbc = i - 1;

- if (st->caps->has_tsmr) {
- reg |= AT91_ADC_TSMR_TSAV_(st->caps->ts_filter_average)
- & AT91_ADC_TSMR_TSAV;
- reg |= AT91_ADC_TSMR_PENDBC_(pendbc) & AT91_ADC_TSMR_PENDBC;
- reg |= AT91_ADC_TSMR_NOTSDMA;
- reg |= AT91_ADC_TSMR_PENDET_ENA;
- reg |= 0x03 << 8; /* TSFREQ, need bigger than TSAV */
-
- at91_adc_writel(st, AT91_ADC_TSMR, reg);
- } else {
- /* TODO: for 9g45 which has no TSMR */
+ if (!st->caps->has_tsmr) {
+ reg = at91_adc_readl(st, AT91_ADC_MR);
+ reg |= AT91_ADC_TSAMOD_TS_ONLY_MODE | AT91_ADC_PENDET;
+
+ reg |= AT91_ADC_PENDBC_(st->ts_pendbc) & AT91_ADC_PENDBC;
+ at91_adc_writel(st, AT91_ADC_MR, reg);
+
+ reg = AT91_ADC_TSR_SHTIM_(TOUCH_SHTIM) & AT91_ADC_TSR_SHTIM;
+ at91_adc_writel(st, AT91_ADC_TSR, reg);
+
+ st->ts_sample_period_val = round_up((TOUCH_SAMPLE_PERIOD_US_RL *
+ adc_clk_khz / 1000) - 1, 1);
+
+ return 0;
}

+ if (st->touchscreen_type == ATMEL_ADC_TOUCHSCREEN_4WIRE)
+ reg = AT91_ADC_TSMR_TSMODE_4WIRE_PRESS;
+ else
+ reg = AT91_ADC_TSMR_TSMODE_5WIRE;
+
+ reg |= AT91_ADC_TSMR_TSAV_(st->caps->ts_filter_average)
+ & AT91_ADC_TSMR_TSAV;
+ reg |= AT91_ADC_TSMR_PENDBC_(st->ts_pendbc) & AT91_ADC_TSMR_PENDBC;
+ reg |= AT91_ADC_TSMR_NOTSDMA;
+ reg |= AT91_ADC_TSMR_PENDET_ENA;
+ reg |= 0x03 << 8; /* TSFREQ, needs to be bigger than TSAV */
+
+ at91_adc_writel(st, AT91_ADC_TSMR, reg);
+
/* Change adc internal resistor value for better pen detection,
* default value is 100 kOhm.
* 0 = 200 kOhm, 1 = 150 kOhm, 2 = 100 kOhm, 3 = 50 kOhm
@@ -864,7 +953,7 @@ static int at91_ts_hw_init(struct at91_adc_state *st, u32 adc_clk_khz)
at91_adc_writel(st, AT91_ADC_ACR, st->caps->ts_pen_detect_sensitivity
& AT91_ADC_ACR_PENDETSENS);

- /* Sample Peroid Time = (TRGPER + 1) / ADCClock */
+ /* Sample Period Time = (TRGPER + 1) / ADCClock */
st->ts_sample_period_val = round_up((TOUCH_SAMPLE_PERIOD_US *
adc_clk_khz / 1000) - 1, 1);

@@ -893,17 +982,37 @@ static int at91_ts_register(struct at91_adc_state *st,
__set_bit(EV_ABS, input->evbit);
__set_bit(EV_KEY, input->evbit);
__set_bit(BTN_TOUCH, input->keybit);
- input_set_abs_params(input, ABS_X, 0, (1 << MAX_POS_BITS) - 1, 0, 0);
- input_set_abs_params(input, ABS_Y, 0, (1 << MAX_POS_BITS) - 1, 0, 0);
- input_set_abs_params(input, ABS_PRESSURE, 0, 0xffffff, 0, 0);
+ if (st->caps->has_tsmr) {
+ input_set_abs_params(input, ABS_X, 0, (1 << MAX_POS_BITS) - 1,
+ 0, 0);
+ input_set_abs_params(input, ABS_Y, 0, (1 << MAX_POS_BITS) - 1,
+ 0, 0);
+ input_set_abs_params(input, ABS_PRESSURE, 0, 0xffffff, 0, 0);
+ } else {
+ if (st->touchscreen_type != ATMEL_ADC_TOUCHSCREEN_4WIRE) {
+ dev_err(&pdev->dev,
+ "This touchscreen controller only support 4 wires\n");
+ ret = -EINVAL;
+ goto err;
+ }
+
+ input_set_abs_params(input, ABS_X, 0, (1 << MAX_RLPOS_BITS) - 1,
+ 0, 0);
+ input_set_abs_params(input, ABS_Y, 0, (1 << MAX_RLPOS_BITS) - 1,
+ 0, 0);
+ }

st->ts_input = input;
input_set_drvdata(input, st);

ret = input_register_device(input);
if (ret)
- input_free_device(st->ts_input);
+ goto err;
+
+ return ret;

+err:
+ input_free_device(st->ts_input);
return ret;
}

@@ -1070,12 +1179,6 @@ static int at91_adc_probe(struct platform_device *pdev)
goto error_disable_adc_clk;
}
} else {
- if (!st->caps->has_tsmr) {
- dev_err(&pdev->dev, "We don't support non-TSMR adc\n");
- ret = -ENODEV;
- goto error_disable_adc_clk;
- }
-
ret = at91_ts_register(st, pdev);
if (ret)
goto error_disable_adc_clk;
diff --git a/include/linux/platform_data/at91_adc.h b/include/linux/platform_data/at91_adc.h
index fcf73879dbfe..7819fc787731 100644
--- a/include/linux/platform_data/at91_adc.h
+++ b/include/linux/platform_data/at91_adc.h
@@ -7,6 +7,12 @@
#ifndef _AT91_ADC_H_
#define _AT91_ADC_H_

+enum atmel_adc_ts_type {
This means that the default for existing touch screens (where the platform
data won't include setting this value) will be none. Is that correct?
+ ATMEL_ADC_TOUCHSCREEN_NONE = 0,
+ ATMEL_ADC_TOUCHSCREEN_4WIRE = 4,
+ ATMEL_ADC_TOUCHSCREEN_5WIRE = 5,
+};
+
/**
* struct at91_adc_trigger - description of triggers
* @name: name of the trigger advertised to the user
@@ -28,6 +34,7 @@ struct at91_adc_trigger {
* @trigger_number: Number of triggers available in the ADC
* @use_external_triggers: does the board has external triggers availables
* @vref: Reference voltage for the ADC in millivolts
+ * @touchscreen_type: If a touchscreen is connected, its type (4 or 5 wires)
*/
struct at91_adc_data {
unsigned long channels_used;
@@ -36,6 +43,7 @@ struct at91_adc_data {
u8 trigger_number;
bool use_external_triggers;
u16 vref;
+ enum atmel_adc_ts_type touchscreen_type;
};

extern void __init at91_add_device_adc(struct at91_adc_data *data);


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