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iio: adc: at91_adc: Add support for touchscreens without TSMR
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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@free-electrons.com>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
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Alexandre Belloni authored and Nicolas Ferre committed May 7, 2014
1 parent 2de0c01 commit 84882b0
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Showing 3 changed files with 174 additions and 47 deletions.
13 changes: 13 additions & 0 deletions arch/arm/mach-at91/include/mach/at91_adc.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand All @@ -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)
Expand All @@ -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 */
Expand All @@ -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)
Expand Down Expand Up @@ -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
200 changes: 153 additions & 47 deletions drivers/iio/adc/at91_adc.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -133,6 +131,11 @@ struct at91_adc_state {

u16 ts_sample_period_val;
u32 ts_pressure_threshold;
u16 ts_pendbc;

bool ts_bufferedmeasure;
u32 ts_prev_absx;
u32 ts_prev_absy;
};

static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
Expand Down Expand Up @@ -239,7 +242,72 @@ static int at91_ts_sample(struct at91_adc_state *st)
return 0;
}

static irqreturn_t at91_adc_interrupt(int irq, void *private)
static irqreturn_t at91_adc_rl_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);
unsigned int reg;

status &= at91_adc_readl(st, AT91_ADC_IMR);
if (status & st->registers->drdy_mask)
handle_adc_eoc_trigger(irq, idev);

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 = false;
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 = true;

/* 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));
}

return IRQ_HANDLED;
}

static irqreturn_t at91_adc_9x5_interrupt(int irq, void *private)
{
struct iio_dev *idev = private;
struct at91_adc_state *st = iio_priv(idev);
Expand Down Expand Up @@ -672,6 +740,8 @@ 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;
Expand Down Expand Up @@ -795,6 +865,7 @@ 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;
}
Expand All @@ -809,53 +880,72 @@ 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;
}

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
Expand All @@ -864,7 +954,7 @@ 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);

Expand Down Expand Up @@ -893,17 +983,37 @@ 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;
}

Expand Down Expand Up @@ -962,11 +1072,13 @@ static int at91_adc_probe(struct platform_device *pdev)
*/
at91_adc_writel(st, AT91_ADC_CR, AT91_ADC_SWRST);
at91_adc_writel(st, AT91_ADC_IDR, 0xFFFFFFFF);
ret = request_irq(st->irq,
at91_adc_interrupt,
0,
pdev->dev.driver->name,
idev);

if (st->caps->has_tsmr)
ret = request_irq(st->irq, at91_adc_9x5_interrupt, 0,
pdev->dev.driver->name, idev);
else
ret = request_irq(st->irq, at91_adc_rl_interrupt, 0,
pdev->dev.driver->name, idev);
if (ret) {
dev_err(&pdev->dev, "Failed to allocate IRQ.\n");
return ret;
Expand Down Expand Up @@ -1070,12 +1182,6 @@ 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;
Expand Down
8 changes: 8 additions & 0 deletions include/linux/platform_data/at91_adc.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,12 @@
#ifndef _AT91_ADC_H_
#define _AT91_ADC_H_

enum atmel_adc_ts_type {
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
Expand All @@ -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;
Expand All @@ -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);
Expand Down

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