[PATCH v6 5/9] iio: adc: at91-sama5d2_adc: add support for position and pressure channels

From: Eugen Hristev
Date: Mon May 21 2018 - 05:38:48 EST

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 <eugen.hristev@xxxxxxxxxxxxx>
---
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(-)

diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index 8729d65..58c4c2b 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c
@@ -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:
--
2.7.4