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Input: ads7846 - handle HSYNC GPIO

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Add handling of HSYNC signal emitted by the TI ADS7846 if it is hooked
up to a GPIO.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20240430-gpio-leds-miscarm-v1-3-9c94d7711f6c@linaro.org
[dtor: dropped Spitz changes, kept platform data wait_for_sync option]
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
This commit is contained in:
Linus Walleij 2024-06-21 13:35:52 -07:00 committed by Dmitry Torokhov
parent e7202f6467
commit 8685f22b5b
1 changed files with 29 additions and 6 deletions
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35
drivers/input/touchscreen/ads7846.c
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@ -138,6 +138,7 @@ struct ads7846 {
void *filter_data;
int (*get_pendown_state)(void);
struct gpio_desc *gpio_pendown;
struct gpio_desc *gpio_hsync;
void (*wait_for_sync)(void);
};
@ -634,10 +635,6 @@ ATTRIBUTE_GROUPS(ads784x);
/*--------------------------------------------------------------------------*/
static void null_wait_for_sync(void)
{
}
static int ads7846_debounce_filter(void *ads, int data_idx, int *val)
{
struct ads7846 *ts = ads;
@ -790,6 +787,28 @@ static int ads7846_filter(struct ads7846 *ts)
return 0;
}
static void ads7846_wait_for_hsync(struct ads7846 *ts)
{
if (ts->wait_for_sync) {
ts->wait_for_sync();
return;
}
if (!ts->gpio_hsync)
return;
/*
* Wait for HSYNC to assert the line should be flagged
* as active low so here we are waiting for it to assert
*/
while (!gpiod_get_value(ts->gpio_hsync))
cpu_relax();
/* Then we wait for it do de-assert */
while (gpiod_get_value(ts->gpio_hsync))
cpu_relax();
}
static void ads7846_read_state(struct ads7846 *ts)
{
struct ads7846_packet *packet = ts->packet;
@ -800,7 +819,7 @@ static void ads7846_read_state(struct ads7846 *ts)
packet->last_cmd_idx = 0;
while (true) {
ts->wait_for_sync();
ads7846_wait_for_hsync(ts);
m = &ts->msg[msg_idx];
error = spi_sync(ts->spi, m);
@ -1258,7 +1277,11 @@ static int ads7846_probe(struct spi_device *spi)
ts->penirq_recheck_delay_usecs =
pdata->penirq_recheck_delay_usecs;
ts->wait_for_sync = pdata->wait_for_sync ? : null_wait_for_sync;
ts->wait_for_sync = pdata->wait_for_sync;
ts->gpio_hsync = devm_gpiod_get_optional(dev, "ti,hsync", GPIOD_IN);
if (IS_ERR(ts->gpio_hsync))
return PTR_ERR(ts->gpio_hsync);
snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(dev));
snprintf(ts->name, sizeof(ts->name), "ADS%d Touchscreen", ts->model);