From 8685f22b5bfdab0b335232eb70a0af3388d35299 Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Fri, 21 Jun 2024 13:35:52 -0700 Subject: [PATCH] Input: ads7846 - handle HSYNC GPIO Add handling of HSYNC signal emitted by the TI ADS7846 if it is hooked up to a GPIO. Signed-off-by: Linus Walleij 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 --- drivers/input/touchscreen/ads7846.c | 35 ++++++++++++++++++++++++----- 1 file changed, 29 insertions(+), 6 deletions(-) diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c index d2bbb436a77df9..6e11cb877ae1af 100644 --- a/drivers/input/touchscreen/ads7846.c +++ b/drivers/input/touchscreen/ads7846.c @@ -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);