[PATCH v4 2/2] HID: i2c-hid: elan: Add ili9882t timing

[Cong Yang]

The ili9882t is a TDDI IC (Touch with Display Driver). The
datasheet specifies there should be 60ms between touch SDA
sleep and panel RESX. Doug's series[1] allows panels and
touchscreens to power on/off together, so we can add the 65 ms
delay in i2c_hid_core_suspend before panel_unprepare.

Beacuse ilitek9882 touchscrgeen is a panel follower, and
needs to use vccio-supply instead of vcc33-supply, so set
it "null" to ili9882t_chip_data, then using dummy regulator.

[1]: https://lore.kernel.org/r/20230607215224.2067679-1-dianders@xxxxxxxxxxxx

Signed-off-by: Cong Yang <yangcong5@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
---
 drivers/hid/i2c-hid/i2c-hid-of-elan.c | 33 +++++++++++++++++++++------
 1 file changed, 26 insertions(+), 7 deletions(-)

diff --git a/drivers/hid/i2c-hid/i2c-hid-of-elan.c b/drivers/hid/i2c-hid/i2c-hid-of-elan.c
index 76ddc8be1cbb..40e6b8ebe8d1 100644
--- a/drivers/hid/i2c-hid/i2c-hid-of-elan.c
+++ b/drivers/hid/i2c-hid/i2c-hid-of-elan.c
@@ -18,9 +18,11 @@
 #include "i2c-hid.h"
 
 struct elan_i2c_hid_chip_data {
-	unsigned int post_gpio_reset_delay_ms;
+	unsigned int post_gpio_reset_on_delay_ms;
+	unsigned int post_gpio_reset_off_delay_ms;
 	unsigned int post_power_delay_ms;
 	u16 hid_descriptor_address;
+	const char *main_supply_name;
 };
 
 struct i2c_hid_of_elan {
@@ -52,8 +54,8 @@ static int elan_i2c_hid_power_up(struct i2chid_ops *ops)
 		msleep(ihid_elan->chip_data->post_power_delay_ms);
 
 	gpiod_set_value_cansleep(ihid_elan->reset_gpio, 0);
-	if (ihid_elan->chip_data->post_gpio_reset_delay_ms)
-		msleep(ihid_elan->chip_data->post_gpio_reset_delay_ms);
+	if (ihid_elan->chip_data->post_gpio_reset_on_delay_ms)
+		msleep(ihid_elan->chip_data->post_gpio_reset_on_delay_ms);
 
 	return 0;
 }
@@ -64,6 +66,9 @@ static void elan_i2c_hid_power_down(struct i2chid_ops *ops)
 		container_of(ops, struct i2c_hid_of_elan, ops);
 
 	gpiod_set_value_cansleep(ihid_elan->reset_gpio, 1);
+	if (ihid_elan->chip_data->post_gpio_reset_off_delay_ms)
+		msleep(ihid_elan->chip_data->post_gpio_reset_off_delay_ms);
+
 	regulator_disable(ihid_elan->vccio);
 	regulator_disable(ihid_elan->vcc33);
 }
@@ -89,24 +94,38 @@ static int i2c_hid_of_elan_probe(struct i2c_client *client)
 	if (IS_ERR(ihid_elan->vccio))
 		return PTR_ERR(ihid_elan->vccio);
 
-	ihid_elan->vcc33 = devm_regulator_get(&client->dev, "vcc33");
+	ihid_elan->chip_data = device_get_match_data(&client->dev);
+
+	ihid_elan->vcc33 = devm_regulator_get(&client->dev, ihid_elan->chip_data->main_supply_name);
 	if (IS_ERR(ihid_elan->vcc33))
 		return PTR_ERR(ihid_elan->vcc33);
 
-	ihid_elan->chip_data = device_get_match_data(&client->dev);
-
 	return i2c_hid_core_probe(client, &ihid_elan->ops,
 				  ihid_elan->chip_data->hid_descriptor_address, 0);
 }
 
 static const struct elan_i2c_hid_chip_data elan_ekth6915_chip_data = {
 	.post_power_delay_ms = 1,
-	.post_gpio_reset_delay_ms = 300,
+	.post_gpio_reset_on_delay_ms = 300,
+	.hid_descriptor_address = 0x0001,
+	.main_supply_name = "vcc33",
+};
+
+static const struct elan_i2c_hid_chip_data ilitek_ili9882t_chip_data = {
+	.post_power_delay_ms = 1,
+	.post_gpio_reset_on_delay_ms = 200,
+	.post_gpio_reset_off_delay_ms = 65,
 	.hid_descriptor_address = 0x0001,
+	/* this touchscreen is tightly integrated with the panel and assumes
+	 * that the relevant power rails (other than the IO rail) have already
+	 * been turned on by the panel driver because we're a panel follower.
+	 */
+	.main_supply_name = "null",
 };
 
 static const struct of_device_id elan_i2c_hid_of_match[] = {
 	{ .compatible = "elan,ekth6915", .data = &elan_ekth6915_chip_data },
+	{ .compatible = "ilitek,ili9882t", .data = &ilitek_ili9882t_chip_data },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, elan_i2c_hid_of_match);
-- 
2.25.1