[PATCH 4/6] Input: edt-ft5x06 - add deep sleep mechanism

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It is possible to bring the device into a deep sleep state. To exit this
state the reset or wakeup pin must be toggeled as documented in [1].
Because of the poor documentation I used the several downstream kernels
[2] and other applications notes [3] to indentify the related registers.

[1] https://www.newhavendisplay.com/appnotes/datasheets/touchpanel/ \
    FT5x26.pdf
[2] https://github.com/linux-sunxi/linux-sunxi/blob/sunxi-3.4/drivers/ \
    input/touchscreen/ft5x_ts.c
    https://github.com/Pablito2020/focaltech-touch-driver/blob/master/ \
    ft5336_driver.c
[3] https://www.newhavendisplay.com/appnotes/datasheets/touchpanel/ \
    FT5x16_registers.pdf

Signed-off-by: Marco Felsch <m.felsch@xxxxxxxxxxxxxx>
---
 drivers/input/touchscreen/edt-ft5x06.c | 42 ++++++++++++++++++++++++--
 1 file changed, 39 insertions(+), 3 deletions(-)

diff --git a/drivers/input/touchscreen/edt-ft5x06.c b/drivers/input/touchscreen/edt-ft5x06.c
index aafb6f4e34d7..b95ce5a7482d 100644
--- a/drivers/input/touchscreen/edt-ft5x06.c
+++ b/drivers/input/touchscreen/edt-ft5x06.c
@@ -37,6 +37,9 @@
 #define WORK_REGISTER_NUM_X		0x33
 #define WORK_REGISTER_NUM_Y		0x34
 
+#define PMOD_REGISTER_ACTIVE		0x00
+#define PMOD_REGISTER_HIBERNATE		0x03
+
 #define M09_REGISTER_THRESHOLD		0x80
 #define M09_REGISTER_GAIN		0x92
 #define M09_REGISTER_OFFSET		0x93
@@ -52,6 +55,7 @@
 
 #define WORK_REGISTER_OPMODE		0x3c
 #define FACTORY_REGISTER_OPMODE		0x01
+#define PMOD_REGISTER_OPMODE		0xa5
 
 #define TOUCH_EVENT_DOWN		0x00
 #define TOUCH_EVENT_UP			0x01
@@ -1204,19 +1208,51 @@ static int edt_ft5x06_ts_remove(struct i2c_client *client)
 static int __maybe_unused edt_ft5x06_ts_suspend(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);
+	struct edt_ft5x06_ts_data *tsdata = i2c_get_clientdata(client);
+	int ret;
 
-	if (device_may_wakeup(dev))
+	if (device_may_wakeup(dev)) {
 		enable_irq_wake(client->irq);
+		return 0;
+	}
 
-	return 0;
+	/*
+	 * Hibernate mode requires reset or wake signal to recover to active
+	 * state.
+	 */
+	if (!tsdata->wake_gpio && !tsdata->reset_gpio)
+		return 0;
+
+	ret = edt_ft5x06_register_write(tsdata, PMOD_REGISTER_OPMODE,
+					PMOD_REGISTER_HIBERNATE);
+	if (ret)
+		dev_err(dev, "Failed to set hibernate mode\n");
+
+	return ret;
 }
 
 static int __maybe_unused edt_ft5x06_ts_resume(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);
+	struct edt_ft5x06_ts_data *tsdata = i2c_get_clientdata(client);
 
-	if (device_may_wakeup(dev))
+	if (device_may_wakeup(dev)) {
 		disable_irq_wake(client->irq);
+		return 0;
+	}
+
+	/* Recover from hibernate mode if hardware supports it */
+	if (tsdata->wake_gpio) {
+		gpiod_set_value_cansleep(tsdata->wake_gpio, 0);
+		usleep_range(5000, 6000);
+		gpiod_set_value_cansleep(tsdata->wake_gpio, 1);
+		msleep(300);
+	} else if (tsdata->reset_gpio) {
+		gpiod_set_value_cansleep(tsdata->reset_gpio, 1);
+		usleep_range(5000, 6000);
+		gpiod_set_value_cansleep(tsdata->reset_gpio, 0);
+		msleep(300);
+	}
 
 	return 0;
 }
-- 
2.20.1




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