[PATCH v3 6/6] Input: edt-ft5x06 - improve power management operations

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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.

Furthermore I added the support to disable the device completely. This is
the most effective power-saving mechanism. Disabling the device don't
change the suspend logic because the hibernate mode needs a hardware
reset anyway.

[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>
Tested-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
v3:
- drop enable/disable_irq_wake()

v2:
- adapt commit message
- don't return errors during suspend/resume
- replace dev_err() by dev_warn()
- add support to disable the regulator too
---
 drivers/input/touchscreen/edt-ft5x06.c | 65 ++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)

diff --git a/drivers/input/touchscreen/edt-ft5x06.c b/drivers/input/touchscreen/edt-ft5x06.c
index d2587724c52a..4fd97758cbdd 100644
--- a/drivers/input/touchscreen/edt-ft5x06.c
+++ b/drivers/input/touchscreen/edt-ft5x06.c
@@ -38,6 +38,9 @@
 #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
@@ -53,6 +56,7 @@
 
 #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
@@ -1227,6 +1231,66 @@ static int edt_ft5x06_ts_remove(struct i2c_client *client)
 	return 0;
 }
 
+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))
+		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_warn(dev, "Failed to set hibernate mode\n");
+
+	ret = regulator_disable(tsdata->vcc);
+	if (ret)
+		dev_warn(dev, "Failed to disable vcc\n");
+
+	return 0;
+}
+
+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);
+	int ret;
+
+	if (device_may_wakeup(dev))
+		return 0;
+
+	ret = regulator_enable(tsdata->vcc);
+	if (ret)
+		dev_warn(dev, "Failed to enable vcc\n");
+
+	/* 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;
+}
+
+static SIMPLE_DEV_PM_OPS(edt_ft5x06_ts_pm_ops,
+			 edt_ft5x06_ts_suspend, edt_ft5x06_ts_resume);
+
 static const struct edt_i2c_chip_data edt_ft5x06_data = {
 	.max_support_points = 5,
 };
@@ -1265,6 +1329,7 @@ static struct i2c_driver edt_ft5x06_ts_driver = {
 	.driver = {
 		.name = "edt_ft5x06",
 		.of_match_table = edt_ft5x06_of_match,
+		.pm = &edt_ft5x06_ts_pm_ops,
 	},
 	.id_table = edt_ft5x06_ts_id,
 	.probe    = edt_ft5x06_ts_probe,
-- 
2.20.1




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