Input: edt-ft5x06 - improve power management operations

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 which
is obviously the most effective power-saving mechanism. This mechanism
needs the reset pin to ensure the power-up/down sequence.

We can't apply any of these power-saving mechanism if both pins are
missing (not connected) or if it is a wakeup device.

[1] https://www.newhavendisplay.com/appnotes/datasheets/touchpanel/FT5x26.pdf
    https://www.newhavendisplay.com/appnotes/datasheets/touchpanel/FT5x06.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@pengutronix.de>
Link: https://lore.kernel.org/r/20200227112819.16754-4-m.felsch@pengutronix.de
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/drivers/input/touchscreen/edt-ft5x06.c b/drivers/input/touchscreen/edt-ft5x06.c
index bb910709379620375c044764936b36558659acc8..d423bd6bfeda441a6a6c877045ab50684f475d90 100644 (file)
--- 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
@@ -65,6 +69,12 @@
 #define EDT_RAW_DATA_RETRIES           100
 #define EDT_RAW_DATA_DELAY             1000 /* usec */
 
+enum edt_pmode {
+       EDT_PMODE_NOT_SUPPORTED,
+       EDT_PMODE_HIBERNATE,
+       EDT_PMODE_POWEROFF,
+};
+
 enum edt_ver {
        EDT_M06,
        EDT_M09,
@@ -103,6 +113,7 @@ struct edt_ft5x06_ts_data {
 
        struct mutex mutex;
        bool factory_mode;
+       enum edt_pmode suspend_mode;
        int threshold;
        int gain;
        int offset;
@@ -767,9 +778,8 @@ static const struct file_operations debugfs_raw_data_fops = {
        .read = edt_ft5x06_debugfs_raw_data_read,
 };
 
-static void
-edt_ft5x06_ts_prepare_debugfs(struct edt_ft5x06_ts_data *tsdata,
-                             const char *debugfs_name)
+static void edt_ft5x06_ts_prepare_debugfs(struct edt_ft5x06_ts_data *tsdata,
+                                         const char *debugfs_name)
 {
        tsdata->debug_dir = debugfs_create_dir(debugfs_name, NULL);
 
@@ -782,8 +792,7 @@ edt_ft5x06_ts_prepare_debugfs(struct edt_ft5x06_ts_data *tsdata,
                            tsdata->debug_dir, tsdata, &debugfs_raw_data_fops);
 }
 
-static void
-edt_ft5x06_ts_teardown_debugfs(struct edt_ft5x06_ts_data *tsdata)
+static void edt_ft5x06_ts_teardown_debugfs(struct edt_ft5x06_ts_data *tsdata)
 {
        debugfs_remove_recursive(tsdata->debug_dir);
        kfree(tsdata->raw_buffer);
@@ -791,14 +800,17 @@ edt_ft5x06_ts_teardown_debugfs(struct edt_ft5x06_ts_data *tsdata)
 
 #else
 
-static inline void
-edt_ft5x06_ts_prepare_debugfs(struct edt_ft5x06_ts_data *tsdata,
-                             const char *debugfs_name)
+static int edt_ft5x06_factory_mode(struct edt_ft5x06_ts_data *tsdata)
 {
+       return -ENOSYS;
 }
 
-static inline void
-edt_ft5x06_ts_teardown_debugfs(struct edt_ft5x06_ts_data *tsdata)
+static void edt_ft5x06_ts_prepare_debugfs(struct edt_ft5x06_ts_data *tsdata,
+                                         const char *debugfs_name)
+{
+}
+
+static void edt_ft5x06_ts_teardown_debugfs(struct edt_ft5x06_ts_data *tsdata)
 {
 }
 
@@ -1125,6 +1137,19 @@ static int edt_ft5x06_ts_probe(struct i2c_client *client,
                return error;
        }
 
+       /*
+        * Check which sleep modes we can support. Power-off requieres the
+        * reset-pin to ensure correct power-down/power-up behaviour. Start with
+        * the EDT_PMODE_POWEROFF test since this is the deepest possible sleep
+        * mode.
+        */
+       if (tsdata->reset_gpio)
+               tsdata->suspend_mode = EDT_PMODE_POWEROFF;
+       else if (tsdata->wake_gpio)
+               tsdata->suspend_mode = EDT_PMODE_HIBERNATE;
+       else
+               tsdata->suspend_mode = EDT_PMODE_NOT_SUPPORTED;
+
        if (tsdata->wake_gpio) {
                usleep_range(5000, 6000);
                gpiod_set_value_cansleep(tsdata->wake_gpio, 1);
@@ -1238,6 +1263,102 @@ 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);
+       struct gpio_desc *reset_gpio = tsdata->reset_gpio;
+       int ret;
+
+       if (device_may_wakeup(dev))
+               return 0;
+
+       if (tsdata->suspend_mode == EDT_PMODE_NOT_SUPPORTED)
+               return 0;
+
+       /* Enter hibernate mode. */
+       ret = edt_ft5x06_register_write(tsdata, PMOD_REGISTER_OPMODE,
+                                       PMOD_REGISTER_HIBERNATE);
+       if (ret)
+               dev_warn(dev, "Failed to set hibernate mode\n");
+
+       if (tsdata->suspend_mode == EDT_PMODE_HIBERNATE)
+               return 0;
+
+       /*
+        * Power-off according the datasheet. Cut the power may leaf the irq
+        * line in an undefined state depending on the host pull resistor
+        * settings. Disable the irq to avoid adjusting each host till the
+        * device is back in a full functional state.
+        */
+       disable_irq(tsdata->client->irq);
+
+       gpiod_set_value_cansleep(reset_gpio, 1);
+       usleep_range(1000, 2000);
+
+       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 = 0;
+
+       if (device_may_wakeup(dev))
+               return 0;
+
+       if (tsdata->suspend_mode == EDT_PMODE_NOT_SUPPORTED)
+               return 0;
+
+       if (tsdata->suspend_mode == EDT_PMODE_POWEROFF) {
+               struct gpio_desc *reset_gpio = tsdata->reset_gpio;
+
+               /*
+                * We can't check if the regulator is a dummy or a real
+                * regulator. So we need to specify the 5ms reset time (T_rst)
+                * here instead of the 100us T_rtp time. We also need to wait
+                * 300ms in case it was a real supply and the power was cutted
+                * of. Toggle the reset pin is also a way to exit the hibernate
+                * mode.
+                */
+               gpiod_set_value_cansleep(reset_gpio, 1);
+               usleep_range(5000, 6000);
+
+               ret = regulator_enable(tsdata->vcc);
+               if (ret) {
+                       dev_err(dev, "Failed to enable vcc\n");
+                       return ret;
+               }
+
+               usleep_range(1000, 2000);
+               gpiod_set_value_cansleep(reset_gpio, 0);
+               msleep(300);
+
+               edt_ft5x06_restore_reg_parameters(tsdata);
+               enable_irq(tsdata->client->irq);
+
+               if (tsdata->factory_mode)
+                       ret = edt_ft5x06_factory_mode(tsdata);
+       } else {
+               struct gpio_desc *wake_gpio = tsdata->wake_gpio;
+
+               gpiod_set_value_cansleep(wake_gpio, 0);
+               usleep_range(5000, 6000);
+               gpiod_set_value_cansleep(wake_gpio, 1);
+       }
+
+
+       return ret;
+}
+
+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,
 };
@@ -1276,6 +1397,7 @@ 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,