[PATCH 2/2] mfd: lp87565: handle optional reset pin

[Luca Ceresoli]

Optionally handle the NRST pin (active low reset) in order to start from a
known state during boot and to shut down the chip when rebooting.

Signed-off-by: Luca Ceresoli <l...@lucaceresoli.net>
---
 drivers/mfd/lp87565.c       | 27 +++++++++++++++++++++++++++
 include/linux/mfd/lp87565.h |  1 +
 2 files changed, 28 insertions(+)

diff --git a/drivers/mfd/lp87565.c b/drivers/mfd/lp87565.c
index 9c21483d9653..a52ab76febb3 100644
--- a/drivers/mfd/lp87565.c
+++ b/drivers/mfd/lp87565.c
@@ -5,6 +5,7 @@
  * Author: Keerthy <j-keer...@ti.com>
  */
 
+#include <linux/gpio/consumer.h>
 #include <linux/interrupt.h>
 #include <linux/mfd/core.h>
 #include <linux/module.h>
@@ -64,6 +65,24 @@ static int lp87565_probe(struct i2c_client *client,
                return ret;
        }
 
+       lp87565->reset_gpio = devm_gpiod_get_optional(lp87565->dev, "reset",
+                                                     GPIOD_OUT_LOW);
+       if (IS_ERR(lp87565->reset_gpio)) {
+               ret = PTR_ERR(lp87565->reset_gpio);
+               if (ret == -EPROBE_DEFER)
+                       return ret;
+       }
+
+       if (lp87565->reset_gpio) {
+               gpiod_set_value_cansleep(lp87565->reset_gpio, 1);
+               /* The minimum assertion time is undocumented, just guess */
+               usleep_range(2000, 4000);
+
+               gpiod_set_value_cansleep(lp87565->reset_gpio, 0);
+               /* Min 1.2 ms before first I2C transaction */
+               usleep_range(1500, 3000);
+       }
+
        ret = regmap_read(lp87565->regmap, LP87565_REG_OTP_REV, &otpid);
        if (ret) {
                dev_err(lp87565->dev, "Failed to read OTP ID\n");
@@ -83,6 +102,13 @@ static int lp87565_probe(struct i2c_client *client,
                                    NULL, 0, NULL);
 }
 
+static void lp87565_shutdown(struct i2c_client *client)
+{
+       struct lp87565 *lp87565 = i2c_get_clientdata(client);
+
+       gpiod_set_value_cansleep(lp87565->reset_gpio, 1);
+}
+
 static const struct i2c_device_id lp87565_id_table[] = {
        { "lp87565-q1", 0 },
        { },
@@ -95,6 +121,7 @@ static struct i2c_driver lp87565_driver = {
                .of_match_table = of_lp87565_match_table,
        },
        .probe = lp87565_probe,
+       .shutdown = lp87565_shutdown,
        .id_table = lp87565_id_table,
 };
 module_i2c_driver(lp87565_driver);
diff --git a/include/linux/mfd/lp87565.h b/include/linux/mfd/lp87565.h
index 94cb581af34b..4c895072d91b 100644
--- a/include/linux/mfd/lp87565.h
+++ b/include/linux/mfd/lp87565.h
@@ -252,5 +252,6 @@ struct lp87565 {
        u8 rev;
        u8 dev_type;
        struct regmap *regmap;
+       struct gpio_desc *reset_gpio;
 };
 #endif /* __LINUX_MFD_LP87565_H */
-- 
2.30.0