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mfd: lp87565: Handle optional reset pin 

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 <luca@lucaceresoli.net>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
This commit is contained in:
Luca Ceresoli 2021-02-26 15:28:52 +01:00 committed by Lee Jones
parent 4700ef3265
commit 50e4d7a2a6
2 changed files with 28 additions and 0 deletions
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27
drivers/mfd/lp87565.c
View File

@ -5,6 +5,7 @@
* Author: Keerthy <j-keerthy@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);

1
include/linux/mfd/lp87565.h
View File

@ -252,5 +252,6 @@ struct lp87565 {
u8 rev;
u8 dev_type;
struct regmap *regmap;
struct gpio_desc *reset_gpio;
};
#endif /* __LINUX_MFD_LP87565_H */