diff options
Diffstat (limited to 'drivers/gpio/gpio-pcf857x.c')
| -rw-r--r-- | drivers/gpio/gpio-pcf857x.c | 29 |
1 files changed, 27 insertions, 2 deletions
diff --git a/drivers/gpio/gpio-pcf857x.c b/drivers/gpio/gpio-pcf857x.c index 7c57eaeb0afe..2e5f5d7f8865 100644 --- a/drivers/gpio/gpio-pcf857x.c +++ b/drivers/gpio/gpio-pcf857x.c @@ -5,6 +5,8 @@ * Copyright (C) 2007 David Brownell */ +#include <linux/delay.h> +#include <linux/gpio/consumer.h> #include <linux/gpio/driver.h> #include <linux/i2c.h> #include <linux/interrupt.h> @@ -272,12 +274,11 @@ static const struct irq_chip pcf857x_irq_chip = { static int pcf857x_probe(struct i2c_client *client) { + struct gpio_desc *reset_gpio; struct pcf857x *gpio; unsigned int n_latch = 0; int status; - device_property_read_u32(&client->dev, "lines-initial-states", &n_latch); - /* Allocate, initialize, and register this gpio_chip. */ gpio = devm_kzalloc(&client->dev, sizeof(*gpio), GFP_KERNEL); if (!gpio) @@ -297,6 +298,30 @@ static int pcf857x_probe(struct i2c_client *client) gpio->chip.direction_output = pcf857x_output; gpio->chip.ngpio = (uintptr_t)i2c_get_match_data(client); + reset_gpio = devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_HIGH); + if (IS_ERR(reset_gpio)) + return dev_err_probe(&client->dev, PTR_ERR(reset_gpio), + "failed to get reset GPIO\n"); + + if (reset_gpio) { + /* Reset already held with devm_gpiod_get_optional with GPIOD_OUT_HIGH */ + fsleep(4); /* tw(rst) > 4us */ + gpiod_set_value_cansleep(reset_gpio, 0); + fsleep(100); /* trst > 100uS */ + + /* + * Performing a reset means "The PCA9670 registers and I2C-bus + * state machine will be held in their default state until the + * RESET input is once again HIGH". + * + * This is the same as writing 1 for all pins, which is the same + * as n_latch=0, the default value of the variable. + */ + } else { + device_property_read_u32(&client->dev, "lines-initial-states", + &n_latch); + } + /* NOTE: the OnSemi jlc1562b is also largely compatible with * these parts, notably for output. It has a low-resolution * DAC instead of pin change IRQs; and its inputs can be the |