diff options
| author | Hui Wang <hui.wang@canonical.com> | 2024-06-18 13:26:20 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-06-24 16:10:36 +0200 |
| commit | 4fb92bdb8e84e618f8c289dc56a923b914a72cac (patch) | |
| tree | 5a38cebd7028b24291047e56635ded7372a18b4b /drivers/tty/serial | |
| parent | dt-bindings: serial: sc16is7xx: add reset-gpios (diff) | |
| download | linux-4fb92bdb8e84e618f8c289dc56a923b914a72cac.tar.xz linux-4fb92bdb8e84e618f8c289dc56a923b914a72cac.zip | |
serial: sc16is7xx: hardware reset chip if reset-gpios is defined in DT
Some boards connect a GPIO to the reset pin, and the reset pin needs
to be set up correctly before accessing the chip.
Add a function to handle the chip reset. If the reset-gpios is defined
in the DT, do hardware reset through this GPIO, otherwise do software
reset as before.
Reviewed-by: Lech Perczak <lech.perczak@camlingroup.com>
Tested-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Reviewed-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Signed-off-by: Hui Wang <hui.wang@canonical.com>
Link: https://lore.kernel.org/r/20240618112620.152848-2-hui.wang@canonical.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial')
| -rw-r--r-- | drivers/tty/serial/sc16is7xx.c | 31 |
1 files changed, 28 insertions, 3 deletions
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c index bf0065d1c8e9..c79dcd7c8d1a 100644 --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -14,6 +14,7 @@ #include <linux/delay.h> #include <linux/device.h> #include <linux/export.h> +#include <linux/gpio/consumer.h> #include <linux/gpio/driver.h> #include <linux/idr.h> #include <linux/kthread.h> @@ -1467,6 +1468,29 @@ static const struct serial_rs485 sc16is7xx_rs485_supported = { .delay_rts_after_send = 1, /* Not supported but keep returning -EINVAL */ }; +/* Reset device, purging any pending irq / data */ +static int sc16is7xx_reset(struct device *dev, struct regmap *regmap) +{ + struct gpio_desc *reset_gpio; + + /* Assert reset GPIO if defined and valid. */ + reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH); + if (IS_ERR(reset_gpio)) + return dev_err_probe(dev, PTR_ERR(reset_gpio), "Failed to get reset GPIO\n"); + + if (reset_gpio) { + /* The minimum reset pulse width is 3 us. */ + fsleep(5); + gpiod_set_value_cansleep(reset_gpio, 0); /* Deassert GPIO */ + } else { + /* Software reset */ + regmap_write(regmap, SC16IS7XX_IOCONTROL_REG, + SC16IS7XX_IOCONTROL_SRESET_BIT); + } + + return 0; +} + int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype, struct regmap *regmaps[], int irq) { @@ -1536,9 +1560,9 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype, } sched_set_fifo(s->kworker_task); - /* reset device, purging any pending irq / data */ - regmap_write(regmaps[0], SC16IS7XX_IOCONTROL_REG, - SC16IS7XX_IOCONTROL_SRESET_BIT); + ret = sc16is7xx_reset(dev, regmaps[0]); + if (ret) + goto out_kthread; /* Mark each port line and status as uninitialised. */ for (i = 0; i < devtype->nr_uart; ++i) { @@ -1663,6 +1687,7 @@ out_ports: uart_remove_one_port(&sc16is7xx_uart, &s->p[i].port); } +out_kthread: kthread_stop(s->kworker_task); out_clk: |