On Wed, 12 Jun 2024 21:14:54 +0800
Hui Wang <hui.wang@xxxxxxxxxxxxx> wrote:
Hi Hui,
> Some boards connect a GPIO to the reset pin, and the reset pin needs
> to be setup 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, othwerwise do software
> reset as before.
>
> Signed-off-by: Hui Wang <hui.wang@xxxxxxxxxxxxx>
> ---
> In the v3:
> - drop Reviewed-by
> - adjust the sequence of if, else if and else
> - replace PTR_ERR(reset_gpiod) with dev_err_probe
> - change GPIOD_OUT_LOW to GPIOD_OUT_HIGH, this will assert the reset pin after requesting the GPIO
> - change the 2nd parameter struct regmap *regmap[] to struct regmap *regmap
> - address all spelling and description issues in the v2
>
> drivers/tty/serial/sc16is7xx.c | 33 +++++++++++++++++++++++++++++----
> 1 file changed, 29 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
> index bf0065d1c8e9..8c7e0fe76049 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 +1468,30 @@ 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;
> +
> + /* The reset GPIO is ACTIVE_LOW, flag GPIOD_OUT_HIGH asserts the reset GPIO */
> + 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. */
> + udelay(5);
> + gpiod_set_value_cansleep(reset_gpio, 0);
> + /* Deassert GPIO */
Move this comment after its corresponding statement:
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)
> {
> @@ -1527,6 +1552,10 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype,
> s->devtype = devtype;
> dev_set_drvdata(dev, s);
>
> + ret = sc16is7xx_reset(dev, regmaps[0]);
> + if (ret)
> + goto out_clk;
> +
You could move this block where the original software reset was
located, unless you have a good reason to move it here? This will make
the review (diff) easier...
> kthread_init_worker(&s->kworker);
> s->kworker_task = kthread_run(kthread_worker_fn, &s->kworker,
> "sc16is7xx");
> @@ -1536,10 +1565,6 @@ 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);
> -
> /* Mark each port line and status as uninitialised. */
> for (i = 0; i < devtype->nr_uart; ++i) {
> s->p[i].port.line = SC16IS7XX_MAX_DEVS;
> --
> 2.34.1
--
Hugo Villeneuve
