Commit 4fb92bdb authored by Hui Wang's avatar Hui Wang Committed by Greg Kroah-Hartman
Browse files

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: default avatarLech Perczak <lech.perczak@camlingroup.com>
Tested-by: default avatarHugo Villeneuve <hvilleneuve@dimonoff.com>
Reviewed-by: default avatarHugo Villeneuve <hvilleneuve@dimonoff.com>
Signed-off-by: default avatarHui Wang <hui.wang@canonical.com>
Link: https://lore.kernel.org/r/20240618112620.152848-2-hui.wang@canonical.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a9411ef1

drivers/tty/serial/sc16is7xx.c

+28 −3
Original line number Diff line number Diff line
@@ -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 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype, 
			uart_remove_one_port(&sc16is7xx_uart, &s->p[i].port);

	}



out_kthread:

	kthread_stop(s->kworker_task);



out_clk: