Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-12-02 09:01:34 +00:00
Code Issues Packages Projects Releases Wiki Activity

serial: sc16is7xx: hardware reset chip if reset-gpios is defined in DT

Browse Source 
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>
This commit is contained in:
Hui Wang 2024-06-18 19:26:20 +08:00 committed by Greg Kroah-Hartman
parent a9411ef13f
commit 4fb92bdb8e
1 changed files with 28 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
drivers/tty/serial/sc16is7xx.c
View File

@ -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: