On 6/4/24 22:23, Hugo Villeneuve wrote:
On Tue, 4 Jun 2024 21:27:26 +0800
Hui Wang <hui.wang@xxxxxxxxxxxxx> wrote:
Hi Hui,
Certain designs connect a gpio to the reset pin, and the reset pin
needs to be setup correctly before accessing the chip.
Here adding a function to handle the chip reset. If the reset-gpios is
defined in the dt, do the hard reset through this gpio, othwerwise do
the soft reset as before.
Reviewed-by: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
I never gave you permission to add this tag, remove it. Make sure you
fully understand the meaning of tags by reading patches submission
guidelines.
I misunderstood the meaning of "reviewed-by", will remove it and study
the guidelines.
Signed-off-by: Hui Wang <hui.wang@xxxxxxxxxxxxx>
---
In the v2:
- move the soft reset and hard reset into one fucntion
- move the reset function to sc16is7xx.c and call it in _probe()
- add udelay(5) before deasserting the gpio reset pin
drivers/tty/serial/sc16is7xx.c | 28 ++++++++++++++++++++++++----
1 file changed, 24 insertions(+), 4 deletions(-)
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index bf0065d1c8e9..119abfb4607c 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 +1468,25 @@ static const struct serial_rs485 sc16is7xx_rs485_supported = {
.delay_rts_after_send = 1, /* Not supported but keep returning -EINVAL */
};
Add function description from original comment "Reset device,
purging any pending irq / data", since the comment applies to both
hardware and software reset,
Got it.
+static int sc16is7xx_reset(struct device *dev, struct regmap *regmaps[])
Simply pass "struct regmap *regmap" as the second argument. See
sc16is7xx_setup_mctrl_ports() for example.
Got it.
+{
+ struct gpio_desc *reset_gpiod;
reset_gpiod -> reset_gpio
Got it.
+
+ reset_gpiod = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
+ if (!reset_gpiod)
Follow Andy's suggestion here.
OK.
+ /* soft reset device, purging any pending irq / data */
"Software reset".
Got it.
+ regmap_write(regmaps[0], SC16IS7XX_IOCONTROL_REG,
+ SC16IS7XX_IOCONTROL_SRESET_BIT);
+ else if (!IS_ERR(reset_gpiod)) {
+ /* delay 5 us (at least 3 us) and deassert the gpio to exit the hard reset */
You can omit the "delay 5 us" since it is obvious from the code. Maybe
add that "The minimum reset pulse width is 3 us" as stated in the
datasheet.
As a general note for your comments: capitalize the first letter,
ex: "Deassert GPIO" and not "deassert GPIO".
OK.
+ udelay(5);
+ gpiod_set_value_cansleep(reset_gpiod, 0);
Move the comment "deassert the gpio to exit the hard reset" here. You
could also simplify it as "Deassert GPIO.".
OK.
+ } else
+ return PTR_ERR(reset_gpiod);
return dev_err_probe(dev, PTR_ERR(reset_gpiod), "Failed to get reset
GPIO\n");
Got it, will address all comment in the v3.
Thanks.
+
+ return 0;
+}
+
int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype,
struct regmap *regmaps[], int irq)
{
@@ -1527,6 +1547,10 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype,
s->devtype = devtype;
dev_set_drvdata(dev, s);
+ ret = sc16is7xx_reset(dev, regmaps);
+ if (ret)
+ goto out_clk;
+
kthread_init_worker(&s->kworker);
s->kworker_task = kthread_run(kthread_worker_fn, &s->kworker,
"sc16is7xx");
@@ -1536,10 +1560,6 @@ 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
