[PATCH v5 3/3] gnss: ubx: add support for the reset gpio

Wolfram Sang
2023-11-13T00:52:42Z

The Renesas KingFisher board includes a U-Blox Neo-M8 chip. This chip
has a reset pin which is also wired on the board. When Linux starts,
reset is asserted by the firmware. Deassert the reset pin when probing
this driver.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
Changes since v4:

* don't touch reset during open/close. Only deassert it during probe.

drivers/gnss/ubx.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/drivers/gnss/ubx.c b/drivers/gnss/ubx.c
index 9b76b101ba5e..84cb50670644 100644
--- a/drivers/gnss/ubx.c
+++ b/drivers/gnss/ubx.c
@@ -7,6 +7,7 @@

#include <linux/errno.h>
#include <linux/gnss.h>
+#include <linux/gpio/consumer.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
@@ -64,6 +65,7 @@ static const struct gnss_serial_ops ubx_gserial_ops = {

static int ubx_probe(struct serdev_device *serdev)
{
+ struct gpio_desc *reset_gpio;
struct gnss_serial *gserial;
struct ubx_data *data;
int ret;
@@ -90,6 +92,13 @@ static int ubx_probe(struct serdev_device *serdev)
if (ret < 0 && ret != -ENODEV)
goto err_free_gserial;

+ /* Deassert Reset */
+ reset_gpio = devm_gpiod_get_optional(&serdev->dev, "reset", GPIOD_OUT_LOW);
+ if (IS_ERR(reset_gpio)) {
+ ret = PTR_ERR(reset_gpio);
+ goto err_free_gserial;
+ }
+
ret = gnss_serial_register(gserial);
if (ret)
goto err_free_gserial;
--
2.35.1