[PATCH v6 2/4] media: i2c: ds90ub953: Add back channel GPIO support

Guoniu Zhou
2026-04-24T01:40:06Z

From: Guoniu Zhou <guoniu.zhou@nxp.com>

The ds90ub953 supports GPIO0 through GPIO3. When enabled as an output,
each GPIO pin can be programed to output remote data coming from the
compatible deserializer using the register LOCAL_GPIO_DATA[7:4] field.

Add back channel GPIO support by parsing flags from device tree.

Signed-off-by: Guoniu Zhou <guoniu.zhou@nxp.com>
---
Changes in v6:
- Changed approach from extending GPIO range (v5) to using a custom GPIO
flag (GPIO_DATA_SOURCE_REMOTE) as suggested by the driver maintainer

Changes in v4:
- Only log GPIO 0-3 stats since remote GPIO 4-7 reuse GPIO 0-3 pins.

Changes in v3:
- Update driver to expand GPIO range.

Changes in v2:
- Parse gpio third cell to select which GPIO pin the data from remote
compatible deserializer.
---
drivers/media/i2c/ds90ub953.c | 51 ++++++++++++++++++++++++++++++++++++++-----
1 file changed, 45 insertions(+), 6 deletions(-)

diff --git a/drivers/media/i2c/ds90ub953.c b/drivers/media/i2c/ds90ub953.c
index a8ab67f4137f..da63dcfbbbc3 100644
--- a/drivers/media/i2c/ds90ub953.c
+++ b/drivers/media/i2c/ds90ub953.c
@@ -27,6 +27,8 @@
#include <media/v4l2-mediabus.h>
#include <media/v4l2-subdev.h>

+#include <dt-bindings/gpio/gpio.h>
+
#include "ds90ub953.h"

#define UB953_PAD_SINK 0
@@ -71,6 +73,7 @@ struct ub953_data {
bool non_continous_clk;

struct gpio_chip gpio_chip;
+ u32 gpio_flags[UB953_NUM_GPIOS];

struct v4l2_subdev sd;
struct media_pad pads[2];
@@ -258,6 +261,12 @@ static int ub953_write_ind(struct ub953_data *priv, u8 block, u8 reg, u8 val,
/*
* GPIO chip
*/
+
+static inline bool ub953_gpio_is_remote(unsigned int flag)
+{
+ return !!(flag & GPIO_DATA_SOURCE_REMOTE);
+}
+
static int ub953_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
{
struct ub953_data *priv = gpiochip_get_data(gc);
@@ -288,13 +297,23 @@ static int ub953_gpio_direction_out(struct gpio_chip *gc, unsigned int offset,
int value)
{
struct ub953_data *priv = gpiochip_get_data(gc);
+ bool is_remote = ub953_gpio_is_remote(priv->gpio_flags[offset]);
+ unsigned int mask, val;
int ret;

- ret = regmap_update_bits(priv->regmap, UB953_REG_LOCAL_GPIO_DATA,
- UB953_REG_LOCAL_GPIO_DATA_GPIO_OUT_SRC(offset),
- value ? UB953_REG_LOCAL_GPIO_DATA_GPIO_OUT_SRC(offset) :
- 0);
+ mask = UB953_REG_LOCAL_GPIO_DATA_GPIO_OUT_SRC(offset) |
+ UB953_REG_LOCAL_GPIO_DATA_GPIO_RMTEN(offset);

+ if (is_remote) {
+ /* Enable remote deserializer GPIO data on local GPIO */
+ val = UB953_REG_LOCAL_GPIO_DATA_GPIO_RMTEN(offset);
+ } else {
+ /* Set output value on local GPIO and disable remote mode */
+ val = value ? UB953_REG_LOCAL_GPIO_DATA_GPIO_OUT_SRC(offset) : 0;
+ }
+
+ ret = regmap_update_bits(priv->regmap, UB953_REG_LOCAL_GPIO_DATA,
+ mask, val);
if (ret)
return ret;

@@ -330,10 +349,30 @@ static int ub953_gpio_of_xlate(struct gpio_chip *gc,
const struct of_phandle_args *gpiospec,
u32 *flags)
{
+ struct ub953_data *priv = gpiochip_get_data(gc);
+ struct device *dev = &priv->client->dev;
+ u32 pin;
+
+ if (WARN_ON(gc->of_gpio_n_cells < 2))
+ return -EINVAL;
+
+ if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells))
+ return -EINVAL;
+
+ pin = gpiospec->args[0];
+ if (pin >= UB953_NUM_GPIOS) {
+ dev_err(dev, "Invalid GPIO pin number: %u\n", pin);
+ return -EINVAL;
+ }
+
+ /* Store GPIO flags for each pin */
+ priv->gpio_flags[pin] = gpiospec->args[1];
+
+ /* Return standard flags to GPIO core */
if (flags)
- *flags = gpiospec->args[1];
+ *flags = gpiospec->args[1] & ~GPIO_DATA_SOURCE_REMOTE;

- return gpiospec->args[0];
+ return pin;
}

static int ub953_gpiochip_probe(struct ub953_data *priv)

--
2.34.1