pinctrl: sunxi: Implement gpiochip::get_direction()

After commit e623c4303ed1 ("gpiolib: sanitize the return value of gpio_chip::get_direction()"), a warning will be printed if the gpio driver does not implement this callback.

Implement it for the sunxi driver. This is simply a matter of reading out the mux value from the registers, then checking if it is one of the GPIO functions and which direction it is.

Signed-off-by Chen-Yu Tsai <[email protected]>

After commit e623c4303ed1 ("gpiolib: sanitize the return value of gpio_chip::get_direction()"), a warning will be printed if the gpio driver does not implement this callback.

Implement it for the sunxi driver. This is simply a matter of reading out the mux value from the registers, then checking if it is one of the GPIO functions and which direction it is.

Signed-off-by Chen-Yu Tsai <[email protected]>

---

After commit e623c4303ed1 ("gpiolib: sanitize the return value of gpio_chip::get_direction()"), a warning will be printed if the gpio driver does not implement this callback.

Implement it for the sunxi driver. This is simply a matter of reading out the mux value from the registers, then checking if it is one of the GPIO functions and which direction it is.

Signed-off-by Chen-Yu Tsai <[email protected]>

---
This is an alternative to James's version. My version does one lookup instead of three.

 drivers/pinctrl/sunxi/pinctrl-sunxi.c | 51 +++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

drivers/pinctrl/sunxi/pinctrl-sunxi.c +51 -0

index 0fb057a07dcc..27b2a3e9d78d 100644
@@ -204,6 +204,32 @@ sunxi_pinctrl_desc_find_function_by_pin(struct sunxi_pinctrl *pctl,
 	return NULL;
 }
 
+static struct sunxi_desc_function *
+sunxi_pinctrl_desc_find_function_by_pin_and_mux(struct sunxi_pinctrl *pctl,
+						const u16 pin_num,
+						const u8 muxval)
+{
+	for (unsigned int i = 0; i < pctl->desc->npins; i++) {
+		const struct sunxi_desc_pin *pin = pctl->desc->pins + i;
+		struct sunxi_desc_function *func = pin->functions;
+
+		if (pin->pin.number != pin_num)
+			continue;
+
+		if (pin->variant && !(pctl->variant & pin->variant))
+			continue;
+
+		while (func->name) {
+			if (func->muxval == muxval)
+				return func;
+
+			func++;
+		}
+	}
+
+	return NULL;
+}
+
 static int sunxi_pctrl_get_groups_count(struct pinctrl_dev *pctldev)
 {
 	struct sunxi_pinctrl *pctl = pinctrl_dev_get_drvdata(pctldev);

@@ -930,6 +956,30 @@ static const struct pinmux_ops sunxi_pmx_ops = {
 	.strict			= true,
 };
 
+static int sunxi_pinctrl_gpio_get_direction(struct gpio_chip *chip,
+					    unsigned int offset)
+{
+	struct sunxi_pinctrl *pctl = gpiochip_get_data(chip);
+	const struct sunxi_desc_function *func;
+	u32 pin = offset + chip->base;
+	u32 reg, shift, mask;
+	u8 muxval;
+
+	sunxi_mux_reg(pctl, offset, &reg, &shift, &mask);
+
+	muxval = (readl(pctl->membase + reg) & mask) >> shift;
+
+	func = sunxi_pinctrl_desc_find_function_by_pin_and_mux(pctl, pin, muxval);
+	if (!func)
+		return -ENODEV;
+
+	if (!strcmp(func->name, "gpio_out"))
+		return GPIO_LINE_DIRECTION_OUT;
+	if (!strcmp(func->name, "gpio_in") || !strcmp(func->name, "irq"))
+		return GPIO_LINE_DIRECTION_IN;
+	return -EINVAL;
+}
+
 static int sunxi_pinctrl_gpio_direction_input(struct gpio_chip *chip,
 					unsigned offset)
 {

@@ -1601,6 +1651,7 @@ int sunxi_pinctrl_init_with_flags(struct platform_device *pdev,
 	pctl->chip->request = gpiochip_generic_request;
 	pctl->chip->free = gpiochip_generic_free;
 	pctl->chip->set_config = gpiochip_generic_config;
+	pctl->chip->get_direction = sunxi_pinctrl_gpio_get_direction;
 	pctl->chip->direction_input = sunxi_pinctrl_gpio_direction_input;
 	pctl->chip->direction_output = sunxi_pinctrl_gpio_direction_output;
 	pctl->chip->get = sunxi_pinctrl_gpio_get;

On Tue, 17 Feb 2026 00:09:45 +0800
Chen-Yu Tsai <[email protected]> wrote:

Quoted 3 lines

After commit e623c4303ed1 ("gpiolib: sanitize the return value of gpio_chip::get_direction()"), a warning will be printed if the gpio driver does not implement this callback.

I am curious how this could slip through? Did the get_direction() callback become mandatory at one point, but no one noticed that it was missing for sunxi? It looks like the situation was even worse before that patch, as it was dereferencing the function pointer without any check?

Quoted 3 lines

Implement it for the sunxi driver. This is simply a matter of reading out the mux value from the registers, then checking if it is one of the GPIO functions and which direction it is.

Mmh, it feels a bit backwards to resort to the function name *string* for comparison, when it's always 0 for in and 1 for out (which we actually set in pinctrl-sunxi-dt.c now). But the mux value for IRQ is different between SoC generations, and I guess for historic reasons function strings are a thing in pinctrl, so this is probably the best solution after all:

Quoted 1 line

Signed-off-by Chen-Yu Tsai <[email protected]>

FWIW:

Reviewed-by Andre Przywara <[email protected]>

After commit e623c4303ed1 ("gpiolib: sanitize the return value of gpio_chip::get_direction()"), a warning will be printed if the gpio driver does not implement this callback.

Implement it for the sunxi driver. This is simply a matter of reading out the mux value from the registers, then checking if it is one of the GPIO functions and which direction it is.

Signed-off-by Chen-Yu Tsai <[email protected]>

Quoted 4 lines · Chen-Yu Tsai

After commit e623c4303ed1 ("gpiolib: sanitize the return value of gpio_chip::get_direction()"), a warning will be printed if the gpio driver does not implement this callback.

Quoted 5 lines

Implement it for the sunxi driver. This is simply a matter of reading out the mux value from the registers, then checking if it is one of the GPIO functions and which direction it is.

Signed-off-by Chen-Yu Tsai <[email protected]>

Patch applied for fixes since everyone likes this patch and everyone is unhappy with the warning.