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serial: max310x: implement gpio_chip::get_direction()

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[ Upstream commit a483b1a91b ]

It's strongly recommended for GPIO drivers to always implement the
.get_direction() callback - even when the direction is tracked in
software. The GPIO core emits a warning when the callback is missing
and a user reads the direction of a line, e.g. via
/sys/kernel/debug/gpio.

The MAX310X keeps the GPIO direction in the GPIOCFG register (a set bit
selects output), which the existing direction_input/output callbacks
already program, so the current direction can be read back directly.

Fixes: f65444187a ("serial: New serial driver MAX310X")
Cc: stable <stable@kernel.org>
Signed-off-by: Tapio Reijonen <tapio.reijonen@vaisala.com>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Reviewed-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://patch.msgid.link/20260615-b4-serial-max310x-gpio-get-direction-v2-1-4704ba2b181a@vaisala.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tapio Reijonen
2026-08-03 11:15:34 +02:00
committed by Greg Kroah-Hartman
parent 10a9d4fde5
commit c071d94d3f
1 changed files with 12 additions and 0 deletions
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drivers/tty/serial/max310x.c
+12
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@@ -1229,6 +1229,17 @@ static void max310x_gpio_set(struct gpio_chip *chip, unsigned int offset, int va
value ? 1 << (offset % 4) : 0);
}
static int max310x_gpio_get_direction(struct gpio_chip *chip, unsigned int offset)
{
struct max310x_port *s = gpiochip_get_data(chip);
struct uart_port *port = &s->p[offset / 4].port;
unsigned int val;
val = max310x_port_read(port, MAX310X_GPIOCFG_REG);
return val & BIT(offset % 4) ? GPIO_LINE_DIRECTION_OUT : GPIO_LINE_DIRECTION_IN;
}
static int max310x_gpio_direction_input(struct gpio_chip *chip, unsigned int offset)
{
struct max310x_port *s = gpiochip_get_data(chip);
@@ -1442,6 +1453,7 @@ static int max310x_probe(struct device *dev, const struct max310x_devtype *devty
s->gpio.owner = THIS_MODULE;
s->gpio.parent = dev;
s->gpio.label = devtype->name;
s->gpio.get_direction = max310x_gpio_get_direction;
s->gpio.direction_input = max310x_gpio_direction_input;
s->gpio.get = max310x_gpio_get;
s->gpio.direction_output= max310x_gpio_direction_output;