From c071d94d3fb9f0c1f975d4843caeaddcb1fd4d50 Mon Sep 17 00:00:00 2001 From: Tapio Reijonen Date: Wed, 22 Jul 2026 09:54:28 -0400 Subject: [PATCH] serial: max310x: implement gpio_chip::get_direction() [ Upstream commit a483b1a91b33b7533280e7c3efd2bc1275caef18 ] 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: f65444187a66 ("serial: New serial driver MAX310X") Cc: stable Signed-off-by: Tapio Reijonen Reviewed-by: Linus Walleij Reviewed-by: Bartosz Golaszewski Reviewed-by: Hugo Villeneuve Link: https://patch.msgid.link/20260615-b4-serial-max310x-gpio-get-direction-v2-1-4704ba2b181a@vaisala.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/max310x.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c index 6db83ecf77d6..1cee4e1f3122 100644 --- a/drivers/tty/serial/max310x.c +++ b/drivers/tty/serial/max310x.c @@ -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;