From c663e5f56737757db4d0b317c510ab505f93cecb Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Tue, 22 Mar 2016 10:51:16 +0100 Subject: gpio: support native single-ended hardware drivers Some GPIO controllers has a special hardware bit we can flip to support open drain / source. This means that on these hardwares we do not need to emulate OD/OS by setting the line to input instead of actively driving it high/low. Add an optional vtable callback to the driver set_single_ended() so that driver can implement this in hardware if they have it. We may need a pinctrl_gpio_set_config() call at some point to propagate this down to a backing pin control device on systems with split GPIO/pin control. Reported-by: Michael Hennerich Signed-off-by: Linus Walleij --- include/linux/gpio/driver.h | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) (limited to 'include/linux/gpio') diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h index bee976f82788..50882e09289b 100644 --- a/include/linux/gpio/driver.h +++ b/include/linux/gpio/driver.h @@ -19,6 +19,18 @@ struct gpio_device; #ifdef CONFIG_GPIOLIB +/** + * enum single_ended_mode - mode for single ended operation + * @LINE_MODE_PUSH_PULL: normal mode for a GPIO line, drive actively high/low + * @LINE_MODE_OPEN_DRAIN: set line to be open drain + * @LINE_MODE_OPEN_SOURCE: set line to be open source + */ +enum single_ended_mode { + LINE_MODE_PUSH_PULL, + LINE_MODE_OPEN_DRAIN, + LINE_MODE_OPEN_SOURCE, +}; + /** * struct gpio_chip - abstract a GPIO controller * @label: a functional name for the GPIO device, such as a part @@ -38,7 +50,15 @@ struct gpio_device; * @set: assigns output value for signal "offset" * @set_multiple: assigns output values for multiple signals defined by "mask" * @set_debounce: optional hook for setting debounce time for specified gpio in - * interrupt triggered gpio chips + * interrupt triggered gpio chips + * @set_single_ended: optional hook for setting a line as open drain, open + * source, or non-single ended (restore from open drain/source to normal + * push-pull mode) this should be implemented if the hardware supports + * open drain or open source settings. The GPIOlib will otherwise try + * to emulate open drain/source by not actively driving lines high/low + * if a consumer request this. The driver may return -ENOTSUPP if e.g. + * it supports just open drain but not open source and is called + * with LINE_MODE_OPEN_SOURCE as mode argument. * @to_irq: optional hook supporting non-static gpio_to_irq() mappings; * implementation may not sleep * @dbg_show: optional routine to show contents in debugfs; default code @@ -130,6 +150,9 @@ struct gpio_chip { int (*set_debounce)(struct gpio_chip *chip, unsigned offset, unsigned debounce); + int (*set_single_ended)(struct gpio_chip *chip, + unsigned offset, + enum single_ended_mode mode); int (*to_irq)(struct gpio_chip *chip, unsigned offset); -- cgit v1.2.3