GPIO hogging means that the GPIO controller can "hog" and configure certain GPIOs without need for a driver or userspace to do that. This is useful in open-connected boards where BIOS cannot possibly know beforehand which devices will be connected to the board.
This adds GPIO hogging mechanism to ACPI analogous to Device Tree. Signed-off-by: Mika Westerberg <[email protected]> --- Documentation/acpi/gpio-properties.txt | 26 ++++++++++++ drivers/gpio/gpiolib-acpi.c | 72 ++++++++++++++++++++++++++++++++++ 2 files changed, 98 insertions(+) diff --git a/Documentation/acpi/gpio-properties.txt b/Documentation/acpi/gpio-properties.txt index 7875974823ae..46df91c3512b 100644 --- a/Documentation/acpi/gpio-properties.txt +++ b/Documentation/acpi/gpio-properties.txt @@ -69,6 +69,32 @@ Example: } } +- gpio-hog +- output-high +- output-low +- input +- line-name + +Example: + + Name (_DSD, Package () { + // _DSD Hierarchical Properties Extension UUID + ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"), + Package () { + Package () {"hog-gpio8", "G8PU"} + } + }) + + Name (G8PU, Package () { + ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"), + Package () { + Package () {"gpio-hog", 1}, + Package () {"gpios", Package () {8, 0}}, + Package () {"output-high", 1}, + Package () {"line-name", "gpio8-pullup"}, + } + }) + See Documentation/devicetree/bindings/gpio/gpio.tx for more information about these properties. diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c index 202cf1b842de..4e50f8f5d597 100644 --- a/drivers/gpio/gpiolib-acpi.c +++ b/drivers/gpio/gpiolib-acpi.c @@ -14,6 +14,7 @@ #include <linux/gpio.h> #include <linux/gpio/consumer.h> #include <linux/gpio/driver.h> +#include <linux/gpio/machine.h> #include <linux/export.h> #include <linux/acpi.h> #include <linux/interrupt.h> @@ -845,6 +846,76 @@ static void acpi_gpiochip_set_names(struct acpi_gpio_chip *achip) kfree(names); } +struct gpio_desc *acpi_gpiochip_parse_own_gpio(struct acpi_gpio_chip *achip, + struct fwnode_handle *fwnode, const char **name, unsigned int *lflags, + unsigned int *dflags) +{ + struct gpio_chip *chip = achip->chip; + struct gpio_desc *desc; + u32 gpios[2]; + int ret; + + ret = fwnode_property_read_u32_array(fwnode, "gpios", gpios, + ARRAY_SIZE(gpios)); + if (ret < 0) + return ERR_PTR(ret); + + ret = acpi_gpiochip_pin_to_gpio_offset(chip->gpiodev, gpios[0]); + if (ret < 0) + return ERR_PTR(ret); + + desc = gpiochip_get_desc(chip, ret); + if (IS_ERR(desc)) + return desc; + + *lflags = 0; + *dflags = 0; + *name = NULL; + + if (gpios[1]) + *lflags |= GPIO_ACTIVE_LOW; + + if (fwnode_property_present(fwnode, "input")) + *dflags |= GPIOD_IN; + else if (fwnode_property_present(fwnode, "output-low")) + *dflags |= GPIOD_OUT_LOW; + else if (fwnode_property_present(fwnode, "output-high")) + *dflags |= GPIOD_OUT_HIGH; + else + return ERR_PTR(-EINVAL); + + fwnode_property_read_string(fwnode, "line-name", name); + + return desc; +} + +static void acpi_gpiochip_scan_gpios(struct acpi_gpio_chip *achip) +{ + struct gpio_chip *chip = achip->chip; + struct fwnode_handle *fwnode; + + device_for_each_child_node(chip->parent, fwnode) { + unsigned int lflags, dflags; + struct gpio_desc *desc; + const char *name; + int ret; + + if (!fwnode_property_present(fwnode, "gpio-hog")) + continue; + + desc = acpi_gpiochip_parse_own_gpio(achip, fwnode, &name, + &lflags, &dflags); + if (IS_ERR(desc)) + continue; + + ret = gpiod_hog(desc, name, lflags, dflags); + if (ret) { + dev_err(chip->parent, "Failed to hog GPIO\n"); + return; + } + } +} + void acpi_gpiochip_add(struct gpio_chip *chip) { struct acpi_gpio_chip *acpi_gpio; @@ -879,6 +950,7 @@ void acpi_gpiochip_add(struct gpio_chip *chip) acpi_gpiochip_set_names(acpi_gpio); acpi_gpiochip_request_regions(acpi_gpio); + acpi_gpiochip_scan_gpios(acpi_gpio); acpi_walk_dep_device_list(handle); } -- 2.9.3
