diff options
| -rw-r--r-- | Documentation/driver-api/gpio/board.rst | 16 | ||||
| -rw-r--r-- | drivers/gpio/gpiolib.c | 67 | ||||
| -rw-r--r-- | include/linux/gpio/machine.h | 31 |
3 files changed, 114 insertions, 0 deletions
diff --git a/Documentation/driver-api/gpio/board.rst b/Documentation/driver-api/gpio/board.rst index 25d62b2e9fd0..2c112553df84 100644 --- a/Documentation/driver-api/gpio/board.rst +++ b/Documentation/driver-api/gpio/board.rst @@ -177,3 +177,19 @@ mapping and is thus transparent to GPIO consumers. A set of functions such as gpiod_set_value() is available to work with the new descriptor-oriented interface. + +Boards using platform data can also hog GPIO lines by defining GPIO hog tables. + +.. code-block:: c + + struct gpiod_hog gpio_hog_table[] = { + GPIO_HOG("gpio.0", 10, "foo", GPIO_ACTIVE_LOW, GPIOD_OUT_HIGH), + { } + }; + +And the table can be added to the board code as follows:: + + gpiod_add_hogs(gpio_hog_table); + +The line will be hogged as soon as the gpiochip is created or - in case the +chip was created earlier - when the hog table is registered. diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 43aeb07343ec..547adc149b62 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -71,6 +71,9 @@ static DEFINE_MUTEX(gpio_lookup_lock); static LIST_HEAD(gpio_lookup_list); LIST_HEAD(gpio_devices); +static DEFINE_MUTEX(gpio_machine_hogs_mutex); +static LIST_HEAD(gpio_machine_hogs); + static void gpiochip_free_hogs(struct gpio_chip *chip); static int gpiochip_add_irqchip(struct gpio_chip *gpiochip, struct lock_class_key *lock_key, @@ -1171,6 +1174,41 @@ err_remove_device: return status; } +static void gpiochip_machine_hog(struct gpio_chip *chip, struct gpiod_hog *hog) +{ + struct gpio_desc *desc; + int rv; + + desc = gpiochip_get_desc(chip, hog->chip_hwnum); + if (IS_ERR(desc)) { + pr_err("%s: unable to get GPIO desc: %ld\n", + __func__, PTR_ERR(desc)); + return; + } + + if (desc->flags & FLAG_IS_HOGGED) + return; + + rv = gpiod_hog(desc, hog->line_name, hog->lflags, hog->dflags); + if (rv) + pr_err("%s: unable to hog GPIO line (%s:%u): %d\n", + __func__, chip->label, hog->chip_hwnum, rv); +} + +static void machine_gpiochip_add(struct gpio_chip *chip) +{ + struct gpiod_hog *hog; + + mutex_lock(&gpio_machine_hogs_mutex); + + list_for_each_entry(hog, &gpio_machine_hogs, list) { + if (!strcmp(chip->label, hog->chip_label)) + gpiochip_machine_hog(chip, hog); + } + + mutex_unlock(&gpio_machine_hogs_mutex); +} + static void gpiochip_setup_devs(void) { struct gpio_device *gdev; @@ -1326,6 +1364,8 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data, acpi_gpiochip_add(chip); + machine_gpiochip_add(chip); + /* * By first adding the chardev, and then adding the device, * we get a device node entry in sysfs under @@ -3462,6 +3502,33 @@ void gpiod_remove_lookup_table(struct gpiod_lookup_table *table) } EXPORT_SYMBOL_GPL(gpiod_remove_lookup_table); +/** + * gpiod_add_hogs() - register a set of GPIO hogs from machine code + * @hogs: table of gpio hog entries with a zeroed sentinel at the end + */ +void gpiod_add_hogs(struct gpiod_hog *hogs) +{ + struct gpio_chip *chip; + struct gpiod_hog *hog; + + mutex_lock(&gpio_machine_hogs_mutex); + + for (hog = &hogs[0]; hog->chip_label; hog++) { + list_add_tail(&hog->list, &gpio_machine_hogs); + + /* + * The chip may have been registered earlier, so check if it + * exists and, if so, try to hog the line now. + */ + chip = find_chip_by_name(hog->chip_label); + if (chip) + gpiochip_machine_hog(chip, hog); + } + + mutex_unlock(&gpio_machine_hogs_mutex); +} +EXPORT_SYMBOL_GPL(gpiod_add_hogs); + static struct gpiod_lookup_table *gpiod_find_lookup_table(struct device *dev) { const char *dev_id = dev ? dev_name(dev) : NULL; diff --git a/include/linux/gpio/machine.h b/include/linux/gpio/machine.h index b2f2dc638463..daa44eac9241 100644 --- a/include/linux/gpio/machine.h +++ b/include/linux/gpio/machine.h @@ -39,6 +39,23 @@ struct gpiod_lookup_table { struct gpiod_lookup table[]; }; +/** + * struct gpiod_hog - GPIO line hog table + * @chip_label: name of the chip the GPIO belongs to + * @chip_hwnum: hardware number (i.e. relative to the chip) of the GPIO + * @line_name: consumer name for the hogged line + * @lflags: mask of GPIO lookup flags + * @dflags: GPIO flags used to specify the direction and value + */ +struct gpiod_hog { + struct list_head list; + const char *chip_label; + u16 chip_hwnum; + const char *line_name; + enum gpio_lookup_flags lflags; + int dflags; +}; + /* * Simple definition of a single GPIO under a con_id */ @@ -59,10 +76,23 @@ struct gpiod_lookup_table { .flags = _flags, \ } +/* + * Simple definition of a single GPIO hog in an array. + */ +#define GPIO_HOG(_chip_label, _chip_hwnum, _line_name, _lflags, _dflags) \ +{ \ + .chip_label = _chip_label, \ + .chip_hwnum = _chip_hwnum, \ + .line_name = _line_name, \ + .lflags = _lflags, \ + .dflags = _dflags, \ +} + #ifdef CONFIG_GPIOLIB void gpiod_add_lookup_table(struct gpiod_lookup_table *table); void gpiod_add_lookup_tables(struct gpiod_lookup_table **tables, size_t n); void gpiod_remove_lookup_table(struct gpiod_lookup_table *table); +void gpiod_add_hogs(struct gpiod_hog *hogs); #else static inline void gpiod_add_lookup_table(struct gpiod_lookup_table *table) {} @@ -70,6 +100,7 @@ static inline void gpiod_add_lookup_tables(struct gpiod_lookup_table **tables, size_t n) {} static inline void gpiod_remove_lookup_table(struct gpiod_lookup_table *table) {} +static inline void gpiod_add_hogs(struct gpiod_hog *hogs) {} #endif #endif /* __LINUX_GPIO_MACHINE_H */ |