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-rw-r--r--Documentation/driver-api/gpio/board.rst16
-rw-r--r--drivers/gpio/gpiolib.c67
-rw-r--r--include/linux/gpio/machine.h31
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 */
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