The of_xlate function can be used to by drivers which need a other gpio
encoding than:
gpio = <&phandle gpio-nr gpio-flags>;
The of_xlate code is as close as possible to the kernel counter part
which makes it easier to add 'struct gpio_desc' support later on.
Signed-off-by: Marco Felsch <m.felsch@xxxxxxxxxxxxxx>
---
drivers/gpio/gpiolib.c | 51 ++++++++++++++++++++++++++++++++++++++
drivers/of/of_gpio.c | 56 +++++++++++++++++++++++++++++++++---------
include/gpio.h | 25 +++++++++++++++++++
3 files changed, 120 insertions(+), 12 deletions(-)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index d1087aa583..ab9a0e30be 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -592,6 +592,43 @@ static int of_gpiochip_set_names(struct gpio_chip *chip)
return 0;
}
+/**
+ * of_gpio_simple_xlate - translate gpiospec to the GPIO number and flags
+ * @gc: pointer to the gpio_chip structure
+ * @gpiospec: GPIO specifier as found in the device tree
+ * @flags: a flags pointer to fill in
+ *
+ * This is simple translation function, suitable for the most 1:1 mapped
+ * GPIO chips. This function performs only one sanity check: whether GPIO
+ * is less than ngpios (that is specified in the gpio_chip).
+ */
+static int of_gpio_simple_xlate(struct gpio_chip *gc,
+ const struct of_phandle_args *gpiospec,
+ u32 *flags)
+{
+ /*
+ * We're discouraging gpio_cells < 2, since that way you'll have to
+ * write your own xlate function (that will have to retrieve the GPIO
+ * number and the flags from a single gpio cell -- this is possible,
+ * but not recommended).
+ */
+ if (gc->of_gpio_n_cells < 2) {
+ WARN_ON(1);
+ return -EINVAL;
+ }
+
+ if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells))
+ return -EINVAL;
+
+ if (gpiospec->args[0] >= gc->ngpio)
+ return -EINVAL;
+
+ if (flags)
+ *flags = gpiospec->args[1];
+
+ return gc->base + gpiospec->args[0];
+}
+
static int of_gpiochip_add(struct gpio_chip *chip)
{
struct device_node *np;
@@ -601,6 +638,20 @@ static int of_gpiochip_add(struct gpio_chip *chip)
if (!np)
return 0;
+ if (!chip->ops->of_xlate)
+ chip->ops->of_xlate = of_gpio_simple_xlate;
+
+ /*
+ * Seperate check since the 'struct gpio_ops' is alawys the same for
+ * every 'struct gpio_chip' of the same instance (e.g. 'struct
+ * imx_gpio_chip').
+ */
+ if (chip->ops->of_xlate == of_gpio_simple_xlate)
+ chip->of_gpio_n_cells = 2;
+
+ if (chip->of_gpio_n_cells > MAX_PHANDLE_ARGS)
+ return -EINVAL;
+
ret = of_gpiochip_set_names(chip);
if (ret)
return ret;
diff --git a/drivers/of/of_gpio.c b/drivers/of/of_gpio.c
index 76398f7542..a1fa563a35 100644
--- a/drivers/of/of_gpio.c
+++ b/drivers/of/of_gpio.c
@@ -46,6 +46,44 @@ static void of_gpio_flags_quirks(struct device_node *np,
}
+static struct gpio_chip *of_find_gpiochip_by_xlate(
+ struct of_phandle_args *gpiospec)
+{
+ struct gpio_chip *chip;
+ struct device *dev;
+
+ dev = of_find_device_by_node(gpiospec->np);
+ if (!dev) {
+ pr_debug("%s: unable to find device of node %s\n",
+ __func__, gpiospec->np->full_name);
+ return NULL;
+ }
+
+ chip = gpio_get_chip_by_dev(dev);
+ if (!chip) {
+ pr_debug("%s: unable to find gpiochip\n", __func__);
+ return NULL;
+ }
+
+ if (chip->ops->of_xlate &&
+ chip->ops->of_xlate(chip, gpiospec, NULL) >= 0)
+ return chip;
+
+ pr_err("%s: failed to execute of_xlate\n", __func__);
+
+ return NULL;
+}
+
+static int of_xlate_and_get_gpiod_flags(struct gpio_chip *chip,
+ struct of_phandle_args *gpiospec,
+ enum of_gpio_flags *flags)
+{
+ if (chip->of_gpio_n_cells != gpiospec->args_count)
+ return -EINVAL;
+
+ return chip->ops->of_xlate(chip, gpiospec, flags);
+}
+
/**
* of_get_named_gpio_flags() - Get a GPIO number and flags to use with GPIO API
* @np: device node to get GPIO from
@@ -61,7 +99,7 @@ int of_get_named_gpio_flags(struct device_node *np, const char *propname,
int index, enum of_gpio_flags *flags)
{
struct of_phandle_args gpiospec;
- struct device *dev;
+ struct gpio_chip *chip;
int ret;
ret = of_parse_phandle_with_args(np, propname, "#gpio-cells",
@@ -72,27 +110,21 @@ int of_get_named_gpio_flags(struct device_node *np, const char *propname,
return ret;
}
- dev = of_find_device_by_node(gpiospec.np);
- if (!dev) {
- pr_debug("%s: unable to find device of node %s\n",
- __func__, gpiospec.np->full_name);
+ chip = of_find_gpiochip_by_xlate(&gpiospec);
+ if (!chip) {
ret = -EPROBE_DEFER;
goto out;
}
- ret = gpio_get_num(dev, gpiospec.args[0]);
- if (ret == -EPROBE_DEFER)
- goto out;
+ ret = of_xlate_and_get_gpiod_flags(chip, &gpiospec, flags);
if (ret < 0) {
pr_err("%s: unable to get gpio num of device %s: %d\n",
- __func__, dev_name(dev), ret);
+ __func__, dev_name(chip->dev), ret);
goto out;
}
- if (flags) {
- *flags = gpiospec.args[1];
+ if (flags)
of_gpio_flags_quirks(np, propname, flags, index);
- }
out:
of_node_put(gpiospec.np);
diff --git a/include/gpio.h b/include/gpio.h
index 5f2c16584c..d82b4505e0 100644
--- a/include/gpio.h
+++ b/include/gpio.h
@@ -177,6 +177,22 @@ struct gpio_ops {
int (*get_direction)(struct gpio_chip *chip, unsigned offset);
int (*get)(struct gpio_chip *chip, unsigned offset);
void (*set)(struct gpio_chip *chip, unsigned offset, int value);
+
+#if defined(CONFIG_OF_GPIO)
+ /*
+ * If CONFIG_OF_GPIO is enabled, then all GPIO controllers described in
+ * the device tree automatically may have an OF translation
+ */
+
+ /**
+ * @of_xlate:
+ *
+ * Callback to translate a device tree GPIO specifier into a chip-
+ * relative GPIO number and flags.
+ */
+ int (*of_xlate)(struct gpio_chip *gc,
+ const struct of_phandle_args *gpiospec, u32 *flags);
+#endif
};
struct gpio_chip {
@@ -185,6 +201,15 @@ struct gpio_chip {
int base;
int ngpio;
+#if defined(CONFIG_OF_GPIO)
+ /**
+ * @of_gpio_n_cells:
+ *
+ * Number of cells used to form the GPIO specifier.
+ */
+ unsigned int of_gpio_n_cells;
+#endif
+
struct gpio_ops *ops;
struct list_head list;
--
2.39.2
