Add export possibility to sysfs with given name in device tree. It is nice for
users to have board specific gpios exported at boot-time and with their names.
It renames some functions in gpiolib and adds name as parameter. If it is passed
NULL as name everything works like before, export by chip name.
It can be done by extra function export_with_name without changing original
export function but I think there would not to be twice almost the same.
Even if gpio sysfs interface is almost to be deprecated, I would like to add
this, cause new chardev interface is in farness future.
Rebased from older unapplyed patch: [PATCH] owrt: GPIO: add gpio_export_with_name.
v3:
change to "linux,gpio-export"
removed arrays of gpios, just one child node -> one GPIO line
simplified node properties like as it's in gpio-leds
if not label -> uses child node name
Signed-off-by: Jiri Prchal <jiri.prchal@xxxxxxxxxxx>
---
Documentation/devicetree/bindings/gpio/gpio.txt | 44 ++++++++++++++++++
drivers/gpio/gpiolib-of.c | 56 +++++++++++++++++++++++
drivers/gpio/gpiolib.c | 27 +++++++----
include/asm-generic/gpio.h | 6 ++-
include/linux/gpio.h | 23 +++++++++-
5 files changed, 144 insertions(+), 12 deletions(-)
diff --git a/Documentation/devicetree/bindings/gpio/gpio.txt b/Documentation/devicetree/bindings/gpio/gpio.txt
index 6cec6ff..9888186 100644
--- a/Documentation/devicetree/bindings/gpio/gpio.txt
+++ b/Documentation/devicetree/bindings/gpio/gpio.txt
@@ -117,3 +117,47 @@ Example:
Here, a single GPIO controller has GPIOs 0..9 routed to pin controller
pinctrl1's pins 20..29, and GPIOs 10..19 routed to pin controller pinctrl2's
pins 50..59.
+
+3) gpio-export
+--------------
+
+gpio-export will allow you to export a GPIO line to linux sysfs.
+Can be used to describe hw GPIO lines by "name" and to have them exported at
+boot-time to make it convenient for users.
+
+required properties:
+- compatible: Should be "linux,gpio-export"
+
+in each child node will represent a GPIO line
+
+required properties:
+- gpios: GPIO line to export
+
+optional properties:
+ - label: export name, if not present, child node name used
+ - output: to set it as output with default value
+ if not present gpio as input
+ - direction-may-change: boolean to allow the direction to be controllable
+
+Example:
+
+gpio_export {
+ compatible = "linux,gpio-export";
+
+ in {
+ label = "in";
+ gpios = <&pioC 20 0>;
+ };
+
+ out {
+ label = "out";
+ output = <1>;
+ direction-may-change;
+ gpios = <&pioC 21 0>;
+ };
+
+ in_out {
+ direction-may-change;
+ gpios = <&pioC 22 0>;
+ };
+};
diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index 0dfaf20..7ecdf1b 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -21,6 +21,8 @@
#include <linux/of_gpio.h>
#include <linux/pinctrl/pinctrl.h>
#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
/* Private data structure for of_gpiochip_find_and_xlate */
struct gg_data {
@@ -243,3 +245,57 @@ void of_gpiochip_remove(struct gpio_chip *chip)
if (chip->of_node)
of_node_put(chip->of_node);
}
+
+static struct of_device_id gpio_export_ids[] = {
+ { .compatible = "linux,gpio-export" },
+ { /* sentinel */ }
+};
+
+static int __init of_gpio_export_probe(struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ struct device_node *cnp;
+ u32 val;
+ int nb = 0;
+
+ for_each_child_of_node(np, cnp) {
+ const char *name = NULL;
+ int gpio;
+ bool dmc;
+
+ of_property_read_string(cnp, "label", &name);
+ if (!name)
+ name = cnp->name;
+
+ gpio = of_get_gpio(cnp, 0);
+ if (devm_gpio_request(&pdev->dev, gpio, name))
+ continue;
+
+ if (!of_property_read_u32(cnp, "output", &val))
+ gpio_direction_output(gpio, val);
+ else
+ gpio_direction_input(gpio);
+
+ dmc = of_property_read_bool(np, "direction-may-change");
+ gpio_export_with_name(gpio, dmc, name);
+ nb++;
+ }
+
+ dev_info(&pdev->dev, "%d gpio(s) exported\n", nb);
+
+ return 0;
+}
+
+static struct platform_driver gpio_export_driver = {
+ .driver = {
+ .name = "linux,gpio-export",
+ .owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(gpio_export_ids),
+ },
+};
+
+static int __init of_gpio_export_init(void)
+{
+ return platform_driver_probe(&gpio_export_driver, of_gpio_export_probe);
+}
+device_initcall(of_gpio_export_init);
\ No newline at end of file
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 86ef346..c7494d1 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -96,7 +96,8 @@ static int gpiod_get_value(const struct gpio_desc *desc);
static void gpiod_set_value(struct gpio_desc *desc, int value);
static int gpiod_cansleep(const struct gpio_desc *desc);
static int gpiod_to_irq(const struct gpio_desc *desc);
-static int gpiod_export(struct gpio_desc *desc, bool direction_may_change);
+static int gpiod_export_with_name(struct gpio_desc *desc,
+ bool direction_may_change, const char *name);
static int gpiod_export_link(struct device *dev, const char *name,
struct gpio_desc *desc);
static int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value);
@@ -674,7 +675,7 @@ static ssize_t export_store(struct class *class,
status = -ENODEV;
goto done;
}
- status = gpiod_export(desc, true);
+ status = gpiod_export_with_name(desc, true, NULL);
if (status < 0)
gpiod_free(desc);
else
@@ -736,9 +737,10 @@ static struct class gpio_class = {
/**
- * gpio_export - export a GPIO through sysfs
+ * gpiod_export_with_name - export a GPIO through sysfs
* @gpio: gpio to make available, already requested
* @direction_may_change: true if userspace may change gpio direction
+ * @name: gpio name
* Context: arch_initcall or later
*
* When drivers want to make a GPIO accessible to userspace after they
@@ -750,7 +752,8 @@ static struct class gpio_class = {
*
* Returns zero on success, else an error.
*/
-static int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
+int gpiod_export_with_name(struct gpio_desc *desc, bool direction_may_change,
+ const char *name)
{
unsigned long flags;
int status;
@@ -788,7 +791,9 @@ static int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
spin_unlock_irqrestore(&gpio_lock, flags);
offset = gpio_chip_hwgpio(desc);
- if (desc->chip->names && desc->chip->names[offset])
+ if (name)
+ ioname = name;
+ else if (desc->chip->names && desc->chip->names[offset])
ioname = desc->chip->names[offset];
dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
@@ -829,11 +834,13 @@ fail_unlock:
return status;
}
-int gpio_export(unsigned gpio, bool direction_may_change)
+int gpio_export_with_name(unsigned gpio, bool direction_may_change,
+ const char *name)
{
- return gpiod_export(gpio_to_desc(gpio), direction_may_change);
+ return gpiod_export_with_name(gpio_to_desc(gpio), direction_may_change,
+ name);
}
-EXPORT_SYMBOL_GPL(gpio_export);
+EXPORT_SYMBOL_GPL(gpio_export_with_name);
static int match_export(struct device *dev, const void *data)
{
@@ -1531,7 +1538,9 @@ int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)
goto free_gpio;
if (flags & GPIOF_EXPORT) {
- err = gpiod_export(desc, flags & GPIOF_EXPORT_CHANGEABLE);
+ err = gpiod_export_with_name(desc,
+ flags & GPIOF_EXPORT_CHANGEABLE,
+ NULL);
if (err)
goto free_gpio;
}
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index bde6469..d0970e3 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -202,7 +202,8 @@ extern void gpio_free_array(const struct gpio *array, size_t num);
* A sysfs interface can be exported by individual drivers if they want,
* but more typically is configured entirely from userspace.
*/
-extern int gpio_export(unsigned gpio, bool direction_may_change);
+extern int gpio_export_with_name(unsigned gpio, bool direction_may_change,
+ const char *name);
extern int gpio_export_link(struct device *dev, const char *name,
unsigned gpio);
extern int gpio_sysfs_set_active_low(unsigned gpio, int value);
@@ -284,7 +285,8 @@ struct device;
/* sysfs support is only available with gpiolib, where it's optional */
-static inline int gpio_export(unsigned gpio, bool direction_may_change)
+static inline int gpio_export_with_name(unsigned gpio, bool direction_may_change,
+ const char *name)
{
return -ENOSYS;
}
diff --git a/include/linux/gpio.h b/include/linux/gpio.h
index 552e3f4..12a6cd2 100644
--- a/include/linux/gpio.h
+++ b/include/linux/gpio.h
@@ -169,7 +169,8 @@ static inline void gpio_set_value_cansleep(unsigned gpio, int value)
WARN_ON(1);
}
-static inline int gpio_export(unsigned gpio, bool direction_may_change)
+static inline int gpio_export_with_name(unsigned gpio, bool direction_may_change,
+ const char *name)
{
/* GPIO can never have been requested or set as {in,out}put */
WARN_ON(1);
@@ -236,4 +237,24 @@ int devm_gpio_request_one(struct device *dev, unsigned gpio,
unsigned long flags, const char *label);
void devm_gpio_free(struct device *dev, unsigned int gpio);
+/**
+ * gpio_export - export a GPIO through sysfs
+ * @gpio: gpio to make available, already requested
+ * @direction_may_change: true if userspace may change gpio direction
+ * Context: arch_initcall or later
+ *
+ * When drivers want to make a GPIO accessible to userspace after they
+ * have requested it -- perhaps while debugging, or as part of their
+ * public interface -- they may use this routine. If the GPIO can
+ * change direction (some can't) and the caller allows it, userspace
+ * will see "direction" sysfs attribute which may be used to change
+ * the gpio's direction. A "value" attribute will always be provided.
+ *
+ * Returns zero on success, else an error.
+ */
+static inline int gpio_export(unsigned gpio,bool direction_may_change)
+{
+ return gpio_export_with_name(gpio, direction_may_change, NULL);
+}
+
#endif /* __LINUX_GPIO_H */
--
1.7.9.5
--
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