Hello Jiri, On Thu, Oct 17, 2013 at 01:08:02PM +0100, Jiri Prchal wrote: > 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.prc...@aksignal.cz> > --- > 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(-)
As I mentioned on v1 of this patch [1], I do not think that this is the right way to go about exporting GPIOs to userspace. Why do we need a binding for a non-device to tell Linux (specifically Linux) whether or not to represent a device to userspace, and how to do so? Why can this policy not be handled within the GPIO framework, or within GPIO drivers? I would appreciate a response this time. [1] http://thread.gmane.org/gmane.linux.drivers.devicetree/47822 Thanks, Mark. > > 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 Is this a boolean property, or a default value to output? This seems like an awfully generic name. > + - 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 > > -- > To unsubscribe from this list: send the line "unsubscribe devicetree" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
