Commit b08ea35a authored by Linus Walleij's avatar Linus Walleij
Browse files

gpio: add a data pointer to gpio_chip 



This adds a void * pointer to gpio_chip so that driver can
assign and retrieve some states. This is done to get rid of
container_of() calls for gpio_chips embedded inside state
containers, so we can remove the need to have the gpio_chip
or later (planned) struct gpio_device be dynamically allocated
at registration time, so that its struct device can be properly
reference counted and not bound to its parent device (e.g.
a platform_device) but instead live on after unregistration
if it is opened by e.g. a char device or sysfs.

The data is added with the new function gpiochip_add_data()
and for compatibility we add static inline wrapper function
gpiochip_add() that will call gpiochip_add_data() with
NULL as argument. The latter will be removed once we have
exorcised gpiochip_add() from the kernel.

gpiochip_get_data() is added as a static inline accessor
for drivers to quickly get their data out.

Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
parent 41d107ad

drivers/gpio/gpiolib.c

+6 −4
Original line number Diff line number Diff line
@@ -301,7 +301,7 @@ static int gpiochip_set_desc_names(struct gpio_chip *gc) 
}



/**

 * gpiochip_add() - register a gpio_chip

 * gpiochip_add_data() - register a gpio_chip

 * @chip: the chip to register, with chip->base initialized

 * Context: potentially before irqs will work

 *
@@ -309,7 +309,7 @@ static int gpiochip_set_desc_names(struct gpio_chip *gc) 
 * because the chip->base is invalid or already associated with a

 * different chip.  Otherwise it returns zero as a success code.

 *

 * When gpiochip_add() is called very early during boot, so that GPIOs

 * When gpiochip_add_data() is called very early during boot, so that GPIOs

 * can be freely used, the chip->parent device must be registered before

 * the gpio framework's arch_initcall().  Otherwise sysfs initialization

 * for GPIOs will fail rudely.
@@ -317,7 +317,7 @@ static int gpiochip_set_desc_names(struct gpio_chip *gc) 
 * If chip->base is negative, this requests dynamic assignment of

 * a range of valid GPIOs.

 */

int gpiochip_add(struct gpio_chip *chip)

int gpiochip_add_data(struct gpio_chip *chip, void *data)

{

	unsigned long	flags;

	int		status = 0;
@@ -329,6 +329,8 @@ int gpiochip_add(struct gpio_chip *chip) 
	if (!descs)

		return -ENOMEM;



	chip->data = data;



	if (chip->ngpio == 0) {

		chip_err(chip, "tried to insert a GPIO chip with zero lines\n");

		return -EINVAL;
@@ -415,7 +417,7 @@ err_free_descs: 
		chip->label ? : "generic");

	return status;

}

EXPORT_SYMBOL_GPL(gpiochip_add);

EXPORT_SYMBOL_GPL(gpiochip_add_data);



/**

 * gpiochip_remove() - unregister a gpio_chip

include/linux/gpio/driver.h

+13 −1
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ struct seq_file; 
 * @parent: optional parent device providing the GPIOs

 * @cdev: class device used by sysfs interface (may be NULL)

 * @owner: helps prevent removal of modules exporting active GPIOs

 * @data: per-instance data assigned by the driver

 * @list: links gpio_chips together for traversal

 * @request: optional hook for chip-specific activation, such as

 *	enabling module power and clock; may sleep
@@ -91,6 +92,7 @@ struct gpio_chip { 
	struct device		*parent;

	struct device		*cdev;

	struct module		*owner;

	void			*data;

	struct list_head        list;



	int			(*request)(struct gpio_chip *chip,
@@ -165,7 +167,11 @@ extern const char *gpiochip_is_requested(struct gpio_chip *chip, 
			unsigned offset);



/* add/remove chips */

extern int gpiochip_add(struct gpio_chip *chip);

extern int gpiochip_add_data(struct gpio_chip *chip, void *data);

static inline int gpiochip_add(struct gpio_chip *chip)

{

	return gpiochip_add_data(chip, NULL);

}

extern void gpiochip_remove(struct gpio_chip *chip);

extern struct gpio_chip *gpiochip_find(void *data,

			      int (*match)(struct gpio_chip *chip, void *data));
@@ -174,6 +180,12 @@ extern struct gpio_chip *gpiochip_find(void *data, 
int gpiochip_lock_as_irq(struct gpio_chip *chip, unsigned int offset);

void gpiochip_unlock_as_irq(struct gpio_chip *chip, unsigned int offset);



/* get driver data */

static inline void *gpiochip_get_data(struct gpio_chip *chip)

{

	return chip->data;

}



struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc);



#ifdef CONFIG_GPIOLIB_IRQCHIP

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