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gpio: add a data pointer to gpio_chip

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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: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Linus Walleij 2015-12-03 15:14:13 +01:00
parent 41d107ad92
commit b08ea35a32
2 changed files with 19 additions and 5 deletions
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10
drivers/gpio/gpiolib.c
View file

@ -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

14
include/linux/gpio/driver.h
View file

@ -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