[PATCH 4.2.y-ckt 006/218] gpio: add a data pointer to gpio_chip

From: Kamal Mostafa
Date: Thu Mar 31 2016 - 17:27:40 EST

4.2.8-ckt7 -stable review patch. If anyone has any objections, please let me know.


From: Linus Walleij <linus.walleij@xxxxxxxxxx>

commit b08ea35a3296ee25c4cb53a977b752266dafa2c2 upstream.

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@xxxxxxxxxx>
[ kamal: 4.2-stable prereq ]
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
drivers/gpio/gpiolib.c | 10 ++++++----
include/linux/gpio/driver.h | 14 +++++++++++++-
2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 3144d19..27c5079d 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -219,7 +219,7 @@ static int gpiochip_add_to_list(struct gpio_chip *chip)

- * 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
@@ -227,7 +227,7 @@ static int gpiochip_add_to_list(struct gpio_chip *chip)
* 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->dev device must be registered before
* the gpio framework's arch_initcall(). Otherwise sysfs initialization
* for GPIOs will fail rudely.
@@ -235,7 +235,7 @@ static int gpiochip_add_to_list(struct gpio_chip *chip)
* 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;
@@ -247,6 +247,8 @@ 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;
@@ -322,7 +324,7 @@ err_free_descs:
chip->label ? : "generic");
return status;

* gpiochip_remove() - unregister a gpio_chip
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index c8393cd..f819425 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -22,6 +22,7 @@ struct seq_file;
* @dev: optional 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
@@ -80,6 +81,7 @@ struct gpio_chip {
struct device *dev;
struct device *cdev;
struct module *owner;
+ void *data;
struct list_head list;

int (*request)(struct gpio_chip *chip,
@@ -153,7 +155,11 @@ 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));
@@ -162,6 +168,12 @@ 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);