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authorGrant Likely <grant.likely@secretlab.ca>2010-06-08 07:48:16 -0600
committerGrant Likely <grant.likely@secretlab.ca>2010-07-05 16:14:30 -0600
commit594fa265e084073443390c5b93d5410fd28e9bcd (patch)
tree42c0e5536ae2fd016159e1e1bd1f27f0a9f3cac2 /drivers/gpio
parenta19e3da5bc5fc6c10ab73f310bea80f3845b4531 (diff)
downloadlinux-594fa265e084073443390c5b93d5410fd28e9bcd.tar.bz2
of/gpio: stop using device_node data pointer to find gpio_chip
Currently the kernel uses the struct device_node.data pointer to resolve a struct gpio_chip pointer from a device tree node. However, the .data member doesn't provide any type checking and there aren't any rules enforced on what it should be used for. There's no guarantee that the data stored in it actually points to an gpio_chip pointer. Instead of relying on the .data pointer, this patch modifies the code to add a lookup function which scans through the registered gpio_chips and returns the gpio_chip that has a pointer to the specified device_node. Signed-off-by: Grant Likely <grant.likely@secretlab.ca> CC: Andrew Morton <akpm@linux-foundation.org> CC: Anton Vorontsov <avorontsov@ru.mvista.com> CC: Grant Likely <grant.likely@secretlab.ca> CC: David Brownell <dbrownell@users.sourceforge.net> CC: Bill Gatliff <bgat@billgatliff.com> CC: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com> CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> CC: Jean Delvare <khali@linux-fr.org> CC: linux-kernel@vger.kernel.org CC: devicetree-discuss@lists.ozlabs.org
Diffstat (limited to 'drivers/gpio')
-rw-r--r--drivers/gpio/gpiolib.c32
1 files changed, 32 insertions, 0 deletions
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 713ca0e37f23..73fd328f6fe4 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1153,6 +1153,38 @@ int gpiochip_remove(struct gpio_chip *chip)
}
EXPORT_SYMBOL_GPL(gpiochip_remove);
+/**
+ * gpiochip_find() - iterator for locating a specific gpio_chip
+ * @data: data to pass to match function
+ * @callback: Callback function to check gpio_chip
+ *
+ * Similar to bus_find_device. It returns a reference to a gpio_chip as
+ * determined by a user supplied @match callback. The callback should return
+ * 0 if the device doesn't match and non-zero if it does. If the callback is
+ * non-zero, this function will return to the caller and not iterate over any
+ * more gpio_chips.
+ */
+struct gpio_chip *gpiochip_find(void *data,
+ int (*match)(struct gpio_chip *chip, void *data))
+{
+ struct gpio_chip *chip = NULL;
+ unsigned long flags;
+ int i;
+
+ spin_lock_irqsave(&gpio_lock, flags);
+ for (i = 0; i < ARCH_NR_GPIOS; i++) {
+ if (!gpio_desc[i].chip)
+ continue;
+
+ if (match(gpio_desc[i].chip, data)) {
+ chip = gpio_desc[i].chip;
+ break;
+ }
+ }
+ spin_unlock_irqrestore(&gpio_lock, flags);
+
+ return chip;
+}
/* These "optional" allocation calls help prevent drivers from stomping
* on each other, and help provide better diagnostics in debugfs.