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

3 files changed, 5 insertions, 21 deletions

diff --git a/arch/powerpc/platforms/52xx/mpc52xx_gpt.c b/arch/powerpc/platforms/52xx/mpc52xx_gpt.c
index 3f2ee47..6e82bd2 100644
--- a/arch/powerpc/platforms/52xx/mpc52xx_gpt.c
+++ b/arch/powerpc/platforms/52xx/mpc52xx_gpt.c
@@ -350,6 +350,7 @@ mpc52xx_gpt_gpio_setup(struct mpc52xx_gpt_priv *gpt, struct device_node *node)
 	gpt->gc.base = -1;
 	gpt->gc.of_gpio_n_cells = 2;
 	gpt->gc.of_xlate = of_gpio_simple_xlate;
+	gpt->gc.of_node = node;
 	of_node_get(node);
 
 	/* Setup external pin in GPIO mode */
diff --git a/arch/powerpc/platforms/83xx/mcu_mpc8349emitx.c b/arch/powerpc/platforms/83xx/mcu_mpc8349emitx.c
index e49f4bd..f0dbace 100644
--- a/arch/powerpc/platforms/83xx/mcu_mpc8349emitx.c
+++ b/arch/powerpc/platforms/83xx/mcu_mpc8349emitx.c
@@ -35,7 +35,6 @@
 
 struct mcu {
 	struct mutex lock;
-	struct device_node *np;
 	struct i2c_client *client;
 	struct gpio_chip gc;
 	u8 reg_ctrl;
@@ -79,7 +78,6 @@ static int mcu_gpiochip_add(struct mcu *mcu)
 {
 	struct device_node *np;
 	struct gpio_chip *gc = &mcu->gc;
-	int ret;
 
 	np = of_find_compatible_node(NULL, NULL, "fsl,mcu-mpc8349emitx");
 	if (!np)
@@ -94,29 +92,14 @@ static int mcu_gpiochip_add(struct mcu *mcu)
 	gc->direction_output = mcu_gpio_dir_out;
 	gc->of_gpio_n_cells = 2;
 	gc->of_xlate = of_gpio_simple_xlate;
+	gc->of_node = np;
 
-	mcu->np = np;
-
-	/*
-	 * We don't want to lose the node, its ->data and ->full_name...
-	 * So, if succeeded, we don't put the node here.
-	 */
-	ret = gpiochip_add(gc);
-	if (ret)
-		of_node_put(np);
-	return ret;
+	return gpiochip_add(gc);
 }
 
 static int mcu_gpiochip_remove(struct mcu *mcu)
 {
-	int ret;
-
-	ret = gpiochip_remove(&mcu->gc);
-	if (ret)
-		return ret;
-	of_node_put(mcu->np);
-
-	return 0;
+	return gpiochip_remove(&mcu->gc);
 }
 
 static int __devinit mcu_probe(struct i2c_client *client,
diff --git a/arch/powerpc/sysdev/qe_lib/gpio.c b/arch/powerpc/sysdev/qe_lib/gpio.c
index 194478c..32e9440 100644
--- a/arch/powerpc/sysdev/qe_lib/gpio.c
+++ b/arch/powerpc/sysdev/qe_lib/gpio.c
@@ -167,7 +167,7 @@ struct qe_pin *qe_pin_request(struct device_node *np, int index)
 		goto err1;
 	}
 
-	gc = gpio_np->data;
+	gc = of_node_to_gpiochip(gpio_np);
 	if (!gc) {
 		pr_debug("%s: gpio controller %s isn't registered\n",
 			 np->full_name, gpio_np->full_name);