pinctrl: Add devm_ apis for pinctrl_{register, unregister}

Add device managed APIs devm_pinctrl_register() and
devm_pinctrl_unregister() for the APIs pinctrl_register()
and pinctrl_unregister().

This helps in reducing code in error path and sometimes
removal of .remove callback for driver unbind.
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

CVE-2017-18174

(cherry picked from commit 80e0f8d9)
[tyhicks: Added build fix from commit 3024f920]
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Acked-by: Khalid Elmously <khalid.elmously@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

drivers/pinctrl/core.c

@@ -1871,6 +1871,69 @@ void pinctrl_unregister(struct pinctrl_dev *pctldev)
 }
 EXPORT_SYMBOL_GPL(pinctrl_unregister);
 
+static void devm_pinctrl_dev_release(struct device *dev, void *res)
+{
+	struct pinctrl_dev *pctldev = *(struct pinctrl_dev **)res;
+
+	pinctrl_unregister(pctldev);
+}
+
+static int devm_pinctrl_dev_match(struct device *dev, void *res, void *data)
+{
+	struct pctldev **r = res;
+
+	if (WARN_ON(!r || !*r))
+		return 0;
+
+	return *r == data;
+}
+
+/**
+ * devm_pinctrl_register() - Resource managed version of pinctrl_register().
+ * @dev: parent device for this pin controller
+ * @pctldesc: descriptor for this pin controller
+ * @driver_data: private pin controller data for this pin controller
+ *
+ * Returns an error pointer if pincontrol register failed. Otherwise
+ * it returns valid pinctrl handle.
+ *
+ * The pinctrl device will be automatically released when the device is unbound.
+ */
+struct pinctrl_dev *devm_pinctrl_register(struct device *dev,
+					  struct pinctrl_desc *pctldesc,
+					  void *driver_data)
+{
+	struct pinctrl_dev **ptr, *pctldev;
+
+	ptr = devres_alloc(devm_pinctrl_dev_release, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return ERR_PTR(-ENOMEM);
+
+	pctldev = pinctrl_register(pctldesc, dev, driver_data);
+	if (IS_ERR(pctldev)) {
+		devres_free(ptr);
+		return pctldev;
+	}
+
+	*ptr = pctldev;
+	devres_add(dev, ptr);
+
+	return pctldev;
+}
+EXPORT_SYMBOL_GPL(devm_pinctrl_register);
+
+/**
+ * devm_pinctrl_unregister() - Resource managed version of pinctrl_unregister().
+ * @dev: device for which which resource was allocated
+ * @pctldev: the pinctrl device to unregister.
+ */
+void devm_pinctrl_unregister(struct device *dev, struct pinctrl_dev *pctldev)
+{
+	WARN_ON(devres_release(dev, devm_pinctrl_dev_release,
+			       devm_pinctrl_dev_match, pctldev));
+}
+EXPORT_SYMBOL_GPL(devm_pinctrl_unregister);
+
 static int __init pinctrl_init(void)
 {
 	pr_info("initialized pinctrl subsystem\n");

include/linux/pinctrl/pinctrl.h

@@ -144,6 +144,12 @@ struct pinctrl_desc {
 extern struct pinctrl_dev *pinctrl_register(struct pinctrl_desc *pctldesc,
 				struct device *dev, void *driver_data);
 extern void pinctrl_unregister(struct pinctrl_dev *pctldev);
+extern struct pinctrl_dev *devm_pinctrl_register(struct device *dev,
+				struct pinctrl_desc *pctldesc,
+				void *driver_data);
+extern void devm_pinctrl_unregister(struct device *dev,
+				struct pinctrl_dev *pctldev);
+
 extern bool pin_is_valid(struct pinctrl_dev *pctldev, int pin);
 extern void pinctrl_add_gpio_range(struct pinctrl_dev *pctldev,
 				struct pinctrl_gpio_range *range);