[PATCH v23 03/13] power: reset: reboot-mode: Add support for predefined reboot modes

reboot-mode based drivers can define a reboot-mode by adding it under
the reboot-mode node in device tree. This limits such drivers, to define
any predefined reboot-modes statically within the driver and creates a
dependency on device-tree.

Extend the reboot-mode framework to handle predefined modes alongside
those defined in device tree. Drivers can now define their own
reboot-modes and register them via the framework. A centralized init
call has been added to the reboot-mode framework and adopted by
existing drivers. This ensures driver state is initialized together
with predefined modes.

Signed-off-by: Shivendra Pratap <[email protected]>
---
 drivers/power/reset/nvmem-reboot-mode.c  |   4 +-
 drivers/power/reset/qcom-pon.c           |   4 +-
 drivers/power/reset/reboot-mode.c        | 192 ++++++++++++++++++++++++-------
 drivers/power/reset/syscon-reboot-mode.c |   4 +-
 include/linux/reboot-mode.h              |  16 +++
 5 files changed, 175 insertions(+), 45 deletions(-)

diff --git a/drivers/power/reset/nvmem-reboot-mode.c b/drivers/power/reset/nvmem-reboot-mode.c
index ac69b5f39fb4..4909c65ca02d 100644
--- a/drivers/power/reset/nvmem-reboot-mode.c
+++ b/drivers/power/reset/nvmem-reboot-mode.c
@@ -53,8 +53,8 @@ static int nvmem_reboot_mode_probe(struct platform_device *pdev)
 	if (!nvmem_rbm)
 		return -ENOMEM;
 
-	nvmem_rbm->reboot.dev = &pdev->dev;
-	nvmem_rbm->reboot.write = nvmem_reboot_mode_write;
+	reboot_mode_driver_init(&nvmem_rbm->reboot, &pdev->dev,
+				nvmem_reboot_mode_write);
 
 	nvmem_rbm->cell = devm_nvmem_cell_get(&pdev->dev, "reboot-mode");
 	if (IS_ERR(nvmem_rbm->cell)) {
diff --git a/drivers/power/reset/qcom-pon.c b/drivers/power/reset/qcom-pon.c
index a508ab26d03f..5f3c6002ef8a 100644
--- a/drivers/power/reset/qcom-pon.c
+++ b/drivers/power/reset/qcom-pon.c
@@ -72,9 +72,9 @@ static int qcom_pon_probe(struct platform_device *pdev)
 	reason_shift = (long)of_device_get_match_data(&pdev->dev);
 
 	if (reason_shift != NO_REASON_SHIFT) {
-		pon->reboot_mode.dev = &pdev->dev;
+		reboot_mode_driver_init(&pon->reboot_mode, &pdev->dev,
+					qcom_pon_reboot_mode_write);
 		pon->reason_shift = reason_shift;
-		pon->reboot_mode.write = qcom_pon_reboot_mode_write;
 		error = devm_reboot_mode_register(&pdev->dev, &pon->reboot_mode);
 		if (error) {
 			dev_err(&pdev->dev, "can't register reboot mode\n");
diff --git a/drivers/power/reset/reboot-mode.c b/drivers/power/reset/reboot-mode.c
index db2129c72341..08d5b58fce71 100644
--- a/drivers/power/reset/reboot-mode.c
+++ b/drivers/power/reset/reboot-mode.c
@@ -32,18 +32,30 @@ struct reboot_mode_sysfs_data {
 	struct list_head head;
 };
 
-static inline void reboot_mode_release_list(struct reboot_mode_sysfs_data *priv)
+static inline void reboot_mode_release_list(struct list_head *head)
 {
 	struct mode_info *info;
 	struct mode_info *next;
 
-	list_for_each_entry_safe(info, next, &priv->head, list) {
+	list_for_each_entry_safe(info, next, head, list) {
 		list_del(&info->list);
 		kfree_const(info->mode);
 		kfree(info);
 	}
 }
 
+/**
+ * reboot_mode_reset_predefined_modes - Remove all predefined reboot modes
+ * @reboot: reboot mode driver
+ *
+ * Reset predefined reboot modes added via reboot_mode_add_predefined_modes().
+ */
+void reboot_mode_reset_predefined_modes(struct reboot_mode_driver *reboot)
+{
+	reboot_mode_release_list(&reboot->predefined_modes);
+}
+EXPORT_SYMBOL_GPL(reboot_mode_reset_predefined_modes);
+
 static ssize_t reboot_modes_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
 	struct reboot_mode_sysfs_data *priv;
@@ -117,6 +129,58 @@ static int reboot_mode_notify(struct notifier_block *this,
 	return NOTIFY_DONE;
 }
 
+/**
+ * reboot_mode_driver_init - Initialize reboot-mode state
+ * @reboot: reboot mode driver object to initialize
+ * @dev: backing device
+ * @write: write callback for programming magic
+ *
+ * This function must be called with a valid @dev and @write before calling
+ * reboot_mode_register(), reboot_mode_add_predefined_modes(), or any other
+ * reboot-mode framework API.
+ */
+void reboot_mode_driver_init(struct reboot_mode_driver *reboot,
+			     struct device *dev,
+			     int (*write)(struct reboot_mode_driver *reboot, u32 *magic, int count))
+{
+	memset(reboot, 0, sizeof(*reboot));
+	reboot->dev = dev;
+	reboot->write = write;
+	INIT_LIST_HEAD(&reboot->head);
+	INIT_LIST_HEAD(&reboot->predefined_modes);
+}
+EXPORT_SYMBOL_GPL(reboot_mode_driver_init);
+
+static struct mode_info *reboot_mode_create_info(const char *mode, const u32 *magic, int count)
+{
+	struct mode_info *info;
+
+	if (!mode || mode[0] == '\0') {
+		pr_err("invalid mode name\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	info = kzalloc_obj(*info, GFP_KERNEL);
+	if (!info)
+		return ERR_PTR(-ENOMEM);
+
+	info->mode = kstrdup_const(mode, GFP_KERNEL);
+	if (!info->mode) {
+		kfree(info);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	if (!memchr_inv(magic, 0, count * sizeof(u32))) {
+		pr_debug("reboot mode %s with zero magic values\n", mode);
+		info->count = -1;
+	} else {
+		memcpy(info->magic, magic, count * sizeof(u32));
+		info->count = count;
+	}
+
+	return info;
+}
+
 static int reboot_mode_create_device(struct reboot_mode_driver *reboot)
 {
 	struct reboot_mode_sysfs_data *priv;
@@ -158,7 +222,7 @@ static int reboot_mode_create_device(struct reboot_mode_driver *reboot)
 	return 0;
 
 error:
-	reboot_mode_release_list(priv);
+	reboot_mode_release_list(&priv->head);
 	kfree(priv);
 	return ret;
 }
@@ -171,7 +235,7 @@ static int reboot_mode_create_device(struct reboot_mode_driver *reboot)
  */
 int reboot_mode_register(struct reboot_mode_driver *reboot)
 {
-	struct mode_info *info = NULL;
+	struct mode_info *info;
 	struct property *prop;
 	struct device_node *np = reboot->dev->of_node;
 	size_t len = strlen(PREFIX);
@@ -179,11 +243,16 @@ int reboot_mode_register(struct reboot_mode_driver *reboot)
 	int count;
 	int ret;
 
+	if (reboot->reboot_notifier.notifier_call == reboot_mode_notify)
+		return -EBUSY;
+
 	INIT_LIST_HEAD(&reboot->head);
 
+	if (!np)
+		goto predefined_modes;
+
 	for_each_property_of_node(np, prop) {
 		memset(magic, 0, sizeof(magic));
-
 		if (strncmp(prop->name, PREFIX, len))
 			continue;
 
@@ -195,35 +264,17 @@ int reboot_mode_register(struct reboot_mode_driver *reboot)
 			continue;
 		}
 
-		info = kzalloc(sizeof(*info), GFP_KERNEL);
-		if (!info) {
-			ret = -ENOMEM;
-			goto error;
-		}
-
-		if (!memchr_inv(magic, 0, count * sizeof(u32))) {
-			pr_debug("reboot mode %s with zero magic values\n", prop->name);
-			info->count = -1;
-		} else {
-			memcpy(info->magic, magic, count * sizeof(u32));
-			info->count = count;
-		}
-
-		info->mode = kstrdup_const(prop->name + len, GFP_KERNEL);
-		if (!info->mode) {
-			ret =  -ENOMEM;
-			goto error;
-		} else if (info->mode[0] == '\0') {
-			kfree_const(info->mode);
-			ret = -EINVAL;
-			pr_err("invalid mode name(%s): too short!\n", prop->name);
+		info = reboot_mode_create_info(prop->name + len, magic, count);
+		if (IS_ERR(info)) {
+			ret = PTR_ERR(info);
 			goto error;
 		}
 
 		list_add_tail(&info->list, &reboot->head);
-		info = NULL;
 	}
 
+predefined_modes:
+	list_splice_tail_init(&reboot->predefined_modes, &reboot->head);
 	reboot->reboot_notifier.notifier_call = reboot_mode_notify;
 	register_reboot_notifier(&reboot->reboot_notifier);
 
@@ -234,7 +285,6 @@ int reboot_mode_register(struct reboot_mode_driver *reboot)
 	return 0;
 
 error:
-	kfree(info);
 	reboot_mode_unregister(reboot);
 	return ret;
 }
@@ -267,7 +317,7 @@ static inline void reboot_mode_unregister_device(struct reboot_mode_driver *rebo
 	if (!priv)
 		return;
 
-	reboot_mode_release_list(priv);
+	reboot_mode_release_list(&priv->head);
 	kfree(priv);
 }
 
@@ -277,17 +327,12 @@ static inline void reboot_mode_unregister_device(struct reboot_mode_driver *rebo
  */
 int reboot_mode_unregister(struct reboot_mode_driver *reboot)
 {
-	struct mode_info *info;
-	struct mode_info *next;
-
 	unregister_reboot_notifier(&reboot->reboot_notifier);
+	reboot->reboot_notifier.notifier_call = NULL;
 	reboot_mode_unregister_device(reboot);
 
-	list_for_each_entry_safe(info, next, &reboot->head, list) {
-		list_del(&info->list);
-		kfree_const(info->mode);
-		kfree(info);
-	}
+	reboot_mode_release_list(&reboot->head);
+	reboot_mode_release_list(&reboot->predefined_modes);
 
 	return 0;
 }
@@ -312,8 +357,10 @@ int devm_reboot_mode_register(struct device *dev,
 	int rc;
 
 	dr = devres_alloc(devm_reboot_mode_release, sizeof(*dr), GFP_KERNEL);
-	if (!dr)
+	if (!dr) {
+		reboot_mode_reset_predefined_modes(reboot);
 		return -ENOMEM;
+	}
 
 	rc = reboot_mode_register(reboot);
 	if (rc) {
@@ -352,6 +399,73 @@ void devm_reboot_mode_unregister(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(devm_reboot_mode_unregister);
 
+/**
+ * reboot_mode_add_predefined_modes - Add predefined reboot modes
+ * @reboot: reboot mode driver
+ * @modes: array of predefined reboot mode entries
+ * @count: number of entries in @modes
+ *
+ * Add predefined reboot modes before registration.
+ *
+ * The entire list is discarded if any mode entry is invalid. An entry
+ * with a zero or negative magic count, a NULL mode string, or a mode
+ * string containing spaces or "\n" is considered invalid.
+ *
+ * Predefined modes are cleared if registration fails.
+ * Call reboot_mode_reset_predefined_modes() if registration is not
+ * performed after adding predefined modes.
+ *
+ * @reboot must be initialized with reboot_mode_driver_init() before calling
+ * this function.
+ *
+ * Returns: 0 on success,
+ *	    -EINVAL if invalid entry is found in list,
+ *	    -EBUSY if called after reboot_mode_register() or if predefined modes
+ *	    are already set, and, -ENOMEM on allocation failures.
+ */
+int reboot_mode_add_predefined_modes(struct reboot_mode_driver *reboot,
+				     const struct reboot_mode_entry *modes,
+				     size_t count)
+{
+	struct mode_info *info;
+	int ret;
+	size_t i;
+
+	if (reboot->reboot_notifier.notifier_call == reboot_mode_notify ||
+	    !list_empty(&reboot->predefined_modes))
+		return -EBUSY;
+
+	if (!modes || !count)
+		return -EINVAL;
+
+	for (i = 0; i < count; i++) {
+		if (modes[i].name && strpbrk(modes[i].name, "\n ")) {
+			ret = -EINVAL;
+			goto error;
+		}
+
+		if (modes[i].count <= 0 || modes[i].count > ARRAY_SIZE(modes[i].magic)) {
+			ret = -EINVAL;
+			goto error;
+		}
+
+		info = reboot_mode_create_info(modes[i].name, modes[i].magic, modes[i].count);
+		if (IS_ERR(info)) {
+			ret = PTR_ERR(info);
+			goto error;
+		}
+
+		list_add_tail(&info->list, &reboot->predefined_modes);
+	}
+
+	return 0;
+
+error:
+	reboot_mode_release_list(&reboot->predefined_modes);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(reboot_mode_add_predefined_modes);
+
 static int __init reboot_mode_init(void)
 {
 	return class_register(&reboot_mode_class);
diff --git a/drivers/power/reset/syscon-reboot-mode.c b/drivers/power/reset/syscon-reboot-mode.c
index 983b1fbf614a..0c7e11276e6f 100644
--- a/drivers/power/reset/syscon-reboot-mode.c
+++ b/drivers/power/reset/syscon-reboot-mode.c
@@ -47,8 +47,8 @@ static int syscon_reboot_mode_probe(struct platform_device *pdev)
 	if (!syscon_rbm)
 		return -ENOMEM;
 
-	syscon_rbm->reboot.dev = &pdev->dev;
-	syscon_rbm->reboot.write = syscon_reboot_mode_write;
+	reboot_mode_driver_init(&syscon_rbm->reboot, &pdev->dev,
+				syscon_reboot_mode_write);
 	syscon_rbm->mask = 0xffffffff;
 
 	syscon_rbm->map = syscon_node_to_regmap(pdev->dev.parent->of_node);
diff --git a/include/linux/reboot-mode.h b/include/linux/reboot-mode.h
index 34a81e4b4f95..b216c7595f7e 100644
--- a/include/linux/reboot-mode.h
+++ b/include/linux/reboot-mode.h
@@ -4,18 +4,34 @@
 
 #include <linux/types.h>
 
+struct reboot_mode_entry {
+	const char *name;
+	u32 magic[3];
+	int count;
+};
+
 struct reboot_mode_driver {
 	struct device *dev;
 	struct list_head head;
+	/* List of predefined reboot-modes, populated via reboot_mode_add_predefined_modes(). */
+	struct list_head predefined_modes;
 	int (*write)(struct reboot_mode_driver *reboot, u32 *magic, int count);
 	struct notifier_block reboot_notifier;
 };
 
+void reboot_mode_driver_init(struct reboot_mode_driver *reboot,
+			     struct device *dev,
+			     int (*write)(struct reboot_mode_driver *reboot, u32 *magic,
+					  int count));
 int reboot_mode_register(struct reboot_mode_driver *reboot);
 int reboot_mode_unregister(struct reboot_mode_driver *reboot);
 int devm_reboot_mode_register(struct device *dev,
 			      struct reboot_mode_driver *reboot);
 void devm_reboot_mode_unregister(struct device *dev,
 				 struct reboot_mode_driver *reboot);
+int reboot_mode_add_predefined_modes(struct reboot_mode_driver *reboot,
+				     const struct reboot_mode_entry *modes,
+				     size_t count);
+void reboot_mode_reset_predefined_modes(struct reboot_mode_driver *reboot);
 
 #endif

-- 
2.34.1