[v5,01/11] mtd: core: always create master device

Commit Message

Alexander Usyskin Feb. 26, 2025, 12:51 p.m. UTC

Create master device without partition when
CONFIG_MTD_PARTITIONED_MASTER flag is unset.

This streamlines device tree and allows to anchor
runtime power management on master device in all cases.

Signed-off-by: Alexander Usyskin <[e-mail]>
---
 drivers/mtd/mtdcore.c | 135 +++++++++++++++++++++++++++++-------------
 drivers/mtd/mtdcore.h |   2 +-
 drivers/mtd/mtdpart.c |  17 +++---
 3 files changed, 106 insertions(+), 48 deletions(-)

Patch

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 724f917f91ba..eb28f717e301 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -68,7 +68,13 @@  static struct class mtd_class = {
 	.pm = MTD_CLS_PM_OPS,
 };
 
+static struct class mtd_master_class = {
+	.name = "mtd_master",
+	.pm = MTD_CLS_PM_OPS,
+};
+
 static DEFINE_IDR(mtd_idr);
+static DEFINE_IDR(mtd_master_idr);
 
 /* These are exported solely for the purpose of mtd_blkdevs.c. You
    should not use them for _anything_ else */
@@ -83,8 +89,9 @@  EXPORT_SYMBOL_GPL(__mtd_next_device);
 
 static LIST_HEAD(mtd_notifiers);
 
-
+#define MTD_MASTER_DEVS 255
 #define MTD_DEVT(index) MKDEV(MTD_CHAR_MAJOR, (index)*2)
+static dev_t mtd_master_devt;
 
 /* REVISIT once MTD uses the driver model better, whoever allocates
  * the mtd_info will probably want to use the release() hook...
@@ -104,6 +111,17 @@  static void mtd_release(struct device *dev)
 	device_destroy(&mtd_class, index + 1);
 }
 
+static void mtd_master_release(struct device *dev)
+{
+	struct mtd_info *mtd = dev_get_drvdata(dev);
+
+	idr_remove(&mtd_master_idr, mtd->index);
+	of_node_put(mtd_get_of_node(mtd));
+
+	if (mtd_is_partition(mtd))
+		release_mtd_partition(mtd);
+}
+
 static void mtd_device_release(struct kref *kref)
 {
 	struct mtd_info *mtd = container_of(kref, struct mtd_info, refcnt);
@@ -367,6 +385,11 @@  static const struct device_type mtd_devtype = {
 	.release	= mtd_release,
 };
 
+static const struct device_type mtd_master_devtype = {
+	.name		= "mtd_master",
+	.release	= mtd_master_release,
+};
+
 static bool mtd_expert_analysis_mode;
 
 #ifdef CONFIG_DEBUG_FS
@@ -634,13 +657,13 @@  static void mtd_check_of_node(struct mtd_info *mtd)
 /**
  *	add_mtd_device - register an MTD device
  *	@mtd: pointer to new MTD device info structure
+ *	@partitioned: create partitioned device
  *
  *	Add a device to the list of MTD devices present in the system, and
  *	notify each currently active MTD 'user' of its arrival. Returns
  *	zero on success or non-zero on failure.
  */
-
-int add_mtd_device(struct mtd_info *mtd)
+int add_mtd_device(struct mtd_info *mtd, bool partitioned)
 {
 	struct device_node *np = mtd_get_of_node(mtd);
 	struct mtd_info *master = mtd_get_master(mtd);
@@ -687,10 +710,17 @@  int add_mtd_device(struct mtd_info *mtd)
 	ofidx = -1;
 	if (np)
 		ofidx = of_alias_get_id(np, "mtd");
-	if (ofidx >= 0)
-		i = idr_alloc(&mtd_idr, mtd, ofidx, ofidx + 1, GFP_KERNEL);
-	else
-		i = idr_alloc(&mtd_idr, mtd, 0, 0, GFP_KERNEL);
+	if (partitioned) {
+		if (ofidx >= 0)
+			i = idr_alloc(&mtd_idr, mtd, ofidx, ofidx + 1, GFP_KERNEL);
+		else
+			i = idr_alloc(&mtd_idr, mtd, 0, 0, GFP_KERNEL);
+	} else {
+		if (ofidx >= 0)
+			i = idr_alloc(&mtd_master_idr, mtd, ofidx, ofidx + 1, GFP_KERNEL);
+		else
+			i = idr_alloc(&mtd_master_idr, mtd, 0, 0, GFP_KERNEL);
+	}
 	if (i < 0) {
 		error = i;
 		goto fail_locked;
@@ -738,15 +768,23 @@  int add_mtd_device(struct mtd_info *mtd)
 	/* Caller should have set dev.parent to match the
 	 * physical device, if appropriate.
 	 */
-	mtd->dev.type = &mtd_devtype;
-	mtd->dev.class = &mtd_class;
-	mtd->dev.devt = MTD_DEVT(i);
-	dev_set_name(&mtd->dev, "mtd%d", i);
+	if (partitioned) {
+		mtd->dev.type = &mtd_devtype;
+		mtd->dev.class = &mtd_class;
+		mtd->dev.devt = MTD_DEVT(i);
+		dev_set_name(&mtd->dev, "mtd%d", i);
+	} else {
+		mtd->dev.type = &mtd_master_devtype;
+		mtd->dev.class = &mtd_master_class;
+		mtd->dev.devt = MKDEV(MAJOR(mtd_master_devt), i);
+		dev_set_name(&mtd->dev, "mtd_master%d", i);
+	}
 	dev_set_drvdata(&mtd->dev, mtd);
 	mtd_check_of_node(mtd);
 	of_node_get(mtd_get_of_node(mtd));
 	error = device_register(&mtd->dev);
 	if (error) {
+		pr_err("mtd: %s device_register fail %d\n", mtd->name, error);
 		put_device(&mtd->dev);
 		goto fail_added;
 	}
@@ -758,10 +796,13 @@  int add_mtd_device(struct mtd_info *mtd)
 
 	mtd_debugfs_populate(mtd);
 
-	device_create(&mtd_class, mtd->dev.parent, MTD_DEVT(i) + 1, NULL,
-		      "mtd%dro", i);
+	if (partitioned) {
+		device_create(&mtd_class, mtd->dev.parent, MTD_DEVT(i) + 1, NULL,
+			      "mtd%dro", i);
+	}
 
-	pr_debug("mtd: Giving out device %d to %s\n", i, mtd->name);
+	pr_debug("mtd: Giving out %spartitoned device %d to %s\n",
+		 partitioned ? "" : "un-", i, mtd->name);
 	/* No need to get a refcount on the module containing
 	   the notifier, since we hold the mtd_table_mutex */
 	list_for_each_entry(not, &mtd_notifiers, list)
@@ -769,13 +810,16 @@  int add_mtd_device(struct mtd_info *mtd)
 
 	mutex_unlock(&mtd_table_mutex);
 
-	if (of_property_read_bool(mtd_get_of_node(mtd), "linux,rootfs")) {
-		if (IS_BUILTIN(CONFIG_MTD)) {
-			pr_info("mtd: setting mtd%d (%s) as root device\n", mtd->index, mtd->name);
-			ROOT_DEV = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
-		} else {
-			pr_warn("mtd: can't set mtd%d (%s) as root device - mtd must be builtin\n",
-				mtd->index, mtd->name);
+	if (partitioned) {
+		if (of_property_read_bool(mtd_get_of_node(mtd), "linux,rootfs")) {
+			if (IS_BUILTIN(CONFIG_MTD)) {
+				pr_info("mtd: setting mtd%d (%s) as root device\n",
+					mtd->index, mtd->name);
+				ROOT_DEV = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
+			} else {
+				pr_warn("mtd: can't set mtd%d (%s) as root device - mtd must be builtin\n",
+					mtd->index, mtd->name);
+			}
 		}
 	}
 
@@ -790,7 +834,10 @@  int add_mtd_device(struct mtd_info *mtd)
 	device_unregister(&mtd->dev);
 fail_added:
 	of_node_put(mtd_get_of_node(mtd));
-	idr_remove(&mtd_idr, i);
+	if (partitioned)
+		idr_remove(&mtd_idr, i);
+	else
+		idr_remove(&mtd_master_idr, i);
 fail_locked:
 	mutex_unlock(&mtd_table_mutex);
 	return error;
@@ -1061,12 +1108,6 @@  int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types,
 	if (ret)
 		goto out;
 
-	if (IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER)) {
-		ret = add_mtd_device(mtd);
-		if (ret)
-			goto out;
-	}
-
 	/* Prefer parsed partitions over driver-provided fallback */
 	ret = parse_mtd_partitions(mtd, types, parser_data);
 	if (ret == -EPROBE_DEFER)
@@ -1076,10 +1117,8 @@  int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types,
 		ret = 0;
 	else if (nr_parts)
 		ret = add_mtd_partitions(mtd, parts, nr_parts);
-	else if (!device_is_registered(&mtd->dev))
-		ret = add_mtd_device(mtd);
 	else
-		ret = 0;
+		ret = add_mtd_device(mtd, true);
 
 	if (ret)
 		goto out;
@@ -1099,13 +1138,14 @@  int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types,
 		register_reboot_notifier(&mtd->reboot_notifier);
 	}
 
+	return 0;
 out:
-	if (ret) {
-		nvmem_unregister(mtd->otp_user_nvmem);
-		nvmem_unregister(mtd->otp_factory_nvmem);
-	}
+	nvmem_unregister(mtd->otp_user_nvmem);
+	nvmem_unregister(mtd->otp_factory_nvmem);
+
+	del_mtd_partitions(mtd);
 
-	if (ret && device_is_registered(&mtd->dev))
+	if (device_is_registered(&mtd->dev))
 		del_mtd_device(mtd);
 
 	return ret;
@@ -1261,8 +1301,7 @@  int __get_mtd_device(struct mtd_info *mtd)
 		mtd = mtd->parent;
 	}
 
-	if (IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER))
-		kref_get(&master->refcnt);
+	kref_get(&master->refcnt);
 
 	return 0;
 }
@@ -1356,8 +1395,7 @@  void __put_mtd_device(struct mtd_info *mtd)
 		mtd = parent;
 	}
 
-	if (IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER))
-		kref_put(&master->refcnt, mtd_device_release);
+	kref_put(&master->refcnt, mtd_device_release);
 
 	module_put(master->owner);
 
@@ -2524,6 +2562,16 @@  static int __init init_mtd(void)
 	if (ret)
 		goto err_reg;
 
+	ret = class_register(&mtd_master_class);
+	if (ret)
+		goto err_reg2;
+
+	ret = alloc_chrdev_region(&mtd_master_devt, 0, MTD_MASTER_DEVS, "mtd_master");
+	if (ret < 0) {
+		pr_err("unable to allocate char dev region\n");
+		goto err_chrdev;
+	}
+
 	mtd_bdi = mtd_bdi_init("mtd");
 	if (IS_ERR(mtd_bdi)) {
 		ret = PTR_ERR(mtd_bdi);
@@ -2548,6 +2596,10 @@  static int __init init_mtd(void)
 	bdi_unregister(mtd_bdi);
 	bdi_put(mtd_bdi);
 err_bdi:
+	unregister_chrdev_region(mtd_master_devt, MTD_MASTER_DEVS);
+err_chrdev:
+	class_unregister(&mtd_master_class);
+err_reg2:
 	class_unregister(&mtd_class);
 err_reg:
 	pr_err("Error registering mtd class or bdi: %d\n", ret);
@@ -2561,9 +2613,12 @@  static void __exit cleanup_mtd(void)
 	if (proc_mtd)
 		remove_proc_entry("mtd", NULL);
 	class_unregister(&mtd_class);
+	class_unregister(&mtd_master_class);
+	unregister_chrdev_region(mtd_master_devt, MTD_MASTER_DEVS);
 	bdi_unregister(mtd_bdi);
 	bdi_put(mtd_bdi);
 	idr_destroy(&mtd_idr);
+	idr_destroy(&mtd_master_idr);
 }
 
 module_init(init_mtd);
diff --git a/drivers/mtd/mtdcore.h b/drivers/mtd/mtdcore.h
index b014861a06a6..2258d31c5aa6 100644
--- a/drivers/mtd/mtdcore.h
+++ b/drivers/mtd/mtdcore.h
@@ -8,7 +8,7 @@  extern struct mutex mtd_table_mutex;
 extern struct backing_dev_info *mtd_bdi;
 
 struct mtd_info *__mtd_next_device(int i);
-int __must_check add_mtd_device(struct mtd_info *mtd);
+int __must_check add_mtd_device(struct mtd_info *mtd, bool partitioned);
 int del_mtd_device(struct mtd_info *mtd);
 int add_mtd_partitions(struct mtd_info *, const struct mtd_partition *, int);
 int del_mtd_partitions(struct mtd_info *);
diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index 6811a714349d..97505b132313 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -86,8 +86,7 @@  static struct mtd_info *allocate_partition(struct mtd_info *parent,
 	 * parent conditional on that option. Note, this is a way to
 	 * distinguish between the parent and its partitions in sysfs.
 	 */
-	child->dev.parent = IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER) || mtd_is_partition(parent) ?
-			    &parent->dev : parent->dev.parent;
+	child->dev.parent = &parent->dev;
 	child->dev.of_node = part->of_node;
 	child->parent = parent;
 	child->part.offset = part->offset;
@@ -276,7 +275,7 @@  int mtd_add_partition(struct mtd_info *parent, const char *name,
 	list_add_tail(&child->part.node, &parent->partitions);
 	mutex_unlock(&master->master.partitions_lock);
 
-	ret = add_mtd_device(child);
+	ret = add_mtd_device(child, true);
 	if (ret)
 		goto err_remove_part;
 
@@ -402,6 +401,12 @@  int add_mtd_partitions(struct mtd_info *parent,
 	printk(KERN_NOTICE "Creating %d MTD partitions on \"%s\":\n",
 	       nbparts, parent->name);
 
+	if (!mtd_is_partition(parent)) {
+		ret = add_mtd_device(parent, IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER));
+		if (ret)
+			return ret;
+	}
+
 	for (i = 0; i < nbparts; i++) {
 		child = allocate_partition(parent, parts + i, i, cur_offset);
 		if (IS_ERR(child)) {
@@ -413,7 +418,7 @@  int add_mtd_partitions(struct mtd_info *parent,
 		list_add_tail(&child->part.node, &parent->partitions);
 		mutex_unlock(&master->master.partitions_lock);
 
-		ret = add_mtd_device(child);
+		ret = add_mtd_device(child, true);
 		if (ret) {
 			mutex_lock(&master->master.partitions_lock);
 			list_del(&child->part.node);
@@ -590,9 +595,6 @@  static int mtd_part_of_parse(struct mtd_info *master,
 	int ret, err = 0;
 
 	dev = &master->dev;
-	/* Use parent device (controller) if the top level MTD is not registered */
-	if (!IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER) && !mtd_is_partition(master))
-		dev = master->dev.parent;
 
 	np = mtd_get_of_node(master);
 	if (mtd_is_partition(master))
@@ -712,6 +714,7 @@  int parse_mtd_partitions(struct mtd_info *master, const char *const *types,
 		if (ret < 0 && !err)
 			err = ret;
 	}
+
 	return err;
 }