Introducing CONFIG_VIRT_CONCAT to separate the legacy flow from the new
approach, where individual partitions within a concatenated partition are
not registered, as they are likely not needed by the user.
Solution is focusing on fixed-partitions description only because it
depends on device boundaries.
Suggested-by: Bernhard Frauendienst <kernel@xxxxxxxxxxxxxxxxx>
Suggested-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@xxxxxxx>
---
drivers/mtd/Kconfig | 8 ++
drivers/mtd/Makefile | 1 +
drivers/mtd/mtd_virt_concat.c | 254 ++++++++++++++++++++++++++++++++++
drivers/mtd/mtdcore.c | 7 +
drivers/mtd/mtdpart.c | 6 +
include/linux/mtd/concat.h | 24 ++++
6 files changed, 300 insertions(+)
create mode 100644 drivers/mtd/mtd_virt_concat.c
diff --git a/drivers/mtd/Kconfig b/drivers/mtd/Kconfig
index 796a2eccbef0..3dade7c469df 100644
--- a/drivers/mtd/Kconfig
+++ b/drivers/mtd/Kconfig
@@ -206,6 +206,14 @@ config MTD_PARTITIONED_MASTER
the parent of the partition device be the master device, rather than
what lies behind the master.
+config MTD_VIRT_CONCAT
+ tristate "Virtual concatenated MTD devices"
+ help
+ The driver enables the creation of a virtual MTD device
+ by concatenating multiple physical MTD devices into a single
+ entity. This allows for the creation of partitions larger than
+ the individual physical chips, extending across chip boundaries.
+
source "drivers/mtd/chips/Kconfig"
source "drivers/mtd/maps/Kconfig"
diff --git a/drivers/mtd/Makefile b/drivers/mtd/Makefile
index 593d0593a038..d1d577f89a22 100644
--- a/drivers/mtd/Makefile
+++ b/drivers/mtd/Makefile
@@ -22,6 +22,7 @@ obj-$(CONFIG_SM_FTL) += sm_ftl.o
obj-$(CONFIG_MTD_OOPS) += mtdoops.o
obj-$(CONFIG_MTD_PSTORE) += mtdpstore.o
obj-$(CONFIG_MTD_SWAP) += mtdswap.o
+obj-$(CONFIG_MTD_VIRT_CONCAT) += mtd_virt_concat.o
nftl-objs := nftlcore.o nftlmount.o
inftl-objs := inftlcore.o inftlmount.o
diff --git a/drivers/mtd/mtd_virt_concat.c b/drivers/mtd/mtd_virt_concat.c
new file mode 100644
index 000000000000..3de67305a09b
--- /dev/null
+++ b/drivers/mtd/mtd_virt_concat.c
@@ -0,0 +1,254 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Virtual concat MTD device driver
+ *
+ * Copyright (C) 2018 Bernhard Frauendienst
+ * Author: Bernhard Frauendienst <kernel@xxxxxxxxxxxxxxxxx>
+ */
+
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/mtd/mtd.h>
+#include "mtdcore.h"
+#include <linux/mtd/partitions.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/slab.h>
+#include <linux/mtd/concat.h>
+
+#define CONCAT_PROP "part-concat"
+#define MIN_DEV_PER_CONCAT 2
+
+static LIST_HEAD(concat_node_list);
+
+/**
+ * struct mtd_virt_concat_node - components of a concatenation
+ * @head: List handle
+ * @count: Number of nodes
+ * @nodes: Pointer to the nodes (partitions) to concatenate
+ * @concat: Concatenation container
+ */
+struct mtd_virt_concat_node {
+ struct list_head head;
+ unsigned int count;
+ struct device_node **nodes;
+ struct mtd_concat *concat;
+};
+
+static void mtd_virt_concat_put_mtd_devices(struct mtd_concat *concat)
+{
+ int i;
+
+ for (i = 0; i < concat->num_subdev; i++)
+ put_mtd_device(concat->subdev[i]);
+}
+
+static void mtd_virt_concat_destroy_joins(void)
+{
+ struct mtd_virt_concat_node *item, *tmp;
+ struct mtd_info *mtd;
+
+ list_for_each_entry_safe(item, tmp, &concat_node_list, head) {
+ mtd = &item->concat->mtd;
+ if (item->concat) {
+ mtd_device_unregister(mtd);
+ kfree(mtd->name);
+ mtd_concat_destroy(mtd);
+ mtd_virt_concat_put_mtd_devices(item->concat);
+ }
+ }
+}
+
+static int mtd_virt_concat_create_item(struct device_node *parts,
+ unsigned int count)
+{
+ struct mtd_virt_concat_node *item;
+ struct mtd_concat *concat;
+ int i;
+
+ item = kzalloc(sizeof(*item), GFP_KERNEL);
+ if (!item)
+ return -ENOMEM;
+
+ item->count = count;
+ item->nodes = kcalloc(count, sizeof(*item->nodes), GFP_KERNEL);
+ if (!item->nodes) {
+ kfree(item);
+ return -ENOMEM;
+ }
+
+ for (i = 0; i < count; i++)
+ item->nodes[i] = of_parse_phandle(parts, CONCAT_PROP, i);
+
+ concat = kzalloc(sizeof(*concat), GFP_KERNEL);
+ if (!concat) {
+ kfree(item);
+ return -ENOMEM;
+ }
+
+ concat->subdev = kcalloc(count, sizeof(*concat->subdev), GFP_KERNEL);
+ if (!concat->subdev) {
+ kfree(item);
+ kfree(concat);
+ return -ENOMEM;
+ }
+ item->concat = concat;
+
+ list_add_tail(&item->head, &concat_node_list);
+
+ return 0;
+}
+
+static void mtd_virt_concat_destroy_items(void)
+{
+ struct mtd_virt_concat_node *item, *temp;
+ int i;
+
+ list_for_each_entry_safe(item, temp, &concat_node_list, head) {
+ for (i = 0; i < item->count; i++)
+ of_node_put(item->nodes[i]);
+
+ kfree(item->nodes);
+ kfree(item);
+ }
+}
+
+bool mtd_virt_concat_add(struct mtd_info *mtd)
+{
+ struct mtd_virt_concat_node *item;
+ struct mtd_concat *concat;
+ int idx;
+
+ list_for_each_entry(item, &concat_node_list, head) {
+ concat = item->concat;
+ if (item->count == concat->num_subdev)
+ return false;
+
+ for (idx = 0; idx < item->count; idx++) {
+ if (item->nodes[idx] == mtd->dev.of_node) {
+ concat->subdev[concat->num_subdev++] = mtd;
+ return true;
+ }
+ }
+ }
+ return false;
+}
+EXPORT_SYMBOL_GPL(mtd_virt_concat_add);
+
+int mtd_virt_concat_node_create(void)
+{
+ struct mtd_concat *concat;
+ struct device_node *parts = NULL;
+ int ret = 0, count;
+
+ if (!list_empty(&concat_node_list))
+ return 0;
+
+ /* List all the concatenations found in DT */
+ do {
+ parts = of_find_node_with_property(parts, CONCAT_PROP);
+ if (!of_device_is_available(parts))
+ continue;
+
+ count = of_count_phandle_with_args(parts, CONCAT_PROP, NULL);
+ if (count < MIN_DEV_PER_CONCAT)
+ continue;
+
+ ret = mtd_virt_concat_create_item(parts, count);
+ if (ret) {
+ of_node_put(parts);
+ goto destroy_items;
+ }
+ } while (parts);
+
+ concat = kzalloc(sizeof(*concat), GFP_KERNEL);
+ if (!concat) {
+ ret = -ENOMEM;
+ of_node_put(parts);
+ goto destroy_items;
+ }
+
+ concat->subdev = kcalloc(count, sizeof(*concat->subdev), GFP_KERNEL);
+ if (!concat->subdev) {
+ kfree(concat);
+ ret = -ENOMEM;
+ of_node_put(parts);
+ goto destroy_items;
+ }
+
+ return count;
+
+destroy_items:
+ mtd_virt_concat_destroy_items();
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(mtd_virt_concat_node_create);
+
+static int __init mtd_virt_concat_create_join(void)
+{
+ struct mtd_virt_concat_node *item;
+ struct mtd_concat *concat;
+ struct mtd_info *mtd;
+ ssize_t name_sz;
+ char *name;
+ int ret;
+
+ list_for_each_entry(item, &concat_node_list, head) {
+ concat = item->concat;
+ mtd = &concat->mtd;
+ /* Create the virtual device */
+ name_sz = snprintf(NULL, 0, "%s-%s%s-concat",
+ concat->subdev[0]->name,
+ concat->subdev[1]->name,
+ concat->num_subdev > MIN_DEV_PER_CONCAT ?
+ "-+" : "");
+ name = kmalloc(name_sz + 1, GFP_KERNEL);
+ if (!name) {
+ mtd_virt_concat_put_mtd_devices(concat);
+ return -ENOMEM;
+ }
+
+ sprintf(name, "%s-%s%s-concat",
+ concat->subdev[0]->name,
+ concat->subdev[1]->name,
+ concat->num_subdev > MIN_DEV_PER_CONCAT ?
+ "-+" : "");
+
+ mtd = mtd_concat_create(concat->subdev, concat->num_subdev, name);
+ if (!mtd) {
+ kfree(name);
+ return -ENXIO;
+ }
+
+ /* Arbitrary set the first device as parent */
+ mtd->dev.parent = concat->subdev[0]->dev.parent;
+ mtd->dev = concat->subdev[0]->dev;
+
+ /* Register the platform device */
+ ret = mtd_device_register(mtd, NULL, 0);
+ if (ret)
+ goto destroy_concat;
+ }
+
+ return 0;
+
+destroy_concat:
+ mtd_concat_destroy(mtd);
+
+ return ret;
+}
+
+late_initcall(mtd_virt_concat_create_join);
+
+static void __exit mtd_virt_concat_exit(void)
+{
+ mtd_virt_concat_destroy_joins();
+ mtd_virt_concat_destroy_items();
+}
+module_exit(mtd_virt_concat_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Bernhard Frauendienst <kernel@xxxxxxxxxxxxxxxxx>");
+MODULE_AUTHOR("Amit Kumar Mahapatra <amit.kumar-mahapatra@xxxxxxx>");
+MODULE_DESCRIPTION("Virtual concat MTD device driver");
diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 724f917f91ba..2264fe81810f 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -34,6 +34,7 @@
#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>
+#include <linux/mtd/concat.h>
#include "mtdcore.h"
@@ -1067,6 +1068,12 @@ int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types,
goto out;
}
+ if (IS_ENABLED(CONFIG_MTD_VIRT_CONCAT)) {
+ ret = mtd_virt_concat_node_create();
+ if (ret < 0)
+ goto out;
+ }
+
/* Prefer parsed partitions over driver-provided fallback */
ret = parse_mtd_partitions(mtd, types, parser_data);
if (ret == -EPROBE_DEFER)
diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index 6811a714349d..4f50e14b96dd 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -18,6 +18,7 @@
#include <linux/err.h>
#include <linux/of.h>
#include <linux/of_platform.h>
+#include <linux/mtd/concat.h>
#include "mtdcore.h"
@@ -409,6 +410,11 @@ int add_mtd_partitions(struct mtd_info *parent,
goto err_del_partitions;
}
+ if (IS_ENABLED(CONFIG_MTD_VIRT_CONCAT)) {
+ if (mtd_virt_concat_add(child))
+ continue;
+ }
+
mutex_lock(&master->master.partitions_lock);
list_add_tail(&child->part.node, &parent->partitions);
mutex_unlock(&master->master.partitions_lock);
diff --git a/include/linux/mtd/concat.h b/include/linux/mtd/concat.h
index b42d9af87c4e..65c9a18774f6 100644
--- a/include/linux/mtd/concat.h
+++ b/include/linux/mtd/concat.h
@@ -28,5 +28,29 @@ struct mtd_info *mtd_concat_create(
void mtd_concat_destroy(struct mtd_info *mtd);
+/**
+ * mtd_virt_concat_node_create - Create a component for concatenation
+ *
+ * Returns a positive number representing the no. of devices found for
+ * concatenation, or a negative error code.
+ *
+ * List all the devices for concatenations found in DT and create a
+ * component for concatenation.
+ */
+int mtd_virt_concat_node_create(void);
+
+/**
+ * mtd_virt_concat_add - add mtd_info object to the list of subdevices for concatenation
+ * @mtd: pointer to new MTD device info structure
+ *
+ * Returns true if the mtd_info object is added successfully else returns false.
+ *
+ * The mtd_info object is added to the list of subdevices for concatenation.
+ * It returns true if a match is found, and false if all subdevices have
+ * already been added or if the mtd_info object does not match any of the
+ * intended MTD devices.
+ */
+bool mtd_virt_concat_add(struct mtd_info *mtd);
+
#endif
--
2.34.1
