[patch/rfc 2.6.29 1/2] MTD: driver model updates

David Brownell
2009-03-26T07:52:19Z

From: David Brownell <dbrownell@users.sourceforge.net>

Update driver model support in the MTD framework, so it fits
better into the current udev-based hotplug framework:

- Each mtd_info now has a device node. MTD drivers should set
the dev.parent field to point to the physical device, before
setting up partitions or otherwise declaring MTDs.

- Those device nodes always map to /sys/class/mtdX device nodes,
which no longer depend on MTD_CHARDEV.

- Those mtdX sysfs nodes have a "starter set" of attributes;
it's not yet sufficient to replace /proc/mtd.

- Enabling MTD_CHARDEV provides /sys/class/mtdXro/ nodes and the
/sys/class/mtd*/dev attributes (for udev, mdev, etc).

- Include a MODULE_ALIAS_CHARDEV_MAJOR macro. It'll work with
udev creating the /dev/mtd* nodes, not just a static rootfs.

So the sysfs structure is pretty much what you'd expect, except
that readonly chardev nodes are a bit quirky.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
---
Sanity tested with NOR (physmap, omap_nor, m25p80), DataFlash,
NAND (davinci, omap), OneNand (omap); with and without mtdblock.
With converted MTD drivers, /sys/devices/virtual/mtd/* are gone.
Didn't test modular configs.

drivers/mtd/mtd_blkdevs.c | 1
drivers/mtd/mtdchar.c | 47 ++---------------
drivers/mtd/mtdcore.c | 115 ++++++++++++++++++++++++++++++++++++++++++++
drivers/mtd/mtdpart.c | 9 +++
include/linux/mtd/mtd.h | 7 ++
5 files changed, 137 insertions(+), 42 deletions(-)

--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -286,6 +286,7 @@ int add_mtd_blktrans_dev(struct mtd_blkt
gd->private_data = new;
new->blkcore_priv = gd;
gd->queue = tr->blkcore_priv->rq;
+ gd->driverfs_dev = new->mtd->dev.parent;

if (new->readonly)
set_disk_ro(gd, 1);
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -19,33 +19,6 @@

#include <asm/uaccess.h>

-static struct class *mtd_class;
-
-static void mtd_notify_add(struct mtd_info* mtd)
-{
- if (!mtd)
- return;
-
- device_create(mtd_class, NULL, MKDEV(MTD_CHAR_MAJOR, mtd->index*2),
- NULL, "mtd%d", mtd->index);
-
- device_create(mtd_class, NULL, MKDEV(MTD_CHAR_MAJOR, mtd->index*2+1),
- NULL, "mtd%dro", mtd->index);
-}
-
-static void mtd_notify_remove(struct mtd_info* mtd)
-{
- if (!mtd)
- return;
-
- device_destroy(mtd_class, MKDEV(MTD_CHAR_MAJOR, mtd->index*2));
- device_destroy(mtd_class, MKDEV(MTD_CHAR_MAJOR, mtd->index*2+1));
-}
-
-static struct mtd_notifier notifier = {
- .add = mtd_notify_add,
- .remove = mtd_notify_remove,
-};

/*
* Data structure to hold the pointer to the mtd device as well
@@ -793,34 +766,26 @@ static const struct file_operations mtd_

static int __init init_mtdchar(void)
{
- if (register_chrdev(MTD_CHAR_MAJOR, "mtd", &mtd_fops)) {
+ int status;
+
+ status = register_chrdev(MTD_CHAR_MAJOR, "mtd", &mtd_fops);
+ if (status < 0) {
printk(KERN_NOTICE "Can't allocate major number %d for Memory Technology Devices.\n",
MTD_CHAR_MAJOR);
- return -EAGAIN;
}

- mtd_class = class_create(THIS_MODULE, "mtd");
-
- if (IS_ERR(mtd_class)) {
- printk(KERN_ERR "Error creating mtd class.\n");
- unregister_chrdev(MTD_CHAR_MAJOR, "mtd");
- return PTR_ERR(mtd_class);
- }
-
- register_mtd_user(&notifier);
- return 0;
+ return status;
}

static void __exit cleanup_mtdchar(void)
{
- unregister_mtd_user(&notifier);
- class_destroy(mtd_class);
unregister_chrdev(MTD_CHAR_MAJOR, "mtd");
}

module_init(init_mtdchar);
module_exit(cleanup_mtdchar);

+MODULE_ALIAS_CHARDEV_MAJOR(MTD_CHAR_MAJOR);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -22,6 +22,9 @@

#include "mtdcore.h"

+
+static struct class *mtd_class;
+
/* These are exported solely for the purpose of mtd_blkdevs.c. You
should not use them for _anything_ else */
DEFINE_MUTEX(mtd_table_mutex);
@@ -32,6 +35,82 @@ EXPORT_SYMBOL_GPL(mtd_table);

static LIST_HEAD(mtd_notifiers);

+
+#if defined(CONFIG_MTD_CHAR) || defined(CONFIG_MTD_CHAR_MODULE)
+#define MTD_DEVT(index) MKDEV(MTD_CHAR_MAJOR, (index)*2)
+#else
+#define MTD_DEVT(index) 0
+#endif
+
+/* REVISIT once MTD uses the driver model better, whoever allocates
+ * the mtd_info will probably want to use the release() hook...
+ */
+static void mtd_release(struct device *dev)
+{
+ struct mtd_info *mtd = dev_to_mtd(dev);
+
+ /* remove /dev/mtdXro node if needed */
+ if (MTD_DEVT(mtd->index))
+ device_destroy(mtd_class, MTD_DEVT(mtd->index) + 1);
+}
+
+static ssize_t mtd_type_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct mtd_info *mtd = dev_to_mtd(dev);
+ char *type;
+
+ switch (mtd->type) {
+ case MTD_ABSENT:
+ type = "absent";
+ break;
+ case MTD_RAM:
+ type = "ram";
+ break;
+ case MTD_ROM:
+ type = "rom";
+ break;
+ case MTD_NORFLASH:
+ type = "nor";
+ break;
+ case MTD_NANDFLASH:
+ type = "nand";
+ break;
+ case MTD_DATAFLASH:
+ type = "dataflash";
+ break;
+ case MTD_UBIVOLUME:
+ type = "ubi";
+ break;
+ default:
+ type = "unknown";
+ }
+
+ return snprintf(buf, PAGE_SIZE, "%s\n", type);
+}
+static DEVICE_ATTR(mtd_type, S_IRUGO, mtd_type_show, NULL);
+
+static struct attribute *mtd_attrs[] = {
+ &dev_attr_mtd_type.attr,
+ /* FIXME provide a /proc/mtd superset */
+ NULL,
+};
+
+struct attribute_group mtd_group = {
+ .attrs = mtd_attrs,
+};
+
+struct attribute_group *mtd_groups[] = {
+ &mtd_group,
+ NULL,
+};
+
+static struct device_type mtd_devtype = {
+ .name = "mtd",
+ .groups = mtd_groups,
+ .release = mtd_release,
+};
+
/**
* add_mtd_device - register an MTD device
* @mtd: pointer to new MTD device info structure
@@ -40,6 +119,7 @@ static LIST_HEAD(mtd_notifiers);
* notify each currently active MTD 'user' of its arrival. Returns
* zero on success or 1 on failure, which currently will only happen
* if the number of present devices exceeds MAX_MTD_DEVICES (i.e. 16)
+ * or there's a sysfs error.
*/

int add_mtd_device(struct mtd_info *mtd)
@@ -80,6 +160,23 @@ int add_mtd_device(struct mtd_info *mtd)
mtd->name);
}

+ /* Caller should have set dev.parent to match the
+ * physical device.
+ */
+ 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 (device_register(&mtd->dev) != 0) {
+ mtd_table[i] = NULL;
+ break;
+ }
+
+ if (MTD_DEVT(i))
+ device_create(mtd_class, mtd->dev.parent,
+ MTD_DEVT(i) + 1,
+ NULL, "mtd%dro", i);
+
DEBUG(0, "mtd: Giving out device %d to %s\n",i, mtd->name);
/* No need to get a refcount on the module containing
the notifier, since we hold the mtd_table_mutex */
@@ -343,6 +440,24 @@ EXPORT_SYMBOL_GPL(register_mtd_user);
EXPORT_SYMBOL_GPL(unregister_mtd_user);
EXPORT_SYMBOL_GPL(default_mtd_writev);

+static int __init mtd_setup(void)
+{
+ mtd_class = class_create(THIS_MODULE, "mtd");
+
+ if (IS_ERR(mtd_class)) {
+ pr_err("Error creating mtd class.\n");
+ return PTR_ERR(mtd_class);
+ }
+ return 0;
+}
+core_initcall(mtd_setup);
+
+static void __exit mtd_teardown(void)
+{
+ class_destroy(mtd_class);
+}
+__exitcall(mtd_teardown);
+
#ifdef CONFIG_PROC_FS

/*====================================================================*/
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -343,6 +343,11 @@ static struct mtd_part *add_one_partitio
slave->mtd.name = part->name;
slave->mtd.owner = master->owner;

+ /* NOTE: we don't arrange MTDs as a tree; it'd be error-prone
+ * to have the same data be in two different partitions.
+ */
+ slave->mtd.dev.parent = master->dev.parent;
+
slave->mtd.read = part_read;
slave->mtd.write = part_write;

@@ -493,7 +498,9 @@ out_register:
* This function, given a master MTD object and a partition table, creates
* and registers slave MTD objects which are bound to the master according to
* the partition definitions.
- * (Q: should we register the master MTD object as well?)
+ *
+ * We don't register the master, or expect the caller to have done so,
+ * for reasons of data integrity.
*/

int add_mtd_partitions(struct mtd_info *master,
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -11,6 +11,7 @@
#include <linux/module.h>
#include <linux/uio.h>
#include <linux/notifier.h>
+#include <linux/device.h>

#include <linux/mtd/compatmac.h>
#include <mtd/mtd-abi.h>
@@ -223,6 +224,7 @@ struct mtd_info {
void *priv;

struct module *owner;
+ struct device dev;
int usecount;

/* If the driver is something smart, like UBI, it may need to maintain
@@ -233,6 +235,11 @@ struct mtd_info {
void (*put_device) (struct mtd_info *mtd);
};

+static inline struct mtd_info *dev_to_mtd(struct device *dev)
+{
+ return dev ? container_of(dev, struct mtd_info, dev) : NULL;
+}
+
static inline uint32_t mtd_div_by_eb(uint64_t sz, struct mtd_info *mtd)
{
if (mtd->erasesize_shift)