[MTD] driver model updates

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>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

5 files changed, 137 insertions, 42 deletions

diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index 4109e0bb94f5..a49a9c8f2cb1 100644
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -286,6 +286,7 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
         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);
diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index f478f1fc3949..763d3f0a1f42 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -20,33 +20,6 @@
 
 #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
@@ -854,34 +827,26 @@ static const struct file_operations mtd_fops = {
 
 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>");
diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 65a7f3703881..a88f8bc9a534 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -23,6 +23,9 @@
 
 #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);
@@ -33,6 +36,82 @@ 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
@@ -41,6 +120,7 @@ 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)
@@ -95,6 +175,23 @@ 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 */
@@ -358,6 +455,24 @@ 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
 
 /*====================================================================*/
diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index 06d5b9d8853a..02ce38fb1fc3 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -356,6 +356,11 @@ static struct mtd_part *add_one_partition(struct mtd_info *master,
         slave->mtd.owner = master->owner;
         slave->mtd.backing_dev_info = master->backing_dev_info;
 
+        /* 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;
 
@@ -508,7 +513,9 @@ 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,
diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index 0c079fd307a5..5675b63a0631 100644
--- 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>
@@ -237,6 +238,7 @@ 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
@@ -247,6 +249,11 @@ 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)