[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>

1 files changed, 115 insertions, 0 deletions

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
 
 /*====================================================================*/