[MMC] Add MMC class devices

Create a mmc_host class to allow enumeration of MMC host controllers
even though they have no card(s) inserted.

Patch based on work by Pierre Ossman.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

3 files changed, 86 insertions, 14 deletions

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index e02e5df80be9..3c5904834fe8 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -796,17 +796,13 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev)
 {
         struct mmc_host *host;
 
-        host = kmalloc(sizeof(struct mmc_host) + extra, GFP_KERNEL);
+        host = mmc_alloc_host_sysfs(extra, dev);
         if (host) {
-                memset(host, 0, sizeof(struct mmc_host) + extra);
-
                 spin_lock_init(&host->lock);
                 init_waitqueue_head(&host->wq);
                 INIT_LIST_HEAD(&host->cards);
                 INIT_WORK(&host->detect, mmc_rescan, host);
 
-                host->dev = dev;
-
                 /*
                  * By default, hosts do not support SGIO or large requests.
                  * They have to set these according to their abilities.
@@ -828,15 +824,15 @@ EXPORT_SYMBOL(mmc_alloc_host);
  */
 int mmc_add_host(struct mmc_host *host)
 {
-        static unsigned int host_num;
+        int ret;
 
-        snprintf(host->host_name, sizeof(host->host_name),
-                 "mmc%d", host_num++);
-
-        mmc_power_off(host);
-        mmc_detect_change(host);
+        ret = mmc_add_host_sysfs(host);
+        if (ret == 0) {
+                mmc_power_off(host);
+                mmc_detect_change(host);
+        }
 
-        return 0;
+        return ret;
 }
 
 EXPORT_SYMBOL(mmc_add_host);
@@ -859,6 +855,7 @@ void mmc_remove_host(struct mmc_host *host)
         }
 
         mmc_power_off(host);
+        mmc_remove_host_sysfs(host);
 }
 
 EXPORT_SYMBOL(mmc_remove_host);
@@ -872,7 +869,7 @@ EXPORT_SYMBOL(mmc_remove_host);
 void mmc_free_host(struct mmc_host *host)
 {
         flush_scheduled_work();
-        kfree(host);
+        mmc_free_host_sysfs(host);
 }
 
 EXPORT_SYMBOL(mmc_free_host);
diff --git a/drivers/mmc/mmc.h b/drivers/mmc/mmc.h
index b498dffe0b11..97bae00292fa 100644
--- a/drivers/mmc/mmc.h
+++ b/drivers/mmc/mmc.h
@@ -13,4 +13,9 @@
 void mmc_init_card(struct mmc_card *card, struct mmc_host *host);
 int mmc_register_card(struct mmc_card *card);
 void mmc_remove_card(struct mmc_card *card);
+
+struct mmc_host *mmc_alloc_host_sysfs(int extra, struct device *dev);
+int mmc_add_host_sysfs(struct mmc_host *host);
+void mmc_remove_host_sysfs(struct mmc_host *host);
+void mmc_free_host_sysfs(struct mmc_host *host);
 #endif
diff --git a/drivers/mmc/mmc_sysfs.c b/drivers/mmc/mmc_sysfs.c
index 3a6b325a9149..96c192057df3 100644
--- a/drivers/mmc/mmc_sysfs.c
+++ b/drivers/mmc/mmc_sysfs.c
@@ -20,6 +20,7 @@
 
 #define dev_to_mmc_card(d)      container_of(d, struct mmc_card, dev)
 #define to_mmc_driver(d)        container_of(d, struct mmc_driver, drv)
+#define cls_dev_to_mmc_host(d)  container_of(d, struct mmc_host, class_dev)
 
 #define MMC_ATTR(name, fmt, args...)                                    \
 static ssize_t mmc_##name##_show (struct device *dev, struct device_attribute *attr, char *buf) \
@@ -224,13 +225,82 @@ void mmc_remove_card(struct mmc_card *card)
 }
 
 
+static void mmc_host_classdev_release(struct class_device *dev)
+{
+        struct mmc_host *host = cls_dev_to_mmc_host(dev);
+        kfree(host);
+}
+
+static struct class mmc_host_class = {
+        .name           = "mmc_host",
+        .release        = mmc_host_classdev_release,
+};
+
+/*
+ * Internal function. Allocate a new MMC host.
+ */
+struct mmc_host *mmc_alloc_host_sysfs(int extra, struct device *dev)
+{
+        struct mmc_host *host;
+
+        host = kmalloc(sizeof(struct mmc_host) + extra, GFP_KERNEL);
+        if (host) {
+                memset(host, 0, sizeof(struct mmc_host) + extra);
+
+                host->dev = dev;
+                host->class_dev.dev = host->dev;
+                host->class_dev.class = &mmc_host_class;
+                class_device_initialize(&host->class_dev);
+        }
+
+        return host;
+}
+
+/*
+ * Internal function. Register a new MMC host with the MMC class.
+ */
+int mmc_add_host_sysfs(struct mmc_host *host)
+{
+        static unsigned int host_num;
+
+        snprintf(host->host_name, sizeof(host->host_name),
+                 "mmc%d", host_num++);
+
+        strlcpy(host->class_dev.class_id, host->host_name, BUS_ID_SIZE);
+        return class_device_add(&host->class_dev);
+}
+
+/*
+ * Internal function. Unregister a MMC host with the MMC class.
+ */
+void mmc_remove_host_sysfs(struct mmc_host *host)
+{
+        class_device_del(&host->class_dev);
+}
+
+/*
+ * Internal function. Free a MMC host.
+ */
+void mmc_free_host_sysfs(struct mmc_host *host)
+{
+        class_device_put(&host->class_dev);
+}
+
+
 static int __init mmc_init(void)
 {
-        return bus_register(&mmc_bus_type);
+        int ret = bus_register(&mmc_bus_type);
+        if (ret == 0) {
+                ret = class_register(&mmc_host_class);
+                if (ret)
+                        bus_unregister(&mmc_bus_type);
+        }
+        return ret;
 }
 
 static void __exit mmc_exit(void)
 {
+        class_unregister(&mmc_host_class);
         bus_unregister(&mmc_bus_type);
 }