Add boot_enable sysfs attribute to select MMC boot operation partition

Add sysfs attribute to select the eMMC boot mode operation according to the eMMC 4.5 specifications.
Valid values are : 0 for disabled, 1 for first boot partition, 2 for second boot partition, 7 for user area.

---
 drivers/mmc/card/block.c |   72
+++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 71 insertions(+), 1 deletions(-)

index 5bab73b..e11c42e 100644
@@ -114,6 +114,7 @@ struct mmc_blk_data {
      */
     unsigned int    part_curr;
     struct device_attribute force_ro;
+    struct device_attribute boot_enable;
     struct device_attribute power_ro_lock;
     int    area_type;
 };

@@ -264,6 +265,23 @@ static ssize_t force_ro_show(struct device *dev,

struct device_attribute *attr,

     return ret;

}

+static ssize_t boot_enable_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{

+    int ret;
+    struct mmc_card *card;
+    struct mmc_blk_data *md = mmc_blk_get(dev_to_disk(dev));

+
+ md = mmc_blk_get(dev_to_disk(dev));
+ card = md->queue.card;
+
+ ret = snprintf(buf, PAGE_SIZE, "%d",
+ (card->ext_csd.part_config &
+ EXT_CSD_PART_CONFIG_EN_MASK) >> 3);
+ mmc_blk_put(md);
+ return ret;
+}
+
static ssize_t force_ro_store(struct device *dev, struct
device_attribute *attr,
const char *buf, size_t count)
{
@@ -283,6 +301,48 @@ out:

     return ret;

}

+static ssize_t boot_enable_store(struct device *dev,
+ struct device_attribute *attr, const char *buf,
+ size_t count)
+{

+    int ret;
+    char *end;
+    u8 part_config;
+    struct mmc_card *card;
+    struct mmc_blk_data *md = mmc_blk_get(dev_to_disk(dev));
+    unsigned long set = simple_strtoul(buf, &end, 0);
+    if (end == buf) {

+ ret = -EINVAL;
+ goto out;
+ }
+
+ md = mmc_blk_get(dev_to_disk(dev));
+ card = md->queue.card;
+
+ part_config = card->ext_csd.part_config;
+
+ part_config &= EXT_CSD_PART_CONFIG_EN_MASK;
+ part_config |= (set << 3) & EXT_CSD_PART_CONFIG_EN_MASK;
+
+ mmc_claim_host(card->host);
+
+ ret = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+ EXT_CSD_PART_CONFIG, part_config,
+ card->ext_csd.part_time);
+
+ mmc_release_host(card->host);
+
+ if (ret)
+ return ret;
+
+ card->ext_csd.part_config = part_config;
+
+ ret = count;
+out:
+ mmc_blk_put(md);
+ return ret;
+}
+
static int mmc_blk_open(struct block_device *bdev, fmode_t mode)

 {
     struct mmc_blk_data *md = mmc_blk_get(bdev->bd_disk);
@@ -2202,6 +2262,15 @@ static int mmc_add_disk(struct mmc_blk_data *md)
     if (ret)
         goto force_ro_fail;

+    md->boot_enable.show = boot_enable_show;
+    md->boot_enable.store = boot_enable_store;
+    sysfs_attr_init(&md->boot_enable.attr);
+    md->boot_enable.attr.name = "boot_enable";
+    md->boot_enable.attr.mode = S_IRUGO | S_IWUSR;
+    ret = device_create_file(disk_to_dev(md->disk), &md->boot_enable);
+    if (ret)
+        goto boot_enable_fail;
+
     if ((md->area_type & MMC_BLK_DATA_AREA_BOOT) &&
          card->ext_csd.boot_ro_lockable) {
         umode_t mode;
@@ -2225,6 +2294,8 @@ static int mmc_add_disk(struct mmc_blk_data *md)
     return ret;

power_ro_lock_fail:
+ device_remove_file(disk_to_dev(md->disk), &md->boot_enable);
+boot_enable_fail:

     device_remove_file(disk_to_dev(md->disk), &md->force_ro);
 force_ro_fail:
     del_gendisk(md->disk);

@@ -2434,4 +2505,3 @@ module_exit(mmc_blk_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Multimedia Card (MMC) block device driver");
-

1.7.0.4