mmc: MMC boot partitions support.

Allows device MMC boot partitions to be accessed. MMC partitions are
treated effectively as separate block devices on the same MMC card.

Signed-off-by: Andrei Warkentin <andreiw@motorola.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Chris Ball <cjb@laptop.org>

7 files changed, 305 insertions, 42 deletions

diff --git a/Documentation/mmc/00-INDEX b/Documentation/mmc/00-INDEX
index fca586f5b853..93dd7a714075 100644
--- a/Documentation/mmc/00-INDEX
+++ b/Documentation/mmc/00-INDEX
@@ -2,3 +2,5 @@
         - this file
 mmc-dev-attrs.txt
         - info on SD and MMC device attributes
+mmc-dev-parts.txt
+        - info on SD and MMC device partitions
diff --git a/Documentation/mmc/mmc-dev-attrs.txt b/Documentation/mmc/mmc-dev-attrs.txt
index ff2bd685bced..8898a95b41e5 100644
--- a/Documentation/mmc/mmc-dev-attrs.txt
+++ b/Documentation/mmc/mmc-dev-attrs.txt
@@ -1,3 +1,13 @@
+SD and MMC Block Device Attributes
+==================================
+
+These attributes are defined for the block devices associated with the
+SD or MMC device.
+
+The following attributes are read/write.
+
+        force_ro                Enforce read-only access even if write protect switch is off.
+
 SD and MMC Device Attributes
 ============================
 
diff --git a/Documentation/mmc/mmc-dev-parts.txt b/Documentation/mmc/mmc-dev-parts.txt
new file mode 100644
index 000000000000..2db28b8e662f
--- /dev/null
+++ b/Documentation/mmc/mmc-dev-parts.txt
@@ -0,0 +1,27 @@
+SD and MMC Device Partitions
+============================
+
+Device partitions are additional logical block devices present on the
+SD/MMC device.
+
+As of this writing, MMC boot partitions as supported and exposed as
+/dev/mmcblkXboot0 and /dev/mmcblkXboot1, where X is the index of the
+parent /dev/mmcblkX.
+
+MMC Boot Partitions
+===================
+
+Read and write access is provided to the two MMC boot partitions. Due to
+the sensitive nature of the boot partition contents, which often store
+a bootloader or bootloader configuration tables crucial to booting the
+platform, write access is disabled by default to reduce the chance of
+accidental bricking.
+
+To enable write access to /dev/mmcblkXbootY, disable the forced read-only
+access with:
+
+echo 0 > /sys/block/mmcblkXbootY/force_ro
+
+To re-enable read-only access:
+
+echo 1 > /sys/block/mmcblkXbootY/force_ro
diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index 3e9082b729ff..1e6bd910e79e 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -76,9 +76,19 @@ struct mmc_blk_data {
         spinlock_t      lock;
         struct gendisk  *disk;
         struct mmc_queue queue;
+        struct list_head part;
 
         unsigned int    usage;
         unsigned int    read_only;
+        unsigned int    part_type;
+
+        /*
+         * Only set in main mmc_blk_data associated
+         * with mmc_card with mmc_set_drvdata, and keeps
+         * track of the current selected device partition.
+         */
+        unsigned int    part_curr;
+        struct device_attribute force_ro;
 };
 
 static DEFINE_MUTEX(open_lock);
@@ -101,17 +111,22 @@ static struct mmc_blk_data *mmc_blk_get(struct gendisk *disk)
         return md;
 }
 
+static inline int mmc_get_devidx(struct gendisk *disk)
+{
+        int devmaj = MAJOR(disk_devt(disk));
+        int devidx = MINOR(disk_devt(disk)) / perdev_minors;
+
+        if (!devmaj)
+                devidx = disk->first_minor / perdev_minors;
+        return devidx;
+}
+
 static void mmc_blk_put(struct mmc_blk_data *md)
 {
         mutex_lock(&open_lock);
         md->usage--;
         if (md->usage == 0) {
-                int devmaj = MAJOR(disk_devt(md->disk));
-                int devidx = MINOR(disk_devt(md->disk)) / perdev_minors;
-
-                if (!devmaj)
-                        devidx = md->disk->first_minor / perdev_minors;
-
+                int devidx = mmc_get_devidx(md->disk);
                 blk_cleanup_queue(md->queue.queue);
 
                 __clear_bit(devidx, dev_use);
@@ -122,6 +137,38 @@ static void mmc_blk_put(struct mmc_blk_data *md)
         mutex_unlock(&open_lock);
 }
 
+static ssize_t force_ro_show(struct device *dev, struct device_attribute *attr,
+                             char *buf)
+{
+        int ret;
+        struct mmc_blk_data *md = mmc_blk_get(dev_to_disk(dev));
+
+        ret = snprintf(buf, PAGE_SIZE, "%d",
+                       get_disk_ro(dev_to_disk(dev)) ^
+                       md->read_only);
+        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)
+{
+        int ret;
+        char *end;
+        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;
+        }
+
+        set_disk_ro(dev_to_disk(dev), set || md->read_only);
+        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);
@@ -176,6 +223,29 @@ struct mmc_blk_request {
         struct mmc_data         data;
 };
 
+static inline int mmc_blk_part_switch(struct mmc_card *card,
+                                      struct mmc_blk_data *md)
+{
+        int ret;
+        struct mmc_blk_data *main_md = mmc_get_drvdata(card);
+        if (main_md->part_curr == md->part_type)
+                return 0;
+
+        if (mmc_card_mmc(card)) {
+                card->ext_csd.part_config &= ~EXT_CSD_PART_CONFIG_ACC_MASK;
+                card->ext_csd.part_config |= md->part_type;
+
+                ret = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+                                 EXT_CSD_PART_CONFIG, card->ext_csd.part_config,
+                                 card->ext_csd.part_time);
+                if (ret)
+                        return ret;
+}
+
+        main_md->part_curr = md->part_type;
+        return 0;
+}
+
 static u32 mmc_sd_num_wr_blocks(struct mmc_card *card)
 {
         int err;
@@ -620,6 +690,11 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
         struct mmc_card *card = md->queue.card;
 
         mmc_claim_host(card->host);
+        ret = mmc_blk_part_switch(card, md);
+        if (ret) {
+                ret = 0;
+                goto out;
+        }
 
         if (req->cmd_flags & REQ_DISCARD) {
                 if (req->cmd_flags & REQ_SECURE)
@@ -632,6 +707,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
                 ret = mmc_blk_issue_rw_rq(mq, req);
         }
 
+out:
         mmc_release_host(card->host);
         return ret;
 }
@@ -642,7 +718,11 @@ static inline int mmc_blk_readonly(struct mmc_card *card)
                !(card->csd.cmdclass & CCC_BLOCK_WRITE);
 }
 
-static struct mmc_blk_data *mmc_blk_alloc(struct mmc_card *card)
+static struct mmc_blk_data *mmc_blk_alloc_req(struct mmc_card *card,
+                                              struct device *parent,
+                                              sector_t size,
+                                              bool default_ro,
+                                              const char *subname)
 {
         struct mmc_blk_data *md;
         int devidx, ret;
@@ -658,7 +738,6 @@ static struct mmc_blk_data *mmc_blk_alloc(struct mmc_card *card)
                 goto out;
         }
 
-
         /*
          * Set the read-only status based on the supported commands
          * and the write protect switch.
@@ -672,6 +751,7 @@ static struct mmc_blk_data *mmc_blk_alloc(struct mmc_card *card)
         }
 
         spin_lock_init(&md->lock);
+        INIT_LIST_HEAD(&md->part);
         md->usage = 1;
 
         ret = mmc_init_queue(&md->queue, card, &md->lock);
@@ -686,8 +766,8 @@ static struct mmc_blk_data *mmc_blk_alloc(struct mmc_card *card)
         md->disk->fops = &mmc_bdops;
         md->disk->private_data = md;
         md->disk->queue = md->queue.queue;
-        md->disk->driverfs_dev = &card->dev;
-        set_disk_ro(md->disk, md->read_only);
+        md->disk->driverfs_dev = parent;
+        set_disk_ro(md->disk, md->read_only || default_ro);
         if (REL_WRITES_SUPPORTED(card))
                 blk_queue_flush(md->queue.queue, REQ_FLUSH | REQ_FUA);
 
@@ -703,33 +783,97 @@ static struct mmc_blk_data *mmc_blk_alloc(struct mmc_card *card)
          * messages to tell when the card is present.
          */
 
-        snprintf(md->disk->disk_name, sizeof(md->disk->disk_name),
-                "mmcblk%d", devidx);
+        if (subname)
+                snprintf(md->disk->disk_name, sizeof(md->disk->disk_name),
+                         "mmcblk%d%s",
+                         mmc_get_devidx(dev_to_disk(parent)), subname);
+        else
+                snprintf(md->disk->disk_name, sizeof(md->disk->disk_name),
+                         "mmcblk%d", devidx);
 
         blk_queue_logical_block_size(md->queue.queue, 512);
+        set_capacity(md->disk, size);
+        return md;
+
+ err_putdisk:
+        put_disk(md->disk);
+ err_kfree:
+        kfree(md);
+ out:
+        return ERR_PTR(ret);
+}
+
+static struct mmc_blk_data *mmc_blk_alloc(struct mmc_card *card)
+{
+        sector_t size;
+        struct mmc_blk_data *md;
 
         if (!mmc_card_sd(card) && mmc_card_blockaddr(card)) {
                 /*
                  * The EXT_CSD sector count is in number or 512 byte
                  * sectors.
                  */
-                set_capacity(md->disk, card->ext_csd.sectors);
+                size = card->ext_csd.sectors;
         } else {
                 /*
                  * The CSD capacity field is in units of read_blkbits.
                  * set_capacity takes units of 512 bytes.
                  */
-                set_capacity(md->disk,
-                        card->csd.capacity << (card->csd.read_blkbits - 9));
+                size = card->csd.capacity << (card->csd.read_blkbits - 9);
         }
+
+        md = mmc_blk_alloc_req(card, &card->dev, size, false, NULL);
         return md;
+}
 
- err_putdisk:
-        put_disk(md->disk);
- err_kfree:
-        kfree(md);
- out:
-        return ERR_PTR(ret);
+static int mmc_blk_alloc_part(struct mmc_card *card,
+                              struct mmc_blk_data *md,
+                              unsigned int part_type,
+                              sector_t size,
+                              bool default_ro,
+                              const char *subname)
+{
+        char cap_str[10];
+        struct mmc_blk_data *part_md;
+
+        part_md = mmc_blk_alloc_req(card, disk_to_dev(md->disk), size, default_ro,
+                                    subname);
+        if (IS_ERR(part_md))
+                return PTR_ERR(part_md);
+        part_md->part_type = part_type;
+        list_add(&part_md->part, &md->part);
+
+        string_get_size((u64)get_capacity(part_md->disk) << 9, STRING_UNITS_2,
+                        cap_str, sizeof(cap_str));
+        printk(KERN_INFO "%s: %s %s partition %u %s\n",
+               part_md->disk->disk_name, mmc_card_id(card),
+               mmc_card_name(card), part_md->part_type, cap_str);
+        return 0;
+}
+
+static int mmc_blk_alloc_parts(struct mmc_card *card, struct mmc_blk_data *md)
+{
+        int ret = 0;
+
+        if (!mmc_card_mmc(card))
+                return 0;
+
+        if (card->ext_csd.boot_size) {
+                ret = mmc_blk_alloc_part(card, md, EXT_CSD_PART_CONFIG_ACC_BOOT0,
+                                         card->ext_csd.boot_size >> 9,
+                                         true,
+                                         "boot0");
+                if (ret)
+                        return ret;
+                ret = mmc_blk_alloc_part(card, md, EXT_CSD_PART_CONFIG_ACC_BOOT1,
+                                         card->ext_csd.boot_size >> 9,
+                                         true,
+                                         "boot1");
+                if (ret)
+                        return ret;
+        }
+
+        return ret;
 }
 
 static int
@@ -750,9 +894,54 @@ mmc_blk_set_blksize(struct mmc_blk_data *md, struct mmc_card *card)
         return 0;
 }
 
+static void mmc_blk_remove_req(struct mmc_blk_data *md)
+{
+        if (md) {
+                if (md->disk->flags & GENHD_FL_UP) {
+                        device_remove_file(disk_to_dev(md->disk), &md->force_ro);
+
+                        /* Stop new requests from getting into the queue */
+                        del_gendisk(md->disk);
+                }
+
+                /* Then flush out any already in there */
+                mmc_cleanup_queue(&md->queue);
+                mmc_blk_put(md);
+        }
+}
+
+static void mmc_blk_remove_parts(struct mmc_card *card,
+                                 struct mmc_blk_data *md)
+{
+        struct list_head *pos, *q;
+        struct mmc_blk_data *part_md;
+
+        list_for_each_safe(pos, q, &md->part) {
+                part_md = list_entry(pos, struct mmc_blk_data, part);
+                list_del(pos);
+                mmc_blk_remove_req(part_md);
+        }
+}
+
+static int mmc_add_disk(struct mmc_blk_data *md)
+{
+        int ret;
+
+        add_disk(md->disk);
+        md->force_ro.show = force_ro_show;
+        md->force_ro.store = force_ro_store;
+        md->force_ro.attr.name = "force_ro";
+        md->force_ro.attr.mode = S_IRUGO | S_IWUSR;
+        ret = device_create_file(disk_to_dev(md->disk), &md->force_ro);
+        if (ret)
+                del_gendisk(md->disk);
+
+        return ret;
+}
+
 static int mmc_blk_probe(struct mmc_card *card)
 {
-        struct mmc_blk_data *md;
+        struct mmc_blk_data *md, *part_md;
         int err;
         char cap_str[10];
 
@@ -776,14 +965,22 @@ static int mmc_blk_probe(struct mmc_card *card)
                 md->disk->disk_name, mmc_card_id(card), mmc_card_name(card),
                 cap_str, md->read_only ? "(ro)" : "");
 
+        if (mmc_blk_alloc_parts(card, md))
+                goto out;
+
         mmc_set_drvdata(card, md);
-        add_disk(md->disk);
+        if (mmc_add_disk(md))
+                goto out;
+
+        list_for_each_entry(part_md, &md->part, part) {
+                if (mmc_add_disk(part_md))
+                        goto out;
+        }
         return 0;
 
  out:
-        mmc_cleanup_queue(&md->queue);
-        mmc_blk_put(md);
-
+        mmc_blk_remove_parts(card, md);
+        mmc_blk_remove_req(md);
         return err;
 }
 
@@ -791,36 +988,43 @@ static void mmc_blk_remove(struct mmc_card *card)
 {
         struct mmc_blk_data *md = mmc_get_drvdata(card);
 
-        if (md) {
-                /* Stop new requests from getting into the queue */
-                del_gendisk(md->disk);
-
-                /* Then flush out any already in there */
-                mmc_cleanup_queue(&md->queue);
-
-                mmc_blk_put(md);
-        }
+        mmc_blk_remove_parts(card, md);
+        mmc_blk_remove_req(md);
         mmc_set_drvdata(card, NULL);
 }
 
 #ifdef CONFIG_PM
 static int mmc_blk_suspend(struct mmc_card *card, pm_message_t state)
 {
+        struct mmc_blk_data *part_md;
         struct mmc_blk_data *md = mmc_get_drvdata(card);
 
         if (md) {
                 mmc_queue_suspend(&md->queue);
+                list_for_each_entry(part_md, &md->part, part) {
+                        mmc_queue_suspend(&part_md->queue);
+                }
         }
         return 0;
 }
 
 static int mmc_blk_resume(struct mmc_card *card)
 {
+        struct mmc_blk_data *part_md;
         struct mmc_blk_data *md = mmc_get_drvdata(card);
 
         if (md) {
                 mmc_blk_set_blksize(md, card);
+
+                /*
+                 * Resume involves the card going into idle state,
+                 * so current partition is always the main one.
+                 */
+                md->part_curr = md->part_type;
                 mmc_queue_resume(&md->queue);
+                list_for_each_entry(part_md, &md->part, part) {
+                        mmc_queue_resume(&part_md->queue);
+                }
         }
         return 0;
 }
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 396cb23625d2..a2c795e8f9dd 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -288,7 +288,10 @@ static int mmc_read_ext_csd(struct mmc_card *card)
 
         if (card->ext_csd.rev >= 3) {
                 u8 sa_shift = ext_csd[EXT_CSD_S_A_TIMEOUT];
-                card->ext_csd.bootconfig = ext_csd[EXT_CSD_BOOT_CONFIG];
+                card->ext_csd.part_config = ext_csd[EXT_CSD_PART_CONFIG];
+
+                /* EXT_CSD value is in units of 10ms, but we store in ms */
+                card->ext_csd.part_time = 10 * ext_csd[EXT_CSD_PART_SWITCH_TIME];
 
                 /* Sleep / awake timeout in 100ns units */
                 if (sa_shift > 0 && sa_shift <= 0x17)
@@ -302,6 +305,12 @@ static int mmc_read_ext_csd(struct mmc_card *card)
                         ext_csd[EXT_CSD_HC_ERASE_GRP_SIZE] << 10;
 
                 card->ext_csd.rel_sectors = ext_csd[EXT_CSD_REL_WR_SEC_C];
+
+                /*
+                 * There are two boot regions of equal size, defined in
+                 * multiples of 128K.
+                 */
+                card->ext_csd.boot_size = ext_csd[EXT_CSD_BOOT_MULT] << 17;
         }
 
         if (card->ext_csd.rev >= 4) {
@@ -576,10 +585,13 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
         /*
          * Ensure eMMC user default partition is enabled
          */
-        if (card->ext_csd.bootconfig & 0x7) {
-                card->ext_csd.bootconfig &= ~0x7;
-                mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, EXT_CSD_BOOT_CONFIG,
-                           card->ext_csd.bootconfig, 0);
+        if (card->ext_csd.part_config & EXT_CSD_PART_CONFIG_ACC_MASK) {
+                card->ext_csd.part_config &= ~EXT_CSD_PART_CONFIG_ACC_MASK;
+                err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, EXT_CSD_PART_CONFIG,
+                                 card->ext_csd.part_config,
+                                 card->ext_csd.part_time);
+                if (err && err != -EBADMSG)
+                        goto free_card;
         }
 
         /*
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 937f852cf01e..0c7a58b14343 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -48,7 +48,8 @@ struct mmc_ext_csd {
         u8                      sec_feature_support;
         u8                      rel_sectors;
         u8                      rel_param;
-        u8                      bootconfig;
+        u8                      part_config;
+        unsigned int            part_time;              /* Units: ms */
         unsigned int            sa_timeout;             /* Units: 100ns */
         unsigned int            hs_max_dtr;
         unsigned int            sectors;
@@ -61,6 +62,7 @@ struct mmc_ext_csd {
         bool                    enhanced_area_en;       /* enable bit */
         unsigned long long      enhanced_area_offset;   /* Units: Byte */
         unsigned int            enhanced_area_size;     /* Units: KB */
+        unsigned int            boot_size;              /* in bytes */
 };
 
 struct sd_scr {
diff --git a/include/linux/mmc/mmc.h b/include/linux/mmc/mmc.h
index 390aa6eef676..373b2bf5e5b5 100644
--- a/include/linux/mmc/mmc.h
+++ b/include/linux/mmc/mmc.h
@@ -257,19 +257,21 @@ struct _mmc_csd {
 #define EXT_CSD_PARTITION_SUPPORT       160     /* RO */
 #define EXT_CSD_WR_REL_PARAM            166     /* RO */
 #define EXT_CSD_ERASE_GROUP_DEF         175     /* R/W */
-#define EXT_CSD_BOOT_CONFIG             179     /* R/W */
+#define EXT_CSD_PART_CONFIG             179     /* R/W */
 #define EXT_CSD_ERASED_MEM_CONT         181     /* RO */
 #define EXT_CSD_BUS_WIDTH               183     /* R/W */
 #define EXT_CSD_HS_TIMING               185     /* R/W */
 #define EXT_CSD_REV                     192     /* RO */
 #define EXT_CSD_STRUCTURE               194     /* RO */
 #define EXT_CSD_CARD_TYPE               196     /* RO */
+#define EXT_CSD_PART_SWITCH_TIME        199     /* RO */
 #define EXT_CSD_SEC_CNT                 212     /* RO, 4 bytes */
 #define EXT_CSD_S_A_TIMEOUT             217     /* RO */
 #define EXT_CSD_REL_WR_SEC_C            222     /* RO */
 #define EXT_CSD_HC_WP_GRP_SIZE          221     /* RO */
 #define EXT_CSD_ERASE_TIMEOUT_MULT      223     /* RO */
 #define EXT_CSD_HC_ERASE_GRP_SIZE       224     /* RO */
+#define EXT_CSD_BOOT_MULT               226     /* RO */
 #define EXT_CSD_SEC_TRIM_MULT           229     /* RO */
 #define EXT_CSD_SEC_ERASE_MULT          230     /* RO */
 #define EXT_CSD_SEC_FEATURE_SUPPORT     231     /* RO */
@@ -281,6 +283,10 @@ struct _mmc_csd {
 
 #define EXT_CSD_WR_REL_PARAM_EN         (1<<2)
 
+#define EXT_CSD_PART_CONFIG_ACC_MASK    (0x7)
+#define EXT_CSD_PART_CONFIG_ACC_BOOT0   (0x1)
+#define EXT_CSD_PART_CONFIG_ACC_BOOT1   (0x2)
+
 #define EXT_CSD_CMD_SET_NORMAL          (1<<0)
 #define EXT_CSD_CMD_SET_SECURE          (1<<1)
 #define EXT_CSD_CMD_SET_CPSECURE        (1<<2)