diff --git a/doc/usage/index.rst b/doc/usage/index.rst
index 5faf279..d330b14 100644
--- a/doc/usage/index.rst
+++ b/doc/usage/index.rst
@@ -32,6 +32,7 @@
    load
    loady
    mbr
+   mmc
    md
    pstore
    qfw
diff --git a/doc/usage/mmc.rst b/doc/usage/mmc.rst
new file mode 100644
index 0000000..57284ed
--- /dev/null
+++ b/doc/usage/mmc.rst
@@ -0,0 +1,212 @@
+.. SPDX-License-Identifier: GPL-2.0+:
+
+mmc command
+============
+
+Synopsis
+--------
+
+::
+
+    mmc info
+    mmc read addr blk# cnt
+    mmc write addr blk# cnt
+    mmc erase blk# cnt
+    mmc rescan
+    mmc part
+    mmc dev [dev] [part]
+    mmc list
+    mmc wp
+    mmc bootbus <dev> <boot_bus_width> <reset_boot_bus_width> <boot_mode>
+    mmc bootpart-resize <dev> <dev part size MB> <RPMB part size MB>
+    mmc partconf <dev> [boot_ack boot_partition partition_access]
+    mmc rst-function <dev> <value>
+
+Description
+-----------
+
+The mmc command is used to control MMC(eMMC/SD) device.
+
+The 'mmc info' command displays information (Manufacturer ID, OEM, Name, Bus Speed, Mode, ...) of MMC device.
+
+The 'mmc read' command reads raw data to memory address from MMC device with block offset and count.
+
+The 'mmc write' command writes raw data to MMC device from memory address with block offset and count.
+
+    addr
+        memory address
+    blk#
+        start block offset
+    cnt
+        block count
+
+The 'mmc erase' command erases MMC device from block offset until count.
+
+    blk#
+        start block offset
+    cnt
+        block count
+
+The 'mmc rescan' command scans the available MMC device.
+
+The 'mmc part' command displays the list available partition on current mmc device.
+
+The 'mmc dev' command shows or set current mmc device.
+
+    dev
+        device number to change
+    part
+        partition number to change
+
+The 'mmc list' command displays the list available devices.
+
+The 'mmc wp' command enables "power on write protect" function for boot partitions.
+
+The 'mmc bootbus' command sets the BOOT_BUS_WIDTH field. (*Refer to eMMC specification*)
+
+    boot_bus_width
+        0x0
+            x1 (sdr) or x4(ddr) buswidth in boot operation mode (default)
+        0x1
+            x4 (sdr/ddr) buswidth in boot operation mode
+        0x2
+            x8 (sdr/ddr) buswidth in boot operation mode
+        0x3
+            Reserved
+
+    reset_boot_bus_width
+        0x0
+            Reset buswidth to x1, Single data reate and backward compatible timing after boot operation (default)
+        0x1
+            Retain BOOT_BUS_WIDTH and BOOT_MODE value after boot operation. This is relevant to Push-pull mode operation only
+
+    boot_mode
+        0x0
+            Use single data rate + backward compatible timing in boot operation (default)
+        0x1
+            Use single data rate + High Speed timing in boot operation mode
+        0x2
+            Use dual data rate in boot operation
+        0x3
+            Reserved
+
+The 'mmc partconf' command shows or changes PARTITION_CONFIG field.
+
+    boot_ack
+        boot acknowledge value
+    boot_partition
+        boot partition to enable for boot
+            0x0
+                Device not boot enabled(default)
+            0x1
+                Boot partition1 enabled for boot
+            0x2
+                Boot partition2 enabled for boot
+            0x7
+                User area enabled for boot
+            others
+                Reserved
+    partition_access
+        partitions to access
+
+The 'mmc bootpart-resize' command changes sizes of boot and RPMB partitions.
+    dev
+        device number
+    boot part size MB
+        target size of boot partition
+    RPMB part size MB
+        target size of RPMB partition
+
+The 'mmc rst-function' command changes the RST_n_FUNCTION field.
+**WARNING** : This is a write-once field. (*Refer to eMMC specification*)
+
+    value
+        0x0
+            RST_n signal is temporarily disabled (default)
+        0x1
+            RST_n signal is permanently enabled
+        0x2
+            RST_n signal is permanently disabled
+        0x3
+            Reserved
+
+
+Examples
+--------
+
+The 'mmc info' command displays device's capabilities:
+::
+
+    => mmc info
+    Device: EXYNOS DWMMC
+    Manufacturer ID: 45
+    OEM: 100
+    Name: SDW16
+    Bus Speed: 52000000
+    Mode: MMC DDR52 (52MHz)
+    Rd Block Len: 512
+    MMC version 5.0
+    High Capacity: Yes
+    Capacity: 14.7 GiB
+    Bus Width: 8-bit DDR
+    Erase Group Size: 512 KiB
+    HC WP Group Size: 8 MiB
+    User Capacity: 14.7 GiB WRREL
+    Boot Capacity: 4 MiB ENH
+    RPMB Capacity: 4 MiB ENH
+    Boot area 0 is not write protected
+    Boot area 1 is not write protected
+
+The raw data can be read/written via 'mmc read/write' command:
+::
+
+    => mmc read 0x40000000 0x5000 0x100
+    MMC read: dev # 0, block # 20480, count 256 ... 256 blocks read: OK
+
+    => mmc write 0x40000000 0x5000 0x10
+    MMC write: dev # 0, block # 20480, count 256 ... 256 blocks written: OK
+
+The partition list can be shown via 'mmc part' command:
+::
+
+    => mmc part
+    Partition Map for MMC device 0  --   Partition Type: DOS
+
+    Part    Start Sector    Num Sectors     UUID            Type
+      1     8192            131072          dff8751a-01     0e Boot
+      2     139264          6291456         dff8751a-02     83
+      3     6430720         1048576         dff8751a-03     83
+      4     7479296         23298048        dff8751a-04     05 Extd
+      5     7481344         307200          dff8751a-05     83
+      6     7790592         65536           dff8751a-06     83
+      7     7858176         16384           dff8751a-07     83
+      8     7876608         22900736        dff8751a-08     83
+
+The current device can be shown or set via 'mmc dev' command:
+::
+
+    => mmc dev
+    switch to partitions #0, OK
+    mmc0(part0) is current device
+    => mmc dev 2 0
+    switch to partitions #0, OK
+    mmc2 is current device
+
+The list of available devices can be shown via 'mmc list' command:
+::
+
+    => mmc list
+    mmc list
+    EXYNOS DWMMC: 0 (eMMC)
+    EXYNOS DWMMC: 2 (SD)
+
+Configuration
+-------------
+
+The mmc command is only available if CONFIG_CMD_MMC=y.
+Some commands need to enable more configuration.
+
+write, erase
+    CONFIG_MMC_WRITE
+bootbus, bootpart-resize, partconf, rst-function
+    CONFIG_SUPPORT_EMMC_BOOT=y