LAN966x SDMMC

SoC Resources

LAN966x SDMMC controller supports the embedded Multimedia Card (e.MMC) Specification (v5.01) and the SD Memory Card(v3.0).

Kernel configurations

Following kernel config options should be enabled to use LAN966x SDMMC:

  • CONFIG_MMC_SDHCI - SD Host controller config option.

  • CONDFIG_MMC - MMC interface config option

  • CONFIG_MMC_SDHCI_OF_AT91 - SDHCI OF support (for the Atmel SDMMC controller) config option.

Devicetree Configuration

To use SDMMC interface, following configurations are required in device tree.

  • compatible string must be set to microchip,lan966x-sdhci.

  • reg property must be set with base register address and length.

  • pinctrl-0 property must be set to

    • <&emmc_sd_pins>, <&sdmmc_pins> to use SD Card interface.

    • <&emmc_sd_pins>, <&emmc_pins> to use eMMC interface.

      Note

      emmc_sd_pins includes CMD, CLK, D0, D1, D2, D3, RSTN pins for both SD and eMMC, sdmmc_pins includes VSEL, WP, CD, LED pins for SD interface only and emmc_pins includes D4, D5, D6, D7 pins for eMMC interface only. sdmmc_pins and emmc_pins pin numbers are same but driver will take care of configuring different ALT modes for SD and eMMC pins.

pinctrl node CMD pin CLK pin D0 D1 D2 D3 RSTN

emmc_sd_pins

GPIO67

GPIO68

GPIO69

GPIO70

GPIO71

GPIO72

GPIO77
pinctrl node DT Func VSEL pin WP pin CD pin LED pin

sdmmc_pins

sd

GPIO73

GPIO74

GPIO75

GPIO76
pinctrl node DT Func D4 D5 D6 D7

emmc_pins

emmc

GPIO73

GPIO74

GPIO75

GPIO76

  • interrupts property must set with interrupt details. Interrupt number[CPU INTR] corresponding to a sdmmc must be configured as defined below:

SDMMC ID Shared Peripheral Interrupt CPU INTR

sdmmc0

98

66
Note

Shared peripheral interrupt lines start at index ID32. So, CPU INTR must be calculated as [Shared peripheral interrupt number - 32].

  • Input clock clocks property must be set to GCK clock using phandle and GCK ID as <&clk GCK_ID_SDMMC0>.

  • clock-names must be set to hclock and multclk

  • assigned-clocks must be set to <&clks GCK_ID_SDMMC0>.

  • assigned-clock-rates must be set to 45Mhz.

Note

While operating as eMMC interface, tx-phase property must be set to zero. Possible phase shift values are 0 for 180degrees, c for 90 degrees, 4 for 270 degrees, 8 for 360 degrees. 180 degress phase shift is considered as best chioce for generating phase difference between data/command bus and output clock. It provides sufficient time limit to compensate for any board delays/skew and provides sufficient time margin for setup/hold time requirements.

References

Example

Following example shows how a SD/eMMC should be defined in DT:

dtsi file:

sdmmc0: sdio-host@e0830000 {
        compatible = "microchip,lan966x-sdhci";
        reg = <SDMMC_ADDR SDMMC_SIZE>;
        interrupts = <GIC_SPI 66 IRQ_TYPE_LEVEL_HIGH>;
        clocks = <&clks GCK_ID_SDMMC0>, <&clks GCK_ID_SDMMC0>;
        clock-names = "hclock", "multclk";
        assigned-clocks = <&clks GCK_ID_SDMMC0>;
        assigned-clock-rates = <45000000>;
        status = "disabled";
};

dts file changes for eMMC:

&sdmmc0 {
        bus-width = <8>;
        cap-mmc-highspeed;
        cap-mmc-hw-reset;
        non-removable;
        pinctrl-0 = <&emmc_sd_pins>, <&emmc_pins>;
        pinctrl-names = "default";
        no-1-8-v;
        tx-phase = <0>; /* 180 degrees phase shift */
        status = "okay";
};

dts file changes for SD Card:

&sdmmc0 {
        bus-width = <8>;
        pinctrl-0 = <&emmc_sd_pins>, <&sdmmc_pins>;
        pinctrl-names = "default";
        no-1-8-v;
        status = "okay";
};

UserSpace

Steps to Format, Create partitions and Mount SD/eMMC

Confirm instances are created

To confirm if mmc device is created:

  • Check if a mmc device is created in /dev directory.

  • To check card details, mount debugfs using command mount -t debugfs none /sys/kernel/debug/ and then use command cat /sys/kernel/debug/mmc0/ios to get IOs debugging information.

Example on how to use

eMMC Interface testing:

# ls -l /dev/mmc*
brw-------    1 root     root      179,   0 Jan  1 00:00 /dev/mmcblk0
brw-------    1 root     root      179,   8 Jan  1 00:00 /dev/mmcblk0boot0
brw-------    1 root     root      179,  16 Jan  1 00:00 /dev/mmcblk0boot1
crw-------    1 root     root      247,   0 Jan  1 00:00 /dev/mmcblk0rpmb
#
#
# dmesg | grep mmc
[    3.154864] mmc0: SDHCI controller on e0830000.sdio-host [e0830000.sdio-host] using ADMA
[    3.355470] mmc0: new high speed MMC card at address 0001
[    3.365870] mmcblk0: mmc0:0001 IS004G 3.64 GiB
[    3.369463] mmcblk0boot0: mmc0:0001 IS004G partition 1 2.00 MiB
[    3.373726] mmcblk0boot1: mmc0:0001 IS004G partition 2 2.00 MiB
[    3.386894] mmcblk0rpmb: mmc0:0001 IS004G partition 3 512 KiB, chardev (247:0)
[    3.397439]  mmcblk0: p1 p2
#
# mount -t debugfs none /sys/kernel/debug/
# cat /sys/kernel/debug/mmc0/ios
clock:          46000000 Hz
actual clock:   46000000 Hz
vdd:            21 (3.3 ~ 3.4 V)
bus mode:       2 (push-pull)
chip select:    0 (don't care)
power mode:     2 (on)
bus width:      3 (8 bits)
timing spec:    1 (mmc high-speed)
signal voltage: 0 (3.30 V)
driver type:    0 (driver type B)

# dd if=/dev/zero of=/dev/mmcblk0 bs=10M count=1

1+0 records in
1+0 records out
#
# fdisk /dev/mmcblk0
Device contains neither a valid DOS partition table, nor Sun, SGI, OSF or GPT disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that the previous content
won't be recoverable.


The number of cylinders for this disk is set to 119296.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
   (e.g., DOS FDISK, OS/2 FDISK)

Command (m for help): p
Disk /dev/mmcblk0: 3728 MB, 3909091328 bytes, 7634944 sectors
119296 cylinders, 4 heads, 16 sectors/track
Units: sectors of 1 * 512 = 512 bytes

Device       Boot StartCHS    EndCHS        StartLBA     EndLBA    Sectors  Size Id Type

Command (m for help): n
Partition type
   p   primary partition (1-4)
   e   extended
1
Invalid partition number for type '1'
Partition type
   p   primary partition (1-4)
   e   extended
p
Partition number (1-4): 1
First sector (16-7634943, default 16):
Using default value 16
Last sector or +size{,K,M,G,T} (16-7634943, default 7634943): +64M

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): 6
Changed system type of partition 1 to 6 (FAT16)

Command (m for help): n
Partition type
   p   primary partition (1-4)
   e   extended
p
Partition number (1-4): 2
First sector (131088-7634943, default 131088):
Using default value 131088
Last sector or +size{,K,M,G,T} (131088-7634943, default 7634943): +1500M

Command (m for help): p
Disk /dev/mmcblk0: 3728 MB, 3909091328 bytes, 7634944 sectors
119296 cylinders, 4 heads, 16 sectors/track
Units: sectors of 1 * 512 = 512 bytes

Device       Boot StartCHS    EndCHS        StartLBA     EndLBA    Sectors  Size Id Type
/dev/mmcblk0p1    0,1,1       1023,3,16           16     131087     131072 64.0M  6 FAT16
/dev/mmcblk0p2    1023,3,16   1023,3,16       131088    3203087    3072000 1500M 83 Linux

Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table

[   44.720213]  mmcblk0: p1 p2
#
# mkdir /tmp/ext
# mkfs.ext2 /dev/mmcblk0p2
mke2fs 1.45.5 (07-Jan-2020)
/dev/mmcblk0p2 contains a ext2 file system
        last mounted on /tmp/ext on Thu Jan  1 00:02:16 1970
Proceed anyway? (y,N)

# mount -t ext2 /dev/mmcblk0p2 /tmp/ext
#
#
# echo "Hello_World: Welcome" > /tmp/ext/t6.txt
#
# cat /tmp/ext/t6.txt
Hello_World: Welcome
#
#
# umount /tmp/ext/

SD Card Interface testing:

# dmesg | grep mmc
[    1.305841] mmc0: SDHCI controller on e0830000.sdio-host [e0830000.sdio-host] using ADMA
[    1.459624] mmc0: new ultra high speed DDR50 SDHC card at address aaaa
[    1.610121] mmcblk0: mmc0:aaaa SC32G 29.7 GiB
[    1.683630]  mmcblk0: p1 p2
#
#
# mount -t debugfs none /sys/kernel/debug/
# cat /sys/kernel/debug/mmc0/ios
clock:          50000000 Hz
actual clock:   50000000 Hz
vdd:            21 (3.3 ~ 3.4 V)
bus mode:       2 (push-pull)
chip select:    0 (don't care)
power mode:     2 (on)
bus width:      2 (4 bits)
timing spec:    7 (sd uhs DDR50)
signal voltage: 1 (1.80 V)
driver type:    0 (driver type B)
#
# ls -l /dev/mmc*
brw-------    1 root     root      179,   0 Jan  1 00:00 /dev/mmcblk0
brw-------    1 root     root      179,   1 Jan  1 00:00 /dev/mmcblk0p1
brw-------    1 root     root      179,   2 Jan  1 00:00 /dev/mmcblk0p2
#
# cat /proc/interrupts | grep mmc
 43:         89     GIC-0  98 Level     mmc0
#

# dd if=/dev/zero of=/dev/mmcblk0 bs=10M count=1

1+0 records in
1+0 records out
# fdisk /dev/mmcblk0
Device contains neither a valid DOS partition table, nor Sun, SGI, OSF or GPT disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that the previous content
won't be recoverable.


The number of cylinders for this disk is set to 973968.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
   (e.g., DOS FDISK, OS/2 FDISK)

Command (m for help): p
Disk /dev/mmcblk0: 30 GB, 31914983424 bytes, 62333952 sectors
973968 cylinders, 4 heads, 16 sectors/track
Units: sectors of 1 * 512 = 512 bytes

Device       Boot StartCHS    EndCHS        StartLBA     EndLBA    Sectors  Size Id Type

Command (m for help): n
Partition type
   p   primary partition (1-4)
   e   extended
p
Partition number (1-4): 1
First sector (16-62333951, default 16):
Using default value 16
Last sector or +size{,K,M,G,T} (16-62333951, default 62333951): +64M

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): 6
Changed system type of partition 1 to 6 (FAT16)

Command (m for help): n
Partition type
   p   primary partition (1-4)
   e   extended
p
Partition number (1-4): 2
First sector (131088-62333951, default 131088):
Using default value 131088
Last sector or +size{,K,M,G,T} (131088-62333951, default 62333951): +1500M

Command (m for help): p
Disk /dev/mmcblk0: 30 GB, 31914983424 bytes, 62333952 sectors
973968 cylinders, 4 heads, 16 sectors/track
Units: sectors of 1 * 512 = 512 bytes

Device       Boot StartCHS    EndCHS        StartLBA     EndLBA    Sectors  Size Id Type
/dev/mmcblk0p1    0,1,1       1023,3,16           16     131087     131072 64.0M  6 FAT16
/dev/mmcblk0p2    1023,3,16   1023,3,16       131088    3203087    3072000 1500M 83 Linux

Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table
[   63.250316]  mmcblk0: p1 p2
#
# ls -l /dev/mmc*
brw-------    1 root     root      179,   0 Jan  1 00:01 /dev/mmcblk0
brw-------    1 root     root      179,   1 Jan  1 00:01 /dev/mmcblk0p1
brw-------    1 root     root      179,   2 Jan  1 00:01 /dev/mmcblk0p2
# mkdir /tmp/ext
# mount -t ext2 /dev/mmcblk0p2 /tmp/ext
#
# mkfs.ext2 /dev/mmcblk0p2
mke2fs 1.45.6 (20-Mar-2020)
/dev/mmcblk0p2 contains a ext2 file system
        last mounted on /media/vishnu/842a0c11-7809-4b40-a98f-25bae7c7d16c on Thu Aug  5 11:23:26 2021
Proceed anyway? (y,N) y
Discarding device blocks: done
Creating filesystem with 384000 4k blocks and 96000 inodes
Filesystem UUID: b2dde0d3-5b02-458d-9893-07a876e5a6bf
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912

Allocating group tables: done
Writing inode tables: done
Writing superblocks and filesystem accounting information: done
#
#
#
#
# mkdir /tmp/ext
#
# mount -t ext2 /dev/mmcblk0p2 /tmp/ext
# ls -l /tmp/ext/
total 16
drwx------    2 root     root         16384 Jan  1 00:02 lost+found
#
#
#
# echo "3-9-2021: Testing SD card at HS 50Mhz" > /tmp/ext/t1.txt
#
#
#
# cat /tmp/ext/t1.txt
3-9-2021: Testing SD card at HS 50Mhz
#
#
# umount /tmp/ext/
Note

Enable e2fsprogs utility from buildroot to use ext2,ext3,ext4 filesystems.