[PATCH v4] cmd: mmc: Add mmc reg read command for reading card registers

Marek Vasut
2023-10-31T12:20:38Z

Add extension to the 'mmc' command to read out the card registers.
Currently, only the eMMC OCR/CID/CSD/EXTCSD/RCA/DSR register are
supported. A register value can either be displayed or read into
an environment variable.

Tested-by: Jaehoon Chung <jh80.chung@samsung.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Marek Vasut <marex@denx.de>
---
Cc: Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Cc: Jaehoon Chung <jh80.chung@samsung.com>
Cc: Ramon Fried <rfried.dev@gmail.com>
Cc: Roger Knecht <rknecht@pm.me>
Cc: Sean Edmond <seanedmond@microsoft.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Tobias Waldekranz <tobias@waldekranz.com>
---
V2: - Update documentation
V3: - Return CMD_RET_FAILURE on failure
- Add RB/TB from Jaehoon
V4: - Drop default n
---
cmd/Kconfig | 7 ++++
cmd/mmc.c | 96 +++++++++++++++++++++++++++++++++++++++++++
doc/usage/cmd/mmc.rst | 26 ++++++++++++
3 files changed, 129 insertions(+)

diff --git a/cmd/Kconfig b/cmd/Kconfig
index 60aed2c307c..fd16c3a48e5 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1313,6 +1313,13 @@ config CMD_BKOPS_ENABLE
on a eMMC device. The feature is optionally available on eMMC devices
conforming to standard >= 4.41.

+config CMD_MMC_REG
+ bool "Enable support for reading card registers in the mmc command"
+ depends on CMD_MMC
+ help
+ Enable the commands for reading card registers. This is useful
+ mostly for debugging or extracting details from the card.
+
config CMD_MMC_RPMB
bool "Enable support for RPMB in the mmc command"
depends on SUPPORT_EMMC_RPMB
diff --git a/cmd/mmc.c b/cmd/mmc.c
index c6bd81cebbc..96befb27eec 100644
--- a/cmd/mmc.c
+++ b/cmd/mmc.c
@@ -1110,6 +1110,93 @@ static int do_mmc_boot_wp(struct cmd_tbl *cmdtp, int flag,
return CMD_RET_SUCCESS;
}

+#if CONFIG_IS_ENABLED(CMD_MMC_REG)
+static int do_mmc_reg(struct cmd_tbl *cmdtp, int flag,
+ int argc, char *const argv[])
+{
+ ALLOC_CACHE_ALIGN_BUFFER(u8, ext_csd, MMC_MAX_BLOCK_LEN);
+ struct mmc *mmc;
+ int i, ret;
+ u32 off;
+
+ if (argc < 3 || argc > 5)
+ return CMD_RET_USAGE;
+
+ mmc = find_mmc_device(curr_device);
+ if (!mmc) {
+ printf("no mmc device at slot %x\n", curr_device);
+ return CMD_RET_FAILURE;
+ }
+
+ if (IS_SD(mmc)) {
+ printf("SD registers are not supported\n");
+ return CMD_RET_FAILURE;
+ }
+
+ off = simple_strtoul(argv[3], NULL, 10);
+ if (!strcmp(argv[2], "cid")) {
+ if (off > 3)
+ return CMD_RET_USAGE;
+ printf("CID[%i]: 0x%08x\n", off, mmc->cid[off]);
+ if (argv[4])
+ env_set_hex(argv[4], mmc->cid[off]);
+ return CMD_RET_SUCCESS;
+ }
+ if (!strcmp(argv[2], "csd")) {
+ if (off > 3)
+ return CMD_RET_USAGE;
+ printf("CSD[%i]: 0x%08x\n", off, mmc->csd[off]);
+ if (argv[4])
+ env_set_hex(argv[4], mmc->csd[off]);
+ return CMD_RET_SUCCESS;
+ }
+ if (!strcmp(argv[2], "dsr")) {
+ printf("DSR: 0x%08x\n", mmc->dsr);
+ if (argv[4])
+ env_set_hex(argv[4], mmc->dsr);
+ return CMD_RET_SUCCESS;
+ }
+ if (!strcmp(argv[2], "ocr")) {
+ printf("OCR: 0x%08x\n", mmc->ocr);
+ if (argv[4])
+ env_set_hex(argv[4], mmc->ocr);
+ return CMD_RET_SUCCESS;
+ }
+ if (!strcmp(argv[2], "rca")) {
+ printf("RCA: 0x%08x\n", mmc->rca);
+ if (argv[4])
+ env_set_hex(argv[4], mmc->rca);
+ return CMD_RET_SUCCESS;
+ }
+ if (!strcmp(argv[2], "extcsd") &&
+ mmc->version >= MMC_VERSION_4_41) {
+ ret = mmc_send_ext_csd(mmc, ext_csd);
+ if (ret)
+ return CMD_RET_FAILURE;
+ if (!strcmp(argv[3], "all")) {
+ /* Dump the entire register */
+ printf("EXT_CSD:");
+ for (i = 0; i < MMC_MAX_BLOCK_LEN; i++) {
+ if (!(i % 10))
+ printf("\n%03i: ", i);
+ printf(" %02x", ext_csd[i]);
+ }
+ printf("\n");
+ return CMD_RET_SUCCESS;
+ }
+ off = simple_strtoul(argv[3], NULL, 10);
+ if (off > 512)
+ return CMD_RET_USAGE;
+ printf("EXT_CSD[%i]: 0x%02x\n", off, ext_csd[off]);
+ if (argv[4])
+ env_set_hex(argv[4], ext_csd[off]);
+ return CMD_RET_SUCCESS;
+ }
+
+ return CMD_RET_FAILURE;
+}
+#endif
+
static struct cmd_tbl cmd_mmc[] = {
U_BOOT_CMD_MKENT(info, 1, 0, do_mmcinfo, "", ""),
U_BOOT_CMD_MKENT(read, 4, 1, do_mmc_read, "", ""),
@@ -1142,6 +1229,9 @@ static struct cmd_tbl cmd_mmc[] = {
U_BOOT_CMD_MKENT(bkops-enable, 2, 0, do_mmc_bkops_enable, "", ""),
U_BOOT_CMD_MKENT(bkops, 4, 0, do_mmc_bkops, "", ""),
#endif
+#if CONFIG_IS_ENABLED(CMD_MMC_REG)
+ U_BOOT_CMD_MKENT(reg, 5, 0, do_mmc_reg, "", ""),
+#endif
};

static int do_mmcops(struct cmd_tbl *cmdtp, int flag, int argc,
@@ -1229,6 +1319,12 @@ U_BOOT_CMD(
" WARNING: This is a write-once setting.\n"
"mmc bkops <dev> [auto|manual] [enable|disable]\n"
" - configure background operations handshake on device\n"
+#endif
+#if CONFIG_IS_ENABLED(CMD_MMC_REG)
+ "mmc reg read <reg> <offset> [env] - read card register <reg> offset <offset>\n"
+ " (optionally into [env] variable)\n"
+ " - reg: cid/csd/dsr/ocr/rca/extcsd\n"
+ " - offset: for cid/csd [0..3], for extcsd [0..511,all]\n"
#endif
);

diff --git a/doc/usage/cmd/mmc.rst b/doc/usage/cmd/mmc.rst
index 71a0303109c..c0924ba5769 100644
--- a/doc/usage/cmd/mmc.rst
+++ b/doc/usage/cmd/mmc.rst
@@ -21,6 +21,7 @@ Synopsis
mmc bootpart-resize <dev> <dev part size MB> <RPMB part size MB>
mmc partconf <dev> [[varname] | [<boot_ack> <boot_partition> <partition_access>]]
mmc rst-function <dev> <value>
+ mmc reg read <reg> <offset> [env]

Description
-----------
@@ -183,6 +184,31 @@ The 'mmc rst-function' command changes the RST_n_FUNCTION field.
0x3
Reserved

+The 'mmc reg read <reg> <offset> [env]' reads eMMC card register and
+either print it to standard output, or store the value in environment
+variable.
+
+<reg> with
+optional offset <offset> into the register array, and print it to
+standard output or store it into environment variable [env].
+
+ reg
+ cid
+ The Device IDentification (CID) register. Uses offset.
+ csd
+ The Device-Specific Data (CSD) register. Uses offset.
+ dsr
+ The driver stage register (DSR).
+ ocr
+ The operation conditions register (OCR).
+ rca
+ The relative Device address (RCA) register.
+ extcsd
+ The Extended CSD register. Uses offset.
+ offset
+ For 'cid'/'csd' 128 bit registers '[0..3]' in 32-bit increments. For 'extcsd' 512 bit register '[0..512,all]' in 8-bit increments, or 'all' to read the entire register.
+ env
+ Optional environment variable into which 32-bit value read from register should be stored.

Examples
--------
--
2.42.0