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

[Marek Vasut]

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.

Signed-off-by: Marek Vasut <marex at denx.de>
---
 cmd/Kconfig |  8 +++++
 cmd/mmc.c   | 94 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 102 insertions(+)

diff --git a/cmd/Kconfig b/cmd/Kconfig
index 192b3b262f..a0cf03c911 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1104,6 +1104,14 @@ 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
+	default y
+	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 1529a3e05d..55fbfe822e 100644
--- a/cmd/mmc.c
+++ b/cmd/mmc.c
@@ -912,6 +912,93 @@ static int do_mmc_bkops_enable(struct cmd_tbl *cmdtp, int flag,
 }
 #endif
 
+#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;
+	} else {
+		off = simple_strtoul(argv[3], NULL, 10);
+		if (!strcmp(argv[2], "cid")) {
+			if (off > 1)
+				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 ret;
+			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 int do_mmc_boot_wp(struct cmd_tbl *cmdtp, int flag,
 			  int argc, char * const argv[])
 {
@@ -963,6 +1050,9 @@ static struct cmd_tbl cmd_mmc[] = {
 #ifdef CONFIG_CMD_BKOPS_ENABLE
 	U_BOOT_CMD_MKENT(bkops-enable, 2, 0, do_mmc_bkops_enable, "", ""),
 #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,
@@ -1037,6 +1127,10 @@ U_BOOT_CMD(
 #ifdef CONFIG_CMD_BKOPS_ENABLE
 	"mmc bkops-enable <dev> - enable background operations handshake on device\n"
 	"   WARNING: This is a write-once setting.\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"
 #endif
 	);
 
-- 
2.27.0