[PATCH] cmd: mmc: allow 'mmc rst-function' to show the current value

[Rasmus Villemoes]

Extend the 'mmc rst-function' subcommand so that lacking a value to
set, it simply prints the current value, and its interpretation.

Signed-off-by: Rasmus Villemoes <ravi at prevas.dk>
---
 cmd/mmc.c             | 36 +++++++++++++++++++++++++++---------
 doc/usage/cmd/mmc.rst |  4 ++--
 2 files changed, 29 insertions(+), 11 deletions(-)

diff --git a/cmd/mmc.c b/cmd/mmc.c
index 81b1ca4ad84..f217dfdacaa 100644
--- a/cmd/mmc.c
+++ b/cmd/mmc.c
@@ -1012,16 +1012,10 @@ static int do_mmc_rst_func(struct cmd_tbl *cmdtp, int flag,
 	 * The only valid values are 0x0, 0x1 and 0x2 and writing
 	 * a value of 0x1 or 0x2 sets the value permanently.
 	 */
-	if (argc != 3)
+	if (argc < 2 || argc > 3)
 		return CMD_RET_USAGE;
 
 	dev = dectoul(argv[1], NULL);
-	enable = dectoul(argv[2], NULL);
-
-	if (enable > 2) {
-		puts("Invalid RST_n_ENABLE value\n");
-		return CMD_RET_USAGE;
-	}
 
 	mmc = init_mmc_device(dev, false);
 	if (!mmc)
@@ -1032,6 +1026,30 @@ static int do_mmc_rst_func(struct cmd_tbl *cmdtp, int flag,
 		return CMD_RET_FAILURE;
 	}
 
+	if (argc == 2) {
+		ALLOC_CACHE_ALIGN_BUFFER(u8, ext_csd, MMC_MAX_BLOCK_LEN);
+		ret = mmc_send_ext_csd(mmc, ext_csd);
+		if (ret)
+			return CMD_RET_FAILURE;
+
+		printf("RST_n_FUNCTION: 0x%x ", ext_csd[EXT_CSD_RST_N_FUNCTION]);
+		switch (ext_csd[EXT_CSD_RST_N_FUNCTION]) {
+		case 0x0: puts("(temporarily disabled)\n"); break;
+		case 0x1: puts("(permanently enabled)\n"); break;
+		case 0x2: puts("(permanently disabled)\n"); break;
+		default: puts("(unknown)\n");
+		}
+
+		return CMD_RET_SUCCESS;
+	}
+
+	enable = dectoul(argv[2], NULL);
+
+	if (enable > 2) {
+		puts("Invalid RST_n_ENABLE value\n");
+		return CMD_RET_USAGE;
+	}
+
 	ret = mmc_set_rst_n_function(mmc, enable);
 	if (ret != 0)
 		return CMD_RET_FAILURE;
@@ -1344,8 +1362,8 @@ U_BOOT_CMD(
 	"mmc partconf <dev> [[varname] | [<boot_ack> <boot_partition> <partition_access>]]\n"
 	" - Show or change the bits of the PARTITION_CONFIG field of the specified device\n"
 	"   If showing the bits, optionally store the boot_partition field into varname\n"
-	"mmc rst-function <dev> <value>\n"
-	" - Change the RST_n_FUNCTION field of the specified device\n"
+	"mmc rst-function <dev> [<value>]\n"
+	" - Show or change the RST_n_FUNCTION field of the specified device\n"
 	"   WARNING: This is a write-once field and 0 / 1 / 2 are the only valid values.\n"
 #endif
 #if CONFIG_IS_ENABLED(CMD_MMC_RPMB)
diff --git a/doc/usage/cmd/mmc.rst b/doc/usage/cmd/mmc.rst
index 55391fda24c..c6ab334b3d4 100644
--- a/doc/usage/cmd/mmc.rst
+++ b/doc/usage/cmd/mmc.rst
@@ -24,7 +24,7 @@ Synopsis
     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> [[varname] | [<boot_ack> <boot_partition> <partition_access>]]
-    mmc rst-function <dev> <value>
+    mmc rst-function <dev> [<value>]
     mmc reg read <reg> <offset> [env]
 
 Description
@@ -178,7 +178,7 @@ The 'mmc bootpart-resize' command changes sizes of boot and RPMB partitions.
     RPMB part size MB
         target size of RPMB partition
 
-The 'mmc rst-function' command changes the RST_n_FUNCTION field.
+The 'mmc rst-function' command shows or changes the RST_n_FUNCTION field.
 **WARNING** : This is a write-once field. (*Refer to eMMC specification*)
 
     value
-- 
2.53.0