mmc-utils: add ability to enable/disable optional eMMC cache

The MMC4.5 specification added an optional cache for eMMC devices.
This change will add the ability to enable/disable the cache.
Signed-off-by: Al Cooper <acooperx@gmail.com>
Signed-off-by: Chris Ball <chris@printf.net>

mmc.c

@@ -163,6 +163,18 @@ static struct Command commands[] = {
 		  "    mmc rpmb write-block /dev/mmcblk0rpmb 0x02 - -",
 	  NULL
 	},
+	{ do_cache_en, -1,
+	  "cache enable", "<device>\n"
+		"Enable the eMMC cache feature on <device>.\n"
+		"NOTE! The cache is an optional feature on devices >= eMMC4.5.",
+	  NULL
+	},
+	{ do_cache_dis, -1,
+	  "cache disable", "<device>\n"
+		"Disable the eMMC cache feature on <device>.\n"
+		"NOTE! The cache is an optional feature on devices >= eMMC4.5.",
+	  NULL
+	},
 	{ 0, 0, 0, 0 }
 };
 

mmc.h

@@ -42,12 +42,17 @@
 #define EXT_CSD_S_CMD_SET		504
 #define EXT_CSD_HPI_FEATURE		503
 #define EXT_CSD_BKOPS_SUPPORT		502	/* RO */
+#define EXT_CSD_CACHE_SIZE_3		252
+#define EXT_CSD_CACHE_SIZE_2		251
+#define EXT_CSD_CACHE_SIZE_1		250
+#define EXT_CSD_CACHE_SIZE_0		249
 #define EXT_CSD_BOOT_INFO		228	/* R/W */
 #define EXT_CSD_SEC_COUNT_3		215
 #define EXT_CSD_SEC_COUNT_2		214
 #define EXT_CSD_SEC_COUNT_1		213
 #define EXT_CSD_SEC_COUNT_0		212
 #define EXT_CSD_PART_SWITCH_TIME	199
+#define EXT_CSD_REV			192
 #define EXT_CSD_BOOT_CFG		179
 #define EXT_CSD_PART_CONFIG		179
 #define EXT_CSD_BOOT_BUS_CONDITIONS	177
@@ -88,6 +93,7 @@
 #define EXT_CSD_DATA_SECTOR_SIZE	61 /* R */
 #define EXT_CSD_EXT_PARTITIONS_ATTRIBUTE_1	53
 #define EXT_CSD_EXT_PARTITIONS_ATTRIBUTE_0	52
+#define EXT_CSD_CACHE_CTRL		33
 
 /*
  * WR_REL_PARAM field definitions
@@ -131,6 +137,15 @@
 #define EXT_CSD_ENH_2			(1<<2)
 #define EXT_CSD_ENH_1			(1<<1)
 #define EXT_CSD_ENH_USR			(1<<0)
+#define EXT_CSD_REV_V5_1		8
+#define EXT_CSD_REV_V5_0		7
+#define EXT_CSD_REV_V4_5		6
+#define EXT_CSD_REV_V4_4_1		5
+#define EXT_CSD_REV_V4_3		3
+#define EXT_CSD_REV_V4_2		2
+#define EXT_CSD_REV_V4_1		1
+#define EXT_CSD_REV_V4_0		0
+
 
 /* From kernel linux/mmc/core.h */
 #define MMC_RSP_PRESENT	(1 << 0)

mmc_cmds.c

@@ -98,7 +98,7 @@ int send_status(int fd, __u32 *response)
 void print_writeprotect_status(__u8 *ext_csd)
 {
 	__u8 reg;
-	__u8 ext_csd_rev = ext_csd[192];
+	__u8 ext_csd_rev = ext_csd[EXT_CSD_REV];
 
 	/* A43: reserved [174:0] */
 	if (ext_csd_rev >= 5) {
@@ -1014,7 +1014,7 @@ int do_read_extcsd(int nargs, char **argv)
 		exit(1);
 	}
 
-	ext_csd_rev = ext_csd[192];
+	ext_csd_rev = ext_csd[EXT_CSD_REV];
 
 	switch (ext_csd_rev) {
 	case 7:
@@ -1218,7 +1218,7 @@ int do_read_extcsd(int nargs, char **argv)
 	if (reg & 0x01) printf(" HS eMMC @26MHz - at rated device voltage(s)\n");
 
 	printf("CSD structure version [CSD_STRUCTURE: 0x%02x]\n", ext_csd[194]);
-	/* ext_csd_rev = ext_csd[192] (already done!!!) */
+	/* ext_csd_rev = ext_csd[EXT_CSD_REV] (already done!!!) */
 	printf("Command set [CMD_SET: 0x%02x]\n", ext_csd[191]);
 	printf("Command set revision [CMD_SET_REV: 0x%02x]\n", ext_csd[189]);
 	printf("Power class [POWER_CLASS: 0x%02x]\n", ext_csd[187]);
@@ -1971,3 +1971,64 @@ int do_rpmb_write_block(int nargs, char **argv)
 
 	return ret;
 }
+
+int do_cache_ctrl(int value, int nargs, char **argv)
+{
+	__u8 ext_csd[512];
+	int fd, ret;
+	char *device;
+
+	CHECK(nargs != 2, "Usage: mmc cache enable </path/to/mmcblkX>\n",
+			  exit(1));
+
+	device = argv[1];
+
+	fd = open(device, O_RDWR);
+	if (fd < 0) {
+		perror("open");
+		exit(1);
+	}
+
+	ret = read_extcsd(fd, ext_csd);
+	if (ret) {
+		fprintf(stderr, "Could not read EXT_CSD from %s\n", device);
+		exit(1);
+	}
+
+	if (ext_csd[EXT_CSD_REV] < EXT_CSD_REV_V4_5) {
+		fprintf(stderr,
+			"The CACHE option is only availabe on devices >= "
+			"MMC 4.5 %s\n", device);
+		exit(1);
+	}
+
+	/* If the cache size is zero, this device does not have a cache */
+	if (!(ext_csd[EXT_CSD_CACHE_SIZE_3] ||
+			ext_csd[EXT_CSD_CACHE_SIZE_2] ||
+			ext_csd[EXT_CSD_CACHE_SIZE_1] ||
+			ext_csd[EXT_CSD_CACHE_SIZE_0])) {
+		fprintf(stderr,
+			"The CACHE option is not available on %s\n",
+			device);
+		exit(1);
+	}
+	ret = write_extcsd_value(fd, EXT_CSD_CACHE_CTRL, value);
+	if (ret) {
+		fprintf(stderr,
+			"Could not write 0x%02x to EXT_CSD[%d] in %s\n",
+			value, EXT_CSD_CACHE_CTRL, device);
+		exit(1);
+	}
+
+	return ret;
+}
+
+int do_cache_en(int nargs, char **argv)
+{
+	return do_cache_ctrl(1, nargs, argv);
+}
+
+int do_cache_dis(int nargs, char **argv)
+{
+	return do_cache_ctrl(0, nargs, argv);
+}

mmc_cmds.h

@@ -34,3 +34,5 @@ int do_rpmb_write_key(int nargs, char **argv);
 int do_rpmb_read_counter(int nargs, char **argv);
 int do_rpmb_read_block(int nargs, char **argv);
 int do_rpmb_write_block(int nargs, char **argv);
+int do_cache_en(int nargs, char **argv);
+int do_cache_dis(int nargs, char **argv);