mmc: add bkops-enable command

Add new command that provides possibility to enable the
background operations handshake functionality
(BKOPS_EN, EXT_CSD byte [163]) on eMMC devices.

This is an optional feature of eMMCs, the setting is write-once.
The command must be explicitly taken into use with
CONFIG_CMD_BKOPS_ENABLE.

Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>

cmd/Kconfig

@@ -572,6 +572,15 @@ config SYS_AMBAPP_PRINT_ON_STARTUP
 	help
 	  Show AMBA Plug-n-Play information on startup.
 
+config CMD_BKOPS_ENABLE
+	bool "mmc bkops enable"
+	depends on CMD_MMC
+	default n
+	help
+	  Enable command for setting manual background operations handshake
+	  on a eMMC device. The feature is optionally available on eMMC devices
+	  conforming to standard >= 4.41.
+
 config CMD_BLOCK_CACHE
 	bool "blkcache - control and stats for block cache"
 	depends on BLOCK_CACHE

cmd/mmc.c

@@ -729,6 +729,31 @@ static int do_mmc_setdsr(cmd_tbl_t *cmdtp, int flag,
 	return ret;
 }
 
+#ifdef CONFIG_CMD_BKOPS_ENABLE
+static int do_mmc_bkops_enable(cmd_tbl_t *cmdtp, int flag,
+				   int argc, char * const argv[])
+{
+	int dev;
+	struct mmc *mmc;
+
+	if (argc != 2)
+		return CMD_RET_USAGE;
+
+	dev = simple_strtoul(argv[1], NULL, 10);
+
+	mmc = init_mmc_device(dev, false);
+	if (!mmc)
+		return CMD_RET_FAILURE;
+
+	if (IS_SD(mmc)) {
+		puts("BKOPS_EN only exists on eMMC\n");
+		return CMD_RET_FAILURE;
+	}
+
+	return mmc_set_bkops_enable(mmc);
+}
+#endif
+
 static cmd_tbl_t cmd_mmc[] = {
 	U_BOOT_CMD_MKENT(info, 1, 0, do_mmcinfo, "", ""),
 	U_BOOT_CMD_MKENT(read, 4, 1, do_mmc_read, "", ""),
@@ -749,6 +774,9 @@ static cmd_tbl_t cmd_mmc[] = {
 	U_BOOT_CMD_MKENT(rpmb, CONFIG_SYS_MAXARGS, 1, do_mmcrpmb, "", ""),
 #endif
 	U_BOOT_CMD_MKENT(setdsr, 2, 0, do_mmc_setdsr, "", ""),
+#ifdef CONFIG_CMD_BKOPS_ENABLE
+	U_BOOT_CMD_MKENT(bkops-enable, 2, 0, do_mmc_bkops_enable, "", ""),
+#endif
 };
 
 static int do_mmcops(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
@@ -813,6 +841,10 @@ U_BOOT_CMD(
 	"mmc rpmb counter - read the value of the write counter\n"
 #endif
 	"mmc setdsr <value> - set DSR register value\n"
+#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
 	);
 
 /* Old command kept for compatibility. Same as 'mmc info' */

drivers/mmc/mmc.c

@@ -1817,3 +1817,37 @@ int mmc_initialize(bd_t *bis)
 	mmc_do_preinit();
 	return 0;
 }
+
+#ifdef CONFIG_CMD_BKOPS_ENABLE
+int mmc_set_bkops_enable(struct mmc *mmc)
+{
+	int err;
+	ALLOC_CACHE_ALIGN_BUFFER(u8, ext_csd, MMC_MAX_BLOCK_LEN);
+
+	err = mmc_send_ext_csd(mmc, ext_csd);
+	if (err) {
+		puts("Could not get ext_csd register values\n");
+		return err;
+	}
+
+	if (!(ext_csd[EXT_CSD_BKOPS_SUPPORT] & 0x1)) {
+		puts("Background operations not supported on device\n");
+		return -EMEDIUMTYPE;
+	}
+
+	if (ext_csd[EXT_CSD_BKOPS_EN] & 0x1) {
+		puts("Background operations already enabled\n");
+		return 0;
+	}
+
+	err = mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL, EXT_CSD_BKOPS_EN, 1);
+	if (err) {
+		puts("Failed to enable manual background operations\n");
+		return err;
+	}
+
+	puts("Enabled manual background operations\n");
+
+	return 0;
+}
+#endif

include/mmc.h

@@ -174,6 +174,7 @@
 #define EXT_CSD_MAX_ENH_SIZE_MULT	157	/* R */
 #define EXT_CSD_PARTITIONING_SUPPORT	160	/* RO */
 #define EXT_CSD_RST_N_FUNCTION		162	/* R/W */
+#define EXT_CSD_BKOPS_EN		163	/* R/W & R/W/E */
 #define EXT_CSD_WR_REL_PARAM		166	/* R */
 #define EXT_CSD_WR_REL_SET		167	/* R/W */
 #define EXT_CSD_RPMB_MULT		168	/* RO */
@@ -188,6 +189,7 @@
 #define EXT_CSD_HC_WP_GRP_SIZE		221	/* RO */
 #define EXT_CSD_HC_ERASE_GRP_SIZE	224	/* RO */
 #define EXT_CSD_BOOT_MULT		226	/* RO */
+#define EXT_CSD_BKOPS_SUPPORT		502	/* RO */
 
 /*
  * EXT_CSD field definitions
@@ -540,6 +542,10 @@ int mmc_rpmb_read(struct mmc *mmc, void *addr, unsigned short blk,
 		  unsigned short cnt, unsigned char *key);
 int mmc_rpmb_write(struct mmc *mmc, void *addr, unsigned short blk,
 		   unsigned short cnt, unsigned char *key);
+#ifdef CONFIG_CMD_BKOPS_ENABLE
+int mmc_set_bkops_enable(struct mmc *mmc);
+#endif
+
 /**
  * Start device initialization and return immediately; it does not block on
  * polling OCR (operation condition register) status.  Then you should call