drivers: mmc: RPMB support

Access to RPMB always uses the multiple blocks command even if there's
just one block to be handled. RPMB access also requires us to set
the block count. Because the standard says so.

This seems to be different between manufacturers, at least some Micron
memories seem fine without this and just works when reading blocks.
Other memories refuse to do read accesses without this and the standard
also says that it should be done in this way.

src/drivers/mmc/mmc_core.c

@@ -36,6 +36,7 @@ static uint32_t rca;
 static struct mmc_csd_emmc mmc_csd;
 static uint8_t mmc_ext_csd[512] __aligned(64);
 static uint8_t mmc_current_part_config;
+static enum mmc_part mmc_current_part;
 static unsigned int power_off_long_time_ms = 2550;
 static unsigned int generic_cmd6_time_ms = 2550;
 static unsigned int partition_switch_time_ms = 2550;
@@ -742,10 +743,20 @@ int mmc_read(unsigned int lba, size_t length, uintptr_t buf)
         return ret;
     }
 
-    if (length > MMC_BLOCK_SIZE) {
+    /* See comment in 'mmc_write' */
+    if (mmc_current_part == MMC_PART_RPMB) {
+        ret = mmc_send_cmd(MMC_CMD_SET_BLOCK_COUNT, length / 512, MMC_RSP_R1, NULL);
+        if (ret != 0) {
+            return ret;
+        }
+
         cmd_idx = MMC_CMD_READ_MULTIPLE_BLOCK;
     } else {
-        cmd_idx = MMC_CMD_READ_SINGLE_BLOCK;
+        if (length > MMC_BLOCK_SIZE) {
+            cmd_idx = MMC_CMD_READ_MULTIPLE_BLOCK;
+        } else {
+            cmd_idx = MMC_CMD_READ_SINGLE_BLOCK;
+        }
     }
 
     ret = mmc_send_cmd(cmd_idx, lba, MMC_RSP_R1, NULL);
@@ -786,10 +797,28 @@ int mmc_write(unsigned int lba, size_t length, const uintptr_t buf)
         return ret;
     }
 
-    if (length > MMC_BLOCK_SIZE) {
+    /* Access to RPMB always uses the multiple blocks command even if there's
+     * just one block to be handled. RPMB access also requires us to set
+     * the block count. Because the standard says so.
+     *
+     * This seems to be different between manufacturers, at least some Micron
+     * memories seem fine without this and just works when reading blocks.
+     * Other memories refuse to do read accesses without this and the standard
+     * also says that it should be done in this way.
+     */
+    if (mmc_current_part == MMC_PART_RPMB) {
+        ret = mmc_send_cmd(MMC_CMD_SET_BLOCK_COUNT, length / 512, MMC_RSP_R1, NULL);
+        if (ret != 0) {
+            return ret;
+        }
+
         cmd_idx = MMC_CMD_WRITE_MULTIPLE_BLOCK;
     } else {
-        cmd_idx = MMC_CMD_WRITE_SINGLE_BLOCK;
+        if (length > MMC_BLOCK_SIZE) {
+            cmd_idx = MMC_CMD_WRITE_MULTIPLE_BLOCK;
+        } else {
+            cmd_idx = MMC_CMD_WRITE_SINGLE_BLOCK;
+        }
     }
 
     ret = mmc_send_cmd(cmd_idx, lba, MMC_RSP_R1, NULL);
@@ -844,6 +873,8 @@ int mmc_part_switch(enum mmc_part part)
         return -PB_ERR_IO;
     }
 
+    mmc_current_part = part;
+
     /* Switch active partition */
     if (value != mmc_current_part_config) {
         mmc_current_part_config = value;