[PATCH v2 u-boot-mvebu 2/4] mmc: Read eMMC partition access bits before card reset

Pali Rohár
2023-04-13T20:59:41Z

eMMC specification in section "Access partitions" says that all reset
events will restore the access bits in PARTITION_CONFIG CSD register to
default User Data Area value (0b000).

So read partition access bits from PARTITION_CONFIG CSD register before
issuing card reset. This allows SPL/U-Boot to get information which eMMC
partition was in use before SPL/U-Boot was booted. For some platforms this
is the way how to determinate boot partition from which BootROM loaded SPL.

Signed-off-by: Pali Rohár <pali@kernel.org>
---
drivers/mmc/mmc.c | 31 ++++++++++++++++++++++++++++---
1 file changed, 28 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index dde251c87bc7..771432de354d 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -2329,8 +2329,17 @@ static int mmc_startup_v4(struct mmc *mmc)
/* store the partition info of emmc */
mmc->part_support = ext_csd[EXT_CSD_PARTITIONING_SUPPORT];
if ((ext_csd[EXT_CSD_PARTITIONING_SUPPORT] & PART_SUPPORT) ||
- ext_csd[EXT_CSD_BOOT_MULT])
- mmc->part_config = ext_csd[EXT_CSD_PART_CONF];
+ ext_csd[EXT_CSD_BOOT_MULT]) {
+ /*
+ * At this stage PART_ACCESS_MASK bits in ext_csd[] are already cleared.
+ * But it is possible that they were already filled into mmc->part_config.
+ */
+ if (mmc->part_config == MMCPART_NOAVAILABLE)
+ mmc->part_config = ext_csd[EXT_CSD_PART_CONF];
+ else
+ mmc->part_config = (ext_csd[EXT_CSD_PART_CONF] & ~PART_ACCESS_MASK) |
+ (mmc->part_config & PART_ACCESS_MASK);
+ }
if (part_completed &&
(ext_csd[EXT_CSD_PARTITIONING_SUPPORT] & ENHNCD_SUPPORT))
mmc->part_attr = ext_csd[EXT_CSD_PARTITIONS_ATTRIBUTE];
@@ -2600,7 +2609,6 @@ static int mmc_startup(struct mmc *mmc)
#if CONFIG_IS_ENABLED(MMC_WRITE)
mmc->erase_grp_size = 1;
#endif
- mmc->part_config = MMCPART_NOAVAILABLE;

err = mmc_startup_v4(mmc);
if (err)
@@ -2848,9 +2856,26 @@ int mmc_get_op_cond(struct mmc *mmc, bool quiet)
return err;
mmc->ddr_mode = 0;

+ mmc->part_config = MMCPART_NOAVAILABLE;
+
retry:
mmc_set_initial_state(mmc);

+ /*
+ * Read partition access bits from partition config register before card reset command
+ * because these bits are reset to default value (User Data Area) during card reset.
+ * This allows us to preserve original value of partition access bits used by the code
+ * which loaded us (for example BootROM) and use it for board specific boot purposes.
+ */
+ if (mmc->part_config == MMCPART_NOAVAILABLE) {
+ ALLOC_CACHE_ALIGN_BUFFER(u8, ext_csd, MMC_MAX_BLOCK_LEN);
+ err = mmc_send_ext_csd(mmc, ext_csd);
+ if (err == 0 &&
+ ((ext_csd[EXT_CSD_PARTITIONING_SUPPORT] & PART_SUPPORT) ||
+ ext_csd[EXT_CSD_BOOT_MULT]))
+ mmc->part_config = ext_csd[EXT_CSD_PART_CONF] & PART_ACCESS_MASK;
+ }
+
/* Reset the Card */
err = mmc_go_idle(mmc);

--
2.20.1