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Subject[PATCH v2 8/8] partitions/tegra: Implement eMMC boot partitions scanning
Date
Some NVIDIA Tegra devices store partition table on eMMC boot partition.
In order to support this case, the tegra-partition parser will read out
partition table from a boot partition and stash it for the main eMMC
partition.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
block/partitions/tegra.c | 122 +++++++++++++++++++++++++++++++++++----
1 file changed, 110 insertions(+), 12 deletions(-)

diff --git a/block/partitions/tegra.c b/block/partitions/tegra.c
index 6f150a7e3275..153928eef60b 100644
--- a/block/partitions/tegra.c
+++ b/block/partitions/tegra.c
@@ -25,6 +25,7 @@
#include <linux/mmc/blkdev.h>
#include <linux/mmc/card.h>
#include <linux/mmc/host.h>
+#include <linux/mmc/mmc.h>

#include <soc/tegra/common.h>
#include <soc/tegra/partition.h>
@@ -50,7 +51,10 @@
struct tegra_partition_table_parser {
struct tegra_partition_table *pt;
struct parsed_partitions *state;
+ struct mmc_card *card;
bool pt_entry_checked;
+ unsigned int boot_id;
+ bool snapshot_mode;
sector_t sector;
int boot_offset;
u32 dev_instance;
@@ -67,6 +71,7 @@ struct tegra_partition_type {
char *name;
};

+static struct tegra_partition_table *scratch_pt;
static sector_t tegra_pt_sector_address;
static sector_t tegra_pt_sectors_num;

@@ -224,6 +229,10 @@ static bool tegra_partition_valid(struct tegra_partition_table_parser *ptp,
return false;
}

+ /* size will be validated when ptp->snapshot_mode=false */
+ if (ptp->snapshot_mode && size)
+ return true;
+
sect_end = get_capacity(ptp->state->bdev->bd_disk);

/* eMMC boot partitions are below ptp->boot_offset */
@@ -369,6 +378,7 @@ tegra_partition_table_emmc_boot_offset(struct tegra_partition_table_parser *ptp)
{
struct mmc_card *card = mmc_bdev_to_card(ptp->state->bdev);
const struct of_device_id *matched;
+ int part_type, area_type;
const u32 *sdhci_bases;
u32 sdhci_base;
unsigned int i;
@@ -404,6 +414,32 @@ tegra_partition_table_emmc_boot_offset(struct tegra_partition_table_parser *ptp)
ptp->dev_id = TEGRA_PT_SDHCI_DEVICE_ID;
ptp->dev_instance = i;

+ area_type = mmc_bdev_to_area_type(ptp->state->bdev);
+
+ if (WARN_ON(area_type < 0))
+ return -1;
+
+ switch (area_type) {
+ case MMC_BLK_DATA_AREA_BOOT:
+ part_type = mmc_bdev_to_part_type(ptp->state->bdev);
+
+ if (WARN_ON(part_type < 0))
+ return -1;
+
+ ptp->boot_id = part_type - EXT_CSD_PART_CONFIG_ACC_BOOT0;
+ ptp->snapshot_mode = true;
+ break;
+
+ case MMC_BLK_DATA_AREA_MAIN:
+ break;
+
+ default:
+ TEGRA_PT_ERR(ptp, "unexpected area_type: %u\n", area_type);
+ return -1;
+ }
+
+ ptp->card = card;
+
/*
* eMMC storage has two special boot partitions in addition to the
* main one. NVIDIA's bootloader linearizes eMMC boot0->boot1->main
@@ -427,6 +463,9 @@ static int tegra_read_partition_table(struct tegra_partition_table_parser *ptp)
Sector sect;
void *part;

+ if (scratch_pt)
+ return 1;
+
for (i = 0; i < ARRAY_SIZE(ptu->pt_parts); i++) {
/*
* Partition table takes at maximum 4096 bytes, but
@@ -449,29 +488,77 @@ static int tegra_read_partition_table(struct tegra_partition_table_parser *ptp)

int tegra_partition(struct parsed_partitions *state)
{
- struct tegra_partition_table_parser ptp = { .state = state };
+ struct tegra_partition_table_parser ptp = { 0 };
sector_t end_sector;
int ret = 0;

if (!soc_is_tegra())
return 0;

+ ptp.state = state;
+
ptp.boot_offset = tegra_partition_table_emmc_boot_offset(&ptp);
if (ptp.boot_offset < 0)
return 0;

- if (tegra_pt_sector_address < ptp.boot_offset) {
- TEGRA_PT_INFO(&ptp,
- "scanning eMMC boot partitions unimplemented\n");
- return 0;
- }
+ /*
+ * Some devices store partition table on boot MMC partition.
+ * In this case a "snapshot mode" will be used, which will
+ * only read->check->store partition table, the stored table
+ * will be used for the main MMC partition later on.
+ */
+ if (ptp.snapshot_mode) {
+ sector_t boot_start, boot_end, boot_size;

- ptp.pt = kmalloc(sizeof(*ptp.pt), GFP_KERNEL);
- if (!ptp.pt)
- return 0;
+ /* partition is already snapshoted, no need to proceed */
+ if (scratch_pt)
+ return 0;
+
+ boot_size = ptp.boot_offset / MMC_NUM_BOOT_PARTITION;
+ boot_start = ptp.boot_id * boot_size;
+ boot_end = boot_start + boot_size;
+
+ /*
+ * Bail out if partition table isn't located here, at this MMC
+ * partition.
+ */
+ if (tegra_pt_sector_address < boot_start ||
+ tegra_pt_sector_address >= boot_end)
+ return 0;
+
+ ptp.boot_offset = boot_start;
+
+ /*
+ * Note that mmc_blk_probe() always registers boot partitions
+ * after the main and we rely on this feature, otherwise
+ * scratch_pt won't be released (although this is not a big
+ * deal).
+ */
+ ptp.pt = kmalloc(sizeof(*ptp.pt), GFP_KERNEL);
+ if (!ptp.pt)
+ return 0;
+
+ ptp.sector = tegra_pt_sector_address - ptp.boot_offset;
+ end_sector = ptp.sector + tegra_pt_sectors_num;

- ptp.sector = tegra_pt_sector_address - ptp.boot_offset;
- end_sector = ptp.sector + tegra_pt_sectors_num;
+ } else if (scratch_pt) {
+ TEGRA_PT_INFO(&ptp, "using stashed partition table\n");
+
+ ptp.pt = scratch_pt;
+ ptp.sector = 0;
+ end_sector = 1;
+
+ } else {
+ if (tegra_pt_sector_address < ptp.boot_offset)
+ return 0;
+
+ ptp.pt = kmalloc(sizeof(*ptp.pt), GFP_KERNEL);
+ if (!ptp.pt)
+ return 0;
+
+ ptp.sector = tegra_pt_sector_address - ptp.boot_offset;
+ end_sector = ptp.sector + tegra_pt_sectors_num;
+ }

/*
* Partition table is duplicated till the end_sector.
@@ -501,9 +588,20 @@ int tegra_partition(struct parsed_partitions *state)
ptp.sector += TEGRA_PT_SECTOR_SZ;
}

- if (ret == 1)
+ if (ret == 1) {
+ if (ptp.snapshot_mode) {
+ ptp.card->quirks |= MMC_QUIRK_RESCAN_MAIN_BLKDEV;
+ scratch_pt = ptp.pt;
+
+ TEGRA_PT_INFO(&ptp, "stashed partition table\n");
+
+ return 0;
+ }
+
strlcat(state->pp_buf, "\n", PAGE_SIZE);
+ }

+ scratch_pt = NULL;
kfree(ptp.pt);

return ret;
--
2.25.1
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