mtd: nand: add accessors, macros for in-memory BBT

There is an abundance of magic numbers and complicated shifting/masking
logic in the in-memory BBT code which makes the code unnecessary complex
and hard to read.

This patch adds macros to represent the 00b, 01b, 10b, and 11b
memory-BBT magic numbers, as well as two accessor functions for reading
and marking the memory-BBT bitfield for a given block.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

diff --git a/drivers/mtd/nand/nand_bbt.c b/drivers/mtd/nand/nand_bbt.c
index 2672643..4c57a9b 100644 (file)
--- a/drivers/mtd/nand/nand_bbt.c
+++ b/drivers/mtd/nand/nand_bbt.c
@@ -71,6 +71,28 @@
 #include <linux/export.h>
 #include <linux/string.h>
 
+#define BBT_BLOCK_GOOD         0x00
+#define BBT_BLOCK_WORN         0x01
+#define BBT_BLOCK_RESERVED     0x02
+#define BBT_BLOCK_FACTORY_BAD  0x03
+
+#define BBT_ENTRY_MASK         0x03
+#define BBT_ENTRY_SHIFT                2
+
+static inline uint8_t bbt_get_entry(struct nand_chip *chip, int block)
+{
+       uint8_t entry = chip->bbt[block >> BBT_ENTRY_SHIFT];
+       entry >>= (block & BBT_ENTRY_MASK) * 2;
+       return entry & BBT_ENTRY_MASK;
+}
+
+static inline void bbt_mark_entry(struct nand_chip *chip, int block,
+               uint8_t mark)
+{
+       uint8_t msk = (mark & BBT_ENTRY_MASK) << ((block & BBT_ENTRY_MASK) * 2);
+       chip->bbt[block >> BBT_ENTRY_SHIFT] |= msk;
+}
+
 static int check_pattern_no_oob(uint8_t *buf, struct nand_bbt_descr *td)
 {
        if (memcmp(buf, td->pattern, td->len))
@@ -216,7 +238,9 @@ static int read_bbt(struct mtd_info *mtd, uint8_t *buf, int page, int num,
                                if (reserved_block_code && (tmp == reserved_block_code)) {
                                        pr_info("nand_read_bbt: reserved block at 0x%012llx\n",
                                                 (loff_t)((offs << 2) + (act >> 1)) << this->bbt_erase_shift);
-                                       this->bbt[offs + (act >> 3)] |= 0x2 << (act & 0x06);
+                                       bbt_mark_entry(this, (offs << 2) +
+                                                       (act >> 1),
+                                                       BBT_BLOCK_RESERVED);
                                        mtd->ecc_stats.bbtblocks++;
                                        continue;
                                }
@@ -228,9 +252,13 @@ static int read_bbt(struct mtd_info *mtd, uint8_t *buf, int page, int num,
                                         (loff_t)((offs << 2) + (act >> 1)) << this->bbt_erase_shift);
                                /* Factory marked bad or worn out? */
                                if (tmp == 0)
-                                       this->bbt[offs + (act >> 3)] |= 0x3 << (act & 0x06);
+                                       bbt_mark_entry(this, (offs << 2) +
+                                                       (act >> 1),
+                                                       BBT_BLOCK_FACTORY_BAD);
                                else
-                                       this->bbt[offs + (act >> 3)] |= 0x1 << (act & 0x06);
+                                       bbt_mark_entry(this, (offs << 2) +
+                                                       (act >> 1),
+                                                       BBT_BLOCK_WORN);
                                mtd->ecc_stats.badblocks++;
                        }
                }
@@ -526,7 +554,7 @@ static int create_bbt(struct mtd_info *mtd, uint8_t *buf,
                        return ret;
 
                if (ret) {
-                       this->bbt[i >> 3] |= 0x03 << (i & 0x6);
+                       bbt_mark_entry(this, i >> 1, BBT_BLOCK_FACTORY_BAD);
                        pr_warn("Bad eraseblock %d at 0x%012llx\n",
                                i >> 1, (unsigned long long)from);
                        mtd->ecc_stats.badblocks++;
@@ -713,10 +741,9 @@ static int write_bbt(struct mtd_info *mtd, uint8_t *buf,
                for (i = 0; i < td->maxblocks; i++) {
                        int block = startblock + dir * i;
                        /* Check, if the block is bad */
-                       switch ((this->bbt[block >> 2] >>
-                                (2 * (block & 0x03))) & 0x03) {
-                       case 0x01:
-                       case 0x03:
+                       switch (bbt_get_entry(this, block)) {
+                       case BBT_BLOCK_WORN:
+                       case BBT_BLOCK_FACTORY_BAD:
                                continue;
                        }
                        page = block <<
@@ -816,7 +843,7 @@ static int write_bbt(struct mtd_info *mtd, uint8_t *buf,
                /* Walk through the memory table */
                for (i = 0; i < numblocks;) {
                        uint8_t dat;
-                       dat = this->bbt[bbtoffs + (i >> 2)];
+                       dat = bbt_get_entry(this, (bbtoffs << 2) + i);
                        for (j = 0; j < 4; j++, i++) {
                                int sftcnt = (i << (3 - sft)) & sftmsk;
                                /* Do not store the reserved bbt blocks! */
@@ -1009,7 +1036,7 @@ static void mark_bbt_region(struct mtd_info *mtd, struct nand_bbt_descr *td)
 {
        struct nand_chip *this = mtd->priv;
        int i, j, chips, block, nrblocks, update;
-       uint8_t oldval, newval;
+       uint8_t oldval;
 
        /* Do we have a bbt per chip? */
        if (td->options & NAND_BBT_PERCHIP) {
@@ -1027,10 +1054,10 @@ static void mark_bbt_region(struct mtd_info *mtd, struct nand_bbt_descr *td)
                                continue;
                        block = td->pages[i] >> (this->bbt_erase_shift - this->page_shift);
                        block <<= 1;
-                       oldval = this->bbt[(block >> 3)];
-                       newval = oldval | (0x2 << (block & 0x06));
-                       this->bbt[(block >> 3)] = newval;
-                       if ((oldval != newval) && td->reserved_block_code)
+                       oldval = bbt_get_entry(this, block >> 1);
+                       bbt_mark_entry(this, block >> 1, BBT_BLOCK_RESERVED);
+                       if ((oldval != BBT_BLOCK_RESERVED) &&
+                                       td->reserved_block_code)
                                nand_update_bbt(mtd, (loff_t)block << (this->bbt_erase_shift - 1));
                        continue;
                }
@@ -1041,10 +1068,9 @@ static void mark_bbt_region(struct mtd_info *mtd, struct nand_bbt_descr *td)
                        block = i * nrblocks;
                block <<= 1;
                for (j = 0; j < td->maxblocks; j++) {
-                       oldval = this->bbt[(block >> 3)];
-                       newval = oldval | (0x2 << (block & 0x06));
-                       this->bbt[(block >> 3)] = newval;
-                       if (oldval != newval)
+                       oldval = bbt_get_entry(this, block >> 1);
+                       bbt_mark_entry(this, block >> 1, BBT_BLOCK_RESERVED);
+                       if (oldval != BBT_BLOCK_RESERVED)
                                update = 1;
                        block += 2;
                }
@@ -1361,18 +1387,18 @@ int nand_isbad_bbt(struct mtd_info *mtd, loff_t offs, int allowbbt)
 
        /* Get block number * 2 */
        block = (int)(offs >> (this->bbt_erase_shift - 1));
-       res = (this->bbt[block >> 3] >> (block & 0x06)) & 0x03;
+       res = bbt_get_entry(this, block >> 1);
 
        pr_debug("nand_isbad_bbt(): bbt info for offs 0x%08x: "
                        "(block %d) 0x%02x\n",
                        (unsigned int)offs, block >> 1, res);
 
        switch ((int)res) {
-       case 0x00:
+       case BBT_BLOCK_GOOD:
                return 0;
-       case 0x01:
+       case BBT_BLOCK_WORN:
                return 1;
-       case 0x02:
+       case BBT_BLOCK_RESERVED:
                return allowbbt ? 0 : 1;
        }
        return 1;