mtd: cfi_cmdset_0002: Add support for writing OTP memory

This patch adds support for writing the one time programmable (OTP)
memory of Micron M29EW devices.

Signed-off-by: Christian Riesch <christian.riesch@omicron.at>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

1 files changed, 60 insertions, 7 deletions

diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c b/drivers/mtd/chips/cfi_cmdset_0002.c
index 612eb3d6902c..6c575e65010b 100644
--- a/drivers/mtd/chips/cfi_cmdset_0002.c
+++ b/drivers/mtd/chips/cfi_cmdset_0002.c
@@ -67,6 +67,8 @@ static int cfi_amdstd_read_fact_prot_reg(struct mtd_info *, loff_t, size_t,
                                          size_t *, u_char *);
 static int cfi_amdstd_read_user_prot_reg(struct mtd_info *, loff_t, size_t,
                                          size_t *, u_char *);
+static int cfi_amdstd_write_user_prot_reg(struct mtd_info *, loff_t, size_t,
+                                          size_t *, u_char *);
 
 static int cfi_amdstd_panic_write(struct mtd_info *mtd, loff_t to, size_t len,
                                   size_t *retlen, const u_char *buf);
@@ -530,6 +532,7 @@ struct mtd_info *cfi_cmdset_0002(struct map_info *map, int primary)
         mtd->_read_fact_prot_reg = cfi_amdstd_read_fact_prot_reg;
         mtd->_get_fact_prot_info = cfi_amdstd_get_fact_prot_info;
         mtd->_get_user_prot_info = cfi_amdstd_get_user_prot_info;
+        mtd->_write_user_prot_reg = cfi_amdstd_write_user_prot_reg;
         mtd->flags   = MTD_CAP_NORFLASH;
         mtd->name    = map->name;
         mtd->writesize = 1;
@@ -1257,6 +1260,40 @@ static int cfi_amdstd_secsi_read (struct mtd_info *mtd, loff_t from, size_t len,
         return ret;
 }
 
+static int __xipram do_write_oneword(struct map_info *map, struct flchip *chip,
+                                     unsigned long adr, map_word datum,
+                                     int mode);
+
+static int do_otp_write(struct map_info *map, struct flchip *chip, loff_t adr,
+                        size_t len, u_char *buf)
+{
+        int ret;
+        while (len) {
+                unsigned long bus_ofs = adr & ~(map_bankwidth(map)-1);
+                int gap = adr - bus_ofs;
+                int n = min_t(int, len, map_bankwidth(map) - gap);
+                map_word datum;
+
+                if (n != map_bankwidth(map)) {
+                        /* partial write of a word, load old contents */
+                        otp_enter(map, chip, bus_ofs, map_bankwidth(map));
+                        datum = map_read(map, bus_ofs);
+                        otp_exit(map, chip, bus_ofs, map_bankwidth(map));
+                }
+
+                datum = map_word_load_partial(map, datum, buf, gap, n);
+                ret = do_write_oneword(map, chip, bus_ofs, datum, FL_OTP_WRITE);
+                if (ret)
+                        return ret;
+
+                adr += n;
+                buf += n;
+                len -= n;
+        }
+
+        return 0;
+}
+
 static int cfi_amdstd_otp_walk(struct mtd_info *mtd, loff_t from, size_t len,
                                size_t *retlen, u_char *buf,
                                otp_op_t action, int user_regs)
@@ -1400,7 +1437,17 @@ static int cfi_amdstd_read_user_prot_reg(struct mtd_info *mtd, loff_t from,
                                    buf, do_read_secsi_onechip, 1);
 }
 
-static int __xipram do_write_oneword(struct map_info *map, struct flchip *chip, unsigned long adr, map_word datum)
+static int cfi_amdstd_write_user_prot_reg(struct mtd_info *mtd, loff_t from,
+                                          size_t len, size_t *retlen,
+                                          u_char *buf)
+{
+        return cfi_amdstd_otp_walk(mtd, from, len, retlen, buf,
+                                   do_otp_write, 1);
+}
+
+static int __xipram do_write_oneword(struct map_info *map, struct flchip *chip,
+                                     unsigned long adr, map_word datum,
+                                     int mode)
 {
         struct cfi_private *cfi = map->fldrv_priv;
         unsigned long timeo = jiffies + HZ;
@@ -1421,7 +1468,7 @@ static int __xipram do_write_oneword(struct map_info *map, struct flchip *chip,
         adr += chip->start;
 
         mutex_lock(&chip->mutex);
-        ret = get_chip(map, chip, adr, FL_WRITING);
+        ret = get_chip(map, chip, adr, mode);
         if (ret) {
                 mutex_unlock(&chip->mutex);
                 return ret;
@@ -1430,6 +1477,9 @@ static int __xipram do_write_oneword(struct map_info *map, struct flchip *chip,
         pr_debug("MTD %s(): WRITE 0x%.8lx(0x%.8lx)\n",
                __func__, adr, datum.x[0] );
 
+        if (mode == FL_OTP_WRITE)
+                otp_enter(map, chip, adr, map_bankwidth(map));
+
         /*
          * Check for a NOP for the case when the datum to write is already
          * present - it saves time and works around buggy chips that corrupt
@@ -1446,12 +1496,13 @@ static int __xipram do_write_oneword(struct map_info *map, struct flchip *chip,
         XIP_INVAL_CACHED_RANGE(map, adr, map_bankwidth(map));
         ENABLE_VPP(map);
         xip_disable(map, chip, adr);
+
  retry:
         cfi_send_gen_cmd(0xAA, cfi->addr_unlock1, chip->start, map, cfi, cfi->device_type, NULL);
         cfi_send_gen_cmd(0x55, cfi->addr_unlock2, chip->start, map, cfi, cfi->device_type, NULL);
         cfi_send_gen_cmd(0xA0, cfi->addr_unlock1, chip->start, map, cfi, cfi->device_type, NULL);
         map_write(map, datum, adr);
-        chip->state = FL_WRITING;
+        chip->state = mode;
 
         INVALIDATE_CACHE_UDELAY(map, chip,
                                 adr, map_bankwidth(map),
@@ -1460,7 +1511,7 @@ static int __xipram do_write_oneword(struct map_info *map, struct flchip *chip,
         /* See comment above for timeout value. */
         timeo = jiffies + uWriteTimeout;
         for (;;) {
-                if (chip->state != FL_WRITING) {
+                if (chip->state != mode) {
                         /* Someone's suspended the write. Sleep */
                         DECLARE_WAITQUEUE(wait, current);
 
@@ -1500,6 +1551,8 @@ static int __xipram do_write_oneword(struct map_info *map, struct flchip *chip,
         }
         xip_enable(map, chip, adr);
  op_done:
+        if (mode == FL_OTP_WRITE)
+                otp_exit(map, chip, adr, map_bankwidth(map));
         chip->state = FL_READY;
         DISABLE_VPP(map);
         put_chip(map, chip, adr);
@@ -1555,7 +1608,7 @@ static int cfi_amdstd_write_words(struct mtd_info *mtd, loff_t to, size_t len,
                 tmp_buf = map_word_load_partial(map, tmp_buf, buf, i, n);
 
                 ret = do_write_oneword(map, &cfi->chips[chipnum],
-                                       bus_ofs, tmp_buf);
+                                       bus_ofs, tmp_buf, FL_WRITING);
                 if (ret)
                         return ret;
 
@@ -1579,7 +1632,7 @@ static int cfi_amdstd_write_words(struct mtd_info *mtd, loff_t to, size_t len,
                 datum = map_word_load(map, buf);
 
                 ret = do_write_oneword(map, &cfi->chips[chipnum],
-                                       ofs, datum);
+                                       ofs, datum, FL_WRITING);
                 if (ret)
                         return ret;
 
@@ -1622,7 +1675,7 @@ static int cfi_amdstd_write_words(struct mtd_info *mtd, loff_t to, size_t len,
                 tmp_buf = map_word_load_partial(map, tmp_buf, buf, 0, len);
 
                 ret = do_write_oneword(map, &cfi->chips[chipnum],
-                                ofs, tmp_buf);
+                                       ofs, tmp_buf, FL_WRITING);
                 if (ret)
                         return ret;