[MTD] NAND workaround for AG-AND disturb issue. AG-AND recovery

Added workaround for Renesas AG-AND chips "disturb" issue 
for Bad Block Table. 
Added support for the device recovery command sequence 
for Renesas AG-AND chips.

Signed-off-by: David A. Marlin <dmarlin@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 69 insertions, 5 deletions

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 44d5b128911f..2ac452e3ad6b 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -28,6 +28,20 @@
  *              among multiple independend devices. Suggestions and initial patch
  *              from Ben Dooks <ben-mtd@fluff.org>
  *
+ *  12-05-2004  dmarlin: add workaround for Renesas AG-AND chips "disturb" issue.
+ *              Basically, any block not rewritten may lose data when surrounding blocks
+ *              are rewritten many times.  JFFS2 ensures this doesn't happen for blocks 
+ *              it uses, but the Bad Block Table(s) may not be rewritten.  To ensure they
+ *              do not lose data, force them to be rewritten when some of the surrounding
+ *              blocks are erased.  Rather than tracking a specific nearby block (which 
+ *              could itself go bad), use a page address 'mask' to select several blocks 
+ *              in the same area, and rewrite the BBT when any of them are erased.
+ *
+ *  01-03-2005  dmarlin: added support for the device recovery command sequence for Renesas 
+ *              AG-AND chips.  If there was a sudden loss of power during an erase operation,
+ *              a "device recovery" operation must be performed when power is restored
+ *              to ensure correct operation.
+ *
  * Credits:
  *      David Woodhouse for adding multichip support  
  *      
@@ -41,7 +55,7 @@
  *      The AG-AND chips have nice features for speed improvement,
  *      which are not supported yet. Read / program 4 pages in one go.
  *
- * $Id: nand_base.c,v 1.126 2004/12/13 11:22:25 lavinen Exp $
+ * $Id: nand_base.c,v 1.127 2005/01/17 18:35:22 dmarlin Exp $
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -619,7 +633,7 @@ static void nand_command_lp (struct mtd_info *mtd, unsigned command, int column,
         /* Begin command latch cycle */
         this->hwcontrol(mtd, NAND_CTL_SETCLE);
         /* Write out the command to the device. */
-        this->write_byte(mtd, command);
+        this->write_byte(mtd, (command & 0xff));
         /* End command latch cycle */
         this->hwcontrol(mtd, NAND_CTL_CLRCLE);
 
@@ -647,8 +661,8 @@ static void nand_command_lp (struct mtd_info *mtd, unsigned command, int column,
         
         /* 
          * program and erase have their own busy handlers 
-         * status and sequential in needs no delay
-        */
+         * status, sequential in, and deplete1 need no delay
+         */
         switch (command) {
                         
         case NAND_CMD_CACHEDPROG:
@@ -657,8 +671,19 @@ static void nand_command_lp (struct mtd_info *mtd, unsigned command, int column,
         case NAND_CMD_ERASE2:
         case NAND_CMD_SEQIN:
         case NAND_CMD_STATUS:
+        case NAND_CMD_DEPLETE1:
                 return;
 
+        /* 
+         * read error status commands require only a short delay
+         */
+        case NAND_CMD_STATUS_ERROR:
+        case NAND_CMD_STATUS_ERROR0:
+        case NAND_CMD_STATUS_ERROR1:
+        case NAND_CMD_STATUS_ERROR2:
+        case NAND_CMD_STATUS_ERROR3:
+                udelay(this->chip_delay);
+                return;
 
         case NAND_CMD_RESET:
                 if (this->dev_ready)    
@@ -1051,7 +1076,7 @@ static int nand_read_ecc (struct mtd_info *mtd, loff_t from, size_t len,
         }
 
         /* Grab the lock and see if the device is available */
-        nand_get_device (this, mtd ,FL_READING);
+        nand_get_device (this, mtd, FL_READING);
 
         /* use userspace supplied oobinfo, if zero */
         if (oobsel == NULL)
@@ -1987,6 +2012,7 @@ static int nand_erase (struct mtd_info *mtd, struct erase_info *instr)
         return nand_erase_nand (mtd, instr, 0);
 }
  
+#define BBT_PAGE_MASK   0xffffff3f
 /**
  * nand_erase_intern - [NAND Interface] erase block(s)
  * @mtd:        MTD device structure
@@ -1999,6 +2025,10 @@ int nand_erase_nand (struct mtd_info *mtd, struct erase_info *instr, int allowbb
 {
         int page, len, status, pages_per_block, ret, chipnr;
         struct nand_chip *this = mtd->priv;
+        int rewrite_bbt[NAND_MAX_CHIPS]={0};    /* flags to indicate the page, if bbt needs to be rewritten. */
+        unsigned int bbt_masked_page;           /* bbt mask to compare to page being erased. */
+                                                /* It is used to see if the current page is in the same */
+                                                /*   256 block group and the same bank as the bbt. */
 
         DEBUG (MTD_DEBUG_LEVEL3,
                "nand_erase: start = 0x%08x, len = %i\n", (unsigned int) instr->addr, (unsigned int) instr->len);
@@ -2044,6 +2074,13 @@ int nand_erase_nand (struct mtd_info *mtd, struct erase_info *instr, int allowbb
                 goto erase_exit;
         }
 
+        /* if BBT requires refresh, set the BBT page mask to see if the BBT should be rewritten */
+        if (this->options & BBT_AUTO_REFRESH) {
+                bbt_masked_page = this->bbt_td->pages[chipnr] & BBT_PAGE_MASK;
+        } else {
+                bbt_masked_page = 0xffffffff;   /* should not match anything */
+        }
+
         /* Loop through the pages */
         len = instr->len;
 
@@ -2073,6 +2110,14 @@ int nand_erase_nand (struct mtd_info *mtd, struct erase_info *instr, int allowbb
                         instr->fail_addr = (page << this->page_shift);
                         goto erase_exit;
                 }
+
+                /* if BBT requires refresh, set the BBT rewrite flag to the page being erased */
+                if (this->options & BBT_AUTO_REFRESH) {
+                        if (((page & BBT_PAGE_MASK) == bbt_masked_page) && 
+                             (page != this->bbt_td->pages[chipnr])) {
+                                rewrite_bbt[chipnr] = (page << this->page_shift);
+                        }
+                }
                 
                 /* Increment page address and decrement length */
                 len -= (1 << this->phys_erase_shift);
@@ -2083,6 +2128,13 @@ int nand_erase_nand (struct mtd_info *mtd, struct erase_info *instr, int allowbb
                         chipnr++;
                         this->select_chip(mtd, -1);
                         this->select_chip(mtd, chipnr);
+
+                        /* if BBT requires refresh and BBT-PERCHIP, 
+                         *   set the BBT page mask to see if this BBT should be rewritten */
+                        if ((this->options & BBT_AUTO_REFRESH) && (this->bbt_td->options & NAND_BBT_PERCHIP)) {
+                                bbt_masked_page = this->bbt_td->pages[chipnr] & BBT_PAGE_MASK;
+                        }
+
                 }
         }
         instr->state = MTD_ERASE_DONE;
@@ -2097,6 +2149,18 @@ erase_exit:
         /* Deselect and wake up anyone waiting on the device */
         nand_release_device(mtd);
 
+        /* if BBT requires refresh and erase was successful, rewrite any selected bad block tables */
+        if ((this->options & BBT_AUTO_REFRESH) && (!ret)) {
+                for (chipnr = 0; chipnr < this->numchips; chipnr++) {
+                        if (rewrite_bbt[chipnr]) {
+                                /* update the BBT for chip */
+                                DEBUG (MTD_DEBUG_LEVEL0, "nand_erase_nand: nand_update_bbt (%d:0x%0x 0x%0x)\n", 
+                                        chipnr, rewrite_bbt[chipnr], this->bbt_td->pages[chipnr]);
+                                nand_update_bbt (mtd, rewrite_bbt[chipnr]);
+                        }
+                }
+        }
+
         /* Return more or less happy */
         return ret;
 }