drivers/mtd/nand/nand_bcm_umi.c

   1 /*****************************************************************************
   2 * Copyright 2004 - 2009 Broadcom Corporation.  All rights reserved.
   3 *
   4 * Unless you and Broadcom execute a separate written software license
   5 * agreement governing use of this software, this software is licensed to you
   6 * under the terms of the GNU General Public License version 2, available at
   7 * http://www.broadcom.com/licenses/GPLv2.php (the "GPL").
   8 *
   9 * Notwithstanding the above, under no circumstances may you combine this
  10 * software in any way with any other Broadcom software provided under a
  11 * license other than the GPL, without Broadcom's express prior written
  12 * consent.
  13 *****************************************************************************/
  14
  15 /* ---- Include Files ---------------------------------------------------- */
  16 #include <mach/reg_umi.h>
  17 #include "nand_bcm_umi.h"
  18 #ifdef BOOT0_BUILD
  19 #include <uart.h>
  20 #endif
  21
  22 /* ---- External Variable Declarations ----------------------------------- */
  23 /* ---- External Function Prototypes ------------------------------------- */
  24 /* ---- Public Variables ------------------------------------------------- */
  25 /* ---- Private Constants and Types -------------------------------------- */
  26 /* ---- Private Function Prototypes -------------------------------------- */
  27 /* ---- Private Variables ------------------------------------------------ */
  28 /* ---- Private Functions ------------------------------------------------ */
  29
  30 #if NAND_ECC_BCH
  31 /****************************************************************************
  32 *  nand_bch_ecc_flip_bit - Routine to flip an errored bit
  33 *
  34 *  PURPOSE:
  35 *     This is a helper routine that flips the bit (0 -> 1 or 1 -> 0) of the
  36 *     errored bit specified
  37 *
  38 *  PARAMETERS:
  39 *     datap - Container that holds the 512 byte data
  40 *     errorLocation - Location of the bit that needs to be flipped
  41 *
  42 *  RETURNS:
  43 *     None
  44 ****************************************************************************/
  45 static void nand_bcm_umi_bch_ecc_flip_bit(uint8_t *datap, int errorLocation)
  46 {
  47         int locWithinAByte = (errorLocation & REG_UMI_BCH_ERR_LOC_BYTE) >> 0;
  48         int locWithinAWord = (errorLocation & REG_UMI_BCH_ERR_LOC_WORD) >> 3;
  49         int locWithinAPage = (errorLocation & REG_UMI_BCH_ERR_LOC_PAGE) >> 5;
  50
  51         uint8_t errorByte = 0;
  52         uint8_t byteMask = 1 << locWithinAByte;
  53
  54         /* BCH uses big endian, need to change the location
  55          * bits to little endian */
  56         locWithinAWord = 3 - locWithinAWord;
  57
  58         errorByte = datap[locWithinAPage * sizeof(uint32_t) + locWithinAWord];
  59
  60 #ifdef BOOT0_BUILD
  61         puthexs("\nECC Correct Offset: ",
  62                 locWithinAPage * sizeof(uint32_t) + locWithinAWord);
  63         puthexs(" errorByte:", errorByte);
  64         puthex8(" Bit: ", locWithinAByte);
  65 #endif
  66
  67         if (errorByte & byteMask) {
  68                 /* bit needs to be cleared */
  69                 errorByte &= ~byteMask;
  70         } else {
  71                 /* bit needs to be set */
  72                 errorByte |= byteMask;
  73         }
  74
  75         /* write back the value with the fixed bit */
  76         datap[locWithinAPage * sizeof(uint32_t) + locWithinAWord] = errorByte;
  77 }
  78
  79 /****************************************************************************
  80 *  nand_correct_page_bch - Routine to correct bit errors when reading NAND
  81 *
  82 *  PURPOSE:
  83 *     This routine reads the BCH registers to determine if there are any bit
  84 *     errors during the read of the last 512 bytes of data + ECC bytes.  If
  85 *     errors exists, the routine fixes it.
  86 *
  87 *  PARAMETERS:
  88 *     datap - Container that holds the 512 byte data
  89 *
  90 *  RETURNS:
  91 *     0 or greater = Number of errors corrected
  92 *                    (No errors are found or errors have been fixed)
  93 *    -1 = Error(s) cannot be fixed
  94 ****************************************************************************/
  95 int nand_bcm_umi_bch_correct_page(uint8_t *datap, uint8_t *readEccData,
  96                                   int numEccBytes)
  97 {
  98         int numErrors;
  99         int errorLocation;
 100         int idx;
 101         uint32_t regValue;
 102
 103         /* wait for read ECC to be valid */
 104         regValue = nand_bcm_umi_bch_poll_read_ecc_calc();
 105
 106         /*
 107          * read the control status register to determine if there
 108          * are error'ed bits
 109          * see if errors are correctible
 110          */
 111         if ((regValue & REG_UMI_BCH_CTRL_STATUS_UNCORR_ERR) > 0) {
 112                 int i;
 113
 114                 for (i = 0; i < numEccBytes; i++) {
 115                         if (readEccData[i] != 0xff) {
 116                                 /* errors cannot be fixed, return -1 */
 117                                 return -1;
 118                         }
 119                 }
 120                 /* If ECC is unprogrammed then we can't correct,
 121                  * assume everything OK */
 122                 return 0;
 123         }
 124
 125         if ((regValue & REG_UMI_BCH_CTRL_STATUS_CORR_ERR) == 0) {
 126                 /* no errors */
 127                 return 0;
 128         }
 129
 130         /*
 131          * Fix errored bits by doing the following:
 132          * 1. Read the number of errors in the control and status register
 133          * 2. Read the error location registers that corresponds to the number
 134          *    of errors reported
 135          * 3. Invert the bit in the data
 136          */
 137         numErrors = (regValue & REG_UMI_BCH_CTRL_STATUS_NB_CORR_ERROR) >> 20;
 138
 139         for (idx = 0; idx < numErrors; idx++) {
 140                 errorLocation =
 141                     REG_UMI_BCH_ERR_LOC_ADDR(idx) & REG_UMI_BCH_ERR_LOC_MASK;
 142
 143                 /* Flip bit */
 144                 nand_bcm_umi_bch_ecc_flip_bit(datap, errorLocation);
 145         }
 146         /* Errors corrected */
 147         return numErrors;
 148 }
 149 #endif