aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/mtd/nand/nand_bcm_umi.c
blob: 46a6bc9c4b743806f8af3e571bab5b17780bf4de (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
/*****************************************************************************
* Copyright 2004 - 2009 Broadcom Corporation.  All rights reserved.
*
* Unless you and Broadcom execute a separate written software license
* agreement governing use of this software, this software is licensed to you
* under the terms of the GNU General Public License version 2, available at
* http://www.broadcom.com/licenses/GPLv2.php (the "GPL").
*
* Notwithstanding the above, under no circumstances may you combine this
* software in any way with any other Broadcom software provided under a
* license other than the GPL, without Broadcom's express prior written
* consent.
*****************************************************************************/

/* ---- Include Files ---------------------------------------------------- */
#include <mach/reg_umi.h>
#include "nand_bcm_umi.h"
#ifdef BOOT0_BUILD
#include <uart.h>
#endif

/* ---- External Variable Declarations ----------------------------------- */
/* ---- External Function Prototypes ------------------------------------- */
/* ---- Public Variables ------------------------------------------------- */
/* ---- Private Constants and Types -------------------------------------- */
/* ---- Private Function Prototypes -------------------------------------- */
/* ---- Private Variables ------------------------------------------------ */
/* ---- Private Functions ------------------------------------------------ */

#if NAND_ECC_BCH
/****************************************************************************
*  nand_bch_ecc_flip_bit - Routine to flip an errored bit
*
*  PURPOSE:
*     This is a helper routine that flips the bit (0 -> 1 or 1 -> 0) of the
*     errored bit specified
*
*  PARAMETERS:
*     datap - Container that holds the 512 byte data
*     errorLocation - Location of the bit that needs to be flipped
*
*  RETURNS:
*     None
****************************************************************************/
static void nand_bcm_umi_bch_ecc_flip_bit(uint8_t *datap, int errorLocation)
{
	int locWithinAByte = (errorLocation & REG_UMI_BCH_ERR_LOC_BYTE) >> 0;
	int locWithinAWord = (errorLocation & REG_UMI_BCH_ERR_LOC_WORD) >> 3;
	int locWithinAPage = (errorLocation & REG_UMI_BCH_ERR_LOC_PAGE) >> 5;

	uint8_t errorByte = 0;
	uint8_t byteMask = 1 << locWithinAByte;

	/* BCH uses big endian, need to change the location
	 * bits to little endian */
	locWithinAWord = 3 - locWithinAWord;

	errorByte = datap[locWithinAPage * sizeof(uint32_t) + locWithinAWord];

#ifdef BOOT0_BUILD
	puthexs("\nECC Correct Offset: ",
		locWithinAPage * sizeof(uint32_t) + locWithinAWord);
	puthexs(" errorByte:", errorByte);
	puthex8(" Bit: ", locWithinAByte);
#endif

	if (errorByte & byteMask) {
		/* bit needs to be cleared */
		errorByte &= ~byteMask;
	} else {
		/* bit needs to be set */
		errorByte |= byteMask;
	}

	/* write back the value with the fixed bit */
	datap[locWithinAPage * sizeof(uint32_t) + locWithinAWord] = errorByte;
}

/****************************************************************************
*  nand_correct_page_bch - Routine to correct bit errors when reading NAND
*
*  PURPOSE:
*     This routine reads the BCH registers to determine if there are any bit
*     errors during the read of the last 512 bytes of data + ECC bytes.  If
*     errors exists, the routine fixes it.
*
*  PARAMETERS:
*     datap - Container that holds the 512 byte data
*
*  RETURNS:
*     0 or greater = Number of errors corrected
*                    (No errors are found or errors have been fixed)
*    -1 = Error(s) cannot be fixed
****************************************************************************/
int nand_bcm_umi_bch_correct_page(uint8_t *datap, uint8_t *readEccData,
				  int numEccBytes)
{
	int numErrors;
	int errorLocation;
	int idx;
	uint32_t regValue;

	/* wait for read ECC to be valid */
	regValue = nand_bcm_umi_bch_poll_read_ecc_calc();

	/*
	 * read the control status register to determine if there
	 * are error'ed bits
	 * see if errors are correctible
	 */
	if ((regValue & REG_UMI_BCH_CTRL_STATUS_UNCORR_ERR) > 0) {
		int i;

		for (i = 0; i < numEccBytes; i++) {
			if (readEccData[i] != 0xff) {
				/* errors cannot be fixed, return -1 */
				return -1;
			}
		}
		/* If ECC is unprogrammed then we can't correct,
		 * assume everything OK */
		return 0;
	}

	if ((regValue & REG_UMI_BCH_CTRL_STATUS_CORR_ERR) == 0) {
		/* no errors */
		return 0;
	}

	/*
	 * Fix errored bits by doing the following:
	 * 1. Read the number of errors in the control and status register
	 * 2. Read the error location registers that corresponds to the number
	 *    of errors reported
	 * 3. Invert the bit in the data
	 */
	numErrors = (regValue & REG_UMI_BCH_CTRL_STATUS_NB_CORR_ERROR) >> 20;

	for (idx = 0; idx < numErrors; idx++) {
		errorLocation =
		    REG_UMI_BCH_ERR_LOC_ADDR(idx) & REG_UMI_BCH_ERR_LOC_MASK;

		/* Flip bit */
		nand_bcm_umi_bch_ecc_flip_bit(datap, errorLocation);
	}
	/* Errors corrected */
	return numErrors;
}
#endif