[U-Boot] [PATCH 1/3] atmel_nand: if don't have gf table in rom code we will build it runtime

[Bo Shen]

From: Josh Wu <josh.wu at atmel.com>

Add a macro NO_GALOIS_TABLE_IN_ROM. If it is defined we will build a
runtime pmecc galois table.

Signed-off-by: Josh Wu <josh.wu at atmel.com>
Signed-off-by: Bo Shen <voice.shen at atmel.com>
---

 drivers/mtd/nand/atmel_nand.c | 127 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 126 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
index e73834d..7cf7b39 100644
--- a/drivers/mtd/nand/atmel_nand.c
+++ b/drivers/mtd/nand/atmel_nand.c
@@ -761,6 +761,108 @@ static int pmecc_choose_ecc(struct atmel_nand_host *host,
 }
 #endif
 
+#if defined(NO_GALOIS_TABLE_IN_ROM)
+static uint16_t *pmecc_galois_table;
+static int pmecc_build_galois_table(unsigned int mm,
+		int16_t *index_of, int16_t *alpha_to)
+{
+	unsigned int i, mask, nn;
+	unsigned int p[15];
+
+	nn = (1 << mm) - 1;
+	/* set default value */
+	for (i = 1; i < mm; i++)
+		p[i] = 0;
+
+	/* 1 + X^mm */
+	p[0]  = 1;
+	p[mm] = 1;
+
+	/* others  */
+	switch (mm) {
+	case 3:
+	case 4:
+	case 6:
+	case 15:
+		p[1] = 1;
+		break;
+	case 5:
+	case 11:
+		p[2] = 1;
+		break;
+	case 7:
+	case 10:
+		p[3] = 1;
+		break;
+	case 8:
+		p[2] = 1;
+		p[3] = 1;
+		p[4] = 1;
+		break;
+	case 9:
+		p[4] = 1;
+		break;
+	case 12:
+		p[1] = 1;
+		p[4] = 1;
+		p[6] = 1;
+		break;
+	case 13:
+		p[1] = 1;
+		p[3] = 1;
+		p[4] = 1;
+		break;
+	case 14:
+		p[1] = 1;
+		p[6] = 1;
+		p[10] = 1;
+		break;
+	default:
+		/* Error */
+		return -EINVAL;
+	}
+
+	/* Build alpha ^ mm it will help to generate the field (primitiv) */
+	alpha_to[mm] = 0;
+	for (i = 0; i < mm; i++)
+		if (p[i])
+			alpha_to[mm] |= 1 << i;
+
+	/*
+	 * Then build elements from 0 to mm - 1. As degree is less than mm
+	 * so it is just a logical shift.
+	 */
+	mask = 1;
+	for (i = 0; i < mm; i++) {
+		alpha_to[i] = mask;
+		index_of[alpha_to[i]] = i;
+		mask <<= 1;
+	}
+
+	index_of[alpha_to[mm]] = mm;
+
+	/* use a mask to select the MSB bit of the LFSR */
+	mask >>= 1;
+
+	/* then finish the building */
+	for (i = mm + 1; i <= nn; i++) {
+		/* check if the msb bit of the lfsr is set */
+		if (alpha_to[i - 1] & mask)
+			alpha_to[i] = alpha_to[mm] ^
+				((alpha_to[i - 1] ^ mask) << 1);
+		else
+			alpha_to[i] = alpha_to[i - 1] << 1;
+
+		index_of[alpha_to[i]] = i % nn;
+	}
+
+	/* index of 0 is undefined in a multiplicative field */
+	index_of[0] = -1;
+
+	return 0;
+}
+#endif
+
 static int atmel_pmecc_nand_init_params(struct nand_chip *nand,
 		struct mtd_info *mtd)
 {
@@ -808,11 +910,18 @@ static int atmel_pmecc_nand_init_params(struct nand_chip *nand,
 	sector_size = host->pmecc_sector_size;
 
 	/* TODO: need check whether cap & sector_size is validate */
-
+#if defined(NO_GALOIS_TABLE_IN_ROM)
+	/*
+	 * As pmecc_rom_base is the begin of the gallois field table, So the
+	 * index offset just set as 0.
+	 */
+	host->pmecc_index_table_offset = 0;
+#else
 	if (host->pmecc_sector_size == 512)
 		host->pmecc_index_table_offset = ATMEL_PMECC_INDEX_OFFSET_512;
 	else
 		host->pmecc_index_table_offset = ATMEL_PMECC_INDEX_OFFSET_1024;
+#endif
 
 	MTDDEBUG(MTD_DEBUG_LEVEL1,
 		"Initialize PMECC params, cap: %d, sector: %d\n",
@@ -821,7 +930,23 @@ static int atmel_pmecc_nand_init_params(struct nand_chip *nand,
 	host->pmecc = (struct pmecc_regs __iomem *) ATMEL_BASE_PMECC;
 	host->pmerrloc = (struct pmecc_errloc_regs __iomem *)
 			ATMEL_BASE_PMERRLOC;
+#if defined(NO_GALOIS_TABLE_IN_ROM)
+	/* Set pmecc_rom_base as the begin of gf table */
+	int size = host->pmecc_sector_size == 512 ?
+		PMECC_INDEX_TABLE_SIZE_512 :
+		PMECC_INDEX_TABLE_SIZE_1024;
+	pmecc_galois_table = malloc(2 * size * sizeof(uint16_t));
+	if (!pmecc_galois_table)
+		return -ENOMEM;
+
+	host->pmecc_rom_base = pmecc_galois_table;
+	pmecc_build_galois_table((sector_size == 512) ? PMECC_GF_DIMENSION_13 :
+			PMECC_GF_DIMENSION_14,
+			host->pmecc_rom_base,
+			host->pmecc_rom_base + (size * sizeof(int16_t)));
+#else
 	host->pmecc_rom_base = (void __iomem *) ATMEL_BASE_ROM;
+#endif
 
 	/* ECC is calculated for the whole page (1 step) */
 	nand->ecc.size = mtd->writesize;
-- 
2.1.0.24.g4109c28