NAND: DaVinci: V2 Adding 4 BIT ECC support

This patch adds 4 BIT ECC support in the DaVinci NAND
driver. Tested on both the DM355 and DM365.

Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>

1 files changed, 282 insertions, 2 deletions

diff --git a/drivers/mtd/nand/davinci_nand.c b/drivers/mtd/nand/davinci_nand.c
index 7837a8e327..37d8b7312c 100644
--- a/drivers/mtd/nand/davinci_nand.c
+++ b/drivers/mtd/nand/davinci_nand.c
@@ -47,6 +47,16 @@
 #include <asm/arch/nand_defs.h>
 #include <asm/arch/emif_defs.h>
 
+/* Definitions for 4-bit hardware ECC */
+#define NAND_TIMEOUT			10240
+#define NAND_ECC_BUSY			0xC
+#define NAND_4BITECC_MASK		0x03FF03FF
+#define EMIF_NANDFSR_ECC_STATE_MASK  	0x00000F00
+#define ECC_STATE_NO_ERR		0x0
+#define ECC_STATE_TOO_MANY_ERRS		0x1
+#define ECC_STATE_ERR_CORR_COMP_P	0x2
+#define ECC_STATE_ERR_CORR_COMP_N	0x3
+
 static emif_registers *const emif_regs = (void *) DAVINCI_ASYNC_EMIF_CNTRL_BASE;
 
 static void nand_davinci_hwcontrol(struct mtd_info *mtd, int cmd, unsigned int ctrl)
@@ -170,6 +180,268 @@ static int nand_davinci_correct_data(struct mtd_info *mtd, u_char *dat, u_char *
 }
 #endif /* CONFIG_SYS_NAND_HW_ECC */
 
+#ifdef CONFIG_SYS_NAND_4BIT_HW_ECC_OOBFIRST
+static struct nand_ecclayout nand_davinci_4bit_layout_oobfirst = {
+/*
+ * TI uses a different layout for 4K page deviecs. Since the
+ * eccpos filed can hold only a limited number of entries, adding
+ * support for 4K page will result in compilation warnings
+ * 4K Support will be added later
+ */
+#ifdef CONFIG_SYS_NAND_PAGE_2K
+	.eccbytes = 40,
+	.eccpos = {
+		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,
+		},
+	.oobfree = {
+		{.offset = 2, .length = 22, },
+	},
+#endif
+};
+#endif
+
+static void nand_davinci_4bit_enable_hwecc(struct mtd_info *mtd, int mode)
+{
+	u32 val;
+
+	switch (mode) {
+	case NAND_ECC_WRITE:
+	case NAND_ECC_READ:
+		/*
+		 * Start a new ECC calculation for reading or writing 512 bytes
+		 * of data.
+		 */
+		val = (emif_regs->NANDFCR & ~(3 << 4)) | (1 << 12);
+		emif_regs->NANDFCR = val;
+		break;
+	case NAND_ECC_READSYN:
+		val = emif_regs->NAND4BITECC1;
+		break;
+	default:
+		break;
+	}
+}
+
+static u32 nand_davinci_4bit_readecc(struct mtd_info *mtd, unsigned int ecc[4])
+{
+	ecc[0] = emif_regs->NAND4BITECC1 & NAND_4BITECC_MASK;
+	ecc[1] = emif_regs->NAND4BITECC2 & NAND_4BITECC_MASK;
+	ecc[2] = emif_regs->NAND4BITECC3 & NAND_4BITECC_MASK;
+	ecc[3] = emif_regs->NAND4BITECC4 & NAND_4BITECC_MASK;
+
+	return 0;
+}
+
+static int nand_davinci_4bit_calculate_ecc(struct mtd_info *mtd,
+					   const uint8_t *dat,
+					   uint8_t *ecc_code)
+{
+	unsigned int hw_4ecc[4] = { 0, 0, 0, 0 };
+	unsigned int const1 = 0, const2 = 0;
+	unsigned char count1 = 0;
+
+	nand_davinci_4bit_readecc(mtd, hw_4ecc);
+
+	/*Convert 10 bit ecc value to 8 bit */
+	for (count1 = 0; count1 < 2; count1++) {
+		const2 = count1 * 5;
+		const1 = count1 * 2;
+
+		/* Take first 8 bits from val1 (count1=0) or val5 (count1=1) */
+		ecc_code[const2] = hw_4ecc[const1] & 0xFF;
+
+		/*
+		 * Take 2 bits as LSB bits from val1 (count1=0) or val5
+		 * (count1=1) and 6 bits from val2 (count1=0) or
+		 * val5 (count1=1)
+		 */
+		ecc_code[const2 + 1] =
+		    ((hw_4ecc[const1] >> 8) & 0x3) | ((hw_4ecc[const1] >> 14) &
+						      0xFC);
+
+		/*
+		 * Take 4 bits from val2 (count1=0) or val5 (count1=1) and
+		 * 4 bits from val3 (count1=0) or val6 (count1=1)
+		 */
+		ecc_code[const2 + 2] =
+		    ((hw_4ecc[const1] >> 22) & 0xF) |
+		    ((hw_4ecc[const1 + 1] << 4) & 0xF0);
+
+		/*
+		 * Take 6 bits from val3(count1=0) or val6 (count1=1) and
+		 * 2 bits from val4 (count1=0) or  val7 (count1=1)
+		 */
+		ecc_code[const2 + 3] =
+		    ((hw_4ecc[const1 + 1] >> 4) & 0x3F) |
+		    ((hw_4ecc[const1 + 1] >> 10) & 0xC0);
+
+		/* Take 8 bits from val4 (count1=0) or val7 (count1=1) */
+		ecc_code[const2 + 4] = (hw_4ecc[const1 + 1] >> 18) & 0xFF;
+	}
+	return 0;
+}
+
+
+static int nand_davinci_4bit_correct_data(struct mtd_info *mtd, uint8_t *dat,
+					  uint8_t *read_ecc, uint8_t *calc_ecc)
+{
+	struct nand_chip *this = mtd->priv;
+	unsigned short ecc_10bit[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
+	int i;
+	unsigned int hw_4ecc[4] = { 0, 0, 0, 0 }, iserror = 0;
+	unsigned short *pspare = NULL, *pspare1 = NULL;
+	unsigned int numerrors, erroraddress, errorvalue;
+	u32 val;
+
+	/*
+	 * Check for an ECC where all bytes are 0xFF.  If this is the case, we
+	 * will assume we are looking at an erased page and we should ignore
+	 * the ECC.
+	 */
+	for (i = 0; i < 10; i++) {
+		if (read_ecc[i] != 0xFF)
+			break;
+	}
+	if (i == 10)
+		return 0;
+
+	/* Convert 8 bit in to 10 bit */
+	pspare = (unsigned short *)&read_ecc[2];
+	pspare1 = (unsigned short *)&read_ecc[0];
+
+	/* Take 10 bits from 0th and 1st bytes */
+	ecc_10bit[0] = (*pspare1) & 0x3FF;
+
+	/* Take 6 bits from 1st byte and 4 bits from 2nd byte */
+	ecc_10bit[1] = (((*pspare1) >> 10) & 0x3F)
+	    | (((pspare[0]) << 6) & 0x3C0);
+
+	/* Take 4 bits form 2nd bytes and 6 bits from 3rd bytes */
+	ecc_10bit[2] = ((pspare[0]) >> 4) & 0x3FF;
+
+	/*Take 2 bits from 3rd byte and 8 bits from 4th byte */
+	ecc_10bit[3] = (((pspare[0]) >> 14) & 0x3)
+	    | ((((pspare[1])) << 2) & 0x3FC);
+
+	/* Take 8 bits from 5th byte and 2 bits from 6th byte */
+	ecc_10bit[4] = ((pspare[1]) >> 8)
+	    | ((((pspare[2])) << 8) & 0x300);
+
+	/* Take 6 bits from 6th byte and 4 bits from 7th byte */
+	ecc_10bit[5] = (pspare[2] >> 2) & 0x3FF;
+
+	/* Take 4 bits from 7th byte and 6 bits from 8th byte */
+	ecc_10bit[6] = (((pspare[2]) >> 12) & 0xF)
+	    | ((((pspare[3])) << 4) & 0x3F0);
+
+	/*Take 2 bits from 8th byte and 8 bits from 9th byte */
+	ecc_10bit[7] = ((pspare[3]) >> 6) & 0x3FF;
+
+	/*
+	 * Write the parity values in the NAND Flash 4-bit ECC Load register.
+	 * Write each parity value one at a time starting from 4bit_ecc_val8
+	 * to 4bit_ecc_val1.
+	 */
+	for (i = 7; i >= 0; i--)
+		emif_regs->NAND4BITECCLOAD = ecc_10bit[i];
+
+	/*
+	 * Perform a dummy read to the EMIF Revision Code and Status register.
+	 * This is required to ensure time for syndrome calculation after
+	 * writing the ECC values in previous step.
+	 */
+
+	val = emif_regs->NANDFSR;
+
+	/*
+	 * Read the syndrome from the NAND Flash 4-Bit ECC 1-4 registers.
+	 * A syndrome value of 0 means no bit errors. If the syndrome is
+	 * non-zero then go further otherwise return.
+	 */
+	nand_davinci_4bit_readecc(mtd, hw_4ecc);
+
+	if (hw_4ecc[0] == ECC_STATE_NO_ERR && hw_4ecc[1] == ECC_STATE_NO_ERR &&
+	    hw_4ecc[2] == ECC_STATE_NO_ERR && hw_4ecc[3] == ECC_STATE_NO_ERR)
+		return 0;
+
+	/*
+	 * Clear any previous address calculation by doing a dummy read of an
+	 * error address register.
+	 */
+	val = emif_regs->NANDERRADD1;
+
+	/*
+	 * Set the addr_calc_st bit(bit no 13) in the NAND Flash Control
+	 * register to 1.
+	 */
+	emif_regs->NANDFCR |= 1 << 13;
+
+	/*
+	 * Wait for the corr_state field (bits 8 to 11)in the
+	 * NAND Flash Status register to be equal to 0x0, 0x1, 0x2, or 0x3.
+	 */
+	i = NAND_TIMEOUT;
+	do {
+		val = emif_regs->NANDFSR;
+		val &= 0xc00;
+		i--;
+	} while ((i > 0) && val);
+
+	iserror = emif_regs->NANDFSR;
+	iserror &= EMIF_NANDFSR_ECC_STATE_MASK;
+	iserror = iserror >> 8;
+
+	/*
+	 * ECC_STATE_TOO_MANY_ERRS (0x1) means errors cannot be
+	 * corrected (five or more errors).  The number of errors
+	 * calculated (err_num field) differs from the number of errors
+	 * searched.  ECC_STATE_ERR_CORR_COMP_P (0x2) means error
+	 * correction complete (errors on bit 8 or 9).
+	 * ECC_STATE_ERR_CORR_COMP_N (0x3) means error correction
+	 * complete (error exists).
+	 */
+
+	if (iserror == ECC_STATE_NO_ERR) {
+		val = emif_regs->NANDERRVAL1;
+		return 0;
+	} else if (iserror == ECC_STATE_TOO_MANY_ERRS) {
+		val = emif_regs->NANDERRVAL1;
+		return -1;
+	}
+
+	numerrors = ((emif_regs->NANDFSR >> 16) & 0x3) + 1;
+
+	/* Read the error address, error value and correct */
+	for (i = 0; i < numerrors; i++) {
+		if (i > 1) {
+			erroraddress =
+			    ((emif_regs->NANDERRADD2 >>
+			      (16 * (i & 1))) & 0x3FF);
+			erroraddress = ((512 + 7) - erroraddress);
+			errorvalue =
+			    ((emif_regs->NANDERRVAL2 >>
+			      (16 * (i & 1))) & 0xFF);
+		} else {
+			erroraddress =
+			    ((emif_regs->NANDERRADD1 >>
+			      (16 * (i & 1))) & 0x3FF);
+			erroraddress = ((512 + 7) - erroraddress);
+			errorvalue =
+			    ((emif_regs->NANDERRVAL1 >>
+			      (16 * (i & 1))) & 0xFF);
+		}
+		/* xor the corrupt data with error value */
+		if (erroraddress < 512)
+			dat[erroraddress] ^= errorvalue;
+	}
+
+	return numerrors;
+}
+
 static int nand_davinci_dev_ready(struct mtd_info *mtd)
 {
 	return emif_regs->NANDFSR & 0x1;
@@ -215,7 +487,7 @@ void davinci_nand_init(struct nand_chip *nand)
 {
 	nand->chip_delay  = 0;
 #ifdef CONFIG_SYS_NAND_USE_FLASH_BBT
-	nand->options	  = NAND_USE_FLASH_BBT;
+	nand->options	  |= NAND_USE_FLASH_BBT;
 #endif
 #ifdef CONFIG_SYS_NAND_HW_ECC
 	nand->ecc.mode = NAND_ECC_HW;
@@ -227,7 +499,15 @@ void davinci_nand_init(struct nand_chip *nand)
 #else
 	nand->ecc.mode = NAND_ECC_SOFT;
 #endif /* CONFIG_SYS_NAND_HW_ECC */
-
+#ifdef CONFIG_SYS_NAND_4BIT_HW_ECC_OOBFIRST
+	nand->ecc.mode = NAND_ECC_HW_OOB_FIRST;
+	nand->ecc.size = 512;
+	nand->ecc.bytes = 10;
+	nand->ecc.calculate = nand_davinci_4bit_calculate_ecc;
+	nand->ecc.correct = nand_davinci_4bit_correct_data;
+	nand->ecc.hwctl = nand_davinci_4bit_enable_hwecc;
+	nand->ecc.layout = &nand_davinci_4bit_layout_oobfirst;
+#endif
 	/* Set address of hardware control function */
 	nand->cmd_ctrl = nand_davinci_hwcontrol;