From 049f42509973b86f0015e2c1c38d4c79aea408f5 Mon Sep 17 00:00:00 2001 From: Stefan Agner Date: Wed, 2 Sep 2015 18:06:34 -0700 Subject: [PATCH] mtd: nand: vf610_nfc: add hardware BCH-ECC support This adds hardware ECC support using the BCH encoder in the NFC IP. The ECC encoder supports up to 32-bit correction by using 60 error correction bytes. There is no sub-page ECC step, ECC is calculated always across the whole page (up to 2k pages). Limitations: - HW ECC: Only 2K page with 64+ OOB. - HW ECC: Only 24 and 32-bit error correction implemented. Raw writes have been tested using the generic nand_write_page_raw implementation. However, raw reads are currently not possible because the controller need to know whether we are going to use the ECC mode already at NAND_CMD_READ0 command time. At this point we do not have the information whether it is a raw read or a regular read at driver level... Signed-off-by: Bill Pringlemeir Signed-off-by: Stefan Agner Signed-off-by: Brian Norris --- drivers/mtd/nand/Kconfig | 6 +- drivers/mtd/nand/vf610_nfc.c | 203 ++++++++++++++++++++++++++++++++++- 2 files changed, 205 insertions(+), 4 deletions(-) diff --git a/drivers/mtd/nand/Kconfig b/drivers/mtd/nand/Kconfig index 9f9736c76956..ccd1158715be 100644 --- a/drivers/mtd/nand/Kconfig +++ b/drivers/mtd/nand/Kconfig @@ -466,8 +466,10 @@ config MTD_NAND_VF610_NFC help Enables support for NAND Flash Controller on some Freescale processors like the VF610, MPC5125, MCF54418 or Kinetis K70. - The driver supports a maximum 2k page size. The driver - currently does not support hardware ECC. + The driver supports a maximum 2k page size. With 2k pages and + 64 bytes or more of OOB, hardware ECC with up to 32-bit error + correction is supported. Hardware ECC is only enabled through + device tree. config MTD_NAND_MXC tristate "MXC NAND support" diff --git a/drivers/mtd/nand/vf610_nfc.c b/drivers/mtd/nand/vf610_nfc.c index 90a48f470d41..42dad8e4b26f 100644 --- a/drivers/mtd/nand/vf610_nfc.c +++ b/drivers/mtd/nand/vf610_nfc.c @@ -19,8 +19,8 @@ * - Untested on MPC5125 and M54418. * - DMA and pipelining not used. * - 2K pages or less. - * - No chip select, one NAND chip per controller. - * - No hardware ECC. + * - HW ECC: Only 2K page with 64+ OOB. + * - HW ECC: Only 24 and 32-bit error correction implemented. */ #include @@ -77,6 +77,8 @@ /* NFC ECC mode define */ #define ECC_BYPASS 0 +#define ECC_45_BYTE 6 +#define ECC_60_BYTE 7 /*** Register Mask and bit definitions */ @@ -129,6 +131,18 @@ #define CMD_DONE_CLEAR_BIT BIT(18) #define IDLE_CLEAR_BIT BIT(17) +/* + * ECC status - seems to consume 8 bytes (double word). The documented + * status byte is located in the lowest byte of the second word (which is + * the 4th or 7th byte depending on endianness). + * Calculate an offset to store the ECC status at the end of the buffer. + */ +#define ECC_SRAM_ADDR (PAGE_2K + OOB_MAX - 8) + +#define ECC_STATUS 0x4 +#define ECC_STATUS_MASK 0x80 +#define ECC_STATUS_ERR_COUNT 0x3F + enum vf610_nfc_alt_buf { ALT_BUF_DATA = 0, ALT_BUF_ID = 1, @@ -152,10 +166,40 @@ struct vf610_nfc { enum vf610_nfc_alt_buf alt_buf; enum vf610_nfc_variant variant; struct clk *clk; + bool use_hw_ecc; + u32 ecc_mode; }; #define mtd_to_nfc(_mtd) container_of(_mtd, struct vf610_nfc, mtd) +static struct nand_ecclayout vf610_nfc_ecc45 = { + .eccbytes = 45, + .eccpos = {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}, + .oobfree = { + {.offset = 2, + .length = 17} } +}; + +static struct nand_ecclayout vf610_nfc_ecc60 = { + .eccbytes = 60, + .eccpos = { 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 }, + .oobfree = { + {.offset = 2, + .length = 2} } +}; + static inline u32 vf610_nfc_read(struct vf610_nfc *nfc, uint reg) { return readl(nfc->regs + reg); @@ -297,6 +341,13 @@ static void vf610_nfc_addr_cycle(struct vf610_nfc *nfc, int column, int page) ROW_ADDR_SHIFT, page); } +static inline void vf610_nfc_ecc_mode(struct vf610_nfc *nfc, int ecc_mode) +{ + vf610_nfc_set_field(nfc, NFC_FLASH_CONFIG, + CONFIG_ECC_MODE_MASK, + CONFIG_ECC_MODE_SHIFT, ecc_mode); +} + static inline void vf610_nfc_transfer_size(struct vf610_nfc *nfc, int size) { vf610_nfc_write(nfc, NFC_SECTOR_SIZE, size); @@ -315,6 +366,8 @@ static void vf610_nfc_command(struct mtd_info *mtd, unsigned command, case NAND_CMD_SEQIN: /* Use valid column/page from preread... */ vf610_nfc_addr_cycle(nfc, column, page); + nfc->buf_offset = 0; + /* * SEQIN => data => PAGEPROG sequence is done by the controller * hence we do not need to issue the command here... @@ -325,6 +378,10 @@ static void vf610_nfc_command(struct mtd_info *mtd, unsigned command, vf610_nfc_transfer_size(nfc, trfr_sz); vf610_nfc_send_commands(nfc, NAND_CMD_SEQIN, command, PROGRAM_PAGE_CMD_CODE); + if (nfc->use_hw_ecc) + vf610_nfc_ecc_mode(nfc, nfc->ecc_mode); + else + vf610_nfc_ecc_mode(nfc, ECC_BYPASS); break; case NAND_CMD_RESET: @@ -339,6 +396,7 @@ static void vf610_nfc_command(struct mtd_info *mtd, unsigned command, vf610_nfc_send_commands(nfc, NAND_CMD_READ0, NAND_CMD_READSTART, READ_PAGE_CMD_CODE); vf610_nfc_addr_cycle(nfc, column, page); + vf610_nfc_ecc_mode(nfc, ECC_BYPASS); break; case NAND_CMD_READ0: @@ -347,6 +405,7 @@ static void vf610_nfc_command(struct mtd_info *mtd, unsigned command, vf610_nfc_send_commands(nfc, NAND_CMD_READ0, NAND_CMD_READSTART, READ_PAGE_CMD_CODE); vf610_nfc_addr_cycle(nfc, column, page); + vf610_nfc_ecc_mode(nfc, nfc->ecc_mode); break; case NAND_CMD_PARAM: @@ -355,6 +414,7 @@ static void vf610_nfc_command(struct mtd_info *mtd, unsigned command, vf610_nfc_transfer_size(nfc, trfr_sz); vf610_nfc_send_command(nfc, command, READ_ONFI_PARAM_CMD_CODE); vf610_nfc_addr_cycle(nfc, -1, column); + vf610_nfc_ecc_mode(nfc, ECC_BYPASS); break; case NAND_CMD_ERASE1: @@ -383,6 +443,7 @@ static void vf610_nfc_command(struct mtd_info *mtd, unsigned command, vf610_nfc_done(nfc); + nfc->use_hw_ecc = false; nfc->write_sz = 0; } @@ -477,6 +538,94 @@ static void vf610_nfc_select_chip(struct mtd_info *mtd, int chip) vf610_nfc_write(nfc, NFC_ROW_ADDR, tmp); } +/* Count the number of 0's in buff up to max_bits */ +static inline int count_written_bits(uint8_t *buff, int size, int max_bits) +{ + uint32_t *buff32 = (uint32_t *)buff; + int k, written_bits = 0; + + for (k = 0; k < (size / 4); k++) { + written_bits += hweight32(~buff32[k]); + if (unlikely(written_bits > max_bits)) + break; + } + + return written_bits; +} + +static inline int vf610_nfc_correct_data(struct mtd_info *mtd, uint8_t *dat, + uint8_t *oob, int page) +{ + struct vf610_nfc *nfc = mtd_to_nfc(mtd); + u32 ecc_status_off = NFC_MAIN_AREA(0) + ECC_SRAM_ADDR + ECC_STATUS; + u8 ecc_status; + u8 ecc_count; + int flips; + int flips_threshold = nfc->chip.ecc.strength / 2; + + ecc_status = vf610_nfc_read(nfc, ecc_status_off) & 0xff; + ecc_count = ecc_status & ECC_STATUS_ERR_COUNT; + + if (!(ecc_status & ECC_STATUS_MASK)) + return ecc_count; + + /* Read OOB without ECC unit enabled */ + vf610_nfc_command(mtd, NAND_CMD_READOOB, 0, page); + vf610_nfc_read_buf(mtd, oob, mtd->oobsize); + + /* + * On an erased page, bit count (including OOB) should be zero or + * at least less then half of the ECC strength. + */ + flips = count_written_bits(dat, nfc->chip.ecc.size, flips_threshold); + flips += count_written_bits(oob, mtd->oobsize, flips_threshold); + + if (unlikely(flips > flips_threshold)) + return -EINVAL; + + /* Erased page. */ + memset(dat, 0xff, nfc->chip.ecc.size); + memset(oob, 0xff, mtd->oobsize); + return flips; +} + +static int vf610_nfc_read_page(struct mtd_info *mtd, struct nand_chip *chip, + uint8_t *buf, int oob_required, int page) +{ + int eccsize = chip->ecc.size; + int stat; + + vf610_nfc_read_buf(mtd, buf, eccsize); + if (oob_required) + vf610_nfc_read_buf(mtd, chip->oob_poi, mtd->oobsize); + + stat = vf610_nfc_correct_data(mtd, buf, chip->oob_poi, page); + + if (stat < 0) { + mtd->ecc_stats.failed++; + return 0; + } else { + mtd->ecc_stats.corrected += stat; + return stat; + } +} + +static int vf610_nfc_write_page(struct mtd_info *mtd, struct nand_chip *chip, + const uint8_t *buf, int oob_required) +{ + struct vf610_nfc *nfc = mtd_to_nfc(mtd); + + vf610_nfc_write_buf(mtd, buf, mtd->writesize); + if (oob_required) + vf610_nfc_write_buf(mtd, chip->oob_poi, mtd->oobsize); + + /* Always write whole page including OOB due to HW ECC */ + nfc->use_hw_ecc = true; + nfc->write_sz = mtd->writesize + mtd->oobsize; + + return 0; +} + static const struct of_device_id vf610_nfc_dt_ids[] = { { .compatible = "fsl,vf610-nfc", .data = (void *)NFC_VFC610 }, { /* sentinel */ } @@ -503,6 +652,17 @@ static void vf610_nfc_init_controller(struct vf610_nfc *nfc) vf610_nfc_set(nfc, NFC_FLASH_CONFIG, CONFIG_16BIT); else vf610_nfc_clear(nfc, NFC_FLASH_CONFIG, CONFIG_16BIT); + + if (nfc->chip.ecc.mode == NAND_ECC_HW) { + /* Set ECC status offset in SRAM */ + vf610_nfc_set_field(nfc, NFC_FLASH_CONFIG, + CONFIG_ECC_SRAM_ADDR_MASK, + CONFIG_ECC_SRAM_ADDR_SHIFT, + ECC_SRAM_ADDR >> 3); + + /* Enable ECC status in SRAM */ + vf610_nfc_set(nfc, NFC_FLASH_CONFIG, CONFIG_ECC_SRAM_REQ_BIT); + } } static int vf610_nfc_probe(struct platform_device *pdev) @@ -610,6 +770,45 @@ static int vf610_nfc_probe(struct platform_device *pdev) goto error; } + if (chip->ecc.mode == NAND_ECC_HW) { + if (mtd->writesize != PAGE_2K && mtd->oobsize < 64) { + dev_err(nfc->dev, "Unsupported flash with hwecc\n"); + err = -ENXIO; + goto error; + } + + if (chip->ecc.size != mtd->writesize) { + dev_err(nfc->dev, "Step size needs to be page size\n"); + err = -ENXIO; + goto error; + } + + /* Only 64 byte ECC layouts known */ + if (mtd->oobsize > 64) + mtd->oobsize = 64; + + if (chip->ecc.strength == 32) { + nfc->ecc_mode = ECC_60_BYTE; + chip->ecc.bytes = 60; + chip->ecc.layout = &vf610_nfc_ecc60; + } else if (chip->ecc.strength == 24) { + nfc->ecc_mode = ECC_45_BYTE; + chip->ecc.bytes = 45; + chip->ecc.layout = &vf610_nfc_ecc45; + } else { + dev_err(nfc->dev, "Unsupported ECC strength\n"); + err = -ENXIO; + goto error; + } + + /* propagate ecc.layout to mtd_info */ + mtd->ecclayout = chip->ecc.layout; + chip->ecc.read_page = vf610_nfc_read_page; + chip->ecc.write_page = vf610_nfc_write_page; + + chip->ecc.size = PAGE_2K; + } + /* second phase scan */ if (nand_scan_tail(mtd)) { err = -ENXIO; -- 2.20.1