diff options
| -rw-r--r-- | doc/README.nand | 5 | ||||
| -rw-r--r-- | drivers/mtd/nand/omap_gpmc.c | 114 | ||||
| -rw-r--r-- | include/linux/mtd/omap_gpmc.h | 6 |
3 files changed, 122 insertions, 3 deletions
diff --git a/doc/README.nand b/doc/README.nand index e29188f1ec..dee0e00a61 100644 --- a/doc/README.nand +++ b/doc/README.nand @@ -304,6 +304,11 @@ Platform specific options Thus BCH16 can be supported on 4K page NAND. + CONFIG_NAND_OMAP_GPMC_PREFETCH + On OMAP platforms that use the GPMC controller + (CONFIG_NAND_OMAP_GPMC_PREFETCH), this options enables the code that + uses the prefetch mode to speed up read operations. + NOTE: ===== diff --git a/drivers/mtd/nand/omap_gpmc.c b/drivers/mtd/nand/omap_gpmc.c index 459904d81c..fc64f48144 100644 --- a/drivers/mtd/nand/omap_gpmc.c +++ b/drivers/mtd/nand/omap_gpmc.c @@ -441,6 +441,115 @@ static int omap_correct_data_bch(struct mtd_info *mtd, uint8_t *dat, return (err) ? err : error_count; } +#ifdef CONFIG_NAND_OMAP_GPMC_PREFETCH + +#define PREFETCH_CONFIG1_CS_SHIFT 24 +#define PREFETCH_FIFOTHRESHOLD_MAX 0x40 +#define PREFETCH_FIFOTHRESHOLD(val) ((val) << 8) +#define PREFETCH_STATUS_COUNT(val) (val & 0x00003fff) +#define PREFETCH_STATUS_FIFO_CNT(val) ((val >> 24) & 0x7F) +#define ENABLE_PREFETCH (1 << 7) + +/** + * omap_prefetch_enable - configures and starts prefetch transfer + * @fifo_th: fifo threshold to be used for read/ write + * @count: number of bytes to be transferred + * @is_write: prefetch read(0) or write post(1) mode + * @cs: chip select to use + */ +static int omap_prefetch_enable(int fifo_th, unsigned int count, int is_write, int cs) +{ + uint32_t val; + + if (fifo_th > PREFETCH_FIFOTHRESHOLD_MAX) + return -EINVAL; + + if (readl(&gpmc_cfg->prefetch_control)) + return -EBUSY; + + /* Set the amount of bytes to be prefetched */ + writel(count, &gpmc_cfg->prefetch_config2); + + val = (cs << PREFETCH_CONFIG1_CS_SHIFT) | (is_write & 1) | + PREFETCH_FIFOTHRESHOLD(fifo_th) | ENABLE_PREFETCH; + writel(val, &gpmc_cfg->prefetch_config1); + + /* Start the prefetch engine */ + writel(1, &gpmc_cfg->prefetch_control); + + return 0; +} + +/** + * omap_prefetch_reset - disables and stops the prefetch engine + */ +static void omap_prefetch_reset(void) +{ + writel(0, &gpmc_cfg->prefetch_control); + writel(0, &gpmc_cfg->prefetch_config1); +} + +static int __read_prefetch_aligned(struct nand_chip *chip, uint32_t *buf, int len) +{ + int ret; + uint32_t cnt; + struct omap_nand_info *info = chip->priv; + + ret = omap_prefetch_enable(PREFETCH_FIFOTHRESHOLD_MAX, len, 0, info->cs); + if (ret < 0) + return ret; + + do { + int i; + + cnt = readl(&gpmc_cfg->prefetch_status); + cnt = PREFETCH_STATUS_FIFO_CNT(cnt); + + for (i = 0; i < cnt / 4; i++) { + *buf++ = readl(CONFIG_SYS_NAND_BASE); + len -= 4; + } + } while (len); + + omap_prefetch_reset(); + + return 0; +} + +static void omap_nand_read_prefetch8(struct mtd_info *mtd, uint8_t *buf, int len) +{ + int ret; + uint32_t head, tail; + struct nand_chip *chip = mtd->priv; + + /* + * If the destination buffer is unaligned, start with reading + * the overlap byte-wise. + */ + head = ((uint32_t) buf) % 4; + if (head) { + nand_read_buf(mtd, buf, head); + buf += head; + len -= head; + } + + /* + * Only transfer multiples of 4 bytes in a pre-fetched fashion. + * If there's a residue, care for it byte-wise afterwards. + */ + tail = len % 4; + + ret = __read_prefetch_aligned(chip, (uint32_t *) buf, len - tail); + if (ret < 0) { + /* fallback in case the prefetch engine is busy */ + nand_read_buf(mtd, buf, len); + } else if (tail) { + buf += len - tail; + nand_read_buf(mtd, buf, tail); + } +} +#endif /* CONFIG_NAND_OMAP_GPMC_PREFETCH */ + /** * omap_read_page_bch - hardware ecc based page read function * @mtd: mtd info structure @@ -880,11 +989,12 @@ int board_nand_init(struct nand_chip *nand) if (err) return err; -#ifdef CONFIG_SPL_BUILD +#ifdef CONFIG_NAND_OMAP_GPMC_PREFETCH + /* TODO: Implement for 16-bit bus width */ if (nand->options & NAND_BUSWIDTH_16) nand->read_buf = nand_read_buf16; else - nand->read_buf = nand_read_buf; + nand->read_buf = omap_nand_read_prefetch8; #endif nand->dev_ready = omap_dev_ready; diff --git a/include/linux/mtd/omap_gpmc.h b/include/linux/mtd/omap_gpmc.h index 9a8658257f..6cbae45022 100644 --- a/include/linux/mtd/omap_gpmc.h +++ b/include/linux/mtd/omap_gpmc.h @@ -66,7 +66,11 @@ struct gpmc { u32 status; /* 0x54 */ u8 res5[0x8]; /* 0x58 */ struct gpmc_cs cs[8]; /* 0x60, 0x90, .. */ - u8 res6[0x14]; /* 0x1E0 */ + u32 prefetch_config1; /* 0x1E0 */ + u32 prefetch_config2; /* 0x1E4 */ + u32 res6; /* 0x1E8 */ + u32 prefetch_control; /* 0x1EC */ + u32 prefetch_status; /* 0x1F0 */ u32 ecc_config; /* 0x1F4 */ u32 ecc_control; /* 0x1F8 */ u32 ecc_size_config; /* 0x1FC */ |