From 604e75444fa82cfdcba339e3bd4da1dfd6947539 Mon Sep 17 00:00:00 2001 From: Vipin Kumar Date: Wed, 14 Mar 2012 11:47:17 +0530 Subject: [PATCH] mtd: nand/fsmc: Access the NAND device word by word whenever possible The default way of accessing nand device is using the nand width. This means that 8bit devices are using u8 * and 16bit devices are accessed using u16 *. This results in a non-optimal performance since the FSMC is designed to translate the normal word accesses into device width based accesses. This patch implements read_buf and write_buf callbacks using word by word accesses. Signed-off-by: Vipin Kumar Reviewed-by: Viresh Kumar Signed-off-by: Artem Bityutskiy Signed-off-by: David Woodhouse --- drivers/mtd/nand/fsmc_nand.c | 55 ++++++++++++++++++++++++++++++++++++ include/linux/mtd/fsmc.h | 6 ++++ 2 files changed, 61 insertions(+) diff --git a/drivers/mtd/nand/fsmc_nand.c b/drivers/mtd/nand/fsmc_nand.c index c41f45faa09e..81fc8e6b8cb8 100644 --- a/drivers/mtd/nand/fsmc_nand.c +++ b/drivers/mtd/nand/fsmc_nand.c @@ -523,6 +523,52 @@ static int count_written_bits(uint8_t *buff, int size, int max_bits) return written_bits; } +/* + * fsmc_write_buf - write buffer to chip + * @mtd: MTD device structure + * @buf: data buffer + * @len: number of bytes to write + */ +static void fsmc_write_buf(struct mtd_info *mtd, const uint8_t *buf, int len) +{ + int i; + struct nand_chip *chip = mtd->priv; + + if (IS_ALIGNED((uint32_t)buf, sizeof(uint32_t)) && + IS_ALIGNED(len, sizeof(uint32_t))) { + uint32_t *p = (uint32_t *)buf; + len = len >> 2; + for (i = 0; i < len; i++) + writel(p[i], chip->IO_ADDR_W); + } else { + for (i = 0; i < len; i++) + writeb(buf[i], chip->IO_ADDR_W); + } +} + +/* + * fsmc_read_buf - read chip data into buffer + * @mtd: MTD device structure + * @buf: buffer to store date + * @len: number of bytes to read + */ +static void fsmc_read_buf(struct mtd_info *mtd, uint8_t *buf, int len) +{ + int i; + struct nand_chip *chip = mtd->priv; + + if (IS_ALIGNED((uint32_t)buf, sizeof(uint32_t)) && + IS_ALIGNED(len, sizeof(uint32_t))) { + uint32_t *p = (uint32_t *)buf; + len = len >> 2; + for (i = 0; i < len; i++) + p[i] = readl(chip->IO_ADDR_R); + } else { + for (i = 0; i < len; i++) + buf[i] = readb(chip->IO_ADDR_R); + } +} + /* * fsmc_read_page_hwecc * @mtd: mtd info structure @@ -825,6 +871,15 @@ static int __init fsmc_nand_probe(struct platform_device *pdev) if (pdata->width == FSMC_NAND_BW16) nand->options |= NAND_BUSWIDTH_16; + /* + * use customized (word by word) version of read_buf, write_buf if + * access_with_dev_width is reset supported + */ + if (pdata->mode == USE_WORD_ACCESS) { + nand->read_buf = fsmc_read_buf; + nand->write_buf = fsmc_write_buf; + } + fsmc_nand_setup(regs, host->bank, nand->options & NAND_BUSWIDTH_16, host->dev_timings); diff --git a/include/linux/mtd/fsmc.h b/include/linux/mtd/fsmc.h index c4ac07a19691..1edd2b3ac38e 100644 --- a/include/linux/mtd/fsmc.h +++ b/include/linux/mtd/fsmc.h @@ -141,6 +141,11 @@ struct fsmc_nand_timings { uint8_t tset; }; +enum access_mode { + USE_DMA_ACCESS = 1, + USE_WORD_ACCESS, +}; + /** * fsmc_nand_platform_data - platform specific NAND controller config * @partitions: partition table for the platform, use a default fallback @@ -164,6 +169,7 @@ struct fsmc_nand_platform_data { /* CLE, ALE offsets */ unsigned long cle_off; unsigned long ale_off; + enum access_mode mode; void (*select_bank)(uint32_t bank, uint32_t busw); }; -- 2.39.5