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-rw-r--r--doc/README.nand5
-rw-r--r--drivers/mtd/nand/omap_gpmc.c114
-rw-r--r--include/linux/mtd/omap_gpmc.h6
3 files changed, 122 insertions, 3 deletions
diff --git a/doc/README.nand b/doc/README.nand
index e29188f..dee0e00 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 459904d..fc64f48 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 9a86582..6cbae45 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 */