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 <vipin.kumar@st.com>
Reviewed-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/nand/fsmc_nand.c b/drivers/mtd/nand/fsmc_nand.c
index c41f45f..81fc8e6 100644
--- a/drivers/mtd/nand/fsmc_nand.c
+++ b/drivers/mtd/nand/fsmc_nand.c
@@ -524,6 +524,52 @@
}
/*
+ * 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
* @chip: nand chip info structure
@@ -825,6 +871,15 @@
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);