[PATCH 4/4] mtd: atmel_nand: enable Nand Flash Controller (NFC) write via sram
Josh Wu
josh.wu at atmel.com
Tue Apr 23 06:29:57 EDT 2013
This patch enable writing nand flash via NFC SRAM. It will minimize the CPU
overhead. The SRAM write only support ECC_NONE and ECC_HW with PMECC.
This driver has been tested on SAMA5D3X-EK with JFFS2, YAFFS2, UBIFS and
mtd-utils.
Here is part of mtd_speedtest (writing test) result, compare with non-NFC
writing, it reduces %65 cpu load with loss %12 speed.
- commands use to test:
# insmod /mnt/mtd_speedtest.ko dev=2 &
# top -n 30 -d 1 | grep speedtest
- test result:
=================================================
mtd_speedtest: MTD device: 2
mtd_speedtest: MTD device size 41943040, eraseblock size 131072, page size 2048, count of eraseblocks 320, pages per eraseblock 64, OOB size 64
mtd_speedtest: testing eraseblock write speed
509 495 root D 1164 0% 7% insmod /mnt/mtd_speedtest.ko dev=2
509 495 root D 1164 0% 8% insmod /mnt/mtd_speedtest.ko dev=2
509 495 root R 1164 0% 5% insmod /mnt/mtd_speedtest.ko dev=2
mtd_speedtest: eraseblock write speed is 5194 KiB/s
mtd_speedtest: testing page write speed
509 495 root D 1164 0% 32% insmod /mnt/mtd_speedtest.ko dev=2
509 495 root D 1164 0% 27% insmod /mnt/mtd_speedtest.ko dev=2
509 495 root D 1164 0% 25% insmod /mnt/mtd_speedtest.ko dev=2
509 495 root D 1164 0% 30% insmod /mnt/mtd_speedtest.ko dev=2
mtd_speedtest: page write speed is 5024 KiB/s
Signed-off-by: Josh Wu <josh.wu at atmel.com>
---
drivers/mtd/nand/atmel_nand.c | 90 +++++++++++++++++++++++++++++++++++++++--
1 file changed, 86 insertions(+), 4 deletions(-)
diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
index d16cd2e..56e36ba 100644
--- a/drivers/mtd/nand/atmel_nand.c
+++ b/drivers/mtd/nand/atmel_nand.c
@@ -99,6 +99,7 @@ struct atmel_nfc {
/* Point to the sram bank which include readed data via NFC */
void __iomem *data_in_sram;
+ bool will_write_sram;
};
struct atmel_nand_host {
@@ -218,6 +219,16 @@ static void memcpy32_fromio(void *trg, const void __iomem *src, size_t size)
*t++ = readl_relaxed(s++);
}
+static void memcpy32_toio(void __iomem *trg, const void *src, int size)
+{
+ int i;
+ u32 __iomem *t = trg;
+ const u32 *s = src;
+
+ for (i = 0; i < (size >> 2); i++)
+ writel_relaxed(*s++, t++);
+}
+
/*
* Minimal-overhead PIO for data access.
*/
@@ -339,7 +350,11 @@ static int atmel_nand_dma_op(struct mtd_info *mtd, void *buf, int len,
dma_dst_addr = phys_addr;
} else {
dma_src_addr = phys_addr;
- dma_dst_addr = host->io_phys;
+
+ if (host->use_nfc_sram)
+ dma_dst_addr = nfc_sram_phys(host);
+ else
+ dma_dst_addr = host->io_phys;
}
tx = dma_dev->device_prep_dma_memcpy(host->dma_chan, dma_dst_addr,
@@ -914,9 +929,10 @@ static int atmel_nand_pmecc_write_page(struct mtd_info *mtd,
int i, j;
unsigned long end_time;
- pmecc_enable(host, PMECC_WRITE);
-
- chip->write_buf(mtd, (u8 *)buf, mtd->writesize);
+ if (!host->use_nfc_sram) {
+ pmecc_enable(host, PMECC_WRITE);
+ chip->write_buf(mtd, (u8 *)buf, mtd->writesize);
+ }
end_time = jiffies + msecs_to_jiffies(PMECC_MAX_TIMEOUT_MS);
while ((pmecc_readl_relaxed(host->ecc, SR) & PMECC_SR_BUSY)) {
@@ -1800,6 +1816,8 @@ static void nfc_nand_command(struct mtd_info *mtd, unsigned int command,
case NAND_CMD_SEQIN:
case NAND_CMD_RNDIN:
nfcwr = NFCADDR_CMD_NFCWR;
+ if (host->nfc.will_write_sram && command == NAND_CMD_SEQIN)
+ dataen = NFCADDR_CMD_DATAEN;
break;
default:
break;
@@ -1854,6 +1872,64 @@ static void nfc_nand_command(struct mtd_info *mtd, unsigned int command,
}
}
+static int nfc_sram_write_page(struct mtd_info *mtd, struct nand_chip *chip,
+ const uint8_t *buf, int oob_required, int page,
+ int cached, int raw)
+{
+ int cfg, len;
+ int status = 0;
+ struct atmel_nand_host *host = chip->priv;
+ void __iomem *sram = host->nfc.sram_bank0 + nfc_get_sram_off(host);
+
+ cfg = nfc_readl(host->nfc.hsmc_regs, CFG);
+ len = mtd->writesize;
+
+ if (unlikely(raw)) {
+ len += mtd->oobsize;
+ nfc_writel(host->nfc.hsmc_regs, CFG, cfg | ATMEL_HSMC_WSPARE);
+ } else
+ nfc_writel(host->nfc.hsmc_regs, CFG, cfg & ~ATMEL_HSMC_WSPARE);
+
+ /* Copy page data to sram that will write to nand via NFC */
+ if (use_dma) {
+ if (atmel_nand_dma_op(mtd, (void *)buf, len, 0) != 0)
+ /* Fall back to use cpu copy */
+ memcpy32_toio(sram, buf, len);
+ } else {
+ memcpy32_toio(sram, buf, len);
+ }
+
+ if (chip->ecc.mode == NAND_ECC_HW && host->has_pmecc)
+ /*
+ * When use NFC sram, need set up PMECC before send
+ * NAND_CMD_SEQIN command. Since when the nand command
+ * is sent, nfc will do transfer from sram and nand.
+ */
+ pmecc_enable(host, PMECC_WRITE);
+
+ host->nfc.will_write_sram = true;
+ chip->cmdfunc(mtd, NAND_CMD_SEQIN, 0x00, page);
+ host->nfc.will_write_sram = false;
+
+ if (likely(!raw))
+ /* Need to write ecc into oob */
+ status = chip->ecc.write_page(mtd, chip, buf, oob_required);
+
+ if (status < 0)
+ return status;
+
+ chip->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1);
+ status = chip->waitfunc(mtd, chip);
+
+ if ((status & NAND_STATUS_FAIL) && (chip->errstat))
+ status = chip->errstat(mtd, chip, FL_WRITING, status, page);
+
+ if (status & NAND_STATUS_FAIL)
+ return -EIO;
+
+ return 0;
+}
+
static int nfc_sram_init(struct mtd_info *mtd)
{
struct nand_chip *chip = mtd->priv;
@@ -1892,10 +1968,16 @@ static int nfc_sram_init(struct mtd_info *mtd)
nfc_writel(host->nfc.hsmc_regs, CFG, cfg_nfc);
+ host->nfc.will_write_sram = false;
nfc_set_sram_bank(host, 0);
dev_info(host->dev, "Using NFC Sram\n");
+ /* Use Write page with NFC SRAM only for PMECC or ECC NONE. */
+ if ((chip->ecc.mode == NAND_ECC_HW && host->has_pmecc) ||
+ chip->ecc.mode == NAND_ECC_NONE)
+ chip->write_page = nfc_sram_write_page;
+
return 0;
}
--
1.7.9.5
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