[PATCH 5/6] mtd: atmel_nand: enable Nand Flash Controller (NFC) write via sram
Josh Wu
josh.wu at atmel.com
Mon Jun 10 06:26:53 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.
To enable this NFC write by SRAM feature, you can add a string in dts under
NFC driver node.
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>
---
v2 --> v3:
- use a property of NFC node to enable/disable NFC write via sram.
.../devicetree/bindings/mtd/atmel-nand.txt | 2 +
drivers/mtd/nand/atmel_nand.c | 107 ++++++++++++++++++--
2 files changed, 103 insertions(+), 6 deletions(-)
diff --git a/Documentation/devicetree/bindings/mtd/atmel-nand.txt b/Documentation/devicetree/bindings/mtd/atmel-nand.txt
index 6a267cb..da78e22 100644
--- a/Documentation/devicetree/bindings/mtd/atmel-nand.txt
+++ b/Documentation/devicetree/bindings/mtd/atmel-nand.txt
@@ -35,6 +35,8 @@ Optional properties:
- reg : should specify the address and size used for NFC command registers,
NFC registers and NFC Sram. NFC Sram address and size can be absent
if don't want to use it.
+ - Optional properties:
+ - atmel,write-by-sram: boolean to enable NFC write by sram.
Examples:
nand0: nand at 40000000,0 {
diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
index c2ec740..e3e348b 100644
--- a/drivers/mtd/nand/atmel_nand.c
+++ b/drivers/mtd/nand/atmel_nand.c
@@ -97,12 +97,14 @@ struct atmel_nfc {
void __iomem *sram_bank0;
dma_addr_t sram_bank0_phys;
bool use_nfc_sram;
+ bool write_by_sram;
bool is_initialized;
struct completion comp_nfc;
/* Point to the sram bank which include readed data via NFC */
void __iomem *data_in_sram;
+ bool will_write_sram;
};
static struct atmel_nfc nand_nfc;
@@ -269,6 +271,16 @@ 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.
*/
@@ -390,7 +402,11 @@ 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 (nfc && nfc->write_by_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,
@@ -961,9 +977,10 @@ static int atmel_nand_pmecc_write_page(struct mtd_info *mtd,
int i, j;
unsigned long end_time;
- pmecc_enable(host, NAND_ECC_WRITE);
-
- chip->write_buf(mtd, (u8 *)buf, mtd->writesize);
+ if (!host->nfc || !host->nfc->write_by_sram) {
+ pmecc_enable(host, NAND_ECC_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)) {
@@ -1802,6 +1819,8 @@ 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;
@@ -1846,6 +1865,68 @@ 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,
+ uint32_t offset, int data_len, 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);
+
+ /* Subpage write is not supported */
+ if (offset || (data_len < mtd->writesize))
+ return -EINVAL;
+
+ 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 | NFC_CFG_WSPARE);
+ } else
+ nfc_writel(host->nfc->hsmc_regs, CFG, cfg & ~NFC_CFG_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, NAND_ECC_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;
@@ -1887,10 +1968,20 @@ 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 read\n");
+ /* Use Write page with NFC SRAM only for PMECC or ECC NONE. */
+ if (host->nfc->write_by_sram) {
+ if ((chip->ecc.mode == NAND_ECC_HW && host->has_pmecc) ||
+ chip->ecc.mode == NAND_ECC_NONE)
+ chip->write_page = nfc_sram_write_page;
+ else
+ host->nfc->write_by_sram = false;
+ }
+ dev_info(host->dev, "Using NFC Sram read %s\n",
+ host->nfc->write_by_sram ? "and write" : "");
return 0;
}
@@ -2164,11 +2255,15 @@ static int atmel_nand_nfc_probe(struct platform_device *pdev)
} else {
nfc->use_nfc_sram = true;
nfc->sram_bank0_phys = (dma_addr_t)nfc_sram->start;
+
+ if (pdev->dev.of_node)
+ nfc->write_by_sram = of_property_read_bool(
+ pdev->dev.of_node,
+ "atmel,write-by-sram");
}
}
nfc->is_initialized = true;
-
dev_info(&pdev->dev, "NFC is probed.\n");
return 0;
}
--
1.7.9.5
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