[U-Boot] [PATCH 2/2] mtd: vf610_nfc: implement OOB only read
Stefan Agner
stefan at agner.ch
Thu Apr 2 11:05:11 CEST 2015
Implement read of OOB area only. When using column and sector size
properties, only parts of the page can be read. However, this works
only when hardware ECC is disabled, otherwise the ECC engine would
ruin the data in the buffer. To allow OOB only reads, three points
had to be addressed:
- Set ECC mode per command.
- Handle NAND_CMD_READOOB seperate. Make sure column and sector
size is correctly set up, while disabling ECC.
- Now, the OOB data end up at the beginning of the buffer. Remove
the special handling of OOB (spareonly).
Especially bad block scans benefit from this change. On a 512MiB
SLC NAND device, the bad block scan took 1.5s less than before.
---
During the testing of the first patch, I came accross this
bottleneck. The same measurements as done in the first patch:
Time to "Starting kernel ..."
- without bad block scan & with UBIFS fastmap: 2.01s
- with bad block scan & with UBIFS fastmap: 2.53s
- without bad block scan & without UBIFS fastmap: 4.41s
- with bad block scan & without UBIFS fastmap: 4.95s
While we move more complexity into vf610_nfc_command, given the
simplification of code overall and the improved bad block scanning
performance, it's a worthwhile change.
drivers/mtd/nand/vf610_nfc.c | 103 ++++++++++++++++++-------------------------
1 file changed, 42 insertions(+), 61 deletions(-)
diff --git a/drivers/mtd/nand/vf610_nfc.c b/drivers/mtd/nand/vf610_nfc.c
index fa0bb9d..75c2493 100644
--- a/drivers/mtd/nand/vf610_nfc.c
+++ b/drivers/mtd/nand/vf610_nfc.c
@@ -145,8 +145,6 @@ struct vf610_nfc {
struct nand_chip chip;
void __iomem *regs;
uint column;
- int spareonly;
- int page_sz;
/* Status and ID are in alternate locations. */
int alt_buf;
#define ALT_BUF_ID 1
@@ -319,8 +317,8 @@ static void vf610_nfc_addr_cycle(struct mtd_info *mtd, int column, int page)
{
if (column != -1) {
struct vf610_nfc *nfc = mtd_to_nfc(mtd);
- if (nfc->chip.options | NAND_BUSWIDTH_16)
- column = column/2;
+ if (nfc->chip.options & NAND_BUSWIDTH_16)
+ column = column / 2;
vf610_nfc_set_field(mtd, NFC_COL_ADDR, COL_ADDR_MASK,
COL_ADDR_SHIFT, column);
}
@@ -329,6 +327,13 @@ static void vf610_nfc_addr_cycle(struct mtd_info *mtd, int column, int page)
ROW_ADDR_SHIFT, page);
}
+static inline void vf610_nfc_ecc_mode(struct mtd_info *mtd, int ecc_mode)
+{
+ vf610_nfc_set_field(mtd, NFC_FLASH_CONFIG,
+ CONFIG_ECC_MODE_MASK,
+ CONFIG_ECC_MODE_SHIFT, ecc_mode);
+}
+
static inline void vf610_nfc_transfer_size(void __iomem *regbase, int size)
{
__raw_writel(size, regbase + NFC_SECTOR_SIZE);
@@ -339,36 +344,48 @@ static void vf610_nfc_command(struct mtd_info *mtd, unsigned command,
int column, int page)
{
struct vf610_nfc *nfc = mtd_to_nfc(mtd);
+ int page_sz = nfc->chip.options & NAND_BUSWIDTH_16 ? 1 : 0;
- nfc->column = max(column, 0);
- nfc->spareonly = 0;
- nfc->alt_buf = 0;
+ nfc->column = max(column, 0);
+ nfc->alt_buf = 0;
switch (command) {
case NAND_CMD_PAGEPROG:
- vf610_nfc_transfer_size(nfc->regs, nfc->page_sz);
+ page_sz += mtd->writesize + mtd->oobsize;
+ vf610_nfc_transfer_size(nfc->regs, page_sz);
vf610_nfc_send_commands(nfc->regs, NAND_CMD_SEQIN,
command, PROGRAM_PAGE_CMD_CODE);
vf610_nfc_addr_cycle(mtd, column, page);
+ vf610_nfc_ecc_mode(mtd, ECC_45_BYTE);
break;
case NAND_CMD_RESET:
vf610_nfc_transfer_size(nfc->regs, 0);
vf610_nfc_send_command(nfc->regs, command, RESET_CMD_CODE);
break;
+
+ case NAND_CMD_READOOB:
+ page_sz += mtd->oobsize;
+ column = mtd->writesize;
+ vf610_nfc_transfer_size(nfc->regs, page_sz);
+ vf610_nfc_send_commands(nfc->regs, NAND_CMD_READ0,
+ NAND_CMD_READSTART, READ_PAGE_CMD_CODE);
+ vf610_nfc_addr_cycle(mtd, column, page);
+ vf610_nfc_ecc_mode(mtd, ECC_BYPASS);
+ break;
/*
- * NFC does not support sub-page reads and writes,
+ * NFC does not support sub-page reads and writes when using HW-ECC,
* so emulate them using full page transfers.
*/
- case NAND_CMD_READOOB:
- nfc->spareonly = 1;
case NAND_CMD_SEQIN: /* Pre-read for partial writes. */
case NAND_CMD_READ0:
+ page_sz += mtd->writesize + mtd->oobsize;
column = 0;
- vf610_nfc_transfer_size(nfc->regs, nfc->page_sz);
+ vf610_nfc_transfer_size(nfc->regs, page_sz);
vf610_nfc_send_commands(nfc->regs, NAND_CMD_READ0,
NAND_CMD_READSTART, READ_PAGE_CMD_CODE);
vf610_nfc_addr_cycle(mtd, column, page);
+ vf610_nfc_ecc_mode(mtd, ECC_45_BYTE);
break;
case NAND_CMD_ERASE1:
@@ -397,46 +414,26 @@ static void vf610_nfc_command(struct mtd_info *mtd, unsigned command,
vf610_nfc_done(mtd);
}
-static inline void vf610_nfc_read_spare(struct mtd_info *mtd, void *buf,
- int len)
-{
- struct vf610_nfc *nfc = mtd_to_nfc(mtd);
-
- len = min(mtd->oobsize, (uint)len);
- if (len > 0)
- vf610_nfc_memcpy(buf, nfc->regs + mtd->writesize, len);
-}
-
/* Read data from NFC buffers */
static void vf610_nfc_read_buf(struct mtd_info *mtd, u_char *buf, int len)
{
struct vf610_nfc *nfc = mtd_to_nfc(mtd);
uint c = nfc->column;
- uint l;
- /* Handle main area */
- if (!nfc->spareonly) {
- l = min((uint)len, mtd->writesize - c);
- nfc->column += l;
-
- if (!nfc->alt_buf)
- vf610_nfc_memcpy(buf, nfc->regs + NFC_MAIN_AREA(0) + c,
- l);
- else
- if (nfc->alt_buf & ALT_BUF_ID)
- *buf = vf610_nfc_get_id(mtd, c);
- else
- *buf = vf610_nfc_get_status(mtd);
-
- buf += l;
- len -= l;
+ switch (nfc->alt_buf)
+ {
+ case ALT_BUF_ID:
+ *buf = vf610_nfc_get_id(mtd, c);
+ break;
+ case ALT_BUF_STAT:
+ *buf = vf610_nfc_get_status(mtd);
+ break;
+ default:
+ vf610_nfc_memcpy(buf, nfc->regs + NFC_MAIN_AREA(0) + c, len);
+ break;
}
- /* Handle spare area access */
- if (len) {
- nfc->column += len;
- vf610_nfc_read_spare(mtd, buf, len);
- }
+ nfc->column += len;
}
/* Write data to NFC buffers */
@@ -627,17 +624,9 @@ static int vf610_nfc_nand_init(int devnum, void __iomem *addr)
if (cfg.flash_bbt)
chip->bbt_options = NAND_BBT_USE_FLASH | NAND_BBT_CREATE;
- /* Default to software ECC until flash ID. */
- vf610_nfc_set_field(mtd, NFC_FLASH_CONFIG,
- CONFIG_ECC_MODE_MASK,
- CONFIG_ECC_MODE_SHIFT, ECC_BYPASS);
-
chip->bbt_td = &bbt_main_descr;
chip->bbt_md = &bbt_mirror_descr;
- nfc->page_sz = PAGE_2K + OOB_64;
- nfc->page_sz += cfg.width == 16 ? 1 : 0;
-
/* Set configuration register. */
vf610_nfc_clear(mtd, NFC_FLASH_CONFIG, CONFIG_ADDR_AUTO_INCR_BIT);
vf610_nfc_clear(mtd, NFC_FLASH_CONFIG, CONFIG_BUFNO_AUTO_INCR_BIT);
@@ -665,15 +654,12 @@ static int vf610_nfc_nand_init(int devnum, void __iomem *addr)
chip->ecc.mode = NAND_ECC_SOFT; /* default */
- nfc->page_sz = mtd->writesize + mtd->oobsize;
-
/* Single buffer only, max 256 OOB minus ECC status */
- if (nfc->page_sz > PAGE_2K + 256 - 8) {
+ if (mtd->writesize + mtd->oobsize > PAGE_2K + 256 - 8) {
dev_err(nfc->dev, "Unsupported flash size\n");
err = -ENXIO;
goto error;
}
- nfc->page_sz += cfg.width == 16 ? 1 : 0;
if (cfg.hardware_ecc) {
if (mtd->writesize != PAGE_2K && mtd->oobsize < 64) {
@@ -694,11 +680,6 @@ static int vf610_nfc_nand_init(int devnum, void __iomem *addr)
chip->ecc.size = PAGE_2K;
chip->ecc.strength = 24;
- /* set ECC mode to 45 bytes OOB with 24 bits correction */
- vf610_nfc_set_field(mtd, NFC_FLASH_CONFIG,
- CONFIG_ECC_MODE_MASK,
- CONFIG_ECC_MODE_SHIFT, ECC_45_BYTE);
-
/* Enable ECC_STATUS */
vf610_nfc_set(mtd, NFC_FLASH_CONFIG, CONFIG_ECC_SRAM_REQ_BIT);
}
--
2.3.3
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