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mtd: omap: add support for nand prefetch-read and post-write
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This patch adds prefetch support to access nand flash in mpu mode.
This patch also adds 8-bit nand support (omap_read/write_buf8).
Prefetch can be used for both 8- and 16-bit devices.

Signed-off-by: Vimal Singh <vimalsingh@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
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vimal singh authored and David Woodhouse committed Sep 19, 2009
1 parent 8bff82c commit 59e9c5a
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Showing 4 changed files with 226 additions and 10 deletions.
63 changes: 62 additions & 1 deletion arch/arm/mach-omap2/gpmc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,11 @@
#define GPMC_CHUNK_SHIFT 24 /* 16 MB */
#define GPMC_SECTION_SHIFT 28 /* 128 MB */

#define PREFETCH_FIFOTHRESHOLD (0x40 << 8)
#define CS_NUM_SHIFT 24
#define ENABLE_PREFETCH (0x1 << 7)
#define DMA_MPU_MODE 2

static struct resource gpmc_mem_root;
static struct resource gpmc_cs_mem[GPMC_CS_NUM];
static DEFINE_SPINLOCK(gpmc_mem_lock);
Expand Down Expand Up @@ -386,6 +391,63 @@ void gpmc_cs_free(int cs)
}
EXPORT_SYMBOL(gpmc_cs_free);

/**
* gpmc_prefetch_enable - configures and starts prefetch transfer
* @cs: nand cs (chip select) number
* @dma_mode: dma mode enable (1) or disable (0)
* @u32_count: number of bytes to be transferred
* @is_write: prefetch read(0) or write post(1) mode
*/
int gpmc_prefetch_enable(int cs, int dma_mode,
unsigned int u32_count, int is_write)
{
uint32_t prefetch_config1;

if (!(gpmc_read_reg(GPMC_PREFETCH_CONTROL))) {
/* Set the amount of bytes to be prefetched */
gpmc_write_reg(GPMC_PREFETCH_CONFIG2, u32_count);

/* Set dma/mpu mode, the prefetch read / post write and
* enable the engine. Set which cs is has requested for.
*/
prefetch_config1 = ((cs << CS_NUM_SHIFT) |
PREFETCH_FIFOTHRESHOLD |
ENABLE_PREFETCH |
(dma_mode << DMA_MPU_MODE) |
(0x1 & is_write));
gpmc_write_reg(GPMC_PREFETCH_CONFIG1, prefetch_config1);
} else {
return -EBUSY;
}
/* Start the prefetch engine */
gpmc_write_reg(GPMC_PREFETCH_CONTROL, 0x1);

return 0;
}
EXPORT_SYMBOL(gpmc_prefetch_enable);

/**
* gpmc_prefetch_reset - disables and stops the prefetch engine
*/
void gpmc_prefetch_reset(void)
{
/* Stop the PFPW engine */
gpmc_write_reg(GPMC_PREFETCH_CONTROL, 0x0);

/* Reset/disable the PFPW engine */
gpmc_write_reg(GPMC_PREFETCH_CONFIG1, 0x0);
}
EXPORT_SYMBOL(gpmc_prefetch_reset);

/**
* gpmc_prefetch_status - reads prefetch status of engine
*/
int gpmc_prefetch_status(void)
{
return gpmc_read_reg(GPMC_PREFETCH_STATUS);
}
EXPORT_SYMBOL(gpmc_prefetch_status);

static void __init gpmc_mem_init(void)
{
int cs;
Expand Down Expand Up @@ -452,6 +514,5 @@ void __init gpmc_init(void)
l &= 0x03 << 3;
l |= (0x02 << 3) | (1 << 0);
gpmc_write_reg(GPMC_SYSCONFIG, l);

gpmc_mem_init();
}
4 changes: 4 additions & 0 deletions arch/arm/plat-omap/include/mach/gpmc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -103,6 +103,10 @@ extern int gpmc_cs_request(int cs, unsigned long size, unsigned long *base);
extern void gpmc_cs_free(int cs);
extern int gpmc_cs_set_reserved(int cs, int reserved);
extern int gpmc_cs_reserved(int cs);
extern int gpmc_prefetch_enable(int cs, int dma_mode,
unsigned int u32_count, int is_write);
extern void gpmc_prefetch_reset(void);
extern int gpmc_prefetch_status(void);
extern void __init gpmc_init(void);

#endif
8 changes: 8 additions & 0 deletions drivers/mtd/nand/Kconfig
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Original file line number Diff line number Diff line change
Expand Up @@ -80,6 +80,14 @@ config MTD_NAND_OMAP2
help
Support for NAND flash on Texas Instruments OMAP2 and OMAP3 platforms.

config MTD_NAND_OMAP_PREFETCH
bool "GPMC prefetch support for NAND Flash device"
depends on MTD_NAND && MTD_NAND_OMAP2
default y
help
The NAND device can be accessed for Read/Write using GPMC PREFETCH engine
to improve the performance.

config MTD_NAND_TS7250
tristate "NAND Flash device on TS-7250 board"
depends on MACH_TS72XX
Expand Down
161 changes: 152 additions & 9 deletions drivers/mtd/nand/omap2.c
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Original file line number Diff line number Diff line change
Expand Up @@ -112,6 +112,16 @@
static const char *part_probes[] = { "cmdlinepart", NULL };
#endif

#ifdef CONFIG_MTD_NAND_OMAP_PREFETCH
static int use_prefetch = 1;

/* "modprobe ... use_prefetch=0" etc */
module_param(use_prefetch, bool, 0);
MODULE_PARM_DESC(use_prefetch, "enable/disable use of PREFETCH");
#else
const int use_prefetch;
#endif

struct omap_nand_info {
struct nand_hw_control controller;
struct omap_nand_platform_data *pdata;
Expand All @@ -124,6 +134,7 @@ struct omap_nand_info {
unsigned long phys_base;
void __iomem *gpmc_cs_baseaddr;
void __iomem *gpmc_baseaddr;
void __iomem *nand_pref_fifo_add;
};

/**
Expand Down Expand Up @@ -188,6 +199,38 @@ static void omap_hwcontrol(struct mtd_info *mtd, int cmd, unsigned int ctrl)
__raw_writeb(cmd, info->nand.IO_ADDR_W);
}

/**
* omap_read_buf8 - read data from NAND controller into buffer
* @mtd: MTD device structure
* @buf: buffer to store date
* @len: number of bytes to read
*/
static void omap_read_buf8(struct mtd_info *mtd, u_char *buf, int len)
{
struct nand_chip *nand = mtd->priv;

ioread8_rep(nand->IO_ADDR_R, buf, len);
}

/**
* omap_write_buf8 - write buffer to NAND controller
* @mtd: MTD device structure
* @buf: data buffer
* @len: number of bytes to write
*/
static void omap_write_buf8(struct mtd_info *mtd, const u_char *buf, int len)
{
struct omap_nand_info *info = container_of(mtd,
struct omap_nand_info, mtd);
u_char *p = (u_char *)buf;

while (len--) {
iowrite8(*p++, info->nand.IO_ADDR_W);
while (GPMC_BUF_EMPTY == (readl(info->gpmc_baseaddr +
GPMC_STATUS) & GPMC_BUF_FULL));
}
}

/**
* omap_read_buf16 - read data from NAND controller into buffer
* @mtd: MTD device structure
Expand All @@ -198,7 +241,7 @@ static void omap_read_buf16(struct mtd_info *mtd, u_char *buf, int len)
{
struct nand_chip *nand = mtd->priv;

__raw_readsw(nand->IO_ADDR_R, buf, len / 2);
ioread16_rep(nand->IO_ADDR_R, buf, len / 2);
}

/**
Expand All @@ -217,13 +260,101 @@ static void omap_write_buf16(struct mtd_info *mtd, const u_char * buf, int len)
len >>= 1;

while (len--) {
writew(*p++, info->nand.IO_ADDR_W);
iowrite16(*p++, info->nand.IO_ADDR_W);

while (GPMC_BUF_EMPTY == (readl(info->gpmc_baseaddr +
GPMC_STATUS) & GPMC_BUF_FULL))
;
}
}

/**
* omap_read_buf_pref - read data from NAND controller into buffer
* @mtd: MTD device structure
* @buf: buffer to store date
* @len: number of bytes to read
*/
static void omap_read_buf_pref(struct mtd_info *mtd, u_char *buf, int len)
{
struct omap_nand_info *info = container_of(mtd,
struct omap_nand_info, mtd);
uint32_t pfpw_status = 0, r_count = 0;
int ret = 0;
u32 *p = (u32 *)buf;

/* take care of subpage reads */
for (; len % 4 != 0; ) {
*buf++ = __raw_readb(info->nand.IO_ADDR_R);
len--;
}
p = (u32 *) buf;

/* configure and start prefetch transfer */
ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x0);
if (ret) {
/* PFPW engine is busy, use cpu copy method */
if (info->nand.options & NAND_BUSWIDTH_16)
omap_read_buf16(mtd, buf, len);
else
omap_read_buf8(mtd, buf, len);
} else {
do {
pfpw_status = gpmc_prefetch_status();
r_count = ((pfpw_status >> 24) & 0x7F) >> 2;
ioread32_rep(info->nand_pref_fifo_add, p, r_count);
p += r_count;
len -= r_count << 2;
} while (len);

/* disable and stop the PFPW engine */
gpmc_prefetch_reset();
}
}

/**
* omap_write_buf_pref - write buffer to NAND controller
* @mtd: MTD device structure
* @buf: data buffer
* @len: number of bytes to write
*/
static void omap_write_buf_pref(struct mtd_info *mtd,
const u_char *buf, int len)
{
struct omap_nand_info *info = container_of(mtd,
struct omap_nand_info, mtd);
uint32_t pfpw_status = 0, w_count = 0;
int i = 0, ret = 0;
u16 *p = (u16 *) buf;

/* take care of subpage writes */
if (len % 2 != 0) {
writeb(*buf, info->nand.IO_ADDR_R);
p = (u16 *)(buf + 1);
len--;
}

/* configure and start prefetch transfer */
ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x1);
if (ret) {
/* PFPW engine is busy, use cpu copy method */
if (info->nand.options & NAND_BUSWIDTH_16)
omap_write_buf16(mtd, buf, len);
else
omap_write_buf8(mtd, buf, len);
} else {
pfpw_status = gpmc_prefetch_status();
while (pfpw_status & 0x3FFF) {
w_count = ((pfpw_status >> 24) & 0x7F) >> 1;
for (i = 0; (i < w_count) && len; i++, len -= 2)
iowrite16(*p++, info->nand_pref_fifo_add);
pfpw_status = gpmc_prefetch_status();
}

/* disable and stop the PFPW engine */
gpmc_prefetch_reset();
}
}

/**
* omap_verify_buf - Verify chip data against buffer
* @mtd: MTD device structure
Expand Down Expand Up @@ -658,17 +789,12 @@ static int __devinit omap_nand_probe(struct platform_device *pdev)
err = -ENOMEM;
goto out_release_mem_region;
}

info->nand.controller = &info->controller;

info->nand.IO_ADDR_W = info->nand.IO_ADDR_R;
info->nand.cmd_ctrl = omap_hwcontrol;

/* REVISIT: only supports 16-bit NAND flash */

info->nand.read_buf = omap_read_buf16;
info->nand.write_buf = omap_write_buf16;
info->nand.verify_buf = omap_verify_buf;

/*
* If RDY/BSY line is connected to OMAP then use the omap ready
* funcrtion and the generic nand_wait function which reads the status
Expand All @@ -689,6 +815,23 @@ static int __devinit omap_nand_probe(struct platform_device *pdev)
== 0x1000)
info->nand.options |= NAND_BUSWIDTH_16;

if (use_prefetch) {
/* copy the virtual address of nand base for fifo access */
info->nand_pref_fifo_add = info->nand.IO_ADDR_R;

info->nand.read_buf = omap_read_buf_pref;
info->nand.write_buf = omap_write_buf_pref;
} else {
if (info->nand.options & NAND_BUSWIDTH_16) {
info->nand.read_buf = omap_read_buf16;
info->nand.write_buf = omap_write_buf16;
} else {
info->nand.read_buf = omap_read_buf8;
info->nand.write_buf = omap_write_buf8;
}
}
info->nand.verify_buf = omap_verify_buf;

#ifdef CONFIG_MTD_NAND_OMAP_HWECC
info->nand.ecc.bytes = 3;
info->nand.ecc.size = 512;
Expand Down Expand Up @@ -746,7 +889,7 @@ static int omap_nand_remove(struct platform_device *pdev)
platform_set_drvdata(pdev, NULL);
/* Release NAND device, its internal structures and partitions */
nand_release(&info->mtd);
iounmap(info->nand.IO_ADDR_R);
iounmap(info->nand_pref_fifo_add);
kfree(&info->mtd);
return 0;
}
Expand Down

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