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[MTD] m25p80: add FAST_READ access support to M25Pxx 

Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
This commit is contained in:
Bryan Wu 2008-04-25 12:07:32 +08:00 committed by David Woodhouse
parent afc4bca639
commit 2230b76b38
2 changed files with 28 additions and 10 deletions
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7
drivers/mtd/devices/Kconfig
View File

@ -77,6 +77,13 @@ config MTD_M25P80
if you want to specify device partitioning or to use a device which
doesn't support the JEDEC ID instruction.
config M25PXX_USE_FAST_READ
bool "Use FAST_READ OPCode allowing SPI CLK <= 50MHz"
depends on MTD_M25P80
default y
help
This option enables FAST_READ access supported by ST M25Pxx.
config MTD_SLRAM
tristate "Uncached system RAM"
help

31
drivers/mtd/devices/m25p80.c
View File

@ -33,7 +33,7 @@
/* Flash opcodes. */
#define OPCODE_WREN 0x06 /* Write enable */
#define OPCODE_RDSR 0x05 /* Read status register */
#define OPCODE_READ 0x03 /* Read data bytes (low frequency) */
#define OPCODE_NORM_READ 0x03 /* Read data bytes (low frequency) */
#define OPCODE_FAST_READ 0x0b /* Read data bytes (high frequency) */
#define OPCODE_PP 0x02 /* Page program (up to 256 bytes) */
#define OPCODE_BE_4K 0x20 /* Erase 4KiB block */
@ -52,7 +52,15 @@
/* Define max times to check status register before we give up. */
#define MAX_READY_WAIT_COUNT 100000
#define CMD_SIZE 4
#ifdef CONFIG_M25PXX_USE_FAST_READ
#define OPCODE_READ OPCODE_FAST_READ
#define FAST_READ_DUMMY_BYTE 1
#else
#define OPCODE_READ OPCODE_NORM_READ
#define FAST_READ_DUMMY_BYTE 0
#endif
#ifdef CONFIG_MTD_PARTITIONS
#define mtd_has_partitions() (1)
@ -68,7 +76,7 @@ struct m25p {
struct mtd_info mtd;
unsigned partitioned:1;
u8 erase_opcode;
u8 command[4];
u8 command[CMD_SIZE + FAST_READ_DUMMY_BYTE];
};
static inline struct m25p *mtd_to_m25p(struct mtd_info *mtd)
@ -167,7 +175,7 @@ static int erase_sector(struct m25p *flash, u32 offset)
flash->command[2] = offset >> 8;
flash->command[3] = offset;
spi_write(flash->spi, flash->command, sizeof(flash->command));
spi_write(flash->spi, flash->command, CMD_SIZE);
return 0;
}
@ -253,8 +261,12 @@ static int m25p80_read(struct mtd_info *mtd, loff_t from, size_t len,
spi_message_init(&m);
memset(t, 0, (sizeof t));
/* NOTE:
* OPCODE_FAST_READ (if available) is faster.
* Should add 1 byte DUMMY_BYTE.
*/
t[0].tx_buf = flash->command;
t[0].len = sizeof(flash->command);
t[0].len = CMD_SIZE + FAST_READ_DUMMY_BYTE;
spi_message_add_tail(&t[0], &m);
t[1].rx_buf = buf;
@ -287,7 +299,7 @@ static int m25p80_read(struct mtd_info *mtd, loff_t from, size_t len,
spi_sync(flash->spi, &m);
*retlen = m.actual_length - sizeof(flash->command);
*retlen = m.actual_length - CMD_SIZE - FAST_READ_DUMMY_BYTE;
mutex_unlock(&flash->lock);
@ -325,7 +337,7 @@ static int m25p80_write(struct mtd_info *mtd, loff_t to, size_t len,
memset(t, 0, (sizeof t));
t[0].tx_buf = flash->command;
t[0].len = sizeof(flash->command);
t[0].len = CMD_SIZE;
spi_message_add_tail(&t[0], &m);
t[1].tx_buf = buf;
@ -354,7 +366,7 @@ static int m25p80_write(struct mtd_info *mtd, loff_t to, size_t len,
spi_sync(flash->spi, &m);
*retlen = m.actual_length - sizeof(flash->command);
*retlen = m.actual_length - CMD_SIZE;
} else {
u32 i;
@ -364,7 +376,7 @@ static int m25p80_write(struct mtd_info *mtd, loff_t to, size_t len,
t[1].len = page_size;
spi_sync(flash->spi, &m);
*retlen = m.actual_length - sizeof(flash->command);
*retlen = m.actual_length - CMD_SIZE;
/* write everything in PAGESIZE chunks */
for (i = page_size; i < len; i += page_size) {
@ -387,8 +399,7 @@ static int m25p80_write(struct mtd_info *mtd, loff_t to, size_t len,
spi_sync(flash->spi, &m);
if (retlen)
*retlen += m.actual_length
- sizeof(flash->command);
*retlen += m.actual_length - CMD_SIZE;
}
}