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nor m25p80: implement fast read 

The fast read command is needed for spi speeds > 25MHz, so use it for
higher speeds.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
This commit is contained in:
Sascha Hauer 2012-07-31 13:55:30 +02:00
parent 85bdbb1c52
commit 8895e7512e
2 changed files with 9 additions and 13 deletions
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12
drivers/nor/m25p80.c
View File

@ -267,6 +267,7 @@ ssize_t m25p80_read(struct cdev *cdev, void *buf, size_t count, loff_t offset,
struct spi_transfer t[2];
struct spi_message m;
ssize_t retlen;
int fast_read = 0;
/* sanity checks */
if (!count)
@ -275,6 +276,9 @@ ssize_t m25p80_read(struct cdev *cdev, void *buf, size_t count, loff_t offset,
if (offset + count > flash->size)
return -EINVAL;
if (flash->spi->max_speed_hz >= 25000000)
fast_read = 1;
spi_message_init(&m);
memset(t, 0, (sizeof t));
@ -283,7 +287,7 @@ ssize_t m25p80_read(struct cdev *cdev, void *buf, size_t count, loff_t offset,
* Should add 1 byte DUMMY_BYTE.
*/
t[0].tx_buf = flash->command;
t[0].len = m25p_cmdsz(flash) + FAST_READ_DUMMY_BYTE;
t[0].len = m25p_cmdsz(flash) + fast_read;
spi_message_add_tail(&t[0], &m);
t[1].rx_buf = buf;
@ -303,12 +307,12 @@ ssize_t m25p80_read(struct cdev *cdev, void *buf, size_t count, loff_t offset,
*/
/* Set up the write data buffer. */
flash->command[0] = OPCODE_READ;
flash->command[0] = fast_read ? OPCODE_FAST_READ : OPCODE_NORM_READ;
m25p_addr2cmd(flash, offset, flash->command);
spi_sync(flash->spi, &m);
retlen = m.actual_length - m25p_cmdsz(flash) - FAST_READ_DUMMY_BYTE;
retlen = m.actual_length - m25p_cmdsz(flash) - fast_read;
return retlen;
}
@ -756,7 +760,7 @@ static int m25p_probe(struct device_d *dev)
}
flash = xzalloc(sizeof *flash);
flash->command = xmalloc(MAX_CMD_SIZE + FAST_READ_DUMMY_BYTE);
flash->command = xmalloc(MAX_CMD_SIZE);
flash->spi = spi;
dev->priv = (void *)flash;

10
drivers/nor/m25p80.h
View File

@ -34,15 +34,7 @@
/* Define max times to check status register before we give up. */
#define MAX_READY_WAIT 40 /* M25P16 specs 40s max chip erase */
#define MAX_CMD_SIZE 5
#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
#define MAX_CMD_SIZE 6
#define SPI_NAME_SIZE 32