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mtd: m25p80: add support for AAI programming with SST SPI flashes 

The SST SPI flashes are a bit non-standard in that they can be programmed
one byte at a time (including address!), or they can be written two bytes
at a time with auto address incrementing (AAI).  The latter form is
obviously much better for performance, so let's use it when possible.

Signed-off-by: Graf Yang <graf.yang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
This commit is contained in:
Graf Yang 2009-06-15 08:23:41 +00:00 committed by David Woodhouse
parent 80f53da0ac
commit 49aac4aec5
1 changed files with 125 additions and 1 deletions
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126
drivers/mtd/devices/m25p80.c
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@ -44,6 +44,11 @@
#define OPCODE_SE 0xd8 /* Sector erase (usually 64KiB) */
#define OPCODE_RDID 0x9f /* Read JEDEC ID */
/* Used for SST flashes only. */
#define OPCODE_BP 0x02 /* Byte program */
#define OPCODE_WRDI 0x04 /* Write disable */
#define OPCODE_AAI_WP 0xad /* Auto address increment word program */
/* Status Register bits. */
#define SR_WIP 1 /* Write in progress */
#define SR_WEL 2 /* Write enable latch */
@ -132,6 +137,15 @@ static inline int write_enable(struct m25p *flash)
return spi_write_then_read(flash->spi, &code, 1, NULL, 0);
}
/*
* Send write disble instruction to the chip.
*/
static inline int write_disable(struct m25p *flash)
{
u8 code = OPCODE_WRDI;
return spi_write_then_read(flash->spi, &code, 1, NULL, 0);
}
/*
* Service routine to read status register until ready, or timeout occurs.
@ -454,6 +468,111 @@ static int m25p80_write(struct mtd_info *mtd, loff_t to, size_t len,
return 0;
}
static int sst_write(struct mtd_info *mtd, loff_t to, size_t len,
size_t *retlen, const u_char *buf)
{
struct m25p *flash = mtd_to_m25p(mtd);
struct spi_transfer t[2];
struct spi_message m;
size_t actual;
int cmd_sz, ret;
if (retlen)
*retlen = 0;
/* sanity checks */
if (!len)
return 0;
if (to + len > flash->mtd.size)
return -EINVAL;
spi_message_init(&m);
memset(t, 0, (sizeof t));
t[0].tx_buf = flash->command;
t[0].len = CMD_SIZE;
spi_message_add_tail(&t[0], &m);
t[1].tx_buf = buf;
spi_message_add_tail(&t[1], &m);
mutex_lock(&flash->lock);
/* Wait until finished previous write command. */
ret = wait_till_ready(flash);
if (ret)
goto time_out;
write_enable(flash);
actual = to % 2;
/* Start write from odd address. */
if (actual) {
flash->command[0] = OPCODE_BP;
flash->command[1] = to >> 16;
flash->command[2] = to >> 8;
flash->command[3] = to;
/* write one byte. */
t[1].len = 1;
spi_sync(flash->spi, &m);
ret = wait_till_ready(flash);
if (ret)
goto time_out;
*retlen += m.actual_length - CMD_SIZE;
}
to += actual;
flash->command[0] = OPCODE_AAI_WP;
flash->command[1] = to >> 16;
flash->command[2] = to >> 8;
flash->command[3] = to;
/* Write out most of the data here. */
cmd_sz = CMD_SIZE;
for (; actual < len - 1; actual += 2) {
t[0].len = cmd_sz;
/* write two bytes. */
t[1].len = 2;
t[1].tx_buf = buf + actual;
spi_sync(flash->spi, &m);
ret = wait_till_ready(flash);
if (ret)
goto time_out;
*retlen += m.actual_length - cmd_sz;
cmd_sz = 1;
to += 2;
}
write_disable(flash);
ret = wait_till_ready(flash);
if (ret)
goto time_out;
/* Write out trailing byte if it exists. */
if (actual != len) {
write_enable(flash);
flash->command[0] = OPCODE_BP;
flash->command[1] = to >> 16;
flash->command[2] = to >> 8;
flash->command[3] = to;
t[0].len = CMD_SIZE;
t[1].len = 1;
t[1].tx_buf = buf + actual;
spi_sync(flash->spi, &m);
ret = wait_till_ready(flash);
if (ret)
goto time_out;
*retlen += m.actual_length - CMD_SIZE;
write_disable(flash);
}
time_out:
mutex_unlock(&flash->lock);
return ret;
}
/****************************************************************************/
@ -670,7 +789,12 @@ static int __devinit m25p_probe(struct spi_device *spi)
flash->mtd.size = info->sector_size * info->n_sectors;
flash->mtd.erase = m25p80_erase;
flash->mtd.read = m25p80_read;
flash->mtd.write = m25p80_write;
/* sst flash chips use AAI word program */
if (info->jedec_id >> 16 == 0xbf)
flash->mtd.write = sst_write;
else
flash->mtd.write = m25p80_write;
/* prefer "small sector" erase if possible */
if (info->flags & SECT_4K) {