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authorGraf Yang <graf.yang@analog.com>2009-06-15 08:23:41 +0000
committerDavid Woodhouse <David.Woodhouse@intel.com>2009-09-19 13:10:16 -0700
commit49aac4aec53c523f16343b4668a5a239b69659f1 (patch)
treea43ad86944551dc05b94058359fdef8a623c7055 /drivers/mtd
parent80f53da0ac752fe16a01ffeddaea658670974a05 (diff)
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>
Diffstat (limited to 'drivers/mtd')
-rw-r--r--drivers/mtd/devices/m25p80.c126
1 files changed, 125 insertions, 1 deletions
diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index 6d8d265ae91..53de9f05ad5 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -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) {