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Subject[PATCH 1/1] mtd m25p80: fix bug - ATmel spi flash fails to be copied to
Date
From: Michael Hennerich <michael.hennerich@analog.com>

Atmel serial flash tends to power up with the protection status bits set.
http://blackfin.uclinux.org/gf/project/uclinux-dist/tracker/?action=TrackerItemEdit&tracker_item_id=4089

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
---
drivers/mtd/devices/m25p80.c | 24 ++++++++++++++++++++++++
1 files changed, 24 insertions(+), 0 deletions(-)

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index 25efd33..b10649b 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -33,6 +33,7 @@
/* Flash opcodes. */
#define OPCODE_WREN 0x06 /* Write enable */
#define OPCODE_RDSR 0x05 /* Read status register */
+#define OPCODE_WRSR 0x01 /* Write status register 1 byte */
#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) */
@@ -112,6 +113,19 @@ static int read_sr(struct m25p *flash)
return val;
}

+/*
+ * Write status register 1 byte
+ * Returns negative if error occurred.
+ */
+static int write_sr(struct m25p *flash, u8 val)
+{
+ flash->command[0] = OPCODE_WRSR;
+ flash->command[1] = val;
+
+ spi_write(flash->spi, flash->command, 2);
+
+ return spi_write(flash->spi, flash->command, 2);
+}

/*
* Set write enable latch with Write Enable command.
@@ -587,6 +601,16 @@ static int __devinit m25p_probe(struct spi_device *spi)
mutex_init(&flash->lock);
dev_set_drvdata(&spi->dev, flash);

+ /*
+ * Atmel serial flash tend to power up
+ * with the software protection bits set
+ */
+
+ if (info->jedec_id >> 16 == 0x1f) {
+ write_enable(flash);
+ write_sr(flash, 0);
+ }
+
if (data && data->name)
flash->mtd.name = data->name;
else
--
1.5.5


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