[MTD] m25p80: fix bug - ATmel spi flash fails to be copied to

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

[michael.hennerich@analog.com: remove duplicate code]
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index b402269301f6..b35c3333e210 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 +113,17 @@ 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;
+
+        return spi_write(flash->spi, flash->command, 2);
+}
 
 /*
  * Set write enable latch with Write Enable command.
@@ -589,6 +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