diff options
| author | Silvan Wicki <linux_wi@tinag.ch> | 2015-06-16 17:40:59 +0200 |
|---|---|---|
| committer | Wolfram Sang <wsa@the-dreams.de> | 2015-06-17 14:35:09 +0200 |
| commit | 7b618638a518ce7083fcca1bc7181a5c6337277a (patch) | |
| tree | 1e65bfeed5e977e1b6d28c8fe23426256ceccc1d /drivers/i2c | |
| parent | b6eba5598dc69d1f3a79183d2521da53d336006e (diff) | |
i2c: bcm2835: clear reserved bits in S-Register
The datasheet mentions on page 31 that the bits 10-31 must be read as
don't care and written as 0.
https://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf
We cannot guarantee that we read bits 10-31 as always 0 (because the
datasheet says read as don't care). We clear the bits with a bitmask to
prevent writing back unknown data at the reserved bits.
Signed-off-by: Silvan Wicki <linux_wi@tinag.ch>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/busses/i2c-bcm2835.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c index c9336a3202d5..aa06da17e30e 100644 --- a/drivers/i2c/busses/i2c-bcm2835.c +++ b/drivers/i2c/busses/i2c-bcm2835.c @@ -50,6 +50,8 @@ #define BCM2835_I2C_S_CLKT BIT(9) #define BCM2835_I2C_S_LEN BIT(10) /* Fake bit for SW error reporting */ +#define BCM2835_I2C_BITMSK_S 0x03FF + #define BCM2835_I2C_TIMEOUT (msecs_to_jiffies(1000)) struct bcm2835_i2c_dev { @@ -111,6 +113,7 @@ static irqreturn_t bcm2835_i2c_isr(int this_irq, void *data) u32 val, err; val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S); + val &= BCM2835_I2C_BITMSK_S; bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_S, val); err = val & (BCM2835_I2C_S_CLKT | BCM2835_I2C_S_ERR); |