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authorSilvan Wicki <linux_wi@tinag.ch>2015-06-16 17:40:59 +0200
committerWolfram Sang <wsa@the-dreams.de>2015-06-17 14:35:09 +0200
commit7b618638a518ce7083fcca1bc7181a5c6337277a (patch)
tree1e65bfeed5e977e1b6d28c8fe23426256ceccc1d /drivers/i2c
parentb6eba5598dc69d1f3a79183d2521da53d336006e (diff)
downloadop-kernel-dev-7b618638a518ce7083fcca1bc7181a5c6337277a.zip
op-kernel-dev-7b618638a518ce7083fcca1bc7181a5c6337277a.tar.gz
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.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c
index c9336a3..aa06da1 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);
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