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Diffstat (limited to 'drivers/i2c/busses/i2c-bcm2835.c')
-rw-r--r--drivers/i2c/busses/i2c-bcm2835.c21
1 files changed, 20 insertions, 1 deletions
diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c
index cd07a69e2e93..44deae78913e 100644
--- a/drivers/i2c/busses/i2c-bcm2835.c
+++ b/drivers/i2c/busses/i2c-bcm2835.c
@@ -50,6 +50,9 @@
#define BCM2835_I2C_S_CLKT BIT(9)
#define BCM2835_I2C_S_LEN BIT(10) /* Fake bit for SW error reporting */
+#define BCM2835_I2C_FEDL_SHIFT 16
+#define BCM2835_I2C_REDL_SHIFT 0
+
#define BCM2835_I2C_CDIV_MIN 0x0002
#define BCM2835_I2C_CDIV_MAX 0xFFFE
@@ -81,7 +84,7 @@ static inline u32 bcm2835_i2c_readl(struct bcm2835_i2c_dev *i2c_dev, u32 reg)
static int bcm2835_i2c_set_divider(struct bcm2835_i2c_dev *i2c_dev)
{
- u32 divider;
+ u32 divider, redl, fedl;
divider = DIV_ROUND_UP(clk_get_rate(i2c_dev->clk),
i2c_dev->bus_clk_rate);
@@ -100,6 +103,22 @@ static int bcm2835_i2c_set_divider(struct bcm2835_i2c_dev *i2c_dev)
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DIV, divider);
+ /*
+ * Number of core clocks to wait after falling edge before
+ * outputting the next data bit. Note that both FEDL and REDL
+ * can't be greater than CDIV/2.
+ */
+ fedl = max(divider / 16, 1u);
+
+ /*
+ * Number of core clocks to wait after rising edge before
+ * sampling the next incoming data bit.
+ */
+ redl = max(divider / 4, 1u);
+
+ bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DEL,
+ (fedl << BCM2835_I2C_FEDL_SHIFT) |
+ (redl << BCM2835_I2C_REDL_SHIFT));
return 0;
}