i2c: bcm2835: Set up the rising/falling edge delays

1/1

---
 drivers/i2c/busses/i2c-bcm2835.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)
index cd07a69e2e93..44deae78913e 100644
@@ -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;
 }
 

2.14.1

Boris Brezillon