i2c: exynos5: Preserve high speed master code

When the driver starts to send a message with the MASTER_ID field
set (high speed), the whole I2C_ADDR register is overwritten including
MASTER_ID as the SLV_ADDR_MAS field is set.

This patch preserves already written fields in I2C_ADDR when writing
SLV_ADDR_MAS.

Fixes: 8a73cd4c ("i2c: exynos5: add High Speed I2C controller driver")
Signed-off-by: Mårten Lindahl <martenli@axis.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Tested-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/busses/i2c-exynos5.c

@@ -606,6 +606,7 @@ static void exynos5_i2c_message_start(struct exynos5_i2c *i2c, int stop)
 	u32 i2c_ctl;
 	u32 int_en = 0;
 	u32 i2c_auto_conf = 0;
+	u32 i2c_addr = 0;
 	u32 fifo_ctl;
 	unsigned long flags;
 	unsigned short trig_lvl;
@@ -640,7 +641,12 @@ static void exynos5_i2c_message_start(struct exynos5_i2c *i2c, int stop)
 		int_en |= HSI2C_INT_TX_ALMOSTEMPTY_EN;
 	}
 
-	writel(HSI2C_SLV_ADDR_MAS(i2c->msg->addr), i2c->regs + HSI2C_ADDR);
+	i2c_addr = HSI2C_SLV_ADDR_MAS(i2c->msg->addr);
+
+	if (i2c->op_clock >= I2C_MAX_FAST_MODE_PLUS_FREQ)
+		i2c_addr |= HSI2C_MASTER_ID(MASTER_ID(i2c->adap.nr));
+
+	writel(i2c_addr, i2c->regs + HSI2C_ADDR);
 
 	writel(fifo_ctl, i2c->regs + HSI2C_FIFO_CTL);
 	writel(i2c_ctl, i2c->regs + HSI2C_CTL);