i2c-designware: make SDA hold time configurable

This patch makes the SDA hold time configurable through device tree.

Signed-off-by: Christian Ruppert <christian.ruppert@abilis.com>
Signed-off-by: Pierrick Hascoet <pierrick.hascoet@abilis.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com> for arch/arc bits
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index ee46c92..def79b5 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -34,6 +34,7 @@
 #include <linux/sched.h>
 #include <linux/err.h>
 #include <linux/interrupt.h>
+#include <linux/of.h>
 #include <linux/of_i2c.h>
 #include <linux/platform_device.h>
 #include <linux/pm.h>
@@ -115,6 +116,15 @@
 		return PTR_ERR(dev->clk);
 	clk_prepare_enable(dev->clk);
 
+	if (pdev->dev.of_node) {
+		u32 ht = 0;
+		u32 ic_clk = dev->get_clk_rate_khz(dev);
+
+		of_property_read_u32(pdev->dev.of_node,
+					"i2c-sda-hold-time-ns", &ht);
+		dev->sda_hold_time = ((u64)ic_clk * ht + 500000) / 1000000;
+	}
+
 	dev->functionality =
 		I2C_FUNC_I2C |
 		I2C_FUNC_10BIT_ADDR |