i2c: designware: Enable fast mode plus

This patch enabled fast mode plus. The fast mode plus and fast speed
share the same HCNT and LCNT register. So, the fast mode plus will only
run when the HCNT and LCNT value is provided. Else, it will run at fast
speed as default.

Signed-off-by: Weifeng Voon <weifeng.voon@intel.com>
Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
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 cbe4fb3..ea92e9f 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -196,10 +196,13 @@
 		dw_i2c_acpi_configure(pdev);
 
 	/*
-	 * Only standard mode at 100kHz and fast mode at 400kHz are supported.
+	 * Only standard mode at 100kHz, fast mode at 400kHz,
+	 * and fast mode plus at 1MHz are supported.
 	 */
-	if (dev->clk_freq != 100000 && dev->clk_freq != 400000) {
-		dev_err(&pdev->dev, "Only 100kHz and 400kHz supported");
+	if (dev->clk_freq != 100000 && dev->clk_freq != 400000
+	    && dev->clk_freq != 1000000) {
+		dev_err(&pdev->dev,
+			"Only 100kHz, 400kHz and 1MHz are supported");
 		return -EINVAL;
 	}