i2c: mediatek: add i2c resume support

mt65xx i2c controller initial setting will be cleared after system suspend,
so we should init mt65xx i2c controller again when system resume.
Signed-off-by: Liguo Zhang <liguo.zhang@mediatek.com>
Signed-off-by: Eddie Huang <eddie.huang@mediatek.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-mt65xx.c

@@ -728,11 +728,27 @@ static int mtk_i2c_remove(struct platform_device *pdev)
 	return 0;
 }
 
+#ifdef CONFIG_PM_SLEEP
+static int mtk_i2c_resume(struct device *dev)
+{
+	struct mtk_i2c *i2c = dev_get_drvdata(dev);
+
+	mtk_i2c_init_hw(i2c);
+
+	return 0;
+}
+#endif
+
+static const struct dev_pm_ops mtk_i2c_pm = {
+	SET_SYSTEM_SLEEP_PM_OPS(NULL, mtk_i2c_resume)
+};
+
 static struct platform_driver mtk_i2c_driver = {
 	.probe = mtk_i2c_probe,
 	.remove = mtk_i2c_remove,
 	.driver = {
 		.name = I2C_DRV_NAME,
+		.pm = &mtk_i2c_pm,
 		.of_match_table = of_match_ptr(mtk_i2c_of_match),
 	},
 };