clk: at91: clk-system: add set/get_rate operations

To support set/get the clock rate, add set/get_rate operations.

Signed-off-by: Wenyou Yang <wenyou.yang@microchip.com>
diff --git a/drivers/clk/at91/clk-system.c b/drivers/clk/at91/clk-system.c
index 24b271a..81fe47a 100644
--- a/drivers/clk/at91/clk-system.c
+++ b/drivers/clk/at91/clk-system.c
@@ -44,6 +44,30 @@
 	return (id >= 8) && (id <= 15);
 }
 
+static ulong system_clk_get_rate(struct clk *clk)
+{
+	struct clk clk_dev;
+	int ret;
+
+	ret = clk_get_by_index(clk->dev, 0, &clk_dev);
+	if (ret)
+		return -EINVAL;
+
+	return clk_get_rate(&clk_dev);
+}
+
+static ulong system_clk_set_rate(struct clk *clk, ulong rate)
+{
+	struct clk clk_dev;
+	int ret;
+
+	ret = clk_get_by_index(clk->dev, 0, &clk_dev);
+	if (ret)
+		return -EINVAL;
+
+	return clk_set_rate(&clk_dev, rate);
+}
+
 static int system_clk_enable(struct clk *clk)
 {
 	struct pmc_platdata *plat = dev_get_platdata(clk->dev);
@@ -73,6 +97,8 @@
 
 static struct clk_ops system_clk_ops = {
 	.of_xlate = at91_clk_of_xlate,
+	.get_rate = system_clk_get_rate,
+	.set_rate = system_clk_set_rate,
 	.enable = system_clk_enable,
 };