clk: Propagate clk_set_rate() if CLK_SET_PARENT_RATE present
Sometimes clocks provided to a consumer might not have .set_rate
operation (like gate or mux clocks), but have CLK_SET_PARENT_RATE flag
set. In that case it's usually possible to find a parent up the tree
which is capable of setting the rate (div, pll, etc). Implement a simple
lookup procedure for such cases, to traverse the clock tree until
.set_rate capable parent is found, and use that parent to actually
change the rate. The search will stop once the first .set_rate capable
clock is found, which is usually enough to handle most cases.
Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
diff --git a/drivers/clk/clk-uclass.c b/drivers/clk/clk-uclass.c
index a9937c2..353ae47 100644
--- a/drivers/clk/clk-uclass.c
+++ b/drivers/clk/clk-uclass.c
@@ -569,8 +569,20 @@
return 0;
ops = clk_dev_ops(clk->dev);
- if (!ops->set_rate)
- return -ENOSYS;
+ /* Try to find parents which can set rate */
+ while (!ops->set_rate) {
+ struct clk *parent;
+
+ if (!(clk->flags & CLK_SET_RATE_PARENT))
+ return -ENOSYS;
+
+ parent = clk_get_parent(clk);
+ if (IS_ERR_OR_NULL(parent) || !clk_valid(parent))
+ return -ENODEV;
+
+ clk = parent;
+ ops = clk_dev_ops(clk->dev);
+ }
/* get private clock struct used for cache */
clk_get_priv(clk, &clkp);