Sometimes a clock needs to know the rate of its parent before itself is
registered to the framework. An example is that a PLL may need to
initialize itself to a specific VCO frequency, before registering to the
framework. The parent rate needs to be known, for PLL multipliers and
divisors to be configured properly.
Introduce helper function of_clk_get_parent_rate, which can be used to
obtain the parent rate of a clock, given a device node and index.
Signed-off-by: Ray Jui <rjui@xxxxxxxxxxxx>
---
drivers/clk/clk.c | 17 +++++++++++++++++
include/linux/clk-provider.h | 6 +++++-
2 files changed, 22 insertions(+), 1 deletion(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index d48ac71..e1893a2 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2581,6 +2581,23 @@ const char *of_clk_get_parent_name(struct device_node *np, int index)
}
EXPORT_SYMBOL_GPL(of_clk_get_parent_name);
+unsigned long of_clk_get_parent_rate(struct device_node *np, int index)
+{
+ const char *parent_name;
+ struct clk *parent_clk;
+
+ parent_name = of_clk_get_parent_name(np, index);
+ if (!parent_name)
+ return 0;
+
+ parent_clk = __clk_lookup(parent_name);
+ if (!parent_clk)
+ return 0;
+
+ return clk_get_rate(parent_clk);
+}
+EXPORT_SYMBOL_GPL(of_clk_get_parent_rate);
+
struct clock_provider {
of_clk_init_cb_t clk_init_cb;
struct device_node *np;
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index d936409..e1e2d95 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -585,7 +585,7 @@ struct clk *of_clk_src_simple_get(struct of_phandle_args *clkspec,
struct clk *of_clk_src_onecell_get(struct of_phandle_args *clkspec, void *data);
int of_clk_get_parent_count(struct device_node *np);
const char *of_clk_get_parent_name(struct device_node *np, int index);
-
+unsigned long of_clk_get_parent_rate(struct device_node *np, int index);
void of_clk_init(const struct of_device_id *matches);
#else /* !CONFIG_OF */
@@ -614,6 +614,10 @@ static inline const char *of_clk_get_parent_name(struct device_node *np,
{
return NULL;
}
+static unsigned long of_clk_get_parent_rate(struct device_node *np, int index)
+{
+ return 0;
+}
#define of_clk_init(matches) \
{ while (0); }
#endif /* CONFIG_OF */
--
1.7.9.5
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
