[PATCH 3/4] clk: Provide always-on clock support

Lee Jones
2015-02-27T21:14:33Z

Lots of platforms contain clocks which if turned off would prove fatal.
The only way to recover from these catastrophic failures is to restart
the board(s). Now, when a clock is registered with the framework it is
compared against a list of provided always-on clock names which must be
kept ungated. If it matches, we enable the existing CLK_IGNORE_UNUSED
flag, which will prevent the common clk framework from attempting to
gate it during the clk_disable_unused() procedure.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
drivers/clk/clk.c | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 61c3fc5..3aab75e 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2856,6 +2856,9 @@ int of_clk_add_provider(struct device_node *np,
void *data)
{
struct of_clk_provider *cp;
+ struct property *prop;
+ struct clk *clk;
+ const char *clkname;
int ret;

cp = kzalloc(sizeof(struct of_clk_provider), GFP_KERNEL);
@@ -2875,6 +2878,14 @@ int of_clk_add_provider(struct device_node *np,
if (ret < 0)
of_clk_del_provider(np);

+ of_property_for_each_string(np, "clock-always-on", prop, clkname) {
+ clk = __clk_lookup(clkname);
+ if (!clk)
+ continue;
+
+ clk->core->flags |= CLK_IGNORE_UNUSED;
+ }
+
return ret;
}
EXPORT_SYMBOL_GPL(of_clk_add_provider);
--
1.9.1