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

Lee Jones
2015-02-27T21:51:20Z

On Fri, 27 Feb 2015, Lee Jones wrote:

> 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;

Might save a few cycles by breaking here.

> + }
> +
> return ret;
> }
> EXPORT_SYMBOL_GPL(of_clk_add_provider);

--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org ? Open source software for ARM SoCs
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