[PATCH v6 3/4] clk: Provide always-on clock support

Stephen Boyd
2015-04-08T05:02:57Z

On 04/07, 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 provider is registered with the
> framework it is possible for a list of always-on clocks to be supplied
> which must be kept ungated. Each clock mentioned in the newly
> introduced 'clock-always-on' will be clk_prepare_enable()d where the
> normal references will be taken. This will prevent the common clk
> framework from attempting to gate them during the clk_disable_unused()
> and disable_clock() procedures.
>
> Signed-off-by: Lee Jones <lee.jones@linaro.org>
> ---
> drivers/clk/clk-conf.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 42 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/clk/clk-conf.c b/drivers/clk/clk-conf.c
> index aad4796..a07aced 100644
> --- a/drivers/clk/clk-conf.c
> +++ b/drivers/clk/clk-conf.c
> @@ -116,6 +116,43 @@ static int __set_clk_rates(struct device_node *node, bool clk_supplier)
> return 0;
> }
>
> +static int __set_clk_always_on(struct device_node *node, bool clk_supplier)
> +{
> + struct of_phandle_args clkspec;
> + struct clk *clk;
> + struct property *prop;
> + const __be32 *cur;
> + uint32_t index;

u32 please

> + int ret;
> +
> + if (!clk_supplier)
> + return 0;
> +
> + of_property_for_each_u32(node, "clock-always-on", prop, cur, index) {
> + clkspec.np = node;
> + clkspec.args_count = 1;
> + clkspec.args[0] = index;
> +
> + clk = of_clk_get_from_provider(&clkspec);
> + if (IS_ERR(clk)) {
> + pr_err("clk: couldn't get clock %u for %s\n",
> + index, node->full_name);
> + return PTR_ERR(clk);
> + }
> +
> + ret = clk_prepare_enable(clk);
> + if (ret) {
> + pr_err("Failed to enable clock %u for %s: %d\n",
> + index, node->full_name, ret);
> + return ret;
> + }

I guess we don't have a clk_put() here because we want to keep the
refcount high forever? We should at least put a comment here
explaining why we left out clk_put() if so.

> +
> + pr_debug("Setting clock as always-on %pC\n", clk);
> + }
> +
> + return 0;
> +}
> +
> /**
> * of_clk_set_defaults() - parse and set assigned clocks configuration
> * @node: device node to apply clock settings for

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