[PATCH] clk: gate: add CLK_GATE_ALWAYS_ON

[Viresh Kumar]

Added linaro-kernel & patches at linaro.org in cc list..

On 6 August 2013 09:27, Shaojie Sun <shaojie.sun at linaro.org> wrote:
> By default gate clock could be enable and disable. but
> in some debug condition, must keep clock on, and never be closed.
> setting this flag then gate clock never be closed.

Consider rewriting it as:

By default gate clk can be enabled/disabled but during debugging we
may want to disable clk-disabling feature.

This patch adds a flag for it..

> Signed-off-by: Shaojie Sun <shaojie.sun at linaro.com>
> ---
>  drivers/clk/clk-gate.c       |   24 ++++++++++++++++++++++++
>  include/linux/clk-provider.h |    4 ++++
>  2 files changed, 28 insertions(+)

Honestly speaking, I am not sure if this patch is really required or not.
And so Mike can decide on that. I will do a simple code review in
that time.

> diff --git a/drivers/clk/clk-gate.c b/drivers/clk/clk-gate.c
> index 790306e..cc2b00e 100644
> --- a/drivers/clk/clk-gate.c
> +++ b/drivers/clk/clk-gate.c
> @@ -15,6 +15,7 @@
>  #include <linux/io.h>
>  #include <linux/err.h>
>  #include <linux/string.h>
> +#include <linux/device.h>

why?

>  /**
>   * DOC: basic gatable clock which can gate and ungate it's ouput
> @@ -48,6 +49,9 @@ static void clk_gate_endisable(struct clk_hw *hw, int enable)
>         unsigned long flags = 0;
>         u32 reg;
>
> +       if (!enable && (gate->flags & CLK_GATE_ALWAYS_ON))
> +               return;
> +
>         set ^= enable;
>
>         if (gate->lock)
> @@ -159,5 +163,25 @@ struct clk *clk_register_gate(struct device *dev, const char *name,
>         if (IS_ERR(clk))
>                 kfree(gate);
>
> +       if (clk_gate_flags & CLK_GATE_ALWAYS_ON) {
> +               int ret;
> +               if (flags & CLK_SET_PARENT_GATE)
> +                       pr_debug("%s: %salways on, but need parent gate.\n",
> +                                       __func__, name);
> +
> +               ret = clk_prepare(clk);
> +               if (ret) {
> +                       pr_debug("%s: %s could not be prepared.\n",
> +                                       __func__, name);
> +                       return clk;
> +               }
> +               ret = clk_enable(clk);
> +               if (ret) {
> +                       pr_debug("%s: %s could not be enabled.\n",
> +                                       __func__, name);
> +                       clk_unprepare(clk);
> +               }

Call clk_prepare_enable instead.

> +       }
> +
>         return clk;
>  }
> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
> index 1ec14a7..641422c 100644
> --- a/include/linux/clk-provider.h
> +++ b/include/linux/clk-provider.h
> @@ -214,6 +214,9 @@ void of_fixed_clk_setup(struct device_node *np);
>   *   of this register, and mask of gate bits are in higher 16-bit of this
>   *   register.  While setting the gate bits, higher 16-bit should also be
>   *   updated to indicate changing gate bits.
> + * CLK_GATE_ALWAYS_ON - by default this clock could be enable and disable. but
> + *   in some debug condition, must keep this clock on, and never be closed.
> + *   setting this flag then this clock never be closed.

Copy some part from the commit log I just suggested..

If this flag is only for debugging we may name it that way.
Maybe: CLK_GATE_DBG_ALWAYS_ON ??