[PATCH 1/4] clk: Introduce optional is_prepared callback

[Ulf Hansson]

On 24 January 2013 19:12, Mike Turquette <mturquette at linaro.org> wrote:
> Quoting Ulf Hansson (2013-01-24 08:45:53)
>> From: Ulf Hansson <ulf.hansson at linaro.org>
>>
>> To reflect whether a clk_hw is prepared the clk_hw may implement
>> the optional is_prepared callback. If not implemented we fall back
>> to use the software prepare counter.
>>
>> Signed-off-by: Ulf Hansson <ulf.hansson at linaro.org>
>> Acked-by: Linus Walleij <linus.walleij at linaro.org>
>> ---
>>  drivers/clk/clk.c            |   21 +++++++++++++++++++++
>>  include/linux/clk-provider.h |    6 ++++++
>>  2 files changed, 27 insertions(+)
>>
>> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
>> index 593a2e4..deb259a 100644
>> --- a/drivers/clk/clk.c
>> +++ b/drivers/clk/clk.c
>> @@ -458,6 +458,27 @@ unsigned long __clk_get_flags(struct clk *clk)
>>         return !clk ? 0 : clk->flags;
>>  }
>>
>> +bool __clk_is_prepared(struct clk *clk)
>> +{
>> +       int ret;
>> +
>> +       if (!clk)
>> +               return false;
>> +
>> +       /*
>> +        * .is_prepared is optional for clocks that can prepare
>> +        * fall back to software usage counter if it is missing
>> +        */
>
> Why not make it mandatory?  This could be as simple as saying "it is
> mandatory", or we could even enforce a check in clk_init, though the
> latter suggestion would be noisy until existing clock providers were
> updated.

I was trying to go "slow" forward and wanted to keep the same
behaviour for how .is_enabled is handled.

I am positive in making this mandatory, but then this should be
applied for is_enabled as well. If we make something mandatory I
definitely think it shall be checked in clk_int, it makes sense to me.

>
> Note that .is_enabled is technically mandatory for any clock that
> implements .enable/.disable but there is no check for compliance.  It is
> only in Documentation/clk.txt and the kerneldoc.

According to the clk-provider.h file:
------
 * @is_enabled: Queries the hardware to determine if the clock is enabled.
 *              This function must not sleep. Optional, if this op is not
 *              set then the enable count will be used.
-----

The  Documentation/clk.txt says it is mandatory. :-) So we have a kind
of mixed message here.

>
> Regards,
> Mike

Kind regards
Ulf Hansson