On 22/02/2024 01:42, Sam Protsenko wrote:
> On Tue, Feb 20, 2024 at 5:04 AM Krzysztof Kozlowski
> <krzysztof.kozlowski@xxxxxxxxxx> wrote:
>>
>> On 16/02/2024 23:32, Sam Protsenko wrote:
>>> Abstract CPU clock registers by keeping their offsets in a dedicated
>>> chip specific structure to accommodate for oncoming Exynos850 support,
>>> which has different offsets for cluster 0 and cluster 1. This rework
>>> also makes it possible to use exynos_set_safe_div() for all chips, so
>>> exynos5433_set_safe_div() is removed here to reduce the code
>>> duplication.
>>>
>>
>> So that's the answer why you could not use flags anymore - you need an
>> enum, not a bitmap. Such short explanation should be in previous commits
>> justifying moving reg layout to new property.
>
> Will do, thanks.
>
>>
>>> No functional change.
>>>
>>> Signed-off-by: Sam Protsenko <semen.protsenko@xxxxxxxxxx>
>>> ---
>>> drivers/clk/samsung/clk-cpu.c | 156 +++++++++++++++++++---------------
>>> 1 file changed, 86 insertions(+), 70 deletions(-)
>>>
>>> diff --git a/drivers/clk/samsung/clk-cpu.c b/drivers/clk/samsung/clk-cpu.c
>>> index 04394d2166c9..744b609c222d 100644
>>> --- a/drivers/clk/samsung/clk-cpu.c
>>> +++ b/drivers/clk/samsung/clk-cpu.c
>>> @@ -44,12 +44,14 @@ typedef int (*exynos_rate_change_fn_t)(struct clk_notifier_data *ndata,
>>>
>>> /**
>>> * struct exynos_cpuclk_chip - Chip specific data for CPU clock
>>> + * @regs: register offsets for CPU related clocks
>>> * @pre_rate_cb: callback to run before CPU clock rate change
>>> * @post_rate_cb: callback to run after CPU clock rate change
>>> */
>>> struct exynos_cpuclk_chip {
>>> - exynos_rate_change_fn_t pre_rate_cb;
>>> - exynos_rate_change_fn_t post_rate_cb;
>>> + const void * const regs;
>>
>> Why this is void?
>>
>
> Different chips can have very different register layout. For example,
> older Exynos chips usually keep multiple CPU divider ratios in one
> single register, whereas more modern chips have a dedicated register
> for each divider clock. Also, old chips usually split divider ratio vs
> DIV clock status between different registers, but in modern chips they
> both live in one single register. Having (void *) makes it possible to
> keep pointers to different structures, and each function for the
> particular chip can "know" which exactly structure is stored there,
> casting (void *) to a needed type. Another way to do that would be to
> have "one-size-fits-all" structure with all possible registers for all
> possible chips. I don't know, I just didn't like that for a couple of
> reasons, so decided to go with (void *).
>
> I'll add some explanation in the commit message in v2.
Currently the one-size-fits-all seems feasible, even if few fields are
not matching, so I would prefer to go this approach.
Best regards,
Krzysztof
