Re: [PATCH v2] clk: shmobile: r8a7795: Add SDHI clocks

[Dirk Behme <dirk.behme@de.bosch.com>]

On 20.01.2016 09:16, Geert Uytterhoeven wrote:
> Hi Dirk,
>
> On Sun, Jan 17, 2016 at 10:47 AM, Dirk Behme <dirk.behme@gmail.com> wrote:
>> On 15.01.2016 11:20, Geert Uytterhoeven wrote:
>>> On Fri, Jan 15, 2016 at 11:11 AM, Dirk Behme <dirk.behme@de.bosch.com>
>>> wrote:
>>>> On 14.01.2016 19:24, Geert Uytterhoeven wrote:
>>>>> On Sat, Jan 9, 2016 at 7:42 AM, Dirk Behme <dirk.behme@gmail.com> wrote:
>>>>>> On 24.12.2015 11:09, Dirk Behme wrote:
>>>>>>> Add R8A7795 SDHI clocks.
>>>>>>> Signed-off-by: Dirk Behme <dirk.behme@gmail.com>
>>>>>>> ---
>>>>>>> Changes in v2: Add the missing *H clocks and correct the dividers.
>
>>>>> The dividers for these clocks are not fixed, they are controlled by the
>>>>> SDnCKCR registers.
>>>>>
>>>>> Unfortunately the register layout is more complicated than on R-Car
>>>>> Gen2,
>>>>> so
>>>>> you can no longer use clk_register_divider_table(), but have to write a
>>>>> custom
>>>>> clock driver.
>>>>>
>>>>> For an initial version, a simple "read-only" version that just calls
>>>>> clk_register_fixed_factor() with divider values read from the hardware
>>>>> registers may be good enough. But for full support, you need a driver
>>>>> that
>>>>> can program the registers, too.
>>>>
>>>> Anything like
>>>>
>>>> https://git.kernel.org/cgit/linux/kernel/git/horms/renesas-bsp.git/commit/drivers/clk/shmobile/clk-rcar-gen3.c?h=v4.2/rcar-3.0.x&id=cd10385afc15cef6bfbaea4aa5da41193b24fe82
>>
>> I've had a look to that.
>>
>> I think we can pick all the functions
>>
>> +static const struct clk_ops cpg_sd_clock_ops = {
>> +       .enable = cpg_sd_clock_enable,
>> +       .disable = cpg_sd_clock_disable,
>> +       .is_enabled = cpg_sd_clock_is_enabled,
>> +       .recalc_rate = cpg_sd_clock_recalc_rate,
>> +       .round_rate = cpg_sd_clock_round_rate,
>> +       .set_rate = cpg_sd_clock_set_rate,
>> +};
>>
>> unchanged from that patch.
>>
>> However, I'm not sure how to interface this to cpg_mssr_probe()? It's
>> similar to cpg_mssr_register_mod_clk(), but not identical so that this could
>> be reused.
>>
>> We could extend r8a7795_cpg_mssr_info by anything like an additional
>>
>> /* Dynamic clocks */
>> .dyn_clks = /* Add an array allowing to pass various clk_ops structs */
>> ...
>>
>> ?
>>
>> Or we could hard code it like
>>
>> https://git.kernel.org/cgit/linux/kernel/git/horms/renesas-bsp.git/commit/drivers/clk/shmobile/clk-rcar-gen3.c?h=v4.2/rcar-3.0.x&id=cd10385afc15cef6bfbaea4aa5da41193b24fe82
>>
>> is doing it with
>>
>> +       } else if (!strcmp(name, "sd0")) {
>> +               return cpg_sd_clk_register(name, cpg->reg + CPG_SD0CKCR,
>> np);
>> +       } else if (!strcmp(name, "sd1")) {
>> +               return cpg_sd_clk_register(name, cpg->reg + CPG_SD1CKCR,
>> np);
>> +       } else if (!strcmp(name, "sd2")) {
>> +               return cpg_sd_clk_register(name, cpg->reg + CPG_SD2CKCR,
>> np);
>> +       } else if (!strcmp(name, "sd3")) {
>> +               return cpg_sd_clk_register(name, cpg->reg + CPG_SD3CKCR,
>> np);
>>
>> and add this to e.g. r8a7795_cpg_clk_register(). But, hmm.
>>
>>
>> What do you think? Opinions? Examples?
>
> Please extend enum r8a7795_clk_types, and handle them in
> r8a7795_cpg_clk_register() based on the enum values.
>
> You can find an (old) example in the prototype I did for r8a7791:
> https://git.kernel.org/cgit/linux/kernel/git/geert/renesas-drivers.git/tree/drivers/clk/shmobile/clk-r8a7791-cpg-mssr.c?h=topic/cpg-mssr-v4


Whats about anything like

http://marc.info/?l=linux-sh&m=145346559429931

?

Best regards

Dirk