[PATCH 2/5] clk: bcm2835: enable management of PCM clock

Geert Uytterhoeven
2016-01-10T19:13:54Z

Hi Martin,

On Sun, Jan 10, 2016 at 8:07 PM, Martin Sperl <kernel@martin.sperl.org> wrote:
>> On 10.01.2016, at 19:56, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>> On Sun, Jan 10, 2016 at 7:01 PM, Martin Sperl <kernel@martin.sperl.org> wrote:
>>>> On 10.01.2016, at 14:02, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>>>> I wrote:
>>>> | Hence it can better be replaced (it seems to be unused in dts files, but you
>>>> | can keep the definition to be 100% sure) by an ARRAY_SIZE() in the C driver.
>>>> | This requires changing the driver to e.g. initialize clks[] in
>>>> |bcm2835_clk_probe() based on a table instead of explicit code.
>>>>
>>>> If you fill in clks[] from a static table, you can take ARRAY_SIZE of
>>>> the static table.
>>>
>>> You mean something like the below?
>>> (note: copy/paste from console issues - spaces instead of tabs)
>>
>> More or less.
>>
>>> };
>>>
>>> static inline void cprman_write(struct bcm2835_cprman *cprman, u32 reg, u32 val
>>> @@ -496,6 +496,14 @@ static const struct bcm2835_pll_data bcm2835_pllh_data = {
>>> .max_fb_rate = BCM2835_MAX_FB_RATE,
>>> };
>>>
>>> +static const struct bcm2835_pll_data *bcm2835_plls[] = {
>>> + [BCM2835_PLLA] = &bcm2835_plla_data,
>>> + [BCM2835_PLLB] = &bcm2835_pllb_data,
>>> + [BCM2835_PLLC] = &bcm2835_pllc_data,
>>> + [BCM2835_PLLD] = &bcm2835_plld_data,
>>> + [BCM2835_PLLH] = &bcm2835_pllh_data,
>>> +};
>>
>> This is a sparse array?
> Yes - for all.
>
>>> struct bcm2835_pll {
>>> struct clk_hw hw;
>>> struct bcm2835_cprman *cprman;
>>> @@ -1560,8 +1600,13 @@ static int bcm2835_clk_probe(struct platform_device *pdev)
>>> struct clk **clks;
>>> struct bcm2835_cprman *cprman;
>>> struct resource *res;
>>> + const int clks_cnt = max(ARRAY_SIZE(bcm2835_plls),
>>> + max(ARRAY_SIZE(bcm2835_pll_divs),
>>> + ARRAY_SIZE(bcm2835_clks))) + 1;
>>> + size_t alloc = sizeof(*cprman) + clks_cnt * sizeof(*clks);
>>> + size_t i;
>>
>> If you combine all 3 arrays in a single non-sparse array, you could get rid
>> of the dynamic allocation using the maximum of the 3 sizes, and can just
>> use a single ARRAY_SIZE().
>
> The problem is that we need different initialization methods for pll, pll-dividers
> and derived clocks, so we can not easily make them a common setting unless we
> would use function and void pointers to work arround this, which would make it
> less readable (and more code again just for the - repeated - assignment).

You can store the clock type in the array elements, too?

I'm doing something similar, cfr. drivers/clk/shmobile/*-cpg-mssr.* in next.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds