Re: [PATCH V2 1/4] clk: bcm2835: avoid the use of BCM2835_CLOCK_COUNT in clk-bcm2835

[Michael Turquette <mturquette@baylibre.com>]

Quoting Michael Turquette (2016-01-13 12:00:12)
> Hi Martin,
> 
> Quoting kernel@martin.sperl.org (2016-01-11 11:55:53)
> >  static int bcm2835_clk_probe(struct platform_device *pdev)
> >  {
> >         struct device *dev = &pdev->dev;
> >         struct clk **clks;
> > +       size_t clk_cnt;
> >         struct bcm2835_cprman *cprman;
> >         struct resource *res;
> > +       size_t i;
> > +
> > +       /* find the max clock index */
> > +       clk_cnt = BCM2835_CLOCK_PERI_IMAGE; /* see below */
> > +       for (i = 0; i < ARRAY_SIZE(bcm2835_register_clocks); i++)
> > +               clk_cnt = max(clk_cnt, bcm2835_register_clocks[i].index);
> > +       clk_cnt += 1;
> 
> I'm not sure how this solution is better than using CLOCK_COUNT. Some
> other bindings use a max value, NR_CLKS or other sentinel.
> 
> Why did you not choose to set clk_cnt equal to BCM2835_CLOCK_PWM? Why
> not initialize it to zero?

OK, I just caught up on the asoc/bcm2835 thread.

Really the best solution would be to have an array of all of the clks in
the driver and just use ARRAY_SIZE on it.

For your driver, could you make an array of clk_hw pointers and call
devm_clk_register on all of them in a loop? This gets rid of the big
pile of explicit calls in bcm2835_clk_probe.

You can also get rid of stuff like bcm2835_plla_core_data by just
stuffing that data into a single struct initialization. Here is a
snippet for how the qcom clk drivers do it:

static struct clk_pll gpll0 = {
	.l_reg = 0x0004,
	.m_reg = 0x0008,
	.n_reg = 0x000c,
	.config_reg = 0x0014,
	.mode_reg = 0x0000,
	.status_reg = 0x001c,
	.status_bit = 17,
	.clkr.hw.init = &(struct clk_init_data){
		.name = "gpll0",
		.parent_names = (const char *[]){ "xo" },
		.num_parents = 1,
		.ops = &clk_pll_ops,
	},
};

Then a single array of clks per driver references this:

static struct clk_regmap *gcc_apq8084_clocks[] = {
	[GPLL0] = &gpll0.clkr,
	...

(in your case you won't reference struct clk_regmap, but struct clk_hw)

The actual registration happens in your probe like so:

static int bcm2835_clk_probe(struct platform_device *pdev)
{
	...
	for (i = 0; i < num_clks; i++) {
		clk = devm_clk_register(dev, array_of_clks[i].hw)
	...
}

Regards,
Mike