linux-kernel - Re: [PATCH] clk: at91: add generated clock driver

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Message-ID: <55883CE9.2060904@atmel.com>
Date:	Mon, 22 Jun 2015 18:50:49 +0200
From:	Nicolas Ferre <nicolas.ferre@...el.com>
To:	Boris Brezillon <boris.brezillon@...e-electrons.com>
CC:	<linux-arm-kernel@...ts.infradead.org>,
	Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
	Ludovic Desroches <ludovic.desroches@...el.com>,
	Josh Wu <josh.wu@...el.com>, <linux-kernel@...r.kernel.org>,
	<mturquette@...libre.com>
Subject: Re: [PATCH] clk: at91: add generated clock driver

Le 18/06/2015 17:25, Boris Brezillon a écrit :
> Hi Nicolas,

Thanks for your review Boris. I'll address your remarks by sending
another revision of this series in several days...

Bye,

> I haven't run checkpatch on your patch, but there seems to be a few
> things to fix ;-).
> 
> On Wed, 17 Jun 2015 15:23:29 +0200
> Nicolas Ferre <nicolas.ferre@...el.com> wrote:
> 
> 
> 
> 
>> +
>> +static long clk_generated_determine_rate(struct clk_hw *hw,
>> +					 unsigned long rate,
>> +					 unsigned long *best_parent_rate,
>> +					 struct clk_hw **best_parent_hw)
> 
> The ->determine_rate() prototype has changed (see [1]).
> 
> 
>> +/* No modification of hardware as we have the flag CLK_SET_RATE_GATE set */
>> +static int clk_generated_set_rate(struct clk_hw *hw,
>> +				    unsigned long rate,
>> +				    unsigned long parent_rate)
>> +{
>> +	struct clk_generated *gck = to_clk_generated(hw);
>> +	u32 div;
>> +
>> +	if (!rate)
>> +		return -EINVAL;
>> +
>> +	if (gck->id < PERIPHERAL_ID_MIN || !gck->range.max) {
>> +		if (parent_rate == rate) {
>> +			gck->gckdiv = 0;
>> +			return 0;
>> +		} else {
>> +			return -EINVAL;
>> +		}
>> +	}
> 
> Do you really need the above check ?
> AFAICT, periph ids inferior to 2 are invalid ids, so they should be
> detected at probe time.
> The !gck->range.max will be caught by the rate > gck->range.max test.
> And finally, the case parent_rate == rate will just give you a div of 1,
> which in turns give a gckdiv of 0.
> 
>> +
>> +	if (rate > gck->range.max)
>> +		return -EINVAL;
>> +
>> +	div = DIV_ROUND_CLOSEST(parent_rate, rate);
>> +	if (div > GENERATED_MAX_DIV + 1 || !div)
>> +		return -EINVAL;
>> +
>> +	gck->gckdiv = div - 1;
>> +	return 0;
>> +}
>> +
>> +static const struct clk_ops generated_ops = {
>> +	.enable = clk_generated_enable,
>> +	.disable = clk_generated_disable,
>> +	.is_enabled = clk_generated_is_enabled,
>> +	.recalc_rate = clk_generated_recalc_rate,
>> +	.determine_rate = clk_generated_determine_rate,
>> +	.get_parent = clk_generated_get_parent,
>> +	.set_parent = clk_generated_set_parent,
>> +	.set_rate = clk_generated_set_rate,
>> +};
>> +
>> +/**
>> + * clk_generated_startup - Initialize a given clock to its default parent and
>> + * divisor parameter.
>> + *
>> + * @gck:	Generated clock to set the startup parameters for.
>> + *
>> + * Take parameters from the hardware and update local clock configuration
>> + * accordingly.
>> + */
>> +static void clk_generated_startup(struct clk_generated *gck)
>> +{
>> +	struct at91_pmc *pmc = gck->pmc;
>> +	u32 tmp;
>> +
>> +	pmc_lock(pmc);
>> +	pmc_write(pmc, AT91_PMC_PCR, (gck->id & AT91_PMC_PCR_PID_MASK));
>> +	tmp = pmc_read(pmc, AT91_PMC_PCR);
>> +	pmc_unlock(pmc);
>> +
>> +	gck->parent_id = (tmp & AT91_PMC_PCR_GCKCSS_MASK) >> AT91_PMC_PCR_GCKCSS_OFFSET;
>> +	gck->gckdiv = (tmp & AT91_PMC_PCR_GCKDIV_MASK) >> AT91_PMC_PCR_GCKDIV_OFFSET;
>> +}
>> +
>> +static struct clk * __init
>> +at91_clk_register_generated(struct at91_pmc *pmc, const char *name,
>> +			    const char **parent_names, u8 num_parents,
>> +			    u8 id, const struct clk_range *range)
>> +{
>> +	struct clk_generated *gck;
>> +	struct clk *clk = NULL;
>> +	struct clk_init_data init;
>> +
>> +	gck = kzalloc(sizeof(*gck), GFP_KERNEL);
>> +	if (!gck)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	init.name = name;
>> +	init.ops = &generated_ops;
>> +	init.parent_names = parent_names;
>> +	init.num_parents = num_parents;
>> +	init.flags = CLK_SET_RATE_GATE | CLK_SET_PARENT_GATE;
>> +
>> +	gck->id = id;
>> +	gck->hw.init = &init;
>> +	gck->pmc = pmc;
>> +	gck->range = *range;
>> +
>> +	clk = clk_register(NULL, &gck->hw);
>> +	if (IS_ERR(clk))
>> +		kfree(gck);
>> +	else
>> +		clk_generated_startup(gck);
>> +
>> +	return clk;
>> +}
>> +
>> +void __init of_sama5d2_clk_generated_setup(struct device_node *np,
>> +					   struct at91_pmc *pmc)
>> +{
>> +	int i;
>> +	int num;
>> +	u32 id;
>> +	const char *name;
>> +	struct clk *clk;
>> +	int num_parents;
>> +	const char *parent_names[GENERATED_SOURCE_MAX];
>> +	struct device_node *gcknp;
>> +	struct clk_range range = CLK_RANGE(0, 0);
>> +
>> +	num_parents = of_count_phandle_with_args(np, "clocks", "#clock-cells");
> 
> Use the of_clk_get_parent_count() [2].
> 
> That's all I got for now.
> 
> Thanks,
> 
> Boris
> 
> 
> [1]http://lxr.free-electrons.com/source/include/linux/clk-provider.h#L178
> [2]http://lxr.free-electrons.com/source/include/linux/clk-provider.h#L626
> 


-- 
Nicolas Ferre
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