linux-kernel - Re: [PATCH v5 1/6] ARM: at91: add TCB registers definitions

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Date:   Thu, 28 Jun 2018 17:15:39 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Alexander Dahl <ada@...rsis.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/6] ARM: at91: add TCB registers definitions

On 19/06/2018 23:19, Alexandre Belloni wrote:
> Add registers and bits definitions for the timer counter blocks found on
> Atmel ARM SoCs.
> 
> Tested-by: Alexander Dahl <ada@...rsis.com>
> Tested-by: Andras Szemzo <szemzo.andras@...il.com>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@...tlin.com>
> ---
>  include/soc/at91/atmel_tcb.h | 216 +++++++++++++++++++++++++++++++++++

Is the header necessary ? Can it be moved in the .c ?

>  1 file changed, 216 insertions(+)
>  create mode 100644 include/soc/at91/atmel_tcb.h
> 
> diff --git a/include/soc/at91/atmel_tcb.h b/include/soc/at91/atmel_tcb.h
> new file mode 100644
> index 000000000000..3ed66031fc76
> --- /dev/null

[ ... ]

> +static inline struct clk *tcb_clk_get(struct device_node *node, int channel)
> +{
> +	struct clk *clk;
> +	char clk_name[] = "t0_clk";
> +
> +	clk_name[1] += channel;

clever :)

> +	clk = of_clk_get_by_name(node->parent, clk_name);
> +	if (!IS_ERR(clk))
> +		return clk;
> +
> +	return of_clk_get_by_name(node->parent, "t0_clk");

Why do you want to return clk from t0_clk if another channel is
requested ? This is prone to error.

I would clarify that at the caller level, if tcb_clk_get fails then try
with channel zero.

> +}
> +
> +static inline int tcb_irq_get(struct device_node *node, int channel)

no inline

> +{
> +	int irq;
> +
> +	irq = of_irq_get(node->parent, channel);
> +	if (irq > 0)
> +		return irq;
> +
> +	return of_irq_get(node->parent, 0);

Same comment than above.

> +}
> +
> +static const u8 atmel_tc_divisors[5] = { 2, 8, 32, 128, 0, };
> +
> +struct atmel_tcb_info {
> +	int bits;
> +};
> +
> +static const struct atmel_tcb_info atmel_tcb_infos[] = {
> +	{ .bits = 16 },
> +	{ .bits = 32 },
> +};

Structuring the code with structure is a good practice. However, this is
too much :)

> +static const struct of_device_id atmel_tcb_dt_ids[] = {
> +	{
> +		.compatible = "atmel,at91rm9200-tcb",
> +		.data = &atmel_tcb_infos[0],

		.data = (void *)16;

> +	}, {
> +		.compatible = "atmel,at91sam9x5-tcb",
> +		.data = &atmel_tcb_infos[1],
> +	}, {
> +		/* sentinel */
> +	}
> +};
> +



> +#endif /* __SOC_ATMEL_TCB_H */
> 


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