linux-kernel - Re: [PATCH v3 18/19] ARM: at91: move pit timer to common clk framework

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Date:	Tue, 8 Oct 2013 18:28:23 +0200
From:	Nicolas Ferre <nicolas.ferre@...el.com>
To:	Boris BREZILLON <b.brezillon@...rkiz.com>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <rob.herring@...xeda.com>,
	Rob Landley <rob@...dley.net>,
	Andrew Victor <linux@...im.org.za>,
	"Jean-Christophe Plagniol-Villard" <plagnioj@...osoft.com>,
	Russell King <linux@....linux.org.uk>,
	Mike Turquette <mturquette@...aro.org>,
	"Felipe Balbi" <balbi@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Ludovic Desroches <ludovic.desroches@...el.com>,
	Josh Wu <josh.wu@...el.com>,
	Richard Genoud <richard.genoud@...il.com>
CC:	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3 18/19] ARM: at91: move pit timer to common clk framework

On 08/08/2013 10:17, Boris BREZILLON :
> Use device tree to get the source clock of the PIT (Periodic Interval Timer).
> If the clock is not found in device tree (or dt is not enabled) we'll try to
> get it using clk_lookup definitions.
>
> Signed-off-by: Boris BREZILLON <b.brezillon@...rkiz.com>

Acked-by: Nicolas Ferre <nicolas.ferre@...el.com>

> ---
>   arch/arm/mach-at91/at91sam926x_time.c |   14 +++++++++++++-
>   1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/mach-at91/at91sam926x_time.c b/arch/arm/mach-at91/at91sam926x_time.c
> index 3a4bc2e..8ac976a 100644
> --- a/arch/arm/mach-at91/at91sam926x_time.c
> +++ b/arch/arm/mach-at91/at91sam926x_time.c
> @@ -39,6 +39,7 @@
>   static u32 pit_cycle;		/* write-once */
>   static u32 pit_cnt;		/* access only w/system irq blocked */
>   static void __iomem *pit_base_addr __read_mostly;
> +static struct clk *mck;
>
>   static inline unsigned int pit_read(unsigned int reg_offset)
>   {
> @@ -195,10 +196,14 @@ static int __init of_at91sam926x_pit_init(void)
>   	if (!pit_base_addr)
>   		goto node_err;
>
> +	mck = of_clk_get(np, 0);
> +
>   	/* Get the interrupts property */
>   	ret = irq_of_parse_and_map(np, 0);
>   	if (!ret) {
>   		pr_crit("AT91: PIT: Unable to get IRQ from DT\n");
> +		if (!IS_ERR(mck))
> +			clk_put(mck);
>   		goto ioremap_err;
>   	}
>   	at91sam926x_pit_irq.irq = ret;
> @@ -230,6 +235,8 @@ void __init at91sam926x_pit_init(void)
>   	unsigned	bits;
>   	int		ret;
>
> +	mck = ERR_PTR(-ENOENT);
> +
>   	/* For device tree enabled device: initialize here */
>   	of_at91sam926x_pit_init();
>
> @@ -237,7 +244,12 @@ void __init at91sam926x_pit_init(void)
>   	 * Use our actual MCK to figure out how many MCK/16 ticks per
>   	 * 1/HZ period (instead of a compile-time constant LATCH).
>   	 */
> -	pit_rate = clk_get_rate(clk_get(NULL, "mck")) / 16;
> +	if (IS_ERR(mck))
> +		mck = clk_get(NULL, "mck");
> +
> +	if (IS_ERR(mck))
> +		panic("AT91: PIT: Unable to get mck clk\n");
> +	pit_rate = clk_get_rate(mck) / 16;
>   	pit_cycle = (pit_rate + HZ/2) / HZ;
>   	WARN_ON(((pit_cycle - 1) & ~AT91_PIT_PIV) != 0);
>
>


-- 
Nicolas Ferre
--
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