Re: [PATCH v2 12/12] clocksource: samsung-time: Add Device Tree support

From: Rob Herring <robherring2@gmail.com>
To: Tomasz Figa <tomasz.figa@gmail.com>
Cc: linux-arm-kernel@lists.infradead.org, ghcstop@gmail.com,
	Kukjin Kim <kgene.kim@samsung.com>,
	linux@arm.linux.org.uk, kwangwoo.lee@gmail.com,
	devicetree-discuss@lists.ozlabs.org,
	broonie@opensource.wolfsonmicro.com, mcuelenaere@gmail.com,
	christer@weinigel.se, kyungmin.park@samsung.com,
	linux-samsung-soc@vger.kernel.org, buserror@gmail.com,
	augulis.darius@gmail.com,
	Sylwester Nawrocki <sylvester.nawrocki@gmail.com>,
	linux@simtec.co.uk, jekhor@gmail.com
Subject: Re: [PATCH v2 12/12] clocksource: samsung-time: Add Device Tree support
Date: Sun, 17 Feb 2013 20:39:54 -0600	[thread overview]
Message-ID: <5121947A.20908@gmail.com> (raw)
In-Reply-To: <1361033044-27629-13-git-send-email-tomasz.figa@gmail.com>

On 02/16/2013 10:44 AM, Tomasz Figa wrote:
> This patch adds support for parsing all platform-specific data from
> Device Tree and instantiation using clocksource_of_init to samsung-time
> clocksource driver.

> +Optional properties:
> +- samsung,source-timer: index of timer to be used as clocksource (defaults to 4)
> +- samsung,event-timer: index of timer to be used as clock event (defaults to 3)

This is Linux specific, not a h/w property. Define the h/w properties of
the timers so that Linux can decide which timer to use. See the omap2
timers for an example.

> +- samsung,prescale-divisor: PWM prescaler divisor (from 1 to 256)
> +- samsung,divisor: PWM main divider divisor (1, 2, 4, 8 or 16)
> +
> +Example:
> +	timer@7f006000 {
> +		compatible = "samsung,s3c64xx-pwm-timer";
> +		reg = <0x7f006000 0x1000>;
> +		interrupt-parent = <&vic0>;
> +		interrupts = <23>, <24>, <25>, <27>, <28>;
> +		samsung,source-timer = <4>;
> +		samsung,event-timer = <3>;
> +		samsung,prescale-divisor = <2>;
> +		samsung,divisor = <1>;
> +	};
> diff --git a/drivers/clocksource/samsung-time.c b/drivers/clocksource/samsung-time.c
> index 4134811..76a15ca 100644
> --- a/drivers/clocksource/samsung-time.c
> +++ b/drivers/clocksource/samsung-time.c
> @@ -14,6 +14,9 @@
>  #include <linux/err.h>
>  #include <linux/clk.h>
>  #include <linux/clockchips.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
>  #include <linux/platform_device.h>
>  
>  #include <clocksource/samsung-time.h>
> @@ -480,9 +483,12 @@ static void __init samsung_timer_resources(void)
>  	unsigned long source_id = timer_source.source_id;
>  	char devname[15];
>  
> -	timer_base = ioremap_nocache(timer_variant.reg_base, SZ_4K);
> -	if (!timer_base)
> -		panic("failed to map timer registers");
> +	if (!timer_base) {
> +		/* Compatibility fallback for non-DT platforms */
> +		timer_base = ioremap_nocache(timer_variant.reg_base, SZ_4K);
> +		if (!timer_base)
> +			panic("failed to map timer registers");
> +	}
>  
>  	timerclk = clk_get(NULL, "timers");
>  	if (IS_ERR(timerclk))
> @@ -515,8 +521,102 @@ static void __init samsung_timer_resources(void)
>  	clk_enable(tin_source);
>  }
>  
> +enum {
> +	TYPE_S3C24XX,
> +	TYPE_S3C64XX,
> +};
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id samsung_timer_ids[] = {
> +	{ .compatible = "samsung,s3c24xx-pwm-timer",
> +					.data = (void *)TYPE_S3C24XX, },
> +	{ .compatible = "samsung,s3c64xx-pwm-timer",
> +					.data = (void *)TYPE_S3C64XX, },

Shouldn't need 2 match tables and the data here is kind of pointless
when you can just use the compatible string.

> +	{},
> +};
> +
> +static void samsung_timer_parse_dt(struct device_node *np,
> +					const struct of_device_id *match)
> +{
> +	int i;
> +	u32 val;
> +
> +	timer_base = of_iomap(np, 0);
> +	if (!timer_base)
> +		panic("failed to map timer registers");
> +
> +	for (i = 0; i < SAMSUNG_PWM_NUM; ++i)
> +		timer_variant.irqs[i] = irq_of_parse_and_map(np, i);
> +
> +	if (!timer_variant.irqs[timer_source.event_id])
> +		panic("no clock event irq provided");
> +
> +	switch ((unsigned int)match->data) {
> +	case TYPE_S3C24XX:
> +		timer_variant.bits = 16;
> +		timer_variant.prescale = 25;
> +		timer_variant.prescale = 50;
> +		timer_variant.has_tint_cstat = false;
> +		break;
> +	case TYPE_S3C64XX:
> +		timer_variant.bits = 32;
> +		timer_variant.prescale = 2;
> +		timer_variant.divisor = 2;
> +		timer_variant.has_tint_cstat = true;
> +		break;
> +	}
> +
> +	timer_source.source_id = 4;
> +	if (!of_property_read_u32(np, "samsung,source-timer", &val)) {
> +		if (val >= SAMSUNG_PWM_NUM)
> +			panic("samsung,source-timer property out of range");
> +		timer_source.source_id = val;
> +	}
> +
> +	timer_source.event_id = 3;
> +	if (!of_property_read_u32(np, "samsung,event-timer", &val)) {
> +		if (val >= SAMSUNG_PWM_NUM)
> +			panic("samsung,event-timer property out of range");
> +		timer_source.event_id = val;
> +	}
> +
> +	if (!of_property_read_u32(np, "samsung,prescale-divisor", &val)) {
> +		if (val < 1 || val > 256)
> +			panic("samsung,prescale-divisor property out of range");
> +		timer_variant.prescale = val;
> +	}
> +
> +	if (!of_property_read_u32(np, "samsung,divisor", &val)) {
> +		switch (val) {
> +		case 1:
> +		case 2:
> +		case 4:
> +		case 8:
> +		case 16:
> +			timer_variant.divisor = timer_variant.prescale * val;
> +			break;
> +		default:
> +			panic("invalid value of samsung,divisor property");
> +		}
> +	}
> +}
> +#endif
> +
>  void __init samsung_timer_init(void)
>  {
> +#ifdef CONFIG_OF
> +	struct device_node *np;
> +	const struct of_device_id *match;
> +
> +	if (of_have_populated_dt()) {

Separate the OF and non-OF code to avoid this and the ifdef.

> +		np = of_find_matching_node_and_match(NULL,
> +						samsung_timer_ids, &match);
> +		if (!np)
> +			panic("timer node not found");

I have a patch to change this function to pass in the node ptr and avoid
matching twice. It should be in arm-soc shortly after rc1.

Rob

> +
> +		samsung_timer_parse_dt(np, match);
> +	}
> +#endif
>  	if (!timer_source.source_id && !timer_source.event_id)
>  		panic("timer sources not set (see samsung_set_timer_source)!\n");
>  
> @@ -527,3 +627,10 @@ void __init samsung_timer_init(void)
>  	samsung_clockevent_init();
>  	samsung_clocksource_init();
>  }
> +
> +#ifdef CONFIG_CLKSRC_OF
> +CLOCKSOURCE_OF_DECLARE(s3c24xx_timer,
> +			"samsung,s3c24xx-pwm-timer", samsung_timer_init)
> +CLOCKSOURCE_OF_DECLARE(s3c64xx_timer,
> +			"samsung,s3c64xx-pwm-timer", samsung_timer_init)
> +#endif
> 