Subject: [PATCH-V2 3/3] ARM: OMAP: Make OMAP clocksource source selection runtime

From: [email-masked] (Santosh Shilimkar)
Date: Mon, 02 Apr 2012 12:26:11 +0530

On Friday 30 March 2012 07:24 PM, Vaibhav Hiremath wrote:
> Current OMAP code supports couple of clocksource options based
> on compilation flag (CONFIG_OMAP_32K_TIMER). The 32KHz sync-timer
> and a gptimer which can run on 32KHz or system clock (e.g 38.4 MHz).
> So there can be 3 options -
> 
> 1. 32KHz sync-timer
> 2. Sys_clock based (e.g 13/19.2/26/38.4 MHz) gptimer
> 3. 32KHz based gptimer.
> 
> The optional gptimer based clocksource was added so that it can
> give the high precision than sync-timer, so expected usage was 2
> and not 3.
> Unfortunately option 2, clocksource doesn't meet the requirement of
> free-running clock as per clocksource need. It stops in low power states
> when sys_clock is cut. That makes gptimer based clocksource option
> useless for OMAP2/3/4 devices with sys_clock as a clock input.
> Option 3 will still work but it is no better than 32K sync-timer
> based clocksource.
> 
> So ideally we can kill the gptimer based clocksource option but there
> are some OMAP based derivative SoCs like AM33XX which doesn't have
> 32K sync-timer hardware IP and need to fallback on 32KHz based gptimer
> clocksource.
> Considering above, make sync-timer and gptimer clocksource runtime
> selectable so that both OMAP and AMXXXX continue to use the same code.
> 
> Use hwmod database lookup mechanism, through which at run-time
> we can identify availability of 32k-sync timer on the device,
> else fall back to gptimer.
> 
> Signed-off-by: Vaibhav Hiremath <[email-masked]>
> Signed-off-by: Felipe Balbi <[email-masked]>
> CC: Santosh Shilimkar <[email-masked]>
> Cc: Benoit Cousson <[email-masked]>
> Cc: Tony Lindgren <[email-masked]>
> Cc: Paul Walmsley <[email-masked]>
> Cc: Tarun Kanti DebBarma <[email-masked]>
> Cc: Ming Lei <[email-masked]>
> ---

Thanks for the change log update Vaibhav.
Some more comments.

>  arch/arm/mach-omap1/timer32k.c           |    6 ++-
>  arch/arm/mach-omap2/timer.c              |   45 +++++++++-------
>  arch/arm/plat-omap/counter_32k.c         |   86 ++++++++++++-----------------
>  arch/arm/plat-omap/include/plat/common.h |    2 +-
>  4 files changed, 68 insertions(+), 71 deletions(-)
> 
> diff --git a/arch/arm/mach-omap1/timer32k.c b/arch/arm/mach-omap1/timer32k.c
> index a2e6d07..3f96a00 100644
> --- a/arch/arm/mach-omap1/timer32k.c
> +++ b/arch/arm/mach-omap1/timer32k.c
> @@ -72,6 +72,7 @@
> 
>  /* 16xx specific defines */
>  #define OMAP1_32K_TIMER_BASE		0xfffb9000
> +#define OMAP1_32KSYNC_TIMER_BASE	0xfffbc410
Shouldn't you just update OMAP1_32K_TIMER_BASE ?

>  #define OMAP1_32K_TIMER_CR		0x08
>  #define OMAP1_32K_TIMER_TVR		0x00
>  #define OMAP1_32K_TIMER_TCR		0x04
> @@ -185,7 +186,10 @@ static __init void omap_init_32k_timer(void)
>   */
>  bool __init omap_32k_timer_init(void)
>  {
> -	omap_init_clocksource_32k();
> +	u32 pbase;
> +
> +	pbase = cpu_is_omap16xx() ? OMAP1_32KSYNC_TIMER_BASE : NULL;
> +	omap_init_clocksource_32k(pbase, SZ_1K);
If pbase is NULL, you might not want to call the init.

>  	omap_init_32k_timer();
> 
>  	return true;
> diff --git a/arch/arm/mach-omap2/timer.c b/arch/arm/mach-omap2/timer.c
> index 5c9acea..f35db1a 100644
> --- a/arch/arm/mach-omap2/timer.c
> +++ b/arch/arm/mach-omap2/timer.c
> @@ -234,21 +234,6 @@ static void __init omap2_gp_clockevent_init(int gptimer_id,
>  }
> 
>  /* Clocksource code */
> -
> -#ifdef CONFIG_OMAP_32K_TIMER
> -/*
> - * When 32k-timer is enabled, don't use GPTimer for clocksource
> - * instead, just leave default clocksource which uses the 32k
> - * sync counter.  See clocksource setup in plat-omap/counter_32k.c
> - */
> -
> -static void __init omap2_gp_clocksource_init(int unused, const char *dummy)
> -{
> -	omap_init_clocksource_32k();
> -}
> -
> -#else
> -
>  static struct omap_dm_timer clksrc;
> 
>  /*
> @@ -280,13 +265,33 @@ static void __init omap2_gp_clocksource_init(int gptimer_id,
>  						const char *fck_source)
>  {
>  	int res;
> +	struct omap_hwmod *oh;
> +	const char *oh_name = "counter_32k";
> +
> +	/*
> +	 * First check for availability for 32k-sync timer.
> +	 *
> +	 * In case of failure in finding 32k_counter module or
> +	 * registering it as clocksource, execution will fallback to
> +	 * gp-timer.
> +	 */
> +	oh = omap_hwmod_lookup(oh_name);
> +	if (oh && oh->slaves_cnt != 0) {
> +		u32 pbase;
> +		unsigned long size;
> +
> +		pbase = oh->slaves[0]->addr->pa_start + 0x10;
Don't hardcode the offset here. This is error prone when the IP
changes so use the register define.

> +		size = oh->slaves[0]->addr->pa_end -
> +			oh->slaves[0]->addr->pa_start;
> +		res = omap_init_clocksource_32k(pbase, size);
> +		if (!res)
> +			return;
> +	}
> 
If 'OMAP_32K_TIMER' is not selected, does omap_init_clocksource_32k()
fails too ?

> +	/* Fall back to gp-timer code */
>  	res = omap_dm_timer_init_one(&clksrc, gptimer_id, fck_source);
>  	BUG_ON(res);
> 
> -	pr_info("OMAP clocksource: GPTIMER%d at %lu Hz\n",
> -		gptimer_id, clksrc.rate);
> -
>  	__omap_dm_timer_load_start(&clksrc,
>  			OMAP_TIMER_CTRL_ST | OMAP_TIMER_CTRL_AR, 0, 1);
>  	setup_sched_clock(dmtimer_read_sched_clock, 32, clksrc.rate);
> @@ -294,8 +299,10 @@ static void __init omap2_gp_clocksource_init(int gptimer_id,
>  	if (clocksource_register_hz(&clocksource_gpt, clksrc.rate))
>  		pr_err("Could not register clocksource %s\n",
>  			clocksource_gpt.name);
> +	else
> +		pr_info("OMAP clocksource: GPTIMER%d at %lu Hz\n",
> +			gptimer_id, clksrc.rate);
>  }
> -#endif
> 
>  #define OMAP_SYS_TIMER_INIT(name, clkev_nr, clkev_src,			\
>  				clksrc_nr, clksrc_src)			\
> diff --git a/arch/arm/plat-omap/counter_32k.c b/arch/arm/plat-omap/counter_32k.c
> index 5068fe5..c1af18c 100644
> --- a/arch/arm/plat-omap/counter_32k.c
> +++ b/arch/arm/plat-omap/counter_32k.c
> @@ -35,8 +35,6 @@
>   */
>  static void __iomem *timer_32k_base;
> 
> -#define OMAP16XX_TIMER_32K_SYNCHRONIZED		0xfffbc410
> -
>  static u32 notrace omap_32k_read_sched_clock(void)
>  {
>  	return timer_32k_base ? __raw_readl(timer_32k_base) : 0;
> @@ -68,54 +66,42 @@ void read_persistent_clock(struct timespec *ts)
>  	*ts = *tsp;
>  }
> 
> -int __init omap_init_clocksource_32k(void)
> +int __init omap_init_clocksource_32k(u32 pbase, unsigned long size)
>  {
> -	static char err[] __initdata = KERN_ERR
> -			"%s: can't register clocksource!\n";
> -
> -	if (cpu_is_omap16xx() || cpu_class_is_omap2()) {
> -		u32 pbase;
> -		unsigned long size = SZ_4K;
> -		void __iomem *base;
> -		struct clk *sync_32k_ick;
> -
> -		if (cpu_is_omap16xx()) {
> -			pbase = OMAP16XX_TIMER_32K_SYNCHRONIZED;
> -			size = SZ_1K;
> -		} else if (cpu_is_omap2420())
> -			pbase = OMAP2420_32KSYNCT_BASE + 0x10;
> -		else if (cpu_is_omap2430())
> -			pbase = OMAP2430_32KSYNCT_BASE + 0x10;
> -		else if (cpu_is_omap34xx())
> -			pbase = OMAP3430_32KSYNCT_BASE + 0x10;
> -		else if (cpu_is_omap44xx())
> -			pbase = OMAP4430_32KSYNCT_BASE + 0x10;
> -		else
> -			return -ENODEV;
Thanks for thsi clean-up. Much appreciated.
Apart from the minor comments, patch looks fine to me.

Acked-by: Santosh Shilimkar <[email-masked]>

Regards
Santosh