Re: [PATCH v22 02/11] clocksource: arm_arch_timer: separate out device-tree code and remove arch_timer_detect_rate

[Daniel Lezcano]

On Wed, Mar 22, 2017 at 12:31:13AM +0800, fu.wei@xxxxxxxxxx wrote:
> From: Fu Wei <fu.wei@xxxxxxxxxx>
> 
> Currently, the counter frequency detection call(arch_timer_detect_rate)
> includes getting the frequency from the device-tree property, the per-cpu
> arch-timer and the memory-mapped (MMIO) timer interfaces.
> But reading device-tree property will be needed only when system boot with
> device-tree, and reading from the per-cpu arch-timer and the memory-mapped
> (MMIO) timer interfaces will be needed only when the system initializes
> the relevant timer.
> 
> This patch separates out device-tree code, keep them in device-tree init
> function, and removes arch_timer_detect_rate founction, then uses the
> arch_timer_get_cntfrq and arch_timer_mem_get_cntfrq directly.
> 
> Signed-off-by: Fu Wei <fu.wei@xxxxxxxxxx>
> ---
>  drivers/clocksource/arm_arch_timer.c | 58 +++++++++++++++++++-----------------
>  1 file changed, 30 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
> index 843f923..29ca7d6 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -560,30 +560,6 @@ static u32 arch_timer_mem_get_cntfrq(void __iomem *cntbase)
>  	return readl_relaxed(cntbase + CNTFRQ);
>  }
>  
> -static void
> -arch_timer_detect_rate(void __iomem *cntbase, struct device_node *np)
> -{
> -	/* Who has more than one independent system counter? */
> -	if (arch_timer_rate)
> -		return;
> -
> -	/*
> -	 * Try to determine the frequency from the device tree or CNTFRQ,
> -	 * if ACPI is enabled, get the frequency from CNTFRQ ONLY.
> -	 */
> -	if (!acpi_disabled ||
> -	    of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) {
> -		if (cntbase)
> -			arch_timer_rate = arch_timer_mem_get_cntfrq(cntbase);
> -		else
> -			arch_timer_rate = arch_timer_get_cntfrq();
> -	}
> -
> -	/* Check the timer frequency. */
> -	if (arch_timer_rate == 0)
> -		pr_warn("frequency not available\n");
> -}
> -
>  static void arch_timer_banner(unsigned type)
>  {
>  	pr_info("%s%s%s timer(s) running at %lu.%02luMHz (%s%s%s).\n",
> @@ -958,7 +934,17 @@ static int __init arch_timer_of_init(struct device_node *np)
>  	for (i = ARCH_TIMER_PHYS_SECURE_PPI; i < ARCH_TIMER_MAX_TIMER_PPI; i++)
>  		arch_timer_ppi[i] = irq_of_parse_and_map(np, i);
>  
> -	arch_timer_detect_rate(NULL, np);
> +	/*
> +	 * Try to determine the frequency from the device tree,
> +	 * if fail, get the frequency from the sysreg CNTFRQ.
> +	 */
> +	if (!arch_timer_rate &&

This variable is set only if "arm,armv7-timer" and "arm,armv7-timer-mem" are
declared together in the DT, right ?

Two declarations for a single variable ? Ignore the !arch_timer_rate.

> +	    of_property_read_u32(np, "clock-frequency", &arch_timer_rate))
> +		arch_timer_rate = arch_timer_get_cntfrq();
> +	if (!arch_timer_rate) {
> +		pr_err(FW_BUG "frequency not available.\n");
> +		return -EINVAL;
> +	}

Please, clarify this block, the conditions are unclear.

>  
>  	arch_timer_c3stop = !of_property_read_bool(np, "always-on");
>  
> @@ -1069,7 +1055,19 @@ static int __init arch_timer_mem_init(struct device_node *np)
>  		goto out;
>  	}
>  
> -	arch_timer_detect_rate(base, np);
> +	/*
> +	 * Try to determine the frequency from the device tree,
> +	 * if fail, get the frequency from the CNTFRQ reg of MMIO timer.
> +	 */
> +	if (!arch_timer_rate &&
> +	    of_property_read_u32(np, "clock-frequency", &arch_timer_rate))
> +		arch_timer_rate = arch_timer_mem_get_cntfrq(base);
> +	if (!arch_timer_rate) {
> +		pr_err(FW_BUG "MMIO frequency not available.\n");
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
>  	ret = arch_timer_mem_register(base, irq);
>  	if (ret)
>  		goto out;
> @@ -1130,8 +1128,12 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table)
>  		map_generic_timer_interrupt(gtdt->non_secure_el2_interrupt,
>  		gtdt->non_secure_el2_flags);
>  
> -	/* Get the frequency from CNTFRQ */
> -	arch_timer_detect_rate(NULL, NULL);
> +	/* Get the frequency from the sysreg CNTFRQ */
> +	arch_timer_rate = arch_timer_get_cntfrq();
> +	if (!arch_timer_rate) {
> +		pr_err(FW_BUG "frequency not available.\n");
> +		return -EINVAL;
> +	}
>  
>  	arch_timer_uses_ppi = arch_timer_select_ppi();
>  	if (!arch_timer_ppi[arch_timer_uses_ppi]) {
> -- 
> 2.9.3
> 

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