Subject: Re: [PATCH v3 5/5] powernv:cpufreq: Implement the driver->get() method

From: Gautham R Shenoy <[email-masked]>
Date: Fri, 21 Mar 2014 11:55:23 +0530

On Thu, Mar 20, 2014 at 05:41:00PM +0530, Gautham R. Shenoy wrote:
> From: "Gautham R. Shenoy" <[email-masked]>
> 
> The current frequency of a cpu is reported through the sysfs file
> cpuinfo_cur_freq. This requires the driver to implement a
> "->get(unsigned int cpu)" method which will return the current
> operating frequency.
> 
> Implement a function named powernv_cpufreq_get() which reads the local
> pstate from the PMSR and returns the corresponding frequency.
> 
> Set the powernv_cpufreq_driver.get hook to powernv_cpufreq_get().

Forgot to add 

  Reviewed-by: Preeti U Murthy <[email-masked]>
> 
> Signed-off-by: Gautham R. Shenoy <[email-masked]>
> ---
>  drivers/cpufreq/powernv-cpufreq.c | 38 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 38 insertions(+)
> 
> diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
> index 46bee8a..ef6ed8c 100644
> --- a/drivers/cpufreq/powernv-cpufreq.c
> +++ b/drivers/cpufreq/powernv-cpufreq.c
> @@ -206,6 +206,43 @@ static inline void set_pmspr(unsigned long sprn, unsigned long val)
>  	BUG();
>  }
> 
> +/*
> + * Computes the current frequency on this cpu
> + * and stores the result in *ret_freq.
> + */
> +static void powernv_read_cpu_freq(void *ret_freq)
> +{
> +	unsigned long pmspr_val;
> +	s8 local_pstate_id;
> +	int *cur_freq, freq, pstate_id;
> +
> +	cur_freq = (int *)ret_freq;
> +	pmspr_val = get_pmspr(SPRN_PMSR);
> +
> +	/* The local pstate id corresponds bits 48..55 in the PMSR.
> +         * Note: Watch out for the sign! */
> +	local_pstate_id = (pmspr_val >> 48) & 0xFF;
> +	pstate_id = local_pstate_id;
> +
> +	freq = pstate_id_to_freq(pstate_id);
> +	pr_debug("cpu %d pmsr %lx pstate_id %d frequency %d \n",
> +		smp_processor_id(), pmspr_val, pstate_id, freq);
> +	*cur_freq = freq;
> +}
> +
> +/*
> + * Returns the cpu frequency as reported by the firmware for 'cpu'.
> + * This value is reported through the sysfs file cpuinfo_cur_freq.
> + */
> +unsigned int powernv_cpufreq_get(unsigned int cpu)
> +{
> +	int ret_freq;
> +
> +	smp_call_function_any(cpu_sibling_mask(cpu), powernv_read_cpu_freq,
> +			&ret_freq, 1);
> +	return ret_freq;
> +}
> +
>  static void set_pstate(void *pstate)
>  {
>  	unsigned long val;
> @@ -297,6 +334,7 @@ static int powernv_cpufreq_target(struct cpufreq_policy *policy,
>  static struct cpufreq_driver powernv_cpufreq_driver = {
>  	.verify		= powernv_cpufreq_verify,
>  	.target		= powernv_cpufreq_target,
> +	.get		= powernv_cpufreq_get,
>  	.init		= powernv_cpufreq_cpu_init,
>  	.exit		= powernv_cpufreq_cpu_exit,
>  	.name		= "powernv-cpufreq",
> -- 
> 1.8.3.1
>