linux-kernel - Re: [PATCH v6 1/9] cpufreq: CPPC: Add generic helpers for sysfs show/store

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Message-ID: <bd194325-784d-4b9d-b4ca-aaab16a2c596@huawei.com>
Date: Thu, 22 Jan 2026 16:27:09 +0800
From: "zhenglifeng (A)" <zhenglifeng1@...wei.com>
To: Sumit Gupta <sumitg@...dia.com>
CC: <rafael@...nel.org>, <viresh.kumar@...aro.org>, <pierre.gondois@....com>,
	<ionela.voinescu@....com>, <lenb@...nel.org>, <robert.moore@...el.com>,
	<corbet@....net>, <rdunlap@...radead.org>, <ray.huang@....com>,
	<gautham.shenoy@....com>, <mario.limonciello@....com>, <perry.yuan@....com>,
	<zhanjie9@...ilicon.com>, <linux-pm@...r.kernel.org>,
	<linux-acpi@...r.kernel.org>, <linux-doc@...r.kernel.org>,
	<acpica-devel@...ts.linux.dev>, <linux-kernel@...r.kernel.org>,
	<linux-tegra@...r.kernel.org>, <treding@...dia.com>, <jonathanh@...dia.com>,
	<vsethi@...dia.com>, <ksitaraman@...dia.com>, <sanjayc@...dia.com>,
	<nhartman@...dia.com>, <bbasu@...dia.com>
Subject: Re: [PATCH v6 1/9] cpufreq: CPPC: Add generic helpers for sysfs
 show/store

On 2026/1/20 22:56, Sumit Gupta wrote:
> Add generic helper functions for u64 sysfs attributes that follow the
> common pattern of calling CPPC get/set APIs:
> - cppc_cpufreq_sysfs_show_u64(): reads value and handles -EOPNOTSUPP
> - cppc_cpufreq_sysfs_store_u64(): parses input and calls set function
> 
> Add CPPC_CPUFREQ_ATTR_RW_U64() macro to generate show/store functions
> using these helpers, reducing boilerplate for simple attributes.
> 
> Convert auto_act_window and energy_performance_preference_val to use
> the new macro.
> 
> No functional changes.
> 
> Signed-off-by: Sumit Gupta <sumitg@...dia.com>
> ---
>  drivers/cpufreq/cppc_cpufreq.c | 69 ++++++++++++----------------------
>  1 file changed, 25 insertions(+), 44 deletions(-)
> 
> diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
> index 36e8a75a37f1..c95dcd7719c3 100644
> --- a/drivers/cpufreq/cppc_cpufreq.c
> +++ b/drivers/cpufreq/cppc_cpufreq.c
> @@ -863,73 +863,54 @@ static ssize_t store_auto_select(struct cpufreq_policy *policy,
>  	return count;
>  }
>  
> -static ssize_t show_auto_act_window(struct cpufreq_policy *policy, char *buf)
> +static ssize_t cppc_cpufreq_sysfs_show_u64(unsigned int cpu,
> +					   int (*get_func)(int, u64 *),
> +					   char *buf)
>  {
>  	u64 val;
> -	int ret;
> -
> -	ret = cppc_get_auto_act_window(policy->cpu, &val);
> +	int ret = get_func((int)cpu, &val);
>  
> -	/* show "<unsupported>" when this register is not supported by cpc */
>  	if (ret == -EOPNOTSUPP)
>  		return sysfs_emit(buf, "<unsupported>\n");
> -

I think it is better to keep this blank line. Apart from this

Reviewed-by: Lifeng Zheng <zhenglifeng1@...wei.com>

>  	if (ret)
>  		return ret;
>  
>  	return sysfs_emit(buf, "%llu\n", val);
>  }
>  
> -static ssize_t store_auto_act_window(struct cpufreq_policy *policy,
> -				     const char *buf, size_t count)
> +static ssize_t cppc_cpufreq_sysfs_store_u64(unsigned int cpu,
> +					    int (*set_func)(int, u64),
> +					    const char *buf, size_t count)
>  {
> -	u64 usec;
> +	u64 val;
>  	int ret;
>  
> -	ret = kstrtou64(buf, 0, &usec);
> +	ret = kstrtou64(buf, 0, &val);
>  	if (ret)
>  		return ret;
>  
> -	ret = cppc_set_auto_act_window(policy->cpu, usec);
> -	if (ret)
> -		return ret;
> +	ret = set_func((int)cpu, val);
>  
> -	return count;
> +	return ret ? ret : count;
>  }
>  
> -static ssize_t show_energy_performance_preference_val(struct cpufreq_policy *policy, char *buf)
> -{
> -	u64 val;
> -	int ret;
> -
> -	ret = cppc_get_epp_perf(policy->cpu, &val);
> -
> -	/* show "<unsupported>" when this register is not supported by cpc */
> -	if (ret == -EOPNOTSUPP)
> -		return sysfs_emit(buf, "<unsupported>\n");
> -
> -	if (ret)
> -		return ret;
> -
> -	return sysfs_emit(buf, "%llu\n", val);
> +#define CPPC_CPUFREQ_ATTR_RW_U64(_name, _get_func, _set_func)		\
> +static ssize_t show_##_name(struct cpufreq_policy *policy, char *buf)	\
> +{									\
> +	return cppc_cpufreq_sysfs_show_u64(policy->cpu, _get_func, buf);\
> +}									\
> +static ssize_t store_##_name(struct cpufreq_policy *policy,		\
> +			     const char *buf, size_t count)		\
> +{									\
> +	return cppc_cpufreq_sysfs_store_u64(policy->cpu, _set_func,	\
> +					    buf, count);		\
>  }
>  
> -static ssize_t store_energy_performance_preference_val(struct cpufreq_policy *policy,
> -						       const char *buf, size_t count)
> -{
> -	u64 val;
> -	int ret;
> +CPPC_CPUFREQ_ATTR_RW_U64(auto_act_window, cppc_get_auto_act_window,
> +			 cppc_set_auto_act_window)
>  
> -	ret = kstrtou64(buf, 0, &val);
> -	if (ret)
> -		return ret;
> -
> -	ret = cppc_set_epp(policy->cpu, val);
> -	if (ret)
> -		return ret;
> -
> -	return count;
> -}
> +CPPC_CPUFREQ_ATTR_RW_U64(energy_performance_preference_val,
> +			 cppc_get_epp_perf, cppc_set_epp)
>  
>  cpufreq_freq_attr_ro(freqdomain_cpus);
>  cpufreq_freq_attr_rw(auto_select);