Re: [PATCH v10 08/12] cpufreq: amd-pstate: add driver working mode switch support

[Huang Rui]

On Fri, Jan 06, 2023 at 02:14:16PM +0800, Yuan, Perry wrote:
> From: Perry Yuan <Perry.Yuan@xxxxxxx>
> 
> While amd-pstate driver was loaded with specific driver mode, it will
> need to check which mode is enabled for the pstate driver,add this sysfs
> entry to show the current status
> 
> $ cat /sys/devices/system/cpu/amd-pstate/status
> active
> 
> Meanwhile, user can switch the pstate driver mode with writing mode
> string to sysfs entry as below.
> 
> Enable passive mode:
> $ sudo bash -c "echo passive >  /sys/devices/system/cpu/amd-pstate/status"
> 
> Enable active mode (EPP driver mode):
> $ sudo bash -c "echo active > /sys/devices/system/cpu/amd-pstate/status"
> 
> Reviewed-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> Signed-off-by: Perry Yuan <Perry.Yuan@xxxxxxx>

Patch is Acked-by: Huang Rui <ray.huang@xxxxxxx>

Wyes, may we have a ack or any comment from you of this patch, as you are
working on the new guided autonomous mode?

Thanks,
Ray

> ---
>  drivers/cpufreq/amd-pstate.c | 118 +++++++++++++++++++++++++++++++++++
>  1 file changed, 118 insertions(+)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 2c8b126cec5a..d3f4cdd803f3 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -63,6 +63,7 @@ static struct cpufreq_driver *current_pstate_driver;
>  static struct cpufreq_driver amd_pstate_driver;
>  static struct cpufreq_driver amd_pstate_epp_driver;
>  static int cppc_state = AMD_PSTATE_DISABLE;
> +struct kobject *amd_pstate_kobj;
>  
>  static inline int get_mode_idx_from_str(const char *str, size_t size)
>  {
> @@ -631,6 +632,8 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
>  	policy->driver_data = cpudata;
>  
>  	amd_pstate_boost_init(cpudata);
> +	if (!current_pstate_driver->adjust_perf)
> +		current_pstate_driver->adjust_perf = amd_pstate_adjust_perf;
>  
>  	return 0;
>  
> @@ -771,12 +774,99 @@ static ssize_t show_energy_performance_preference(
>  	return sysfs_emit(buf, "%s\n", energy_perf_strings[preference]);
>  }
>  
> +static ssize_t amd_pstate_show_status(char *buf)
> +{
> +	if (!current_pstate_driver)
> +		return sysfs_emit(buf, "disable\n");
> +
> +	return sysfs_emit(buf, "%s\n", amd_pstate_mode_string[cppc_state]);
> +}
> +
> +static void amd_pstate_driver_cleanup(void)
> +{
> +	current_pstate_driver = NULL;
> +}
> +
> +static int amd_pstate_update_status(const char *buf, size_t size)
> +{
> +	int ret;
> +	int mode_idx;
> +
> +	if (size > 7 || size < 6)
> +		return -EINVAL;
> +	mode_idx = get_mode_idx_from_str(buf, size);
> +
> +	switch(mode_idx) {
> +	case AMD_PSTATE_DISABLE:
> +		if (!current_pstate_driver)
> +			return -EINVAL;
> +		if (cppc_state == AMD_PSTATE_ACTIVE)
> +			return -EBUSY;
> +		ret = cpufreq_unregister_driver(current_pstate_driver);
> +		amd_pstate_driver_cleanup();
> +		break;
> +	case AMD_PSTATE_PASSIVE:
> +		if (current_pstate_driver) {
> +			if (current_pstate_driver == &amd_pstate_driver)
> +				return 0;
> +			cpufreq_unregister_driver(current_pstate_driver);
> +			cppc_state = AMD_PSTATE_PASSIVE;
> +			current_pstate_driver = &amd_pstate_driver;
> +		}
> +
> +		ret = cpufreq_register_driver(current_pstate_driver);
> +		break;
> +	case AMD_PSTATE_ACTIVE:
> +		if (current_pstate_driver) {
> +			if (current_pstate_driver == &amd_pstate_epp_driver)
> +				return 0;
> +			cpufreq_unregister_driver(current_pstate_driver);
> +			current_pstate_driver = &amd_pstate_epp_driver;
> +			cppc_state = AMD_PSTATE_ACTIVE;
> +		}
> +
> +		ret = cpufreq_register_driver(current_pstate_driver);
> +		break;
> +	default:
> +		ret = -EINVAL;
> +		break;
> +	}
> +
> +	return ret;
> +}
> +
> +static ssize_t show_status(struct kobject *kobj,
> +			   struct kobj_attribute *attr, char *buf)
> +{
> +	ssize_t ret;
> +
> +	mutex_lock(&amd_pstate_driver_lock);
> +	ret = amd_pstate_show_status(buf);
> +	mutex_unlock(&amd_pstate_driver_lock);
> +
> +	return ret;
> +}
> +
> +static ssize_t store_status(struct kobject *a, struct kobj_attribute *b,
> +			    const char *buf, size_t count)
> +{
> +	char *p = memchr(buf, '\n', count);
> +	int ret;
> +
> +	mutex_lock(&amd_pstate_driver_lock);
> +	ret = amd_pstate_update_status(buf, p ? p - buf : count);
> +	mutex_unlock(&amd_pstate_driver_lock);
> +
> +	return ret < 0 ? ret : count;
> +}
> +
>  cpufreq_freq_attr_ro(amd_pstate_max_freq);
>  cpufreq_freq_attr_ro(amd_pstate_lowest_nonlinear_freq);
>  
>  cpufreq_freq_attr_ro(amd_pstate_highest_perf);
>  cpufreq_freq_attr_rw(energy_performance_preference);
>  cpufreq_freq_attr_ro(energy_performance_available_preferences);
> +define_one_global_rw(status);
>  
>  static struct freq_attr *amd_pstate_attr[] = {
>  	&amd_pstate_max_freq,
> @@ -794,6 +884,15 @@ static struct freq_attr *amd_pstate_epp_attr[] = {
>  	NULL,
>  };
>  
> +static struct attribute *pstate_global_attributes[] = {
> +	&status.attr,
> +	NULL
> +};
> +
> +static const struct attribute_group amd_pstate_global_attr_group = {
> +	.attrs = pstate_global_attributes,
> +};
> +
>  static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
>  {
>  	int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
> @@ -1153,6 +1252,25 @@ static int __init amd_pstate_init(void)
>  	if (ret)
>  		pr_err("failed to register with return %d\n", ret);
>  
> +	amd_pstate_kobj = kobject_create_and_add("amd_pstate", &cpu_subsys.dev_root->kobj);
> +	if (!amd_pstate_kobj) {
> +		ret = -EINVAL;
> +		pr_err("global sysfs registration failed.\n");
> +		goto kobject_free;
> +	}
> +
> +	ret = sysfs_create_group(amd_pstate_kobj, &amd_pstate_global_attr_group);
> +	if (ret) {
> +		pr_err("sysfs attribute export failed with error %d.\n", ret);
> +		goto global_attr_free;
> +	}
> +
> +	return ret;
> +
> +global_attr_free:
> +	kobject_put(amd_pstate_kobj);
> +kobject_free:
> +	cpufreq_unregister_driver(current_pstate_driver);
>  	return ret;
>  }
>  device_initcall(amd_pstate_init);
> -- 
> 2.34.1
>