linux-kernel - Re: [PATCH RESEND v6 5/9] cpupower: Introduce ACPI CPPC library

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Message-ID: <5e7bfce4-f326-930b-4a25-15538f741167@linuxfoundation.org>
Date:   Fri, 18 Feb 2022 16:53:52 -0700
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     Huang Rui <ray.huang@....com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        linux-pm@...r.kernel.org
Cc:     Deepak Sharma <deepak.sharma@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Mario Limonciello <mario.limonciello@....com>,
        Steven Noonan <steven@...vesoftware.com>,
        Nathan Fontenot <nathan.fontenot@....com>,
        Jinzhou Su <Jinzhou.Su@....com>,
        Xiaojian Du <Xiaojian.Du@....com>,
        Perry Yuan <Perry.Yuan@....com>,
        Jassmine Meng <li.meng@....com>,
        Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Giovanni Gherdovich <ggherdovich@...e.cz>,
        linux-kernel@...r.kernel.org,
        Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH RESEND v6 5/9] cpupower: Introduce ACPI CPPC library

On 2/16/22 12:35 AM, Huang Rui wrote:
> Kernel ACPI subsytem introduced the sysfs attributes for acpi cppc
> library in below path:
> 
> /sys/devices/system/cpu/cpuX/acpi_cppc/
> 
> And these attributes will be used for AMD P-State driver to provide some
> performance and frequency values.
> 
> Signed-off-by: Huang Rui <ray.huang@....com>
> ---
>   tools/power/cpupower/Makefile        |  6 +--
>   tools/power/cpupower/lib/acpi_cppc.c | 59 ++++++++++++++++++++++++++++
>   tools/power/cpupower/lib/acpi_cppc.h | 21 ++++++++++
>   3 files changed, 83 insertions(+), 3 deletions(-)
>   create mode 100644 tools/power/cpupower/lib/acpi_cppc.c
>   create mode 100644 tools/power/cpupower/lib/acpi_cppc.h
> 
> diff --git a/tools/power/cpupower/Makefile b/tools/power/cpupower/Makefile
> index 3b1594447f29..e9b6de314654 100644
> --- a/tools/power/cpupower/Makefile
> +++ b/tools/power/cpupower/Makefile
> @@ -143,9 +143,9 @@ UTIL_HEADERS = utils/helpers/helpers.h utils/idle_monitor/cpupower-monitor.h \
>   	utils/helpers/bitmask.h \
>   	utils/idle_monitor/idle_monitors.h utils/idle_monitor/idle_monitors.def
>   
> -LIB_HEADERS = 	lib/cpufreq.h lib/cpupower.h lib/cpuidle.h
> -LIB_SRC = 	lib/cpufreq.c lib/cpupower.c lib/cpuidle.c
> -LIB_OBJS = 	lib/cpufreq.o lib/cpupower.o lib/cpuidle.o
> +LIB_HEADERS = 	lib/cpufreq.h lib/cpupower.h lib/cpuidle.h lib/acpi_cppc.h
> +LIB_SRC = 	lib/cpufreq.c lib/cpupower.c lib/cpuidle.c lib/acpi_cppc.c
> +LIB_OBJS = 	lib/cpufreq.o lib/cpupower.o lib/cpuidle.o lib/acpi_cppc.o
>   LIB_OBJS :=	$(addprefix $(OUTPUT),$(LIB_OBJS))
>   
>   override CFLAGS +=	-pipe
> diff --git a/tools/power/cpupower/lib/acpi_cppc.c b/tools/power/cpupower/lib/acpi_cppc.c
> new file mode 100644
> index 000000000000..a07a8922eca2
> --- /dev/null
> +++ b/tools/power/cpupower/lib/acpi_cppc.c
> @@ -0,0 +1,59 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include <stdio.h>
> +#include <errno.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +#include <fcntl.h>
> +#include <unistd.h>
> +
> +#include "cpupower_intern.h"
> +#include "acpi_cppc.h"
> +
> +/* ACPI CPPC sysfs access ***********************************************/
> +
> +static int acpi_cppc_read_file(unsigned int cpu, const char *fname,
> +			       char *buf, size_t buflen)
> +{
> +	char path[SYSFS_PATH_MAX];
> +
> +	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/acpi_cppc/%s",
> +		 cpu, fname);
> +	return cpupower_read_sysfs(path, buf, buflen);
> +}
> +
> +static const char *acpi_cppc_value_files[] = {
> +	[HIGHEST_PERF] = "highest_perf",
> +	[LOWEST_PERF] = "lowest_perf",
> +	[NOMINAL_PERF] = "nominal_perf",
> +	[LOWEST_NONLINEAR_PERF] = "lowest_nonlinear_perf",
> +	[LOWEST_FREQ] = "lowest_freq",
> +	[NOMINAL_FREQ] = "nominal_freq",
> +	[REFERENCE_PERF] = "reference_perf",
> +	[WRAPAROUND_TIME] = "wraparound_time"
> +};
> +
> +unsigned long acpi_cppc_get_data(unsigned cpu, enum acpi_cppc_value which)

unsigned int cpu

> +{
> +	unsigned long long value;
> +	unsigned int len;
> +	char linebuf[MAX_LINE_LEN];
> +	char *endp;
> +
> +	if (which >= MAX_CPPC_VALUE_FILES)
> +		return 0;
> +
> +	len = acpi_cppc_read_file(cpu, acpi_cppc_value_files[which],
> +				  linebuf, sizeof(linebuf));
> +	if (len == 0)
> +		return 0;
> +
> +	value = strtoull(linebuf, &endp, 0);
> +
> +	if (endp == linebuf || errno == ERANGE)
> +		return 0;
> +
> +	return value;
> +}
> diff --git a/tools/power/cpupower/lib/acpi_cppc.h b/tools/power/cpupower/lib/acpi_cppc.h
> new file mode 100644
> index 000000000000..576291155224
> --- /dev/null
> +++ b/tools/power/cpupower/lib/acpi_cppc.h
> @@ -0,0 +1,21 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +
> +#ifndef __ACPI_CPPC_H__
> +#define __ACPI_CPPC_H__
> +
> +enum acpi_cppc_value {
> +	HIGHEST_PERF,
> +	LOWEST_PERF,
> +	NOMINAL_PERF,
> +	LOWEST_NONLINEAR_PERF,
> +	LOWEST_FREQ,
> +	NOMINAL_FREQ,
> +	REFERENCE_PERF,
> +	WRAPAROUND_TIME,
> +	MAX_CPPC_VALUE_FILES
> +};
> +
> +extern unsigned long acpi_cppc_get_data(unsigned cpu,

extern prototype in .h?

unsigned int cpu

> +					enum acpi_cppc_value which);
> +
> +#endif /* _ACPI_CPPC_H */
> 

thanks,
-- Shuah