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    Subject[PATCH v4 17/22] cpupower: introduce acpi cppc library
    Date
    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-pstate driver to provide some
    performance and frequency values.

    Signed-off-by: Huang Rui <ray.huang@amd.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 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,
    + enum acpi_cppc_value which);
    +
    +#endif /* _ACPI_CPPC_H */
    --
    2.25.1
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