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Subject[PATCH v5 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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