1 files changed, 59 insertions, 0 deletions
diff --git a/tools/power/cpupower/lib/acpi_cppc.c b/tools/power/cpupower/lib/acpi_cppc.c
new file mode 100644
index 000000000..c401ac331
--- /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 * const 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 int 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;
+}