[PATCH v2 14/21] cpupower: add the function to check amd-pstate enabled

[Huang Rui]

The processor with amd-pstate function also supports legacy ACPI
hardware P-States feature as well. Once driver sets amd-pstate eanbled,
the processor will respond the finer grain amd-pstate feature instead of
legacy ACPI P-States. So it introduces the cpupower_amd_pstate_enabled()
to check whether the current kernel enables amd-pstate or acpi-cpufreq
module.

Signed-off-by: Huang Rui <ray.huang@xxxxxxx>
---
 tools/power/cpupower/utils/helpers/helpers.h |  9 +++++++++
 tools/power/cpupower/utils/helpers/misc.c    | 20 ++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/tools/power/cpupower/utils/helpers/helpers.h b/tools/power/cpupower/utils/helpers/helpers.h
index b4813efdfb00..ae96efac759f 100644
--- a/tools/power/cpupower/utils/helpers/helpers.h
+++ b/tools/power/cpupower/utils/helpers/helpers.h
@@ -136,6 +136,12 @@ extern int decode_pstates(unsigned int cpu, int boost_states,
 
 extern int cpufreq_has_boost_support(unsigned int cpu, int *support,
 				     int *active, int * states);
+
+/* AMD P-States stuff **************************/
+extern unsigned long cpupower_amd_pstate_enabled(void);
+
+/* AMD P-States stuff **************************/
+
 /*
  * CPUID functions returning a single datum
  */
@@ -168,6 +174,9 @@ static inline int cpufreq_has_boost_support(unsigned int cpu, int *support,
 					    int *active, int * states)
 { return -1; }
 
+static inline unsigned long cpupower_amd_pstate_enabled(void)
+{ return 0; }
+
 /* cpuid and cpuinfo helpers  **************************/
 
 static inline unsigned int cpuid_eax(unsigned int op) { return 0; };
diff --git a/tools/power/cpupower/utils/helpers/misc.c b/tools/power/cpupower/utils/helpers/misc.c
index fc6e34511721..39ff154ea9cf 100644
--- a/tools/power/cpupower/utils/helpers/misc.c
+++ b/tools/power/cpupower/utils/helpers/misc.c
@@ -83,6 +83,26 @@ int cpupower_intel_set_perf_bias(unsigned int cpu, unsigned int val)
 	return 0;
 }
 
+unsigned long cpupower_amd_pstate_enabled(void)
+{
+	char linebuf[MAX_LINE_LEN];
+	char path[SYSFS_PATH_MAX];
+	unsigned long val;
+	char *endp;
+
+	snprintf(path, sizeof(path),
+		 PATH_TO_CPU "cpu0/cpufreq/is_amd_pstate_enabled");
+
+	if (cpupower_read_sysfs(path, linebuf, MAX_LINE_LEN) == 0)
+		return 0;
+
+	val = strtoul(linebuf, &endp, 0);
+	if (endp == linebuf || errno == ERANGE)
+		return 0;
+
+	return val;
+}
+
 #endif /* #if defined(__i386__) || defined(__x86_64__) */
 
 /* get_cpustate
-- 
2.25.1