cpupower: Add intel_pstate turbo boost support for Intel platforms

On modern Intel platforms, the intel_pstate driver is commonly used and
it provides turbo boost control via
/sys/devices/system/cpu/intel_pstate/no_turbo.

However, cpupower doesn't handle this. it
1. shows turbo boost as "active" blindly for Intel platforms
2. controls turbo boost functionality via the generic
   /sys/devices/system/cpu/cpufreq/boost sysfs interface only.

Enhance the cpupower tool to ensure the "--boost" command works
seamlessly on Intel platforms with intel_pstate driver running.

Without this patch,
   $ echo 1 | sudo tee /sys/devices/system/cpu/intel_pstate/no_turbo
   1
   $ sudo cpupower frequency-info --boost
   analyzing CPU 21:
     boost state support:
       Supported: yes
       Active: yes
   $ sudo cpupower set --boost 0
   Error setting turbo-boost
   $ sudo cpupower set --boost 1
   Error setting turbo-boost

With this patch,
   $ cat /sys/devices/system/cpu/intel_pstate/no_turbo
   0
   $ sudo cpupower set --boost 0
   $ sudo cpupower frequency-info --boost
   analyzing CPU 21:
     boost state support:
       Supported: yes
       Active: no
   $ cat /sys/devices/system/cpu/intel_pstate/no_turbo
   1
   $ sudo cpupower set --boost 1
   $ sudo cpupower frequency-info --boost
   analyzing CPU 28:
     boost state support:
       Supported: yes
       Active: yes
   $ cat /sys/devices/system/cpu/intel_pstate/no_turbo
   0

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/power/cpupower/utils/cpupower-set.c

@@ -124,7 +124,11 @@ int cmd_set(int argc, char **argv)
 	}
 
 	if (params.turbo_boost) {
-		ret = cpupower_set_turbo_boost(turbo_boost);
+		if (cpupower_cpu_info.vendor == X86_VENDOR_INTEL)
+			ret = cpupower_set_intel_turbo_boost(turbo_boost);
+		else
+			ret = cpupower_set_generic_turbo_boost(turbo_boost);
+
 		if (ret)
 			fprintf(stderr, "Error setting turbo-boost\n");
 	}

tools/power/cpupower/utils/helpers/helpers.h

@@ -104,7 +104,7 @@ extern struct cpupower_cpu_info cpupower_cpu_info;
 /* cpuid and cpuinfo helpers  **************************/
 
 int cpufreq_has_generic_boost_support(bool *active);
-int cpupower_set_turbo_boost(int turbo_boost);
+int cpupower_set_generic_turbo_boost(int turbo_boost);
 
 /* X86 ONLY ****************************************/
 #if defined(__i386__) || defined(__x86_64__)
@@ -143,6 +143,7 @@ extern int decode_pstates(unsigned int cpu, int boost_states,
 
 int cpufreq_has_x86_boost_support(unsigned int cpu, int *support,
 				  int *active, int *states);
+int cpupower_set_intel_turbo_boost(int turbo_boost);
 
 /* AMD P-State stuff **************************/
 bool cpupower_amd_pstate_enabled(void);
@@ -189,6 +190,8 @@ static inline int cpupower_set_amd_pstate_mode(char *mode)
 static inline int cpufreq_has_x86_boost_support(unsigned int cpu, int *support,
 						int *active, int *states)
 { return -1; }
+static inline int cpupower_set_intel_turbo_boost(int turbo_boost)
+{ return -1; }
 
 static inline bool cpupower_amd_pstate_enabled(void)
 { return false; }

tools/power/cpupower/utils/helpers/misc.c

@@ -19,6 +19,9 @@ int cpufreq_has_x86_boost_support(unsigned int cpu, int *support, int *active,
 {
 	int ret;
 	unsigned long long val;
+	char linebuf[MAX_LINE_LEN];
+	char path[SYSFS_PATH_MAX];
+	char *endp;
 
 	*support = *active = *states = 0;
 
@@ -42,8 +45,42 @@ int cpufreq_has_x86_boost_support(unsigned int cpu, int *support, int *active,
 		}
 	} else if (cpupower_cpu_info.caps & CPUPOWER_CAP_AMD_PSTATE) {
 		amd_pstate_boost_init(cpu, support, active);
-	} else if (cpupower_cpu_info.caps & CPUPOWER_CAP_INTEL_IDA)
+	} else if (cpupower_cpu_info.caps & CPUPOWER_CAP_INTEL_IDA) {
 		*support = *active = 1;
+
+		snprintf(path, sizeof(path), PATH_TO_CPU "intel_pstate/no_turbo");
+
+		if (!is_valid_path(path))
+			return 0;
+
+		if (cpupower_read_sysfs(path, linebuf, MAX_LINE_LEN) == 0)
+			return -1;
+
+		val = strtol(linebuf, &endp, 0);
+		if (endp == linebuf || errno == ERANGE)
+			return -1;
+
+		*active = !val;
+	}
+	return 0;
+}
+
+int cpupower_set_intel_turbo_boost(int turbo_boost)
+{
+	char path[SYSFS_PATH_MAX];
+	char linebuf[2] = {};
+
+	snprintf(path, sizeof(path), PATH_TO_CPU "intel_pstate/no_turbo");
+
+	/* Fallback to generic solution when intel_pstate driver not running */
+	if (!is_valid_path(path))
+		return cpupower_set_generic_turbo_boost(turbo_boost);
+
+	snprintf(linebuf, sizeof(linebuf), "%d", !turbo_boost);
+
+	if (cpupower_write_sysfs(path, linebuf, 2) <= 0)
+		return -1;
+
 	return 0;
 }
 
@@ -274,7 +311,7 @@ void print_speed(unsigned long speed, int no_rounding)
 	}
 }
 
-int cpupower_set_turbo_boost(int turbo_boost)
+int cpupower_set_generic_turbo_boost(int turbo_boost)
 {
 	char path[SYSFS_PATH_MAX];
 	char linebuf[2] = {};