tools/power/cpupower: Read energy_perf_bias from sysfs

... instead of poking at the MSR. For that, move the accessor functions
to misc.c and add a sysfs-writing function too.

There should be no functional changes resulting from this.

Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Shuah Khan <[email protected]>
Cc: Thomas Renninger <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

Author: suryasaimadhu

tools/power/cpupower/lib/cpupower.c

@@ -16,8 +16,8 @@
 
 unsigned int cpupower_read_sysfs(const char *path, char *buf, size_t buflen)
 {
-	int fd;
 	ssize_t numread;
+	int fd;
 
 	fd = open(path, O_RDONLY);
 	if (fd == -1)
@@ -35,6 +35,27 @@ unsigned int cpupower_read_sysfs(const char *path, char *buf, size_t buflen)
 	return (unsigned int) numread;
 }
 
+unsigned int cpupower_write_sysfs(const char *path, char *buf, size_t buflen)
+{
+	ssize_t numwritten;
+	int fd;
+
+	fd = open(path, O_WRONLY);
+	if (fd == -1)
+		return 0;
+
+	numwritten = write(fd, buf, buflen - 1);
+	if (numwritten < 1) {
+		perror(path);
+		close(fd);
+		return -1;
+	}
+
+	close(fd);
+
+	return (unsigned int) numwritten;
+}
+
 /*
  * Detect whether a CPU is online
  *

tools/power/cpupower/lib/cpupower_intern.h

@@ -1,6 +1,11 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #define PATH_TO_CPU "/sys/devices/system/cpu/"
+
+#ifndef MAX_LINE_LEN
 #define MAX_LINE_LEN 4096
+#endif
+
 #define SYSFS_PATH_MAX 255
 
 unsigned int cpupower_read_sysfs(const char *path, char *buf, size_t buflen);
+unsigned int cpupower_write_sysfs(const char *path, char *buf, size_t buflen);

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

@@ -101,7 +101,7 @@ int cmd_info(int argc, char **argv)
 		}
 
 		if (params.perf_bias) {
-			ret = msr_intel_get_perf_bias(cpu);
+			ret = cpupower_intel_get_perf_bias(cpu);
 			if (ret < 0) {
 				fprintf(stderr,
 			_("Could not read perf-bias value[%d]\n"), ret);

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

@@ -95,7 +95,7 @@ int cmd_set(int argc, char **argv)
 		}
 
 		if (params.perf_bias) {
-			ret = msr_intel_set_perf_bias(cpu, perf_bias);
+			ret = cpupower_intel_set_perf_bias(cpu, perf_bias);
 			if (ret) {
 				fprintf(stderr, _("Error setting perf-bias "
 						  "value on CPU %d\n"), cpu);

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

@@ -105,8 +105,8 @@ extern struct cpupower_cpu_info cpupower_cpu_info;
 extern int read_msr(int cpu, unsigned int idx, unsigned long long *val);
 extern int write_msr(int cpu, unsigned int idx, unsigned long long val);
 
-extern int msr_intel_set_perf_bias(unsigned int cpu, unsigned int val);
-extern int msr_intel_get_perf_bias(unsigned int cpu);
+extern int cpupower_intel_set_perf_bias(unsigned int cpu, unsigned int val);
+extern int cpupower_intel_get_perf_bias(unsigned int cpu);
 extern unsigned long long msr_intel_get_turbo_ratio(unsigned int cpu);
 
 /* Read/Write msr ****************************/
@@ -150,9 +150,9 @@ static inline int read_msr(int cpu, unsigned int idx, unsigned long long *val)
 { return -1; };
 static inline int write_msr(int cpu, unsigned int idx, unsigned long long val)
 { return -1; };
-static inline int msr_intel_set_perf_bias(unsigned int cpu, unsigned int val)
+static inline int cpupower_intel_set_perf_bias(unsigned int cpu, unsigned int val)
 { return -1; };
-static inline int msr_intel_get_perf_bias(unsigned int cpu)
+static inline int cpupower_intel_get_perf_bias(unsigned int cpu)
 { return -1; };
 static inline unsigned long long msr_intel_get_turbo_ratio(unsigned int cpu)
 { return 0; };

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

@@ -1,7 +1,15 @@
 // SPDX-License-Identifier: GPL-2.0
+
+#include <stdio.h>
+#include <errno.h>
+#include <stdlib.h>
+
 #if defined(__i386__) || defined(__x86_64__)
 
 #include "helpers/helpers.h"
+#include "helpers/sysfs.h"
+
+#include "cpupower_intern.h"
 
 #define MSR_AMD_HWCR	0xc0010015
 
@@ -40,4 +48,44 @@ int cpufreq_has_boost_support(unsigned int cpu, int *support, int *active,
 		*support = *active = 1;
 	return 0;
 }
+
+int cpupower_intel_get_perf_bias(unsigned int cpu)
+{
+	char linebuf[MAX_LINE_LEN];
+	char path[SYSFS_PATH_MAX];
+	unsigned long val;
+	char *endp;
+
+	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_PERF_BIAS))
+		return -1;
+
+	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/power/energy_perf_bias", cpu);
+
+	if (cpupower_read_sysfs(path, linebuf, MAX_LINE_LEN) == 0)
+		return -1;
+
+	val = strtol(linebuf, &endp, 0);
+	if (endp == linebuf || errno == ERANGE)
+		return -1;
+
+	return val;
+}
+
+int cpupower_intel_set_perf_bias(unsigned int cpu, unsigned int val)
+{
+	char path[SYSFS_PATH_MAX];
+	char linebuf[3] = {};
+
+	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_PERF_BIAS))
+		return -1;
+
+	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/power/energy_perf_bias", cpu);
+	snprintf(linebuf, sizeof(linebuf), "%d", val);
+
+	if (cpupower_write_sysfs(path, linebuf, 3) <= 0)
+		return -1;
+
+	return 0;
+}
+
 #endif /* #if defined(__i386__) || defined(__x86_64__) */

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

@@ -11,7 +11,6 @@
 /* Intel specific MSRs */
 #define MSR_IA32_PERF_STATUS		0x198
 #define MSR_IA32_MISC_ENABLES		0x1a0
-#define MSR_IA32_ENERGY_PERF_BIAS	0x1b0
 #define MSR_NEHALEM_TURBO_RATIO_LIMIT	0x1ad
 
 /*
@@ -73,33 +72,6 @@ int write_msr(int cpu, unsigned int idx, unsigned long long val)
 	return -1;
 }
 
-int msr_intel_get_perf_bias(unsigned int cpu)
-{
-	unsigned long long val;
-	int ret;
-
-	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_PERF_BIAS))
-		return -1;
-
-	ret = read_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &val);
-	if (ret)
-		return ret;
-	return val;
-}
-
-int msr_intel_set_perf_bias(unsigned int cpu, unsigned int val)
-{
-	int ret;
-
-	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_PERF_BIAS))
-		return -1;
-
-	ret = write_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, val);
-	if (ret)
-		return ret;
-	return 0;
-}
-
 unsigned long long msr_intel_get_turbo_ratio(unsigned int cpu)
 {
 	unsigned long long val;