1 files changed, 471 insertions, 0 deletions
diff --git a/tools/power/cpupower/utils/helpers/sysfs.c b/tools/power/cpupower/utils/helpers/sysfs.c
new file mode 100644
index 000000000..e13ff3832
--- /dev/null
+++ b/tools/power/cpupower/utils/helpers/sysfs.c
@@ -0,0 +1,471 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  (C) 2004-2009  Dominik Brodowski <linux@dominikbrodowski.de>
+ *  (C) 2011       Thomas Renninger <trenn@novell.com> Novell Inc.
+ */
+
+#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 "helpers/sysfs.h"
+
+unsigned int sysfs_read_file(const char *path, char *buf, size_t buflen)
+{
+	int fd;
+	ssize_t numread;
+
+	fd = open(path, O_RDONLY);
+	if (fd == -1)
+		return 0;
+
+	numread = read(fd, buf, buflen - 1);
+	if (numread < 1) {
+		close(fd);
+		return 0;
+	}
+
+	buf[numread] = '\0';
+	close(fd);
+
+	return (unsigned int) numread;
+}
+
+/*
+ * Detect whether a CPU is online
+ *
+ * Returns:
+ *     1 -> if CPU is online
+ *     0 -> if CPU is offline
+ *     negative errno values in error case
+ */
+int sysfs_is_cpu_online(unsigned int cpu)
+{
+	char path[SYSFS_PATH_MAX];
+	int fd;
+	ssize_t numread;
+	unsigned long long value;
+	char linebuf[MAX_LINE_LEN];
+	char *endp;
+	struct stat statbuf;
+
+	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u", cpu);
+
+	if (stat(path, &statbuf) != 0)
+		return 0;
+
+	/*
+	 * kernel without CONFIG_HOTPLUG_CPU
+	 * -> cpuX directory exists, but not cpuX/online file
+	 */
+	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/online", cpu);
+	if (stat(path, &statbuf) != 0)
+		return 1;
+
+	fd = open(path, O_RDONLY);
+	if (fd == -1)
+		return -errno;
+
+	numread = read(fd, linebuf, MAX_LINE_LEN - 1);
+	if (numread < 1) {
+		close(fd);
+		return -EIO;
+	}
+	linebuf[numread] = '\0';
+	close(fd);
+
+	value = strtoull(linebuf, &endp, 0);
+	if (value > 1)
+		return -EINVAL;
+
+	return value;
+}
+
+/* CPUidle idlestate specific /sys/devices/system/cpu/cpuX/cpuidle/ access */
+
+
+/* CPUidle idlestate specific /sys/devices/system/cpu/cpuX/cpuidle/ access */
+
+/*
+ * helper function to check whether a file under "../cpuX/cpuidle/stateX/" dir
+ * exists.
+ * For example the functionality to disable c-states was introduced in later
+ * kernel versions, this function can be used to explicitly check for this
+ * feature.
+ *
+ * returns 1 if the file exists, 0 otherwise.
+ */
+unsigned int sysfs_idlestate_file_exists(unsigned int cpu,
+					 unsigned int idlestate,
+					 const char *fname)
+{
+	char path[SYSFS_PATH_MAX];
+	struct stat statbuf;
+
+
+	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/cpuidle/state%u/%s",
+		 cpu, idlestate, fname);
+	if (stat(path, &statbuf) != 0)
+		return 0;
+	return 1;
+}
+
+/*
+ * helper function to read file from /sys into given buffer
+ * fname is a relative path under "cpuX/cpuidle/stateX/" dir
+ * cstates starting with 0, C0 is not counted as cstate.
+ * This means if you want C1 info, pass 0 as idlestate param
+ */
+unsigned int sysfs_idlestate_read_file(unsigned int cpu, unsigned int idlestate,
+			     const char *fname, char *buf, size_t buflen)
+{
+	char path[SYSFS_PATH_MAX];
+	int fd;
+	ssize_t numread;
+
+	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/cpuidle/state%u/%s",
+		 cpu, idlestate, fname);
+
+	fd = open(path, O_RDONLY);
+	if (fd == -1)
+		return 0;
+
+	numread = read(fd, buf, buflen - 1);
+	if (numread < 1) {
+		close(fd);
+		return 0;
+	}
+
+	buf[numread] = '\0';
+	close(fd);
+
+	return (unsigned int) numread;
+}
+
+/* 
+ * helper function to write a new value to a /sys file
+ * fname is a relative path under "../cpuX/cpuidle/cstateY/" dir
+ *
+ * Returns the number of bytes written or 0 on error
+ */
+static
+unsigned int sysfs_idlestate_write_file(unsigned int cpu,
+					unsigned int idlestate,
+					const char *fname,
+					const char *value, size_t len)
+{
+	char path[SYSFS_PATH_MAX];
+	int fd;
+	ssize_t numwrite;
+
+	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/cpuidle/state%u/%s",
+		 cpu, idlestate, fname);
+
+	fd = open(path, O_WRONLY);
+	if (fd == -1)
+		return 0;
+
+	numwrite = write(fd, value, len);
+	if (numwrite < 1) {
+		close(fd);
+		return 0;
+	}
+
+	close(fd);
+
+	return (unsigned int) numwrite;
+}
+
+/* read access to files which contain one numeric value */
+
+enum idlestate_value {
+	IDLESTATE_USAGE,
+	IDLESTATE_POWER,
+	IDLESTATE_LATENCY,
+	IDLESTATE_TIME,
+	IDLESTATE_DISABLE,
+	MAX_IDLESTATE_VALUE_FILES
+};
+
+static const char *idlestate_value_files[MAX_IDLESTATE_VALUE_FILES] = {
+	[IDLESTATE_USAGE] = "usage",
+	[IDLESTATE_POWER] = "power",
+	[IDLESTATE_LATENCY] = "latency",
+	[IDLESTATE_TIME]  = "time",
+	[IDLESTATE_DISABLE]  = "disable",
+};
+
+static unsigned long long sysfs_idlestate_get_one_value(unsigned int cpu,
+						     unsigned int idlestate,
+						     enum idlestate_value which)
+{
+	unsigned long long value;
+	unsigned int len;
+	char linebuf[MAX_LINE_LEN];
+	char *endp;
+
+	if (which >= MAX_IDLESTATE_VALUE_FILES)
+		return 0;
+
+	len = sysfs_idlestate_read_file(cpu, idlestate,
+					idlestate_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;
+}
+
+/* read access to files which contain one string */
+
+enum idlestate_string {
+	IDLESTATE_DESC,
+	IDLESTATE_NAME,
+	MAX_IDLESTATE_STRING_FILES
+};
+
+static const char *idlestate_string_files[MAX_IDLESTATE_STRING_FILES] = {
+	[IDLESTATE_DESC] = "desc",
+	[IDLESTATE_NAME] = "name",
+};
+
+
+static char *sysfs_idlestate_get_one_string(unsigned int cpu,
+					unsigned int idlestate,
+					enum idlestate_string which)
+{
+	char linebuf[MAX_LINE_LEN];
+	char *result;
+	unsigned int len;
+
+	if (which >= MAX_IDLESTATE_STRING_FILES)
+		return NULL;
+
+	len = sysfs_idlestate_read_file(cpu, idlestate,
+					idlestate_string_files[which],
+					linebuf, sizeof(linebuf));
+	if (len == 0)
+		return NULL;
+
+	result = strdup(linebuf);
+	if (result == NULL)
+		return NULL;
+
+	if (result[strlen(result) - 1] == '\n')
+		result[strlen(result) - 1] = '\0';
+
+	return result;
+}
+
+/*
+ * Returns:
+ *    1  if disabled
+ *    0  if enabled
+ *    -1 if idlestate is not available
+ *    -2 if disabling is not supported by the kernel
+ */
+int sysfs_is_idlestate_disabled(unsigned int cpu,
+				unsigned int idlestate)
+{
+	if (sysfs_get_idlestate_count(cpu) <= idlestate)
+		return -1;
+
+	if (!sysfs_idlestate_file_exists(cpu, idlestate,
+				 idlestate_value_files[IDLESTATE_DISABLE]))
+		return -2;
+	return sysfs_idlestate_get_one_value(cpu, idlestate, IDLESTATE_DISABLE);
+}
+
+/*
+ * Pass 1 as last argument to disable or 0 to enable the state
+ * Returns:
+ *    0  on success
+ *    negative values on error, for example:
+ *      -1 if idlestate is not available
+ *      -2 if disabling is not supported by the kernel
+ *      -3 No write access to disable/enable C-states
+ */
+int sysfs_idlestate_disable(unsigned int cpu,
+			    unsigned int idlestate,
+			    unsigned int disable)
+{
+	char value[SYSFS_PATH_MAX];
+	int bytes_written;
+
+	if (sysfs_get_idlestate_count(cpu) <= idlestate)
+		return -1;
+
+	if (!sysfs_idlestate_file_exists(cpu, idlestate,
+				 idlestate_value_files[IDLESTATE_DISABLE]))
+		return -2;
+
+	snprintf(value, SYSFS_PATH_MAX, "%u", disable);
+
+	bytes_written = sysfs_idlestate_write_file(cpu, idlestate, "disable",
+						   value, sizeof(disable));
+	if (bytes_written)
+		return 0;
+	return -3;
+}
+
+unsigned long sysfs_get_idlestate_latency(unsigned int cpu,
+					  unsigned int idlestate)
+{
+	return sysfs_idlestate_get_one_value(cpu, idlestate, IDLESTATE_LATENCY);
+}
+
+unsigned long sysfs_get_idlestate_usage(unsigned int cpu,
+					unsigned int idlestate)
+{
+	return sysfs_idlestate_get_one_value(cpu, idlestate, IDLESTATE_USAGE);
+}
+
+unsigned long long sysfs_get_idlestate_time(unsigned int cpu,
+					unsigned int idlestate)
+{
+	return sysfs_idlestate_get_one_value(cpu, idlestate, IDLESTATE_TIME);
+}
+
+char *sysfs_get_idlestate_name(unsigned int cpu, unsigned int idlestate)
+{
+	return sysfs_idlestate_get_one_string(cpu, idlestate, IDLESTATE_NAME);
+}
+
+char *sysfs_get_idlestate_desc(unsigned int cpu, unsigned int idlestate)
+{
+	return sysfs_idlestate_get_one_string(cpu, idlestate, IDLESTATE_DESC);
+}
+
+/*
+ * Returns number of supported C-states of CPU core cpu
+ * Negativ in error case
+ * Zero if cpuidle does not export any C-states
+ */
+unsigned int sysfs_get_idlestate_count(unsigned int cpu)
+{
+	char file[SYSFS_PATH_MAX];
+	struct stat statbuf;
+	int idlestates = 1;
+
+
+	snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU "cpuidle");
+	if (stat(file, &statbuf) != 0 || !S_ISDIR(statbuf.st_mode))
+		return 0;
+
+	snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU "cpu%u/cpuidle/state0", cpu);
+	if (stat(file, &statbuf) != 0 || !S_ISDIR(statbuf.st_mode))
+		return 0;
+
+	while (stat(file, &statbuf) == 0 && S_ISDIR(statbuf.st_mode)) {
+		snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU
+			 "cpu%u/cpuidle/state%d", cpu, idlestates);
+		idlestates++;
+	}
+	idlestates--;
+	return idlestates;
+}
+
+/* CPUidle general /sys/devices/system/cpu/cpuidle/ sysfs access ********/
+
+/*
+ * helper function to read file from /sys into given buffer
+ * fname is a relative path under "cpu/cpuidle/" dir
+ */
+static unsigned int sysfs_cpuidle_read_file(const char *fname, char *buf,
+					    size_t buflen)
+{
+	char path[SYSFS_PATH_MAX];
+
+	snprintf(path, sizeof(path), PATH_TO_CPU "cpuidle/%s", fname);
+
+	return sysfs_read_file(path, buf, buflen);
+}
+
+
+
+/* read access to files which contain one string */
+
+enum cpuidle_string {
+	CPUIDLE_GOVERNOR,
+	CPUIDLE_GOVERNOR_RO,
+	CPUIDLE_DRIVER,
+	MAX_CPUIDLE_STRING_FILES
+};
+
+static const char *cpuidle_string_files[MAX_CPUIDLE_STRING_FILES] = {
+	[CPUIDLE_GOVERNOR]	= "current_governor",
+	[CPUIDLE_GOVERNOR_RO]	= "current_governor_ro",
+	[CPUIDLE_DRIVER]	= "current_driver",
+};
+
+
+static char *sysfs_cpuidle_get_one_string(enum cpuidle_string which)
+{
+	char linebuf[MAX_LINE_LEN];
+	char *result;
+	unsigned int len;
+
+	if (which >= MAX_CPUIDLE_STRING_FILES)
+		return NULL;
+
+	len = sysfs_cpuidle_read_file(cpuidle_string_files[which],
+				linebuf, sizeof(linebuf));
+	if (len == 0)
+		return NULL;
+
+	result = strdup(linebuf);
+	if (result == NULL)
+		return NULL;
+
+	if (result[strlen(result) - 1] == '\n')
+		result[strlen(result) - 1] = '\0';
+
+	return result;
+}
+
+char *sysfs_get_cpuidle_governor(void)
+{
+	char *tmp = sysfs_cpuidle_get_one_string(CPUIDLE_GOVERNOR_RO);
+	if (!tmp)
+		return sysfs_cpuidle_get_one_string(CPUIDLE_GOVERNOR);
+	else
+		return tmp;
+}
+
+char *sysfs_get_cpuidle_driver(void)
+{
+	return sysfs_cpuidle_get_one_string(CPUIDLE_DRIVER);
+}
+/* CPUidle idlestate specific /sys/devices/system/cpu/cpuX/cpuidle/ access */
+
+/*
+ * Get sched_mc or sched_smt settings
+ * Pass "mc" or "smt" as argument
+ *
+ * Returns negative value on failure
+ */
+int sysfs_get_sched(const char *smt_mc)
+{
+	return -ENODEV;
+}
+
+/*
+ * Get sched_mc or sched_smt settings
+ * Pass "mc" or "smt" as argument
+ *
+ * Returns negative value on failure
+ */
+int sysfs_set_sched(const char *smt_mc, int val)
+{
+	return -ENODEV;
+}