summaryrefslogtreecommitdiff
path: root/tools/power/cpupower/utils/helpers/sysfs.c
diff options
context:
space:
mode:
authorDavid S. Miller <davem@davemloft.net>2011-09-22 03:23:13 -0400
committerDavid S. Miller <davem@davemloft.net>2011-09-22 03:23:13 -0400
commit8decf868790b48a727d7e7ca164f2bcd3c1389c0 (patch)
treeb759a5f861f842af7ea76f9011b579d06e9d5508 /tools/power/cpupower/utils/helpers/sysfs.c
parent3fc72370186be2f9d4d6ef06d99e1caa5d92c564 (diff)
parentd93dc5c4478c1fd5de85a3e8aece9aad7bbae044 (diff)
Merge branch 'master' of github.com:davem330/net
Conflicts: MAINTAINERS drivers/net/Kconfig drivers/net/ethernet/broadcom/bnx2x/bnx2x_link.c drivers/net/ethernet/broadcom/tg3.c drivers/net/wireless/iwlwifi/iwl-pci.c drivers/net/wireless/iwlwifi/iwl-trans-tx-pcie.c drivers/net/wireless/rt2x00/rt2800usb.c drivers/net/wireless/wl12xx/main.c
Diffstat (limited to 'tools/power/cpupower/utils/helpers/sysfs.c')
-rw-r--r--tools/power/cpupower/utils/helpers/sysfs.c50
1 files changed, 50 insertions, 0 deletions
diff --git a/tools/power/cpupower/utils/helpers/sysfs.c b/tools/power/cpupower/utils/helpers/sysfs.c
index 55e2466674c6..c6343024a611 100644
--- a/tools/power/cpupower/utils/helpers/sysfs.c
+++ b/tools/power/cpupower/utils/helpers/sysfs.c
@@ -56,6 +56,56 @@ static unsigned int sysfs_write_file(const char *path,
return (unsigned int) numwrite;
}
+/*
+ * 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 || value < 0)
+ return -EINVAL;
+
+ return value;
+}
+
/* CPUidle idlestate specific /sys/devices/system/cpu/cpuX/cpuidle/ access */
/*