tools/power x86_energy_perf_policy: Add Android MSR device support

Add support for Android MSR device paths which use /dev/msrN format
instead of the standard Linux /dev/cpu/N/msr format. The tool now
probes both path formats at startup and uses the appropriate one.

This enables x86_energy_perf_policy to work on Android systems where
MSR devices follow a different naming convention while maintaining
full compatibility with standard Linux systems.

Signed-off-by: Kaushlendra Kumar <kaushlendra.kumar@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

diff --git a/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c b/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c
index 884a4c746f32e87e455b705af16078f2735bea6e..5301efc741ceec930b145d6059b0c993cd9506f0 100644 (file)
--- a/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c
+++ b/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c
@@ -95,6 +95,9 @@ unsigned int bdx_highest_ratio;
 #define PATH_TO_CPU "/sys/devices/system/cpu/"
 #define SYSFS_PATH_MAX 255
 
+/* keep Default as a linux path */
+static int use_android_msr_path;
+
 /*
  * maintain compatibility with original implementation, but don't document it:
  */
@@ -678,16 +681,41 @@ void err_on_hypervisor(void)
                    "not supported on this virtual machine");
 }
 
+static void probe_msr_path_format(void)
+{
+       struct stat sb;
+       char test_path[32];
+
+       /* Test standard Linux path */
+       sprintf(test_path, "/dev/cpu/%d/msr", base_cpu);
+       if (stat(test_path, &sb) == 0) {
+               use_android_msr_path = 0;
+               return;
+       }
+
+       /* Test Android-style path */
+       sprintf(test_path, "/dev/msr%d", base_cpu);
+       if (stat(test_path, &sb) == 0) {
+               use_android_msr_path = 1;
+               return;
+       }
+
+       /* If neither exists, keep the default Linux format */
+       use_android_msr_path = 0;
+}
+
 int get_msr(int cpu, int offset, unsigned long long *msr)
 {
        int retval;
        char pathname[32];
        int fd;
 
-       sprintf(pathname, "/dev/cpu/%d/msr", cpu);
+       sprintf(pathname, use_android_msr_path ? "/dev/msr%d" : "/dev/cpu/%d/msr", cpu);
        fd = open(pathname, O_RDONLY);
        if (fd < 0)
-               err(-1, "%s open failed, try chown or chmod +r /dev/cpu/*/msr, or run as root", pathname);
+               err(-1, "%s open failed, try chown or chmod +r %s, or run as root",
+                  pathname, use_android_msr_path ? "/dev/msr*" : "/dev/cpu/*/msr");
+
 
        retval = pread(fd, msr, sizeof(*msr), offset);
        if (retval != sizeof(*msr)) {
@@ -708,10 +736,11 @@ int put_msr(int cpu, int offset, unsigned long long new_msr)
        int retval;
        int fd;
 
-       sprintf(pathname, "/dev/cpu/%d/msr", cpu);
+       sprintf(pathname, use_android_msr_path ? "/dev/msr%d" : "/dev/cpu/%d/msr", cpu);
        fd = open(pathname, O_RDWR);
        if (fd < 0)
-               err(-1, "%s open failed, try chown or chmod +r /dev/cpu/*/msr, or run as root", pathname);
+               err(-1, "%s open failed, try chown or chmod +r %s, or run as root",
+                  pathname, use_android_msr_path ? "/dev/msr*" : "/dev/cpu/*/msr");
 
        retval = pwrite(fd, &new_msr, sizeof(new_msr), offset);
        if (retval != sizeof(new_msr))
@@ -1427,10 +1456,15 @@ void probe_dev_msr(void)
        struct stat sb;
        char pathname[32];
 
-       sprintf(pathname, "/dev/cpu/%d/msr", base_cpu);
-       if (stat(pathname, &sb))
-               if (system("/sbin/modprobe msr > /dev/null 2>&1"))
-                       err(-5, "no /dev/cpu/0/msr, Try \"# modprobe msr\" ");
+       sprintf(pathname, use_android_msr_path ? "/dev/msr%d" : "/dev/cpu/%d/msr", base_cpu);
+       if (stat(pathname, &sb)) {
+               if (system("/sbin/modprobe msr > /dev/null 2>&1")) {
+                       if (use_android_msr_path)
+                               err(-5, "no /dev/msr0, Try \"# modprobe msr\" ");
+                       else
+                               err(-5, "no /dev/cpu/0/msr, Try \"# modprobe msr\" ");
+               }
+       }
 }
 
 static void get_cpuid_or_exit(unsigned int leaf,
@@ -1547,6 +1581,10 @@ void parse_cpuid(void)
 int main(int argc, char **argv)
 {
        set_base_cpu();
+
+       /* probe MSR path */
+       probe_msr_path_format();
+
        probe_dev_msr();
        init_data_structures();