Add effective frequency

Like HWiNFO64, the popular monitoring tool for Windows, this patch
adds support for reading the cores' effective frequency or multiplier
by making use of the undocumented MSR, 0xC0010293.

This MSR was found by reverse-engineering Ryzen Master, the AMD software
for Windows overclocking and monitoring of Zen based processors. Although
this MSR is undocumented, since it is used in software written by AMD
themselves, it is safe to assume it is accurate.

The MSR returns two things, the FID or effective frequency ID and the FDID.
The FID, when divided by the FDID for a core, produces a frequency in
increments of 200 MHz -- the effective frequency.

src/ss/msr.c

@@ -11,6 +11,7 @@
 #include "sysfs.h"
 
 #define MSR_PWR_PRINTF_FORMAT " %8.3f W"
+#define MSR_FID_PRINTF_FORMAT " %8.3f GHz"
 #define MESUREMENT_TIME 0.1
 
 // AMD PPR  = https://www.amd.com/system/files/TechDocs/54945_PPR_Family_17h_Models_00h-0Fh.pdf
@@ -31,8 +32,11 @@ gfloat package_power;
 gfloat package_power_min;
 gfloat package_power_max;
 gfloat *core_power;
+gfloat *core_fid;
 gfloat *core_power_min;
 gfloat *core_power_max;
+gfloat *core_fid_min;
+gfloat *core_fid_max;
 
 
 static gint open_msr(gshort devid) {
@@ -75,6 +79,26 @@ gulong get_core_energy(gint core) {
     return data;
 }
 
+gdouble get_core_fid(gint core) {
+    gdouble ratio;
+    gulong data;
+
+    // By reverse-engineering Ryzen Master, we know that
+    //  this undocumented MSR is responsible for returning
+    //  the FID and FDID for the core used for calculating the
+    //  effective frequency.
+    //
+    // The FID is returned in bits [8:0]
+    // The FDID is returned in bits [14:8]
+    if (!read_msr(msr_files[core], 0xC0010293, &data))
+        return 0;
+
+    ratio = (gdouble)(data & 0xff) / (gdouble)((data >> 8) & 0x3F);
+
+    // The effective ratio is based on increments of 200 MHz.
+    return ratio * 200.0 / 1000.0;
+}
+
 gboolean msr_init() {
     guint i;
 
@@ -98,12 +122,17 @@ gboolean msr_init() {
     core_eng_b = malloc(cores * sizeof (gulong));
     core_eng_a = malloc(cores * sizeof (gulong));
     core_power = malloc(cores * sizeof (gfloat));
+    core_fid = malloc(cores * sizeof (gfloat));
     core_power_min = malloc(cores * sizeof (gfloat));
     core_power_max = malloc(cores * sizeof (gfloat));
+    core_fid_min = malloc(cores * sizeof (gfloat));
+    core_fid_max = malloc(cores * sizeof (gfloat));
 
     msr_update();
     memcpy(core_power_min, core_power, cores * sizeof (gfloat));
     memcpy(core_power_max, core_power, cores * sizeof (gfloat));
+    memcpy(core_fid_min, core_fid, cores * sizeof (gfloat));
+    memcpy(core_fid_max, core_fid, cores * sizeof (gfloat));
     package_power_min = package_power;
     package_power_max = package_power;
 
@@ -143,6 +172,13 @@ void msr_update() {
             if (core_power[i] > core_power_max[i])
                 core_power_max[i] = core_power[i];
         }
+
+        core_fid[i] = get_core_fid(i);
+
+        if (core_fid[i] < core_fid_min[i])
+            core_fid_min[i] = core_fid[i];
+        if (core_fid[i] > core_fid_max[i])
+            core_fid_max[i] = core_fid[i];
     }
 }
 
@@ -154,6 +190,8 @@ void msr_clear_minmax() {
     for (i = 0; i < cores; i++) {
         core_power_min[i] = core_power[i];
         core_power_max[i] = core_power[i];
+        core_fid_min[i] = core_fid[i];
+        core_fid_max[i] = core_fid[i];
     }
 }
 
@@ -170,6 +208,16 @@ GSList* msr_get_sensors() {
     data->printf_format = MSR_PWR_PRINTF_FORMAT;
     list = g_slist_append(list, data);
 
+    for (i = 0; i < cores; i++) {
+        data = sensor_init_new();
+        data->label = g_strdup_printf("Core %d Effective Frequency", display_coreid ? cpu_dev_ids[i].coreid: i);
+        data->value = &(core_fid[i]);
+        data->min = &(core_fid_min[i]);
+        data->max = &(core_fid_max[i]);
+        data->printf_format = MSR_FID_PRINTF_FORMAT;
+        list = g_slist_append(list, data);
+    }
+
     for (i = 0; i < cores; i++) {
         data = sensor_init_new();
         data->label = g_strdup_printf("Core %d Power", display_coreid ? cpu_dev_ids[i].coreid: i);