Fix cpu_freq for Apple silicon

Apple SoC returns empty string after querying the cpu frequency using
sysctl, this information however, can still be extracted from the IOKit
registry. This PR adds a new method that is specific to Apple ARM
architecture.

Fixes #1892

psutil/_psosx.py

@@ -176,7 +176,11 @@ def cpu_freq():
     Also, the returned frequency never changes, see:
     https://arstechnica.com/civis/viewtopic.php?f=19&t=465002
     """
-    curr, min_, max_ = cext.cpu_freq()
+    try:
+        curr, min_, max_ = cext.cpu_freq()
+    except FileNotFoundError:
+        # apple silicon requires specialized call.
+        curr, min_, max_ = cext.arm_cpu_freq()
     return [_common.scpufreq(curr, min_, max_)]
 
 

psutil/_psutil_osx.c

@@ -1723,6 +1723,7 @@ static PyMethodDef mod_methods[] = {
     {"cpu_count_cores", psutil_cpu_count_cores, METH_VARARGS},
     {"cpu_count_logical", psutil_cpu_count_logical, METH_VARARGS},
     {"cpu_freq", psutil_cpu_freq, METH_VARARGS},
+    {"arm_cpu_freq", psutil_arm_cpu_freq, METH_VARARGS},
     {"cpu_stats", psutil_cpu_stats, METH_VARARGS},
     {"cpu_times", psutil_cpu_times, METH_VARARGS},
     {"disk_io_counters", psutil_disk_io_counters, METH_VARARGS},

psutil/arch/osx/cpu.c

@@ -29,6 +29,9 @@ For reference, here's the git history with original implementations:
 #include "../../_psutil_common.h"
 #include "../../_psutil_posix.h"
 
+#include <COreFoundation/CoreFoundation.h>
+#include <IOKit/IOKitLib.h>
+
 
 
 PyObject *
@@ -109,6 +112,48 @@ psutil_cpu_stats(PyObject *self, PyObject *args) {
     );
 }
 
+PyObject *
+psutil_arm_cpu_freq(PyObject *self, PyObject *args) {
+    unsigned int curr;
+    uint32_t min = UINT32_MAX;
+    uint32_t max = 0;
+
+    CFDictionaryRef matching = IOServiceMatching("AppleARMIODevice");
+    io_iterator_t iter;
+
+    IOServiceGetMatchingServices(kIOMainPortDefault, matching, &iter);
+    io_registry_entry_t entry;
+    while ((entry = IOIteratorNext(iter))) {
+        io_name_t name;
+        IORegistryEntryGetName(entry, name);
+
+        if (strncmp(name, "pmgr", 4) == 0) {
+            break;
+        }
+    }
+    IOObjectRelease(iter);
+    CFRelease(matching);
+    CFTypeRef pCoreRef = IORegistryEntryCreateCFProperty(entry, CFSTR("voltage-states5-sram"), kCFAllocatorDefault, 0);
+
+    size_t length = CFDataGetLength(pCoreRef);
+    for (size_t i = 0; i < length - 3; i += 4) {
+        uint32_t curr_freq = 0;
+        CFDataGetBytes(pCoreRef, CFRangeMake(i, sizeof(uint32_t)), (UInt8 *) &curr_freq);
+        if (curr_freq > 1e6 && curr_freq < min) {
+            min = curr_freq;
+        }
+        if (curr_freq > max) {
+            max = curr_freq;
+        }
+    }
+    curr = max;
+
+    return Py_BuildValue(
+            "IKK",
+            curr / 1000 / 1000,
+            min / 1000 / 1000,
+            max / 1000 / 1000);
+}
 
 PyObject *
 psutil_cpu_freq(PyObject *self, PyObject *args) {

psutil/arch/osx/cpu.h

@@ -10,4 +10,5 @@ PyObject *psutil_cpu_count_logical(PyObject *self, PyObject *args);
 PyObject *psutil_cpu_count_cores(PyObject *self, PyObject *args);
 PyObject *psutil_cpu_times(PyObject *self, PyObject *args);
 PyObject *psutil_cpu_freq(PyObject *self, PyObject *args);
+PyObject *psutil_arm_cpu_freq(PyObject *self, PyObject *args);
 PyObject *psutil_cpu_stats(PyObject *self, PyObject *args);