Sensors for Apple M1 MacBooks

sensors.m

// This code is is an adaptation of
// https://github.com/freedomtan/sensors/blob/master/sensors/sensors.m that
// prints the temperatures for Apple M1 MacBooks to the standard output.
// WARNING: ONLY USE WITH APPLE M1 MACBOOKS

// To compile run: 
// `clang -Wall -O3 -v sensors.m -framework IOKit -framework Foundation -o sensors`

// Example ouput:
// > ./sensors
// CPU performance core:           +36.8°C
// CPU efficiency core:            +35.5°C
// GPU core:                       +30.0°C
// Neural engine:                  +30.0°C
// Battery:                        +32.3°C
// Disk:                           +36.0°C

// Here is the original code's license
// BSD 3-Clause License

// Copyright (c) 2016-2018, "freedom" Koan-Sin Tan
// All rights reserved.

// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:

// * Redistributions of source code must retain the above copyright notice, this
//   list of conditions and the following disclaimer.

// * Redistributions in binary form must reproduce the above copyright notice,
//   this list of conditions and the following disclaimer in the documentation
//   and/or other materials provided with the distribution.

// * Neither the name of the copyright holder nor the names of its
//   contributors may be used to endorse or promote products derived from
//   this software without specific prior written permission.

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.

#include <Foundation/Foundation.h>
#include <IOKit/hidsystem/IOHIDEventSystemClient.h>
#include <stdio.h>

typedef struct __IOHIDEvent *IOHIDEventRef;
typedef struct __IOHIDServiceClient *IOHIDServiceClientRef;

#ifdef __LP64__
typedef double IOHIDFloat;
#else
typedef float IOHIDFloat;
#endif

struct Sensor_t {
  char const *keyPrefix;
  char const *name;
  double maxTemperature;
  uint8_t hasReading;
};
typedef struct Sensor_t *Sensor;

struct Sensor_t M1_SPEC[] = {
    {.keyPrefix = "pACC MTR Temp Sensor",
     .name = "CPU performance core:",
     .maxTemperature = 0.0,
     .hasReading = 0.0},
    {.keyPrefix = "eACC MTR Temp Sensor",
     .name = "CPU efficiency core:",
     .maxTemperature = 0.0,
     .hasReading = 0.0},
    {.keyPrefix = "GPU MTR Temp Sensor",
     .name = "GPU core:",
     .maxTemperature = 0.0,
     .hasReading = 0.0},
    {.keyPrefix = "ANE MTR Temp Sensor",
     .name = "Neural engine:",
     .maxTemperature = 0.0,
     .hasReading = 0.0},
    {.keyPrefix = "gas gauge battery",
     .name = "Battery:",
     .maxTemperature = 0.0,
     .hasReading = 0.0},
    {.keyPrefix = "NAND CH",
     .name = "Disk:",
     .maxTemperature = 0.0,
     .hasReading = 0.0},
};

uint8_t testString(CFStringRef cfstring, char const *prefix) {
  char buffer[1024];
  if (!cfstring) {
    return 0;
  }
  CFStringGetCString(cfstring, buffer, 1023, kCFStringEncodingUTF8);
  return strncmp(prefix, buffer, strlen(prefix)) == 0;
}

IOHIDEventSystemClientRef
IOHIDEventSystemClientCreate(CFAllocatorRef allocator);
int IOHIDEventSystemClientSetMatching(IOHIDEventSystemClientRef client,
                                      CFDictionaryRef match);
IOHIDEventRef IOHIDServiceClientCopyEvent(IOHIDServiceClientRef, int64_t,
                                          int32_t, int64_t);
CFStringRef IOHIDServiceClientCopyProperty(IOHIDServiceClientRef service,
                                           CFStringRef property);
IOHIDFloat IOHIDEventGetFloatValue(IOHIDEventRef event, int32_t field);

#define kIOHIDEventTypeTemperature 15
#define IOHIDEventFieldBase(type) (type << 16)

void computeSupportedCapabilities(CFDictionaryRef sensors) {
  int32_t j, c;
  c = sizeof(M1_SPEC) / sizeof(M1_SPEC[0]);
  IOHIDEventSystemClientRef system =
      IOHIDEventSystemClientCreate(kCFAllocatorDefault);
  IOHIDEventSystemClientSetMatching(system, sensors);

  CFArrayRef matchingsrvs = IOHIDEventSystemClientCopyServices(
      system); // matchingsrvs = matching services

  long count = CFArrayGetCount(matchingsrvs);

  for (int i = 0; i < count; i++) {
    IOHIDServiceClientRef sc =
        (IOHIDServiceClientRef)CFArrayGetValueAtIndex(matchingsrvs, i);
    CFStringRef name = IOHIDServiceClientCopyProperty(sc, CFSTR("Product"));
    if (!name) {
      continue;
    }
    IOHIDEventRef event = IOHIDServiceClientCopyEvent(
        sc, kIOHIDEventTypeTemperature, 0, 0); // here we use ...CopyEvent
    if (!event) {
      CFRelease(name);
      continue;
    }
    for (j = 0; j < c; j++) {
      if (testString(name, M1_SPEC[j].keyPrefix)) {
        M1_SPEC[j].hasReading = 1;
        double temp = IOHIDEventGetFloatValue(
            event, IOHIDEventFieldBase(kIOHIDEventTypeTemperature));
        if (temp > M1_SPEC[j].maxTemperature) {
          M1_SPEC[j].maxTemperature = temp;
        }
        break;
      }
    }
    CFRelease(event);
    CFRelease(name);
  }
  CFRelease(matchingsrvs);
  CFRelease(system);
}

// create a dict ref, like for temperature sensor {"PrimaryUsagePage":0xff00,
// "PrimaryUsage":0x5}
CFDictionaryRef matching(int page, int usage) {
  CFNumberRef nums[2];
  CFStringRef keys[2];

  keys[0] = CFStringCreateWithCString(0, "PrimaryUsagePage", 0);
  keys[1] = CFStringCreateWithCString(0, "PrimaryUsage", 0);
  nums[0] = CFNumberCreate(0, kCFNumberSInt32Type, &page);
  nums[1] = CFNumberCreate(0, kCFNumberSInt32Type, &usage);

  CFDictionaryRef dict = CFDictionaryCreate(
      0, (const void **)keys, (const void **)nums, 2,
      &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
  return dict;
}

void dump() {
  int32_t i, c;
  c = sizeof(M1_SPEC) / sizeof(M1_SPEC[0]);
  for (i = 0; i < c; i++) {
    if (!M1_SPEC[i].hasReading) {
      continue;
    }
    if (!M1_SPEC[i].maxTemperature) {
      continue;
    }
    printf("%-32s+%0.1lf°C\n", M1_SPEC[i].name, M1_SPEC[i].maxTemperature);
  }
}

int main() {
  CFDictionaryRef thermalSensors = matching(0xff00, 5); // 65280_10 = FF00_16
  // thermalSensors's PrimaryUsagePage should be 0xff00 for M1 chip, instead of
  // 0xff05 can be checked by ioreg -lfx
  computeSupportedCapabilities(thermalSensors);
  CFRelease(thermalSensors);
  dump();
  return 0;
}