nu/hwmon.c: Add emulated hardware monitoring driver

nu/hwmon.c

@@ -0,0 +1,90 @@
+#include <windows.h>
+
+#include <assert.h>
+#include <string.h>
+
+#include "util/dprintf.h"
+
+#include "hook/iohook.h"
+
+#include "nu/hwmon.h"
+
+enum {
+    HWMON_IOCTL_READ_CPU_TEMP = 0x80006000,
+};
+
+static HRESULT hwmon_handle_irp(struct irp *irp);
+static HRESULT hwmon_handle_open(struct irp *irp);
+static HRESULT hwmon_handle_close(struct irp *irp);
+static HRESULT hwmon_handle_ioctl(struct irp *irp);
+
+static HRESULT hwmon_ioctl_read_cpu_temp(struct irp *irp);
+
+static HANDLE hwmon_fd;
+
+void hwmon_hook_init(void)
+{
+    hwmon_fd = iohook_open_dummy_fd();
+    iohook_push_handler(hwmon_handle_irp);
+}
+
+static HRESULT hwmon_handle_irp(struct irp *irp)
+{
+    assert(irp != NULL);
+
+    if (irp->op != IRP_OP_OPEN && irp->fd != hwmon_fd) {
+        return iohook_invoke_next(irp);
+    }
+
+    switch (irp->op) {
+    case IRP_OP_OPEN:   return hwmon_handle_open(irp);
+    case IRP_OP_CLOSE:  return hwmon_handle_close(irp);
+    case IRP_OP_IOCTL:  return hwmon_handle_ioctl(irp);
+    default:            return HRESULT_FROM_WIN32(ERROR_INVALID_FUNCTION);
+    }
+}
+
+static HRESULT hwmon_handle_open(struct irp *irp)
+{
+    if (wcscmp(irp->open_filename, L"\\\\.\\sghwmonitor") != 0) {
+        return iohook_invoke_next(irp);
+    }
+
+    dprintf("Hwmon: Opened device\n");
+    irp->fd = hwmon_fd;
+
+    return S_OK;
+}
+
+static HRESULT hwmon_handle_close(struct irp *irp)
+{
+    dprintf("Hwmon: Closed device\n");
+
+    return S_OK;
+}
+
+static HRESULT hwmon_handle_ioctl(struct irp *irp)
+{
+    switch (irp->ioctl) {
+    case HWMON_IOCTL_READ_CPU_TEMP:
+        return hwmon_ioctl_read_cpu_temp(irp);
+
+    default:
+        dprintf("Hwmon: Unknown ioctl %08x write %i read %i\n",
+                irp->ioctl,
+                irp->write.nbytes,
+                irp->read.nbytes);
+
+        return HRESULT_FROM_WIN32(ERROR_INVALID_FUNCTION);
+    }
+}
+
+static HRESULT hwmon_ioctl_read_cpu_temp(struct irp *irp)
+{
+    /* Assuming this is Celsius. It also seems to be biased by -23 (based on the
+       caller code) despite being a 32-bit int. */
+
+    dprintf("Hwmon: Read CPU temperature\n");
+
+    return iobuf_write_le32(&irp->read, 52);
+}

nu/hwmon.h

@@ -0,0 +1,3 @@
+#pragma once
+
+void hwmon_hook_init(void);

nu/meson.build

@@ -15,6 +15,8 @@ nu_lib = static_library(
         'gpio.c',
         'gpio.h',
         'guid.c',
+        'hwmon.c',
+        'hwmon.h',
         'nusec.c',
         'nusec.h',
         'nvram.c',