v3dv: implement vkEnumeratePhysicalDevices

Not an actual implementation since this doesn't initialize any actual
physical devices just yet.

Also, this doesn't check that available decices are really compatible
with the driver for now. This is for convenience, so we can move
past this point even if we are not running on actual hardware.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6766>

src/broadcom/vulkan/v3dv_device.c

@@ -27,6 +27,7 @@
 #include <sys/mman.h>
 #include <sys/sysinfo.h>
 #include <unistd.h>
+#include <xf86drm.h>
 
 #include "v3dv_private.h"
 #include "vk_util.h"
@@ -234,14 +235,82 @@ v3dv_DestroyInstance(VkInstance _instance,
    vk_free(&instance->alloc, instance);
 }
 
+static VkResult
+physical_device_init(struct v3dv_physical_device *device,
+                     struct v3dv_instance *instance,
+                     drmDevicePtr drm_device)
+{
+   /* FIXME stub */
+   return VK_SUCCESS;
+}
+
+static VkResult
+enumerate_devices(struct v3dv_instance *instance)
+{
+   /* TODO: Check for more devices? */
+   drmDevicePtr devices[8];
+   VkResult result = VK_ERROR_INCOMPATIBLE_DRIVER;
+   int max_devices;
+
+   instance->physicalDeviceCount = 0;
+
+   max_devices = drmGetDevices2(0, devices, ARRAY_SIZE(devices));
+   if (max_devices < 1)
+      return VK_ERROR_INCOMPATIBLE_DRIVER;
+
+   for (unsigned i = 0; i < (unsigned)max_devices; i++) {
+      if (devices[i]->available_nodes & 1 << DRM_NODE_RENDER &&
+          devices[i]->bustype == DRM_BUS_PCI &&
+          /* FIXME: so we can run past this point for now */
+          (true || devices[i]->deviceinfo.pci->vendor_id == 0x14E4)) {
+         result = physical_device_init(&instance->physicalDevice,
+                                       instance, devices[i]);
+         if (result != VK_ERROR_INCOMPATIBLE_DRIVER)
+            break;
+      }
+   }
+   drmFreeDevices(devices, max_devices);
+
+   if (result == VK_SUCCESS)
+      instance->physicalDeviceCount = 1;
+
+   return result;
+}
+
+static VkResult
+instance_ensure_physical_device(struct v3dv_instance *instance)
+{
+   if (instance->physicalDeviceCount < 0) {
+      VkResult result = enumerate_devices(instance);
+      if (result != VK_SUCCESS &&
+          result != VK_ERROR_INCOMPATIBLE_DRIVER)
+         return result;
+   }
+
+   return VK_SUCCESS;
+}
+
 VkResult
 v3dv_EnumeratePhysicalDevices(VkInstance _instance,
                               uint32_t *pPhysicalDeviceCount,
                               VkPhysicalDevice *pPhysicalDevices)
 {
-   /* FIXME: stub */
+   V3DV_FROM_HANDLE(v3dv_instance, instance, _instance);
+   VK_OUTARRAY_MAKE(out, pPhysicalDevices, pPhysicalDeviceCount);
+ 
+   VkResult result = instance_ensure_physical_device(instance);
+   if (result != VK_SUCCESS)
+      return result;
 
-   return VK_SUCCESS;
+   if (instance->physicalDeviceCount == 0)
+      return VK_SUCCESS;
+
+   assert(instance->physicalDeviceCount == 1);
+   vk_outarray_append(&out, i) {
+      *i = v3dv_physical_device_to_handle(&instance->physicalDevice);
+   }
+
+   return vk_outarray_status(&out);
 }
 
 void