Disable Broadcom network devices on Apple hardware

The Broadcom driver in Apple's UEFI implementation leaves the device DMAing
over memory after ExitBootServices(). Less than ideal. Putting the device
in D3 beforehand avoids the problem.

efi/x86_64/loader/linux.c

@@ -183,6 +183,101 @@ linux_boot (void)
   for (;;);
 }
 
+void
+grub_efi_disable_network (void)
+{
+  grub_efi_guid_t pci_io_guid = GRUB_EFI_PCI_IO_GUID;
+  grub_efi_pci_io_t *pci_proto;
+  grub_efi_uintn_t num_handles;
+  grub_efi_handle_t *handle, *handles;
+
+  handles = grub_efi_locate_handle (GRUB_EFI_BY_PROTOCOL,
+					  &pci_io_guid,
+					  NULL, &num_handles);
+  if (!handles || !num_handles)
+    return;
+
+  for (handle = handles; num_handles--; handle++)
+    {
+      grub_efi_uint8_t class, pos, id, pm = 0;
+      grub_efi_uint16_t pm_state, vendor;
+      int ttl = 48;
+
+      pci_proto = grub_efi_open_protocol (*handle, &pci_io_guid,
+					  GRUB_EFI_OPEN_PROTOCOL_GET_PROTOCOL);
+
+      if (!pci_proto)
+	continue;
+
+      Call_Service_5 (pci_proto->pci.read, pci_proto,
+		      grub_efi_pci_io_width_uint8, 0x0b, 1, &class);
+
+      /* Not a network device */
+      if (class != 0x02)
+	continue;
+
+      Call_Service_5 (pci_proto->pci.read, pci_proto,
+		      grub_efi_pci_io_width_uint16, 0x00, 1, &vendor);
+
+      /* Not a Broadcom */
+      if (vendor != 0x14e4)
+	continue;
+
+      Call_Service_5 (pci_proto->pci.read, pci_proto,
+		      grub_efi_pci_io_width_uint16, 0x2c, 1, &vendor);
+
+      /* Not an Apple */
+      if (vendor != 0x106b)
+	continue;
+
+      pos = 0x34;
+
+      /* Find the power management registers */
+      while (ttl--)
+	{
+	  Call_Service_5 (pci_proto->pci.read, pci_proto,
+			  grub_efi_pci_io_width_uint8, pos, 1, &pos);
+
+	  if (pos < 0x40)
+	    break;
+
+	  pos &= ~3;
+
+	  Call_Service_5 (pci_proto->pci.read, pci_proto,
+			  grub_efi_pci_io_width_uint8, pos, 1, &id);
+
+	  if (id == 0xff)
+	    break;
+
+	  if (id == 0x01)
+	    {
+	      pm = pos;
+	      break;
+	    }
+
+	  pos += 1;
+	}
+
+      if (pm)
+	{
+	  Call_Service_5 (pci_proto->pci.read, pci_proto,
+			  grub_efi_pci_io_width_uint16, pm + 4, 1, &pm_state);
+
+	  pm_state &= ~0x03;
+	  pm_state |= 0x03;
+
+	  /* Set to D3 */
+
+	  Call_Service_5 (pci_proto->pci.write, pci_proto,
+			  grub_efi_pci_io_width_uint16, pm + 4, 1, &pm_state);
+
+	  Call_Service_5 (pci_proto->pci.read, pci_proto,
+			  grub_efi_pci_io_width_uint16, pm + 4, 1,
+			  &pm_state);
+	}
+    }
+}
+
 void
 big_linux_boot (void)
 {
@@ -205,6 +300,8 @@ big_linux_boot (void)
 			 mmap_buf, desc_size, mmap_size);
   params->e820_nr_map = e820_nr_map;
 
+  grub_efi_disable_network();
+
   if (! grub_efi_exit_boot_services (map_key))
     grub_fatal ("cannot exit boot services");