drm/nouveau: attempt to get bios from ACPI v3

Some of the laptops with the switchable graphics, seem to not post the secondary GPU at all, and we can't find a copy of the BIOS anywhere except in the ACPI rom retrieval.

This adds support for ACPI ROM retrieval to nouveau.

Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/nouveau/nouveau_acpi.c

@@ -35,6 +35,7 @@ static struct nouveau_dsm_priv {
 	bool dsm_detected;
 	acpi_handle dhandle;
 	acpi_handle dsm_handle;
+	acpi_handle rom_handle;
 } nouveau_dsm_priv;
 
 static const char nouveau_dsm_muid[] = {
@@ -151,12 +152,13 @@ static bool nouveau_dsm_pci_probe(struct pci_dev *pdev)
 	dhandle = DEVICE_ACPI_HANDLE(&pdev->dev);
 	if (!dhandle)
 		return false;
+
 	status = acpi_get_handle(dhandle, "_DSM", &nvidia_handle);
 	if (ACPI_FAILURE(status)) {
 		return false;
 	}
 
-	ret= nouveau_dsm(nvidia_handle, NOUVEAU_DSM_SUPPORTED,
+	ret = nouveau_dsm(nvidia_handle, NOUVEAU_DSM_SUPPORTED,
 			 NOUVEAU_DSM_SUPPORTED_FUNCTIONS, &result);
 	if (ret < 0)
 		return false;
@@ -173,6 +175,7 @@ static bool nouveau_dsm_detect(void)
 	struct pci_dev *pdev = NULL;
 	int has_dsm = 0;
 	int vga_count = 0;
+
 	while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, pdev)) != NULL) {
 		vga_count++;
 
@@ -204,3 +207,57 @@ void nouveau_unregister_dsm_handler(void)
 {
 	vga_switcheroo_unregister_handler();
 }
+
+/* retrieve the ROM in 4k blocks */
+static int nouveau_rom_call(acpi_handle rom_handle, uint8_t *bios,
+			    int offset, int len)
+{
+	acpi_status status;
+	union acpi_object rom_arg_elements[2], *obj;
+	struct acpi_object_list rom_arg;
+	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL};
+
+	rom_arg.count = 2;
+	rom_arg.pointer = &rom_arg_elements[0];
+
+	rom_arg_elements[0].type = ACPI_TYPE_INTEGER;
+	rom_arg_elements[0].integer.value = offset;
+
+	rom_arg_elements[1].type = ACPI_TYPE_INTEGER;
+	rom_arg_elements[1].integer.value = len;
+
+	status = acpi_evaluate_object(rom_handle, NULL, &rom_arg, &buffer);
+	if (ACPI_FAILURE(status)) {
+		printk(KERN_INFO "failed to evaluate ROM got %s\n", acpi_format_exception(status));
+		return -ENODEV;
+	}
+	obj = (union acpi_object *)buffer.pointer;
+	memcpy(bios+offset, obj->buffer.pointer, len);
+	kfree(buffer.pointer);
+	return len;
+}
+
+bool nouveau_acpi_rom_supported(struct pci_dev *pdev)
+{
+	acpi_status status;
+	acpi_handle dhandle, rom_handle;
+
+	if (!nouveau_dsm_priv.dsm_detected)
+		return false;
+
+	dhandle = DEVICE_ACPI_HANDLE(&pdev->dev);
+	if (!dhandle)
+		return false;
+
+	status = acpi_get_handle(dhandle, "_ROM", &rom_handle);
+	if (ACPI_FAILURE(status))
+		return false;
+
+	nouveau_dsm_priv.rom_handle = rom_handle;
+	return true;
+}
+
+int nouveau_acpi_get_bios_chunk(uint8_t *bios, int offset, int len)
+{
+	return nouveau_rom_call(nouveau_dsm_priv.rom_handle, bios, offset, len);
+}