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Diffstat (limited to 'lib/efi_loader/efi_fdt.c')
-rw-r--r--lib/efi_loader/efi_fdt.c125
1 files changed, 125 insertions, 0 deletions
diff --git a/lib/efi_loader/efi_fdt.c b/lib/efi_loader/efi_fdt.c
new file mode 100644
index 00000000000..f882622fdad
--- /dev/null
+++ b/lib/efi_loader/efi_fdt.c
@@ -0,0 +1,125 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Bootmethod for distro boot via EFI
+ *
+ * Copyright 2021 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#include <efi_loader.h>
+#include <env.h>
+#include <errno.h>
+#include <log.h>
+#include <string.h>
+#include <vsprintf.h>
+
+/**
+ * efi_get_distro_fdt_name() - get the filename for reading the .dtb file
+ *
+ * @fname: buffer for filename
+ * @size: buffer size
+ * @seq: sequence number, to cycle through options (0=first)
+ *
+ * Returns:
+ * 0 on success,
+ * -ENOENT if the "fdtfile" env var does not exist,
+ * -EINVAL if there are no more options,
+ * -EALREADY if the control FDT should be used
+ */
+int efi_get_distro_fdt_name(char *fname, int size, int seq)
+{
+ const char *fdt_fname;
+ const char *prefix;
+
+ /* select the prefix */
+ switch (seq) {
+ case 0:
+ /* this is the default */
+ prefix = "/dtb";
+ break;
+ case 1:
+ prefix = "";
+ break;
+ case 2:
+ prefix = "/dtb/current";
+ break;
+ case 3:
+ prefix = "/dtbs";
+ break;
+ default:
+ return log_msg_ret("pref", -EINVAL);
+ }
+
+ fdt_fname = env_get("fdtfile");
+ if (fdt_fname) {
+ snprintf(fname, size, "%s/%s", prefix, fdt_fname);
+ log_debug("Using device tree: %s\n", fname);
+ } else if (IS_ENABLED(CONFIG_OF_HAS_PRIOR_STAGE)) {
+ strcpy(fname, "<prior>");
+ return log_msg_ret("pref", -EALREADY);
+ /* Use this fallback only for 32-bit ARM */
+ } else if (IS_ENABLED(CONFIG_ARM) && !IS_ENABLED(CONFIG_ARM64)) {
+ const char *soc = env_get("soc");
+ const char *board = env_get("board");
+ const char *boardver = env_get("boardver");
+
+ /* cf the code in label_boot() which seems very complex */
+ snprintf(fname, size, "%s/%s%s%s%s.dtb", prefix,
+ soc ? soc : "", soc ? "-" : "", board ? board : "",
+ boardver ? boardver : "");
+ log_debug("Using default device tree: %s\n", fname);
+ } else {
+ return log_msg_ret("env", -ENOENT);
+ }
+
+ return 0;
+}
+
+/**
+ * efi_load_distro_fdt() - load distro device-tree
+ *
+ * @handle: handle of loaded image
+ * @fdt: on return device-tree, must be freed via efi_free_pages()
+ * @fdt_size: buffer size
+ */
+void efi_load_distro_fdt(efi_handle_t handle, void **fdt, efi_uintn_t *fdt_size)
+{
+ struct efi_device_path *dp;
+ efi_status_t ret;
+ struct efi_handler *handler;
+ struct efi_loaded_image *loaded_image;
+ efi_handle_t device;
+
+ *fdt = NULL;
+
+ /* Get boot device from loaded image protocol */
+ ret = efi_search_protocol(handle, &efi_guid_loaded_image, &handler);
+ if (ret != EFI_SUCCESS)
+ return;
+ loaded_image = handler->protocol_interface;
+ device = loaded_image->device_handle;
+
+ /* Get device path of boot device */
+ ret = efi_search_protocol(device, &efi_guid_device_path, &handler);
+ if (ret != EFI_SUCCESS)
+ return;
+ dp = handler->protocol_interface;
+
+ /* Try the various available names */
+ for (int seq = 0; ; ++seq) {
+ struct efi_device_path *file;
+ char buf[255];
+
+ if (efi_get_distro_fdt_name(buf, sizeof(buf), seq))
+ break;
+ file = efi_dp_from_file(dp, buf);
+ if (!file)
+ break;
+ ret = efi_load_image_from_path(true, file, fdt, fdt_size);
+ efi_free_pool(file);
+ if (ret == EFI_SUCCESS) {
+ log_debug("Fdt %pD loaded\n", file);
+ break;
+ }
+ }
+}