[RFC 14/14] efi_loader: load distro dtb in bootmgr

[Heinrich Schuchardt]

If no device-tree is specified, try to load a device-tree from the boot
device use the $fdtfile concatenated to either of the paths '/dtb/', '/',
'/dtb/current/'.

Signed-off-by: Heinrich Schuchardt <heinrich.schucha...@canonical.com>
---
 include/efi_loader.h         |  1 +
 lib/efi_loader/efi_bootmgr.c | 13 +++++++++--
 lib/efi_loader/efi_fdt.c     | 44 ++++++++++++++++++++++++++++++++++++
 3 files changed, 56 insertions(+), 2 deletions(-)

diff --git a/include/efi_loader.h b/include/efi_loader.h
index 0bf325fdc4b..e0bdce2dbdf 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -1192,5 +1192,6 @@ efi_status_t efi_disk_get_device_name(const efi_handle_t 
handle, char *buf, int
 void efi_add_known_memory(void);
 
 int efi_get_distro_fdt_name(char *fname, int size, int seq);
+void efi_load_distro_fdt(void **fdt, efi_uintn_t *fdt_size);
 
 #endif /* _EFI_LOADER_H */
diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c
index 9ae948bcf08..7987b047f1a 100644
--- a/lib/efi_loader/efi_bootmgr.c
+++ b/lib/efi_loader/efi_bootmgr.c
@@ -1249,7 +1249,8 @@ efi_status_t efi_bootmgr_run(void *fdt)
        efi_handle_t handle;
        void *load_options;
        efi_status_t ret;
-       void *fdt_lo;
+       void *fdt_lo, *fdt_distro = NULL;
+       efi_uintn_t fdt_size;
 
        /* Initialize EFI drivers */
        ret = efi_init_obj_list();
@@ -1269,6 +1270,10 @@ efi_status_t efi_bootmgr_run(void *fdt)
                fdt_lo = load_fdt_from_load_option();
                if (fdt_lo)
                        fdt = fdt_lo;
+               if (!fdt) {
+                       efi_load_distro_fdt(&fdt_distro, &fdt_size);
+                       fdt = fdt_distro;
+               }
        }
 
        /*
@@ -1277,8 +1282,12 @@ efi_status_t efi_bootmgr_run(void *fdt)
         */
        ret = efi_install_fdt(fdt);
 
-       if (!IS_ENABLED(CONFIG_GENERATE_ACPI_TABLE))
+       if (!IS_ENABLED(CONFIG_GENERATE_ACPI_TABLE)) {
                free(fdt_lo);
+               if (fdt_distro)
+                       efi_free_pages((uintptr_t)fdt_distro,
+                                      efi_size_in_pages(fdt_size));
+       }
 
        if (ret != EFI_SUCCESS) {
                if (EFI_CALL(efi_unload_image(handle)) == EFI_SUCCESS)
diff --git a/lib/efi_loader/efi_fdt.c b/lib/efi_loader/efi_fdt.c
index 0edf0c1e2fc..86ba00c2bdd 100644
--- a/lib/efi_loader/efi_fdt.c
+++ b/lib/efi_loader/efi_fdt.c
@@ -71,3 +71,47 @@ int efi_get_distro_fdt_name(char *fname, int size, int seq)
 
        return 0;
 }
+
+/**
+ * efi_load_distro_fdt() - load distro device-tree
+ *
+ * @fdt:       on return device-tree, must be freed via efi_free_pages()
+ * @fdt_size:  buffer size
+ */
+void efi_load_distro_fdt(void **fdt, efi_uintn_t *fdt_size)
+{
+       struct efi_device_path *rem, *dp;
+       efi_status_t  ret;
+       efi_handle_t device;
+
+       *fdt = NULL;
+
+       dp = efi_get_dp_from_boot(NULL);
+       if (!dp)
+               return;
+       device = efi_dp_find_obj(dp, NULL, &rem);
+       ret = efi_search_protocol(device, &efi_simple_file_system_protocol_guid,
+                                 NULL);
+       if (ret != EFI_SUCCESS)
+               goto err;
+       memcpy(rem, &END, sizeof(END));
+
+       /* 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)
+                       break;
+       }
+
+err:
+       efi_free_pool(dp);
+}
-- 
2.43.0