Explicitly specifying the exact filenames of devicetree overlays files
on a U-Boot command line can be quite tedious for users, especially
when it should be made persistent for every boot.

To simplify the task of applying (custom) DT overlays, introduce a
"fdt fsapply" subcommand, that iterates a given directory in any
supported filesystem, and tries to apply every .dtbo file found it
there.

This allows users to simply drop a DT overlay file into a magic
directory, and it will be applied on the next boot automatically,
by the virtue of just a generic U-Boot command call.

Signed-off-by: Andre Przywara <andre.przyw...@arm.com>
---
 cmd/fdt.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 87 insertions(+)

diff --git a/cmd/fdt.c b/cmd/fdt.c
index 1972490bdc2..00f92dbbb5d 100644
--- a/cmd/fdt.c
+++ b/cmd/fdt.c
@@ -12,12 +12,14 @@
 #include <env.h>
 #include <image.h>
 #include <linux/ctype.h>
+#include <linux/sizes.h>
 #include <linux/types.h>
 #include <asm/global_data.h>
 #include <linux/libfdt.h>
 #include <fdt_support.h>
 #include <mapmem.h>
 #include <asm/io.h>
+#include <fs.h>
 
 #define MAX_LEVEL      32              /* how deeply nested we will go */
 #define SCRATCHPAD     1024            /* bytes of scratchpad memory */
@@ -127,6 +129,81 @@ static int fdt_get_header_value(int argc, char *const 
argv[])
        return CMD_RET_FAILURE;
 }
 
+#ifdef CONFIG_OF_LIBFDT_OVERLAY
+static int apply_all_overlays(const char *ifname, const char *dev_part_str,
+                             const char *dirname)
+{
+       unsigned long addr;
+       struct fdt_header *dtbo;
+       const char *addr_str;
+       struct fs_dir_stream *dirs;
+       struct fs_dirent *dent;
+       char fname[256], *name_beg;
+       int ret;
+
+       addr_str = env_get("fdtoverlay_addr_r");
+       if (!addr_str) {
+               printf("Invalid fdtoverlay_addr_r for loading overlays\n");
+               return CMD_RET_FAILURE;
+       }
+       addr = hextoul(addr_str, NULL);
+
+       ret = fs_set_blk_dev(ifname, dev_part_str, FS_TYPE_ANY);
+       if (ret)
+               return CMD_RET_FAILURE;
+
+       if (!dirname)
+               dirname = "/";
+       dirs = fs_opendir(dirname);
+       if (!dirs) {
+               printf("Cannot find directory \"%s\"\n", dirname);
+               return CMD_RET_FAILURE;
+       }
+
+       strcpy(fname, dirname);
+       name_beg = strchr(fname, 0);
+       if (name_beg[-1] != '/')
+               *name_beg++ = '/';
+
+       dtbo = map_sysmem(addr, 0);
+       while ((dent = fs_readdir(dirs))) {
+               loff_t size = 0;
+
+               if (dent->type == FS_DT_DIR)
+                       continue;
+
+               if (strcmp(dent->name + strlen(dent->name) - 5, ".dtbo"))
+                       continue;
+
+               printf("%s: ", dent->name);
+               strcpy(name_beg, dent->name);
+               fs_set_blk_dev(ifname, dev_part_str, FS_TYPE_ANY);
+               if (dent->size > SZ_2M)
+                       size = SZ_2M;
+               else
+                       size = dent->size;
+               ret = fs_read(fname, addr, 0, size, &size);
+               if (ret) {
+                       printf("  errno: %d\n", ret);
+                       continue;
+               }
+               if (!fdt_valid(&dtbo)) {
+                       /* fdt_valid() clears the pointer upon failure */
+                       dtbo = map_sysmem(addr, 0);
+                       continue;
+               }
+
+               if (fdt_overlay_apply_verbose(working_fdt, dtbo) == 0)
+                       printf("applied\n");
+       }
+       unmap_sysmem(dtbo);
+
+       fs_closedir(dirs);
+
+       return 0;
+}
+#endif
+
 /*
  * Flattened Device Tree command, see the help for parameter definitions.
  */
@@ -747,6 +824,15 @@ static int do_fdt(struct cmd_tbl *cmdtp, int flag, int 
argc, char *const argv[])
                ret = fdt_overlay_apply_verbose(working_fdt, blob);
                if (ret)
                        return CMD_RET_FAILURE;
+       /* apply all .dtbo files from a directory */
+       } else if (strncmp(argv[1], "fsap", 4) == 0) {
+               if (argc != 5)
+                       return CMD_RET_USAGE;
+
+               if (!working_fdt)
+                       return CMD_RET_FAILURE;
+
+               return apply_all_overlays(argv[2], argv[3], argv[4]);
        }
 #endif
        /* resize the fdt */
@@ -1104,6 +1190,7 @@ static char fdt_help_text[] =
        "addr [-c] [-q] <addr> [<size>]  - Set the [control] fdt location to 
<addr>\n"
 #ifdef CONFIG_OF_LIBFDT_OVERLAY
        "fdt apply <addr>                    - Apply overlay to the DT\n"
+       "fdt fsapply <ifname> <dev:part> <dir> - Apply all overlays in 
directory\n"
 #endif
 #ifdef CONFIG_OF_BOARD_SETUP
        "fdt boardsetup                      - Do board-specific set up\n"
-- 
2.25.1

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