cmd: pxe: add support for FDT overlays

Upstream commit 69076dff2284ed099cc0583e5e64bd8012d1ab5c

This adds support for specifying FDT overlays in an extlinux/pxelinux
configuration file.

Without this, there is no simple way to apply overlays when the kernel
and fdt is loaded by the pxe command.

This change adds the 'fdtoverlays' keyword for a label, supporting multiple
overlay files to be applied on top of the fdt specified in the 'fdt' or
'devicetree' keyword.

Example:
   label linux
     kernel /Image
     fdt /soc-board.dtb
     fdtoverlays /soc-board-function.dtbo
     append console=ttyS0,115200 root=/dev/mmcblk0p2 rootwait

This code makes usage of a new variable called fdtoverlay_addr_r used to load
the overlay files without overwritting anything important.

Cc: Jernej Å krabec <jernej.skrabec@siol.net>
Cc: Jonas Karlman <jonas@kwiboo.se>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://lists.denx.de/pipermail/u-boot/2019-May/368388.html
[robertcnelson@gmail.com: Backport to TI u-boot]
Signed-off-by: Robert Nelson <robertcnelson@gmail.com>
Signed-off-by: Nishanth Menon <nm@ti.com>

2 files changed, 104 insertions, 0 deletions

diff --git a/cmd/pxe_utils.c b/cmd/pxe_utils.c
index 8716e782f6..25367190a7 100644
--- a/cmd/pxe_utils.c
+++ b/cmd/pxe_utils.c
@@ -13,6 +13,8 @@
 #include <mapmem.h>
 #include <lcd.h>
 #include <net.h>
+#include <fdt_support.h>
+#include <linux/libfdt.h>
 #include <linux/string.h>
 #include <linux/ctype.h>
 #include <errno.h>
@@ -284,6 +286,9 @@ static void label_destroy(struct pxe_label *label)
 	if (label->fdtdir)
 		free(label->fdtdir);
 
+	if (label->fdtoverlays)
+		free(label->fdtoverlays);
+
 	free(label);
 }
 
@@ -332,6 +337,92 @@ static int label_localboot(struct pxe_label *label)
 }
 
 /*
+ * Loads fdt overlays specified in 'fdtoverlays'.
+ */
+#ifdef CONFIG_OF_LIBFDT_OVERLAY
+static void label_boot_fdtoverlay(struct cmd_tbl *cmdtp, struct pxe_label *label)
+{
+	char *fdtoverlay = label->fdtoverlays;
+	struct fdt_header *working_fdt;
+	char *fdtoverlay_addr_env;
+	ulong fdtoverlay_addr;
+	ulong fdt_addr;
+	int err;
+
+	/* Get the main fdt and map it */
+	fdt_addr = simple_strtoul(env_get("fdt_addr_r"), NULL, 16);
+	working_fdt = map_sysmem(fdt_addr, 0);
+	err = fdt_check_header(working_fdt);
+	if (err)
+		return;
+
+	/* Get the specific overlay loading address */
+	fdtoverlay_addr_env = env_get("fdtoverlay_addr_r");
+	if (!fdtoverlay_addr_env) {
+		printf("Invalid fdtoverlay_addr_r for loading overlays\n");
+		return;
+	}
+
+	fdtoverlay_addr = simple_strtoul(fdtoverlay_addr_env, NULL, 16);
+
+	/* Cycle over the overlay files and apply them in order */
+	do {
+		struct fdt_header *blob;
+		char *overlayfile;
+		char *end;
+		int len;
+
+		/* Drop leading spaces */
+		while (*fdtoverlay == ' ')
+			++fdtoverlay;
+
+		/* Copy a single filename if multiple provided */
+		end = strstr(fdtoverlay, " ");
+		if (end) {
+			len = (int)(end - fdtoverlay);
+			overlayfile = malloc(len + 1);
+			strncpy(overlayfile, fdtoverlay, len);
+			overlayfile[len] = '\0';
+		} else
+			overlayfile = fdtoverlay;
+
+		if (!strlen(overlayfile))
+			goto skip_overlay;
+
+		/* Load overlay file */
+		err = get_relfile_envaddr(cmdtp, overlayfile,
+					  "fdtoverlay_addr_r");
+		if (err < 0) {
+			printf("Failed loading overlay %s\n", overlayfile);
+			goto skip_overlay;
+		}
+
+		/* Resize main fdt */
+		fdt_shrink_to_minimum(working_fdt, 8192);
+
+		blob = map_sysmem(fdtoverlay_addr, 0);
+		err = fdt_check_header(blob);
+		if (err) {
+			printf("Invalid overlay %s, skipping\n",
+			       overlayfile);
+			goto skip_overlay;
+		}
+
+		err = fdt_overlay_apply_verbose(working_fdt, blob);
+		if (err) {
+			printf("Failed to apply overlay %s, skipping\n",
+			       overlayfile);
+			goto skip_overlay;
+		}
+
+skip_overlay:
+		if (end)
+			free(overlayfile);
+	} while ((fdtoverlay = strstr(fdtoverlay, " ")));
+}
+#endif
+
+/*
  * Boot according to the contents of a pxe_label.
  *
  * If we can't boot for any reason, we return.  A successful boot never
@@ -525,6 +616,11 @@ static int label_boot(struct cmd_tbl *cmdtp, struct pxe_label *label)
 				       label->name);
 				goto cleanup;
 			}
+
+#ifdef CONFIG_OF_LIBFDT_OVERLAY
+			if (label->fdtoverlays)
+				label_boot_fdtoverlay(cmdtp, label);
+#endif
 		} else {
 			bootm_argv[3] = NULL;
 		}
@@ -582,6 +678,7 @@ enum token_type {
 	T_INCLUDE,
 	T_FDT,
 	T_FDTDIR,
+	T_FDTOVERLAYS,
 	T_ONTIMEOUT,
 	T_IPAPPEND,
 	T_BACKGROUND,
@@ -616,6 +713,7 @@ static const struct token keywords[] = {
 	{"fdt", T_FDT},
 	{"devicetreedir", T_FDTDIR},
 	{"fdtdir", T_FDTDIR},
+	{"fdtoverlays", T_FDTOVERLAYS},
 	{"ontimeout", T_ONTIMEOUT,},
 	{"ipappend", T_IPAPPEND,},
 	{"background", T_BACKGROUND,},
@@ -1048,6 +1146,11 @@ static int parse_label(char **c, struct pxe_menu *cfg)
 				err = parse_sliteral(c, &label->fdtdir);
 			break;
 
+		case T_FDTOVERLAYS:
+			if (!label->fdtoverlays)
+				err = parse_sliteral(c, &label->fdtoverlays);
+			break;
+
 		case T_LOCALBOOT:
 			label->localboot = 1;
 			err = parse_integer(c, &label->localboot_val);
diff --git a/cmd/pxe_utils.h b/cmd/pxe_utils.h
index 77d2588875..6af9523734 100644
--- a/cmd/pxe_utils.h
+++ b/cmd/pxe_utils.h
@@ -43,6 +43,7 @@ struct pxe_label {
 	char *initrd;
 	char *fdt;
 	char *fdtdir;
+	char *fdtoverlays;
 	int ipappend;
 	int attempted;
 	int localboot;