mtd: add logic for TP-Link ramips recovery magic

This adds an option to set the recovery flag of newer TP-Link MediaTek
boards and remove it after a successful write.

To make use of this feature, add the '-t' option to mtd-write.

The '-t' option takes the mtd partition containing the recovery flag
(usually 'romfile') as an argument. Make sure this partition is not
flagged as read-only!

Example:
 > mtd -t romfile write owrt.bin firmware

This command writes the recovery-flag before it begins writing the image
to the firmware partition. After the image-write has been successful,
the recovery flag is removed.

This way, the TP-Link web-recovery is automatically enabled on an
unsucessful flash (e.g. power loss).

This option is only available if the mtd package is compiled for the
ramips target.

Signed-off-by: David Bauer <mail@david-bauer.net>

1 files changed, 94 insertions, 0 deletions

diff --git a/package/system/mtd/src/tpl_ramips_recoveryflag.c b/package/system/mtd/src/tpl_ramips_recoveryflag.c
new file mode 100644
index 0000000000..3711e01317
--- /dev/null
+++ b/package/system/mtd/src/tpl_ramips_recoveryflag.c
@@ -0,0 +1,94 @@
+/*
+ * TP-Link recovery flag set and unset code for ramips target
+ *
+ * Copyright (C) 2018 David Bauer <mail@david-bauer.net>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License v2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stddef.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <errno.h>
+#include <stdint.h>
+
+#include <mtd/mtd-user.h>
+#include <sys/ioctl.h>
+
+#include "mtd.h"
+
+
+#define TPL_RECOVER_MAGIC	0x89abcdef
+#define TPL_NO_RECOVER_MAGIC	0x00000000
+
+
+struct uboot_args {
+	uint32_t magic;
+};
+
+int mtd_tpl_recoverflag_write(const char *mtd, const bool recovery_active)
+{
+	struct erase_info_user erase_info;
+	struct uboot_args *args;
+	uint32_t magic;
+	int ret = 0;
+	int fd;
+
+	args = malloc(erasesize);
+	if (!args) {
+		fprintf(stderr, "Could not allocate memory!\n");
+		return -1;
+	}
+
+	fd = mtd_check_open(mtd);
+	if (fd < 0) {
+		fprintf(stderr, "Could not open mtd device: %s\n", mtd);
+		ret = -1;
+		goto out;
+	}
+
+	/* read first block (containing the magic) */
+	pread(fd, args, erasesize, 0);
+
+	/* set magic to desired value */
+	magic = TPL_RECOVER_MAGIC;
+	if (!recovery_active)
+		magic = TPL_NO_RECOVER_MAGIC;
+
+	/* no need to write when magic is already set correctly */
+	if (magic == args->magic)
+		goto out;
+
+	/* erase first block (containing the magic) */
+	erase_info.start = 0;
+	erase_info.length = erasesize;
+
+	ret = ioctl(fd, MEMERASE, &erase_info);
+	if (ret < 0) {
+		fprintf(stderr, "failed to erase block: %i\n", ret);
+		goto out;
+	}
+
+	/* write magic to flash */
+	args->magic = magic;
+
+	ret = pwrite(fd, args, erasesize, 0);
+	if (ret < 0)
+		fprintf(stderr, "failed to write: %i\n", ret);
+
+	sync();
+out:
+	free(args);
+	close(fd);
+
+	return ret;
+}