1 files changed, 86 insertions, 0 deletions
diff --git a/common/load.c b/common/load.c
new file mode 100644
index 0000000..3a0f8b6
--- /dev/null
+++ b/common/load.c
@@ -0,0 +1,86 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * load.c - pull the payload into RAM. semihosting is the whole story
+ * for now, the bios INT 13h of this loader: the host serves the file,
+ * we read it at the fixed address and let the image header place it.
+ *
+ * Copyright (C) 2026 Bradley Morgan <brads@mainlining.org>
+ */
+
+#include <string.h>
+#include <sys/types.h>
+#include <stdint.h>
+#include <debug.h>
+#include <semihosting.h>
+#include <boot.h>
+
+int tb_load_semihosting(const char *fname, uintptr_t load_addr,
+			struct tb_image *img)
+{
+	long fd, len, ret;
+
+	fd = smh_open(fname, MODE_READ | MODE_BINARY);
+	if (fd < 0)
+		return fd;
+
+	len = smh_flen(fd);
+	if (len < 0) {
+		smh_close(fd);
+		return len;
+	}
+
+	/* header first so placement is known before the big copy */
+	ret = smh_read(fd, (void *)load_addr, 64);
+	if (ret != 64) {
+		smh_close(fd);
+		return -3;
+	}
+
+	if (tb_image_setup(load_addr, img)) {
+		smh_close(fd);
+		return -4;
+	}
+
+	if (img->load != load_addr) {
+		/* the image wants to sit elsewhere, copy the header there */
+		memmove((void *)img->load, (void *)load_addr, 64);
+	}
+
+	ret = smh_read(fd, (void *)(img->load + 64), len - 64);
+	if (ret != len - 64) {
+		smh_close(fd);
+		return -5;
+	}
+
+	smh_close(fd);
+	return 0;
+}
+
+/*
+ * the initrd path, no header, no placement math, bytes to the
+ * address the dtb /chosen already names.
+ */
+int tb_load_raw(const char *fname, uintptr_t load_addr, size_t *sizep)
+{
+	long fd, len, ret;
+
+	fd = smh_open(fname, MODE_READ | MODE_BINARY);
+	if (fd < 0)
+		return fd;
+
+	len = smh_flen(fd);
+	if (len < 0) {
+		smh_close(fd);
+		return len;
+	}
+
+	ret = smh_read(fd, (void *)load_addr, len);
+	smh_close(fd);
+
+	if (ret != len)
+		return -6;
+
+	if (sizep)
+		*sizep = (size_t)len;
+	return 0;
+}