arch/arm/boot/compressed/atags_to_fdt.c

#include <asm/setup.h>
#include <libfdt.h>

#if defined(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND)
#define do_extend_cmdline 1
#else
#define do_extend_cmdline 0
#endif

static int node_offset(void *fdt, const char *node_path)
{
	int offset = fdt_path_offset(fdt, node_path);
	if (offset == -FDT_ERR_NOTFOUND)
		offset = fdt_add_subnode(fdt, 0, node_path);
	return offset;
}

static int setprop_string(void *fdt, const char *node_path,
			  const char *property, const char *string)
{
	int offset = node_offset(fdt, node_path);
	if (offset < 0)
		return offset;
	return fdt_setprop_string(fdt, offset, property, string);
}

static int setprop_cell(void *fdt, const char *node_path,
			const char *property, uint32_t val)
{
	int offset = node_offset(fdt, node_path);
	if (offset < 0)
		return offset;
	return fdt_setprop_cell(fdt, offset, property, val);
}

static const void *getprop(const void *fdt, const char *node_path,
			   const char *property, int *len)
{
	int offset = fdt_path_offset(fdt, node_path);

	if (offset == -FDT_ERR_NOTFOUND)
		return NULL;

	return fdt_getprop(fdt, offset, property, len);
}

static void merge_fdt_bootargs(void *fdt, const char *fdt_cmdline)
{
	char cmdline[COMMAND_LINE_SIZE];
	const char *fdt_bootargs;
	char *ptr = cmdline;
	int len = 0;

	/* copy the fdt command line into the buffer */
	fdt_bootargs = getprop(fdt, "/chosen", "bootargs", &len);
	if (fdt_bootargs)
		if (len < COMMAND_LINE_SIZE) {
			memcpy(ptr, fdt_bootargs, len);
			/* len is the length of the string
			 * including the NULL terminator */
			ptr += len - 1;
		}

	/* and append the ATAG_CMDLINE */
	if (fdt_cmdline) {
		len = strlen(fdt_cmdline);
		if (ptr - cmdline + len + 2 < COMMAND_LINE_SIZE) {
			*ptr++ = ' ';
			memcpy(ptr, fdt_cmdline, len);
			ptr += len;
		}
	}
	*ptr = '\0';

	setprop_string(fdt, "/chosen", "bootargs", cmdline);
}

/*
 * Convert and fold provided ATAGs into the provided FDT.
 *
 * REturn values:
 *    = 0 -> pretend success
 *    = 1 -> bad ATAG (may retry with another possible ATAG pointer)
 *    < 0 -> error from libfdt
 */
int atags_to_fdt(void *atag_list, void *fdt, int total_space)
{
	struct tag *atag = atag_list;
	int ret;

	/* make sure we've got an aligned pointer */
	if ((u32)atag_list & 0x3)
		return 1;

	/* if we get a DTB here we're done already */
	if (*(u32 *)atag_list == fdt32_to_cpu(FDT_MAGIC))
	       return 0;

	/* validate the ATAG */
	if (atag->hdr.tag != ATAG_CORE ||
	    (atag->hdr.size != tag_size(tag_core) &&
	     atag->hdr.size != 2))
		return 1;

	/* let's give it all the room it could need */
	ret = fdt_open_into(fdt, fdt, total_space);
	if (ret < 0)
		return ret;

	for_each_tag(atag, atag_list) {
		if (atag->hdr.tag == ATAG_CMDLINE) {
			/* Append the ATAGS command line to the device tree
			 * command line.
			 * NB: This means that if the same parameter is set in
			 * the device tree and in the tags, the one from the
			 * tags will be chosen.
			 */
			if (do_extend_cmdline)
				merge_fdt_bootargs(fdt,
						   atag->u.cmdline.cmdline);
			else
				setprop_string(fdt, "/chosen", "bootargs",
					       atag->u.cmdline.cmdline);
		} else if (atag->hdr.tag == ATAG_INITRD2) {
			uint32_t initrd_start, initrd_size;
			initrd_start = atag->u.initrd.start;
			initrd_size = atag->u.initrd.size;
			setprop_cell(fdt, "/chosen", "linux,initrd-start",
					initrd_start);
			setprop_cell(fdt, "/chosen", "linux,initrd-end",
					initrd_start + initrd_size);
		}
	}

	return fdt_pack(fdt);
}