path: root/drivers/of/fdt.c

/*
 * Functions for working with the Flattened Device Tree data format
 *
 * Copyright 2009 Benjamin Herrenschmidt, IBM Corp
 * benh@kernel.crashing.org
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 */

#define pr_fmt(fmt)	"OF: fdt:" fmt

#include <linux/crc32.h>
#include <linux/kernel.h>
#include <linux/initrd.h>
#include <linux/memblock.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/of_reserved_mem.h>
#include <linux/sizes.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/libfdt.h>
#include <linux/debugfs.h>
#include <linux/serial_core.h>
#include <linux/sysfs.h>

#include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
#include <asm/page.h>

/*
 * of_fdt_limit_memory - limit the number of regions in the /memory node
 * @limit: maximum entries
 *
 * Adjust the flattened device tree to have at most 'limit' number of
 * memory entries in the /memory node. This function may be called
 * any time after initial_boot_param is set.
 */
void of_fdt_limit_memory(int limit)
{
	int memory;
	int len;
	const void *val;
	int nr_address_cells = OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
	int nr_size_cells = OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
	const uint32_t *addr_prop;
	const uint32_t *size_prop;
	int root_offset;
	int cell_size;

	root_offset = fdt_path_offset(initial_boot_params, "/");
	if (root_offset < 0)
		return;

	addr_prop = fdt_getprop(initial_boot_params, root_offset,
				"#address-cells", NULL);
	if (addr_prop)
		nr_address_cells = fdt32_to_cpu(*addr_prop);

	size_prop = fdt_getprop(initial_boot_params, root_offset,
				"#size-cells", NULL);
	if (size_prop)
		nr_size_cells = fdt32_to_cpu(*size_prop);

	cell_size = sizeof(uint32_t)*(nr_address_cells + nr_size_cells);

	memory = fdt_path_offset(initial_boot_params, "/memory");
	if (memory > 0) {
		val = fdt_getprop(initial_boot_params, memory, "reg", &len);
		if (len > limit*cell_size) {
			len = limit*cell_size;
			pr_debug("Limiting number of entries to %d\n", limit);
			fdt_setprop(initial_boot_params, memory, "reg", val,
					len);
		}
	}
}

/**
 * of_fdt_is_compatible - Return true if given node from the given blob has
 * compat in its compatible list
 * @blob: A device tree blob
 * @node: node to test
 * @compat: compatible string to compare with compatible list.
 *
 * On match, returns a non-zero value with smaller values returned for more
 * specific compatible values.
 */
int of_fdt_is_compatible(const void *blob,
		      unsigned long node, const char *compat)
{
	const char *cp;
	int cplen;
	unsigned long l, score = 0;

	cp = fdt_getprop(blob, node, "compatible", &cplen);
	if (cp == NULL)
		return 0;
	while (cplen > 0) {
		score++;
		if (of_compat_cmp(cp, compat, strlen(compat)) == 0)
			return score;
		l = strlen(cp) + 1;
		cp += l;
		cplen -= l