1. 根目录:
2. drivers
3. of
4. of_i2c.c

/*
 * OF helpers for the I2C API
 *
 * Copyright (c) 2008 Jochen Friedrich <jochen@scram.de>
 *
 * Based on a previous patch from Jon Smirl <jonsmirl@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <linux/i2c.h>
#include <linux/irq.h>
#include <linux/of.h>
#include <linux/of_i2c.h>
#include <linux/of_irq.h>
#include <linux/module.h>

void of_i2c_register_devices(struct i2c_adapter *adap)
{
	void *result;
	struct device_node *node;

	/* Only register child devices if the adapter has a node pointer set */
	if (!adap->dev.of_node)
		return;

	dev_dbg(&adap->dev, "of_i2c: walking child nodes\n");

	for_each_child_of_node(adap->dev.of_node, node) {
		struct i2c_board_info info = {};
		struct dev_archdata dev_ad = {};
		const __be32 *addr;
		int len;

		dev_dbg(&adap->dev, "of_i2c: register %s\n", node->full_name);

		if (of_modalias_node(node, info.type, sizeof(info.type)) < 0) {
			dev_err(&adap->dev, "of_i2c: modalias failure on %s\n",
				node->full_name);
			continue;
		}

		addr = of_get_property(node, "reg", &len);
		if (!addr || (len < sizeof(int))) {
			dev_err(&adap->dev, "of_i2c: invalid reg on %s\n",
				node->full_name);
			continue;
		}

		info.addr = be32_to_cpup(addr);
		if (info.addr > (1 << 10) - 1) {
			dev_err(&adap->dev, "of_i2c: invalid addr=%x on %s\n",
				info.addr, node->full_name);
			continue;
		}

		info.irq = irq_of_parse_and_map(node, 0);
		info.of_node = of_node_get(node);
		info.archdata = &dev_ad;

		request_module("%s%s", I2C_MODULE_PREFIX, info.type);

		result = i2c_new_device(adap, &info);
		if (result == NULL) {
			dev_err(&adap->dev, "of_i2c: Failure registering %s\n",
			        node->full_name);
			of_node_put(node);
			irq_dispose_mapping(info.irq);
			continue;
		}
	}
}
EXPORT_SYMBOL(of_i2c_register_devices);

static int of_dev_node_match(struct device *dev, void *data)
{
        return dev->of_node == data;
}

/* must call put_device() when done with returned i2c_client device */
struct i2c_client *of_find_i2c_device_by_node(struct device_node *node)
{
	struct device *dev;

	dev = bus_find_device(&i2c_bus_type, NULL, node,
					 of_dev_node_match);
	if (!dev)
		return NULL;

	return to_i2c_client(dev);
}
EXPORT_SYMBOL(of_find_i2c_device_by_node);

MODULE_LICENSE("GPL");