text: // SPDX-License-Identifier: GPL-2.0-or-later
  /*
   * Linux I2C core OF support code
   *
   * Copyright (C) 2008 Jochen Friedrich <jochen@scram.de>
   * based on a previous patch from Jon Smirl <jonsmirl@gmail.com>
   *
   * Copyright (C) 2013, 2018 Wolfram Sang <wsa@the-dreams.de>
   */
  
  #include <dt-bindings/i2c/i2c.h>
  #include <linux/device.h>
  #include <linux/err.h>
  #include <linux/i2c.h>
  #include <linux/module.h>
  #include <linux/of.h>
  #include <linux/of_device.h>
  #include <linux/sysfs.h>
  
  #include "i2c-core.h"
  
  int of_i2c_get_board_info(struct device *dev, struct device_node *node,
  			  struct i2c_board_info *info)
  {
  	u32 addr;
  	int ret;
  
  	memset(info, 0, sizeof(*info));
  
  	if (of_modalias_node(node, info->type, sizeof(info->type)) < 0) {
  		dev_err(dev, "of_i2c: modalias failure on %pOF\n", node);
  		return -EINVAL;
  	}
  
  	ret = of_property_read_u32(node, "reg", &addr);
  	if (ret) {
  		dev_err(dev, "of_i2c: invalid reg on %pOF\n", node);
  		return ret;
  	}
  
  	if (addr & I2C_TEN_BIT_ADDRESS) {
  		addr &= ~I2C_TEN_BIT_ADDRESS;
  		info->flags |= I2C_CLIENT_TEN;
  	}
  
  	if (addr & I2C_OWN_SLAVE_ADDRESS) {
  		addr &= ~I2C_OWN_SLAVE_ADDRESS;
  		info->flags |= I2C_CLIENT_SLAVE;
  	}
  
  	info->addr = addr;
  	info->of_node = node;
  
  	if (of_property_read_bool(node, "host-notify"))
  		info->flags |= I2C_CLIENT_HOST_NOTIFY;
  
  	if (of_get_property(node, "wakeup-source", NULL))
  		info->flags |= I2C_CLIENT_WAKE;
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(of_i2c_get_board_info);
  
  static struct i2c_client *of_i2c_register_device(struct i2c_adapter *adap,
  						 struct device_node *node)
  {
  	struct i2c_client *client;
  	struct i2c_board_info info;
  	int ret;
  
  	dev_dbg(&adap->dev, "of_i2c: register %pOF\n", node);
  
  	ret = of_i2c_get_board_info(&adap->dev, node, &info);
  	if (ret)
  		return ERR_PTR(ret);
  
  	client = i2c_new_device(adap, &info);
  	if (!client) {
  		dev_err(&adap->dev, "of_i2c: Failure registering %pOF\n", node);
  		return ERR_PTR(-EINVAL);
  	}
  	return client;
  }
  
  void of_i2c_register_devices(struct i2c_adapter *adap)
  {
  	struct device_node *bus, *node;
  	struct i2c_client *client;
  
  	/* 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");
  
  	bus = of_get_child_by_name(adap->dev.of_node, "i2c-bus");
  	if (!bus)
  		bus = of_node_get(adap->dev.of_node);
  
  	for_each_available_child_of_node(bus, node) {
  		if (of_node_test_and_set_flag(node, OF_POPULATED))
  			continue;
  
  		client = of_i2c_register_device(adap, node);
  		if (IS_ERR(client)) {
  			dev_err(&adap->dev,
  				 "Failed to create I2C device for %pOF\n",
  				 node);
  			of_node_clear_flag(node, OF_POPULATED);
  		}
  	}
  
  	of_node_put(bus);
  }
  
  static int of_dev_node_match(struct device *dev, const void *data)
  {
  	return dev->of_node == data;
  }
  
  static int of_dev_or_parent_node_match(struct device *dev, const void *data)
  {
  	if (dev->of_node == data)
  		return 1;
  
  	if (dev->parent)
  		return dev->parent->of_node == data;
  
  	return 0;
  }
  
  /* 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;
  	struct i2c_client *client;
  
  	dev = bus_find_device(&i2c_bus_type, NULL, node, of_dev_node_match);
  	if (!dev)
  		return NULL;
  
  	client = i2c_verify_client(dev);
  	if (!client)
  		put_device(dev);
  
  	return client;
  }
  EXPORT_SYMBOL(of_find_i2c_device_by_node);
  
  /* must call put_device() when done with returned i2c_adapter device */
  struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
  {
  	struct device *dev;
  	struct i2c_adapter *adapter;
  
  	dev = bus_find_device(&i2c_bus_type, NULL, node,
  			      of_dev_or_parent_node_match);
  	if (!dev)
  		return NULL;
  
  	adapter = i2c_verify_adapter(dev);
  	if (!adapter)
  		put_device(dev);
  
  	return adapter;
  }
  EXPORT_SYMBOL(of_find_i2c_adapter_by_node);
  
  /* must call i2c_put_adapter() when done with returned i2c_adapter device */
  struct i2c_adapter *of_get_i2c_adapter_by_node(struct device_node *node)
  {
  	struct i2c_adapter *adapter;
  
  	adapter = of_find_i2c_adapter_by_node(node);
  	if (!adapter)
  		return NULL;
  
  	if (!try_module_get(adapter->owner)) {
  		put_device(&adapter->dev);
  		adapter = NULL;
  	}
  
  	return adapter;
  }
  EXPORT_SYMBOL(of_get_i2c_adapter_by_node);
  
  static const struct of_device_id*
  i2c_of_match_device_sysfs(const struct of_device_id *matches,
  				  struct i2c_client *client)
  {
  	const char *name;
  
  	for (; matches->compatible[0]; matches++) {
  		/*
  		 * Adding devices through the i2c sysfs interface provides us
  		 * a string to match which may be compatible with the device
  		 * tree compatible strings, however with no actual of_node the
  		 * of_match_device() will not match
  		 */
  		if (sysfs_streq(client->name, matches->compatible))
  			return matches;
  
  		name = strchr(matches->compatible, ',');
  		if (!name)
  			name = matches->compatible;
  		else
  			name++;
  
  		if (sysfs_streq(client->name, name))
  			return matches;
  	}
  
  	return NULL;
  }
  
  const struct of_device_id
  *i2c_of_match_device(const struct of_device_id *matches,
  		     struct i2c_client *client)
  {
  	const struct of_device_id *match;
  
  	if (!(client && matches))
  		return NULL;
  
  	match = of_match_device(matches, &client->dev);
  	if (match)
  		return match;
  
  	return i2c_of_match_device_sysfs(matches, client);
  }
  EXPORT_SYMBOL_GPL(i2c_of_match_device);
  
  #if IS_ENABLED(CONFIG_OF_DYNAMIC)
  static int of_i2c_notify(struct notifier_block *nb, unsigned long action,
  			 void *arg)
  {
  	struct of_reconfig_data *rd = arg;
  	struct i2c_adapter *adap;
  	struct i2c_client *client;
  
  	switch (of_reconfig_get_state_change(action, rd)) {
  	case OF_RECONFIG_CHANGE_ADD:
  		adap = of_find_i2c_adapter_by_node(rd->dn->parent);
  		if (adap == NULL)
  			return NOTIFY_OK;	/* not for us */
  
  		if (of_node_test_and_set_flag(rd->dn, OF_POPULATED)) {
  			put_device(&adap->dev);
  			return NOTIFY_OK;
  		}
  
  		client = of_i2c_register_device(adap, rd->dn);
  		put_device(&adap->dev);
  
  		if (IS_ERR(client)) {
  			dev_err(&adap->dev, "failed to create client for '%pOF'\n",
  				 rd->dn);
  			of_node_clear_flag(rd->dn, OF_POPULATED);
  			return notifier_from_errno(PTR_ERR(client));
  		}
  		break;
  	case OF_RECONFIG_CHANGE_REMOVE:
  		/* already depopulated? */
  		if (!of_node_check_flag(rd->dn, OF_POPULATED))
  			return NOTIFY_OK;
  
  		/* find our device by node */
  		client = of_find_i2c_device_by_node(rd->dn);
  		if (client == NULL)
  			return NOTIFY_OK;	/* no? not meant for us */
  
  		/* unregister takes one ref away */
  		i2c_unregister_device(client);
  
  		/* and put the reference of the find */
  		put_device(&client->dev);
  		break;
  	}
  
  	return NOTIFY_OK;
  }
  
  struct notifier_block i2c_of_notifier = {
  	.notifier_call = of_i2c_notify,
  };
  #endif /* CONFIG_OF_DYNAMIC */
  