i2c-core-slave.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Linux I2C core slave support code
  4 *
  5 * Copyright (C) 2014 by Wolfram Sang <wsa@sang-engineering.com>
  6 */
  7
  8#include <dt-bindings/i2c/i2c.h>
  9#include <linux/acpi.h>
 10#include <linux/device.h>
 11#include <linux/err.h>
 12#include <linux/i2c.h>
 13#include <linux/of.h>
 14#include <linux/property.h>
 15
 16#include "i2c-core.h"
 17
 18#define CREATE_TRACE_POINTS
 19#include <trace/events/i2c_slave.h>
 20
 21int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb)
 22{
 23	int ret;
 24
 25	if (WARN(IS_ERR_OR_NULL(client) || !slave_cb, "insufficient data\n"))
 26		return -EINVAL;
 27
 28	if (!(client->flags & I2C_CLIENT_SLAVE))
 29		dev_warn(&client->dev, "%s: client slave flag not set. You might see address collisions\n",
 30			 __func__);
 31
 32	if (!(client->flags & I2C_CLIENT_TEN)) {
 33		/* Enforce stricter address checking */
 34		ret = i2c_check_7bit_addr_validity_strict(client->addr);
 35		if (ret) {
 36			dev_err(&client->dev, "%s: invalid address\n", __func__);
 37			return ret;
 38		}
 39	}
 40
 41	if (!client->adapter->algo->reg_slave) {
 42		dev_err(&client->dev, "%s: not supported by adapter\n", __func__);
 43		return -EOPNOTSUPP;
 44	}
 45
 46	client->slave_cb = slave_cb;
 47
 48	i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
 49	ret = client->adapter->algo->reg_slave(client);
 50	i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
 51
 52	if (ret) {
 53		client->slave_cb = NULL;
 54		dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);
 55	}
 56
 57	return ret;
 58}
 59EXPORT_SYMBOL_GPL(i2c_slave_register);
 60
 61int i2c_slave_unregister(struct i2c_client *client)
 62{
 63	int ret;
 64
 65	if (IS_ERR_OR_NULL(client))
 66		return -EINVAL;
 67
 68	if (!client->adapter->algo->unreg_slave) {
 69		dev_err(&client->dev, "%s: not supported by adapter\n", __func__);
 70		return -EOPNOTSUPP;
 71	}
 72
 73	i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
 74	ret = client->adapter->algo->unreg_slave(client);
 75	i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
 76
 77	if (ret == 0)
 78		client->slave_cb = NULL;
 79	else
 80		dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);
 81
 82	return ret;
 83}
 84EXPORT_SYMBOL_GPL(i2c_slave_unregister);
 85
 86int i2c_slave_event(struct i2c_client *client,
 87		    enum i2c_slave_event event, u8 *val)
 88{
 89	int ret = client->slave_cb(client, event, val);
 90
 91	if (trace_i2c_slave_enabled())
 92		trace_i2c_slave(client, event, val, ret);
 93
 94	return ret;
 95}
 96EXPORT_SYMBOL_GPL(i2c_slave_event);
 97
 98/**
 99 * i2c_detect_slave_mode - detect operation mode
100 * @dev: The device owning the bus
101 *
102 * This checks the device nodes for an I2C slave by checking the address
103 * used in the reg property. If the address match the I2C_OWN_SLAVE_ADDRESS
104 * flag this means the device is configured to act as a I2C slave and it will
105 * be listening at that address.
106 *
107 * Returns true if an I2C own slave address is detected, otherwise returns
108 * false.
109 */
110bool i2c_detect_slave_mode(struct device *dev)
111{
112	struct fwnode_handle *fwnode = dev_fwnode(dev);
113
114	if (is_of_node(fwnode)) {
115		u32 reg;
116
117		fwnode_for_each_child_node_scoped(fwnode, child) {
118			fwnode_property_read_u32(child, "reg", &reg);
119			if (reg & I2C_OWN_SLAVE_ADDRESS)
120				return true;
121		}
122	} else if (is_acpi_device_node(fwnode)) {
123		dev_dbg(dev, "ACPI slave is not supported yet\n");
124	}
125	return false;
126}
127EXPORT_SYMBOL_GPL(i2c_detect_slave_mode);