1/*
2 * Linux I2C core slave support code
3 *
4 * Copyright (C) 2014 by Wolfram Sang <wsa@sang-engineering.com>
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License as published by the Free
8 * Software Foundation; either version 2 of the License, or (at your option)
9 * any later version.
10 */
11
12#include <dt-bindings/i2c/i2c.h>
13#include <linux/acpi.h>
14#include <linux/device.h>
15#include <linux/err.h>
16#include <linux/i2c.h>
17#include <linux/of.h>
18
19#include "i2c-core.h"
20
21int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb)
22{
23 int ret;
24
25 if (!client || !slave_cb) {
26 WARN(1, "insufficient data\n");
27 return -EINVAL;
28 }
29
30 if (!(client->flags & I2C_CLIENT_SLAVE))
31 dev_warn(&client->dev, "%s: client slave flag not set. You might see address collisions\n",
32 __func__);
33
34 if (!(client->flags & I2C_CLIENT_TEN)) {
35 /* Enforce stricter address checking */
36 ret = i2c_check_7bit_addr_validity_strict(client->addr);
37 if (ret) {
38 dev_err(&client->dev, "%s: invalid address\n", __func__);
39 return ret;
40 }
41 }
42
43 if (!client->adapter->algo->reg_slave) {
44 dev_err(&client->dev, "%s: not supported by adapter\n", __func__);
45 return -EOPNOTSUPP;
46 }
47
48 client->slave_cb = slave_cb;
49
50 i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
51 ret = client->adapter->algo->reg_slave(client);
52 i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
53
54 if (ret) {
55 client->slave_cb = NULL;
56 dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);
57 }
58
59 return ret;
60}
61EXPORT_SYMBOL_GPL(i2c_slave_register);
62
63int i2c_slave_unregister(struct i2c_client *client)
64{
65 int ret;
66
67 if (!client->adapter->algo->unreg_slave) {
68 dev_err(&client->dev, "%s: not supported by adapter\n", __func__);
69 return -EOPNOTSUPP;
70 }
71
72 i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
73 ret = client->adapter->algo->unreg_slave(client);
74 i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
75
76 if (ret == 0)
77 client->slave_cb = NULL;
78 else
79 dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);
80
81 return ret;
82}
83EXPORT_SYMBOL_GPL(i2c_slave_unregister);
84
85/**
86 * i2c_detect_slave_mode - detect operation mode
87 * @dev: The device owning the bus
88 *
89 * This checks the device nodes for an I2C slave by checking the address
90 * used in the reg property. If the address match the I2C_OWN_SLAVE_ADDRESS
91 * flag this means the device is configured to act as a I2C slave and it will
92 * be listening at that address.
93 *
94 * Returns true if an I2C own slave address is detected, otherwise returns
95 * false.
96 */
97bool i2c_detect_slave_mode(struct device *dev)
98{
99 if (IS_BUILTIN(CONFIG_OF) && dev->of_node) {
100 struct device_node *child;
101 u32 reg;
102
103 for_each_child_of_node(dev->of_node, child) {
104 of_property_read_u32(child, "reg", &reg);
105 if (reg & I2C_OWN_SLAVE_ADDRESS) {
106 of_node_put(child);
107 return true;
108 }
109 }
110 } else if (IS_BUILTIN(CONFIG_ACPI) && ACPI_HANDLE(dev)) {
111 dev_dbg(dev, "ACPI slave is not supported yet\n");
112 }
113 return false;
114}
115EXPORT_SYMBOL_GPL(i2c_detect_slave_mode);
116