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
i2c_slave_register(struct i2c_client * client,i2c_slave_cb_t slave_cb)21 int 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 }
59 EXPORT_SYMBOL_GPL(i2c_slave_register);
60
i2c_slave_unregister(struct i2c_client * client)61 int 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 }
84 EXPORT_SYMBOL_GPL(i2c_slave_unregister);
85
86 /**
87 * i2c_detect_slave_mode - detect operation mode
88 * @dev: The device owning the bus
89 *
90 * This checks the device nodes for an I2C slave by checking the address
91 * used in the reg property. If the address match the I2C_OWN_SLAVE_ADDRESS
92 * flag this means the device is configured to act as a I2C slave and it will
93 * be listening at that address.
94 *
95 * Returns true if an I2C own slave address is detected, otherwise returns
96 * false.
97 */
i2c_detect_slave_mode(struct device * dev)98 bool i2c_detect_slave_mode(struct device *dev)
99 {
100 if (IS_BUILTIN(CONFIG_OF) && dev->of_node) {
101 struct device_node *child;
102 u32 reg;
103
104 for_each_child_of_node(dev->of_node, child) {
105 of_property_read_u32(child, "reg", ®);
106 if (reg & I2C_OWN_SLAVE_ADDRESS) {
107 of_node_put(child);
108 return true;
109 }
110 }
111 } else if (IS_BUILTIN(CONFIG_ACPI) && ACPI_HANDLE(dev)) {
112 dev_dbg(dev, "ACPI slave is not supported yet\n");
113 }
114 return false;
115 }
116 EXPORT_SYMBOL_GPL(i2c_detect_slave_mode);
117