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
15 #include "i2c-core.h"
16
i2c_slave_register(struct i2c_client * client,i2c_slave_cb_t slave_cb)17 int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb)
18 {
19 int ret;
20
21 if (WARN(IS_ERR_OR_NULL(client) || !slave_cb, "insufficient data\n"))
22 return -EINVAL;
23
24 if (!(client->flags & I2C_CLIENT_SLAVE))
25 dev_warn(&client->dev, "%s: client slave flag not set. You might see address collisions\n",
26 __func__);
27
28 if (!(client->flags & I2C_CLIENT_TEN)) {
29 /* Enforce stricter address checking */
30 ret = i2c_check_7bit_addr_validity_strict(client->addr);
31 if (ret) {
32 dev_err(&client->dev, "%s: invalid address\n", __func__);
33 return ret;
34 }
35 }
36
37 if (!client->adapter->algo->reg_slave) {
38 dev_err(&client->dev, "%s: not supported by adapter\n", __func__);
39 return -EOPNOTSUPP;
40 }
41
42 client->slave_cb = slave_cb;
43
44 i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
45 ret = client->adapter->algo->reg_slave(client);
46 i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
47
48 if (ret) {
49 client->slave_cb = NULL;
50 dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);
51 }
52
53 return ret;
54 }
55 EXPORT_SYMBOL_GPL(i2c_slave_register);
56
i2c_slave_unregister(struct i2c_client * client)57 int i2c_slave_unregister(struct i2c_client *client)
58 {
59 int ret;
60
61 if (IS_ERR_OR_NULL(client))
62 return -EINVAL;
63
64 if (!client->adapter->algo->unreg_slave) {
65 dev_err(&client->dev, "%s: not supported by adapter\n", __func__);
66 return -EOPNOTSUPP;
67 }
68
69 i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
70 ret = client->adapter->algo->unreg_slave(client);
71 i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
72
73 if (ret == 0)
74 client->slave_cb = NULL;
75 else
76 dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);
77
78 return ret;
79 }
80 EXPORT_SYMBOL_GPL(i2c_slave_unregister);
81
82 /**
83 * i2c_detect_slave_mode - detect operation mode
84 * @dev: The device owning the bus
85 *
86 * This checks the device nodes for an I2C slave by checking the address
87 * used in the reg property. If the address match the I2C_OWN_SLAVE_ADDRESS
88 * flag this means the device is configured to act as a I2C slave and it will
89 * be listening at that address.
90 *
91 * Returns true if an I2C own slave address is detected, otherwise returns
92 * false.
93 */
i2c_detect_slave_mode(struct device * dev)94 bool i2c_detect_slave_mode(struct device *dev)
95 {
96 if (IS_BUILTIN(CONFIG_OF) && dev->of_node) {
97 struct device_node *child;
98 u32 reg;
99
100 for_each_child_of_node(dev->of_node, child) {
101 of_property_read_u32(child, "reg", ®);
102 if (reg & I2C_OWN_SLAVE_ADDRESS) {
103 of_node_put(child);
104 return true;
105 }
106 }
107 } else if (IS_BUILTIN(CONFIG_ACPI) && ACPI_HANDLE(dev)) {
108 dev_dbg(dev, "ACPI slave is not supported yet\n");
109 }
110 return false;
111 }
112 EXPORT_SYMBOL_GPL(i2c_detect_slave_mode);
113