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 
17 #define CREATE_TRACE_POINTS
18 #include <trace/events/i2c_slave.h>
19 
i2c_slave_register(struct i2c_client * client,i2c_slave_cb_t slave_cb)20 int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb)
21 {
22 	int ret;
23 
24 	if (WARN(IS_ERR_OR_NULL(client) || !slave_cb, "insufficient data\n"))
25 		return -EINVAL;
26 
27 	if (!(client->flags & I2C_CLIENT_SLAVE))
28 		dev_warn(&client->dev, "%s: client slave flag not set. You might see address collisions\n",
29 			 __func__);
30 
31 	if (!(client->flags & I2C_CLIENT_TEN)) {
32 		/* Enforce stricter address checking */
33 		ret = i2c_check_7bit_addr_validity_strict(client->addr);
34 		if (ret) {
35 			dev_err(&client->dev, "%s: invalid address\n", __func__);
36 			return ret;
37 		}
38 	}
39 
40 	if (!client->adapter->algo->reg_slave) {
41 		dev_err(&client->dev, "%s: not supported by adapter\n", __func__);
42 		return -EOPNOTSUPP;
43 	}
44 
45 	client->slave_cb = slave_cb;
46 
47 	i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
48 	ret = client->adapter->algo->reg_slave(client);
49 	i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
50 
51 	if (ret) {
52 		client->slave_cb = NULL;
53 		dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);
54 	}
55 
56 	return ret;
57 }
58 EXPORT_SYMBOL_GPL(i2c_slave_register);
59 
i2c_slave_unregister(struct i2c_client * client)60 int i2c_slave_unregister(struct i2c_client *client)
61 {
62 	int ret;
63 
64 	if (IS_ERR_OR_NULL(client))
65 		return -EINVAL;
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 }
83 EXPORT_SYMBOL_GPL(i2c_slave_unregister);
84 
i2c_slave_event(struct i2c_client * client,enum i2c_slave_event event,u8 * val)85 int i2c_slave_event(struct i2c_client *client,
86 		    enum i2c_slave_event event, u8 *val)
87 {
88 	int ret = client->slave_cb(client, event, val);
89 
90 	if (trace_i2c_slave_enabled())
91 		trace_i2c_slave(client, event, val, ret);
92 
93 	return ret;
94 }
95 EXPORT_SYMBOL_GPL(i2c_slave_event);
96 
97 /**
98  * i2c_detect_slave_mode - detect operation mode
99  * @dev: The device owning the bus
100  *
101  * This checks the device nodes for an I2C slave by checking the address
102  * used in the reg property. If the address match the I2C_OWN_SLAVE_ADDRESS
103  * flag this means the device is configured to act as a I2C slave and it will
104  * be listening at that address.
105  *
106  * Returns true if an I2C own slave address is detected, otherwise returns
107  * false.
108  */
i2c_detect_slave_mode(struct device * dev)109 bool i2c_detect_slave_mode(struct device *dev)
110 {
111 	if (IS_BUILTIN(CONFIG_OF) && dev->of_node) {
112 		struct device_node *child;
113 		u32 reg;
114 
115 		for_each_child_of_node(dev->of_node, child) {
116 			of_property_read_u32(child, "reg", &reg);
117 			if (reg & I2C_OWN_SLAVE_ADDRESS) {
118 				of_node_put(child);
119 				return true;
120 			}
121 		}
122 	} else if (IS_BUILTIN(CONFIG_ACPI) && ACPI_HANDLE(dev)) {
123 		dev_dbg(dev, "ACPI slave is not supported yet\n");
124 	}
125 	return false;
126 }
127 EXPORT_SYMBOL_GPL(i2c_detect_slave_mode);
128