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 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 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 */ 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