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 21 int 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_adapter(client->adapter); 51 ret = client->adapter->algo->reg_slave(client); 52 i2c_unlock_adapter(client->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 } 61 EXPORT_SYMBOL_GPL(i2c_slave_register); 62 63 int 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_adapter(client->adapter); 73 ret = client->adapter->algo->unreg_slave(client); 74 i2c_unlock_adapter(client->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 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 */ 97 bool 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", ®); 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 } 115 EXPORT_SYMBOL_GPL(i2c_detect_slave_mode); 116