drivers/i2c/i2c-core-slave.c

   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 (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_adapter(client->adapter);
  49         ret = client->adapter->algo->reg_slave(client);
  50         i2c_unlock_adapter(client->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
  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_adapter(client->adapter);
  74         ret = client->adapter->algo->unreg_slave(client);
  75         i2c_unlock_adapter(client->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  */
  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", &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);