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 (!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_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
  51         ret = client->adapter->algo->reg_slave(client);
  52         i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_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_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
  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", &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);