LXR linux/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
  21int 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}
  61EXPORT_SYMBOL_GPL(i2c_slave_register);
  62
  63int 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}
  83EXPORT_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 */
  97bool 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}
 115EXPORT_SYMBOL_GPL(i2c_detect_slave_mode);
 116