drivers/i2c/busses/i2c-stub.c

   1 /*
   2     i2c-stub.c - Part of lm_sensors, Linux kernel modules for hardware
   3               monitoring
   4
   5     Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com>
   6
   7     This program is free software; you can redistribute it and/or modify
   8     it under the terms of the GNU General Public License as published by
   9     the Free Software Foundation; either version 2 of the License, or
  10     (at your option) any later version.
  11
  12     This program is distributed in the hope that it will be useful,
  13     but WITHOUT ANY WARRANTY; without even the implied warranty of
  14     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15     GNU General Public License for more details.
  16
  17     You should have received a copy of the GNU General Public License
  18     along with this program; if not, write to the Free Software
  19     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 */
  21
  22 #define DEBUG 1
  23
  24 #include <linux/init.h>
  25 #include <linux/module.h>
  26 #include <linux/kernel.h>
  27 #include <linux/errno.h>
  28 #include <linux/i2c.h>
  29
  30 static u8  stub_pointer;
  31 static u8  stub_bytes[256];
  32 static u16 stub_words[256];
  33
  34 /* Return -1 on error. */
  35 static s32 stub_xfer(struct i2c_adapter * adap, u16 addr, unsigned short flags,
  36         char read_write, u8 command, int size, union i2c_smbus_data * data)
  37 {
  38         s32 ret;
  39
  40         switch (size) {
  41
  42         case I2C_SMBUS_QUICK:
  43                 dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr);
  44                 ret = 0;
  45                 break;
  46
  47         case I2C_SMBUS_BYTE:
  48                 if (read_write == I2C_SMBUS_WRITE) {
  49                         stub_pointer = command;
  50                         dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, "
  51                                         "wrote 0x%02x.\n",
  52                                         addr, command);
  53                 } else {
  54                         data->byte = stub_bytes[stub_pointer++];
  55                         dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, "
  56                                         "read  0x%02x.\n",
  57                                         addr, data->byte);
  58                 }
  59
  60                 ret = 0;
  61                 break;
  62
  63         case I2C_SMBUS_BYTE_DATA:
  64                 if (read_write == I2C_SMBUS_WRITE) {
  65                         stub_bytes[command] = data->byte;
  66                         dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, "
  67                                         "wrote 0x%02x at 0x%02x.\n",
  68                                         addr, data->byte, command);
  69                 } else {
  70                         data->byte = stub_bytes[command];
  71                         dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, "
  72                                         "read  0x%02x at 0x%02x.\n",
  73                                         addr, data->byte, command);
  74                 }
  75                 stub_pointer = command + 1;
  76
  77                 ret = 0;
  78                 break;
  79
  80         case I2C_SMBUS_WORD_DATA:
  81                 if (read_write == I2C_SMBUS_WRITE) {
  82                         stub_words[command] = data->word;
  83                         dev_dbg(&adap->dev, "smbus word data - addr 0x%02x, "
  84                                         "wrote 0x%04x at 0x%02x.\n",
  85                                         addr, data->word, command);
  86                 } else {
  87                         data->word = stub_words[command];
  88                         dev_dbg(&adap->dev, "smbus word data - addr 0x%02x, "
  89                                         "read  0x%04x at 0x%02x.\n",
  90                                         addr, data->word, command);
  91                 }
  92
  93                 ret = 0;
  94                 break;
  95
  96         default:
  97                 dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n");
  98                 ret = -1;
  99                 break;
 100         } /* switch (size) */
 101
 102         return ret;
 103 }
 104
 105 static u32 stub_func(struct i2c_adapter *adapter)
 106 {
 107         return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
 108                 I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA;
 109 }
 110
 111 static struct i2c_algorithm smbus_algorithm = {
 112         .id             = I2C_ALGO_SMBUS,
 113         .functionality  = stub_func,
 114         .smbus_xfer     = stub_xfer,
 115 };
 116
 117 static struct i2c_adapter stub_adapter = {
 118         .owner          = THIS_MODULE,
 119         .class          = I2C_CLASS_HWMON,
 120         .algo           = &smbus_algorithm,
 121         .name           = "SMBus stub driver",
 122 };
 123
 124 static int __init i2c_stub_init(void)
 125 {
 126         printk(KERN_INFO "i2c-stub loaded\n");
 127         return i2c_add_adapter(&stub_adapter);
 128 }
 129
 130 static void __exit i2c_stub_exit(void)
 131 {
 132         i2c_del_adapter(&stub_adapter);
 133 }
 134
 135 MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
 136 MODULE_DESCRIPTION("I2C stub driver");
 137 MODULE_LICENSE("GPL");
 138
 139 module_init(i2c_stub_init);
 140 module_exit(i2c_stub_exit);
 141