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/config.h>
  25 #include <linux/init.h>
  26 #include <linux/module.h>
  27 #include <linux/kernel.h>
  28 #include <linux/errno.h>
  29 #include <linux/i2c.h>
  30
  31 static u8  stub_pointer;
  32 static u8  stub_bytes[256];
  33 static u16 stub_words[256];
  34
  35 /* Return -1 on error. */
  36 static s32 stub_xfer(struct i2c_adapter * adap, u16 addr, unsigned short flags,
  37         char read_write, u8 command, int size, union i2c_smbus_data * data)
  38 {
  39         s32 ret;
  40
  41         switch (size) {
  42
  43         case I2C_SMBUS_QUICK:
  44                 dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr);
  45                 ret = 0;
  46                 break;
  47
  48         case I2C_SMBUS_BYTE:
  49                 if (read_write == I2C_SMBUS_WRITE) {
  50                         stub_pointer = command;
  51                         dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, "
  52                                         "wrote 0x%02x.\n",
  53                                         addr, command);
  54                 } else {
  55                         data->byte = stub_bytes[stub_pointer++];
  56                         dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, "
  57                                         "read  0x%02x.\n",
  58                                         addr, data->byte);
  59                 }
  60
  61                 ret = 0;
  62                 break;
  63
  64         case I2C_SMBUS_BYTE_DATA:
  65                 if (read_write == I2C_SMBUS_WRITE) {
  66                         stub_bytes[command] = data->byte;
  67                         dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, "
  68                                         "wrote 0x%02x at 0x%02x.\n",
  69                                         addr, data->byte, command);
  70                 } else {
  71                         data->byte = stub_bytes[command];
  72                         dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, "
  73                                         "read  0x%02x at 0x%02x.\n",
  74                                         addr, data->byte, command);
  75                 }
  76                 stub_pointer = command + 1;
  77
  78                 ret = 0;
  79                 break;
  80
  81         case I2C_SMBUS_WORD_DATA:
  82                 if (read_write == I2C_SMBUS_WRITE) {
  83                         stub_words[command] = data->word;
  84                         dev_dbg(&adap->dev, "smbus word data - addr 0x%02x, "
  85                                         "wrote 0x%04x at 0x%02x.\n",
  86                                         addr, data->word, command);
  87                 } else {
  88                         data->word = stub_words[command];
  89                         dev_dbg(&adap->dev, "smbus word data - addr 0x%02x, "
  90                                         "read  0x%04x at 0x%02x.\n",
  91                                         addr, data->word, command);
  92                 }
  93
  94                 ret = 0;
  95                 break;
  96
  97         default:
  98                 dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n");
  99                 ret = -1;
 100                 break;
 101         } /* switch (size) */
 102
 103         return ret;
 104 }
 105
 106 static u32 stub_func(struct i2c_adapter *adapter)
 107 {
 108         return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
 109                 I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA;
 110 }
 111
 112 static struct i2c_algorithm smbus_algorithm = {
 113         .name           = "Non-I2C SMBus adapter",
 114         .id             = I2C_ALGO_SMBUS,
 115         .functionality  = stub_func,
 116         .smbus_xfer     = stub_xfer,
 117 };
 118
 119 static struct i2c_adapter stub_adapter = {
 120         .owner          = THIS_MODULE,
 121         .class          = I2C_CLASS_HWMON,
 122         .algo           = &smbus_algorithm,
 123         .name           = "SMBus stub driver",
 124 };
 125
 126 static int __init i2c_stub_init(void)
 127 {
 128         printk(KERN_INFO "i2c-stub loaded\n");
 129         return i2c_add_adapter(&stub_adapter);
 130 }
 131
 132 static void __exit i2c_stub_exit(void)
 133 {
 134         i2c_del_adapter(&stub_adapter);
 135 }
 136
 137 MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
 138 MODULE_DESCRIPTION("I2C stub driver");
 139 MODULE_LICENSE("GPL");
 140
 141 module_init(i2c_stub_init);
 142 module_exit(i2c_stub_exit);
 143