summaryrefslogtreecommitdiffstats
path: root/drivers/i2c/busses/i2c-stub.c
blob: a54adc50d162a5a580ae60a709b87bb802280c75 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
/*
    i2c-stub.c - Part of lm_sensors, Linux kernel modules for hardware
              monitoring

    Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#define DEBUG 1

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/i2c.h>

static unsigned short chip_addr;
module_param(chip_addr, ushort, S_IRUGO);
MODULE_PARM_DESC(chip_addr, "Chip address (between 0x03 and 0x77)\n");

static u8  stub_pointer;
static u8  stub_bytes[256];
static u16 stub_words[256];

/* Return -1 on error. */
static s32 stub_xfer(struct i2c_adapter * adap, u16 addr, unsigned short flags,
	char read_write, u8 command, int size, union i2c_smbus_data * data)
{
	s32 ret;

	if (addr != chip_addr)
		return -ENODEV;

	switch (size) {

	case I2C_SMBUS_QUICK:
		dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr);
		ret = 0;
		break;

	case I2C_SMBUS_BYTE:
		if (read_write == I2C_SMBUS_WRITE) {
			stub_pointer = command;
			dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, "
					"wrote 0x%02x.\n",
					addr, command);
		} else {
			data->byte = stub_bytes[stub_pointer++];
			dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, "
					"read  0x%02x.\n",
					addr, data->byte);
		}

		ret = 0;
		break;

	case I2C_SMBUS_BYTE_DATA:
		if (read_write == I2C_SMBUS_WRITE) {
			stub_bytes[command] = data->byte;
			dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, "
					"wrote 0x%02x at 0x%02x.\n",
					addr, data->byte, command);
		} else {
			data->byte = stub_bytes[command];
			dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, "
					"read  0x%02x at 0x%02x.\n",
					addr, data->byte, command);
		}
		stub_pointer = command + 1;

		ret = 0;
		break;

	case I2C_SMBUS_WORD_DATA:
		if (read_write == I2C_SMBUS_WRITE) {
			stub_words[command] = data->word;
			dev_dbg(&adap->dev, "smbus word data - addr 0x%02x, "
					"wrote 0x%04x at 0x%02x.\n",
					addr, data->word, command);
		} else {
			data->word = stub_words[command];
			dev_dbg(&adap->dev, "smbus word data - addr 0x%02x, "
					"read  0x%04x at 0x%02x.\n",
					addr, data->word, command);
		}

		ret = 0;
		break;

	default:
		dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n");
		ret = -1;
		break;
	} /* switch (size) */

	return ret;
}

static u32 stub_func(struct i2c_adapter *adapter)
{
	return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
		I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA;
}

static const struct i2c_algorithm smbus_algorithm = {
	.functionality	= stub_func,
	.smbus_xfer	= stub_xfer,
};

static struct i2c_adapter stub_adapter = {
	.owner		= THIS_MODULE,
	.class		= I2C_CLASS_HWMON,
	.algo		= &smbus_algorithm,
	.name		= "SMBus stub driver",
};

static int __init i2c_stub_init(void)
{
	if (!chip_addr) {
		printk(KERN_ERR "i2c-stub: Please specify a chip address\n");
		return -ENODEV;
	}
	if (chip_addr < 0x03 || chip_addr > 0x77) {
		printk(KERN_ERR "i2c-stub: Invalid chip address 0x%02x\n",
		       chip_addr);
		return -EINVAL;
	}

	printk(KERN_INFO "i2c-stub: Virtual chip at 0x%02x\n", chip_addr);
	return i2c_add_adapter(&stub_adapter);
}

static void __exit i2c_stub_exit(void)
{
	i2c_del_adapter(&stub_adapter);
}

MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
MODULE_DESCRIPTION("I2C stub driver");
MODULE_LICENSE("GPL");

module_init(i2c_stub_init);
module_exit(i2c_stub_exit);