i2c-stub: Support multiple chips
[linux-2.6.git] / 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/slab.h>
28 #include <linux/errno.h>
29 #include <linux/i2c.h>
30
31 #define MAX_CHIPS 10
32
33 static unsigned short chip_addr[MAX_CHIPS];
34 module_param_array(chip_addr, ushort, NULL, S_IRUGO);
35 MODULE_PARM_DESC(chip_addr,
36                  "Chip addresses (up to 10, between 0x03 and 0x77)\n");
37
38 struct stub_chip {
39         u8 pointer;
40         u8 bytes[256];
41         u16 words[256];
42 };
43
44 static struct stub_chip *stub_chips;
45
46 /* Return -1 on error. */
47 static s32 stub_xfer(struct i2c_adapter * adap, u16 addr, unsigned short flags,
48         char read_write, u8 command, int size, union i2c_smbus_data * data)
49 {
50         s32 ret;
51         int i;
52         struct stub_chip *chip = NULL;
53
54         /* Search for the right chip */
55         for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) {
56                 if (addr == chip_addr[i]) {
57                         chip = stub_chips + i;
58                         break;
59                 }
60         }
61         if (!chip)
62                 return -ENODEV;
63
64         switch (size) {
65
66         case I2C_SMBUS_QUICK:
67                 dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr);
68                 ret = 0;
69                 break;
70
71         case I2C_SMBUS_BYTE:
72                 if (read_write == I2C_SMBUS_WRITE) {
73                         chip->pointer = command;
74                         dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, "
75                                         "wrote 0x%02x.\n",
76                                         addr, command);
77                 } else {
78                         data->byte = chip->bytes[chip->pointer++];
79                         dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, "
80                                         "read  0x%02x.\n",
81                                         addr, data->byte);
82                 }
83
84                 ret = 0;
85                 break;
86
87         case I2C_SMBUS_BYTE_DATA:
88                 if (read_write == I2C_SMBUS_WRITE) {
89                         chip->bytes[command] = data->byte;
90                         dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, "
91                                         "wrote 0x%02x at 0x%02x.\n",
92                                         addr, data->byte, command);
93                 } else {
94                         data->byte = chip->bytes[command];
95                         dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, "
96                                         "read  0x%02x at 0x%02x.\n",
97                                         addr, data->byte, command);
98                 }
99                 chip->pointer = command + 1;
100
101                 ret = 0;
102                 break;
103
104         case I2C_SMBUS_WORD_DATA:
105                 if (read_write == I2C_SMBUS_WRITE) {
106                         chip->words[command] = data->word;
107                         dev_dbg(&adap->dev, "smbus word data - addr 0x%02x, "
108                                         "wrote 0x%04x at 0x%02x.\n",
109                                         addr, data->word, command);
110                 } else {
111                         data->word = chip->words[command];
112                         dev_dbg(&adap->dev, "smbus word data - addr 0x%02x, "
113                                         "read  0x%04x at 0x%02x.\n",
114                                         addr, data->word, command);
115                 }
116
117                 ret = 0;
118                 break;
119
120         default:
121                 dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n");
122                 ret = -1;
123                 break;
124         } /* switch (size) */
125
126         return ret;
127 }
128
129 static u32 stub_func(struct i2c_adapter *adapter)
130 {
131         return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
132                 I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA;
133 }
134
135 static const struct i2c_algorithm smbus_algorithm = {
136         .functionality  = stub_func,
137         .smbus_xfer     = stub_xfer,
138 };
139
140 static struct i2c_adapter stub_adapter = {
141         .owner          = THIS_MODULE,
142         .class          = I2C_CLASS_HWMON,
143         .algo           = &smbus_algorithm,
144         .name           = "SMBus stub driver",
145 };
146
147 static int __init i2c_stub_init(void)
148 {
149         int i, ret;
150
151         if (!chip_addr[0]) {
152                 printk(KERN_ERR "i2c-stub: Please specify a chip address\n");
153                 return -ENODEV;
154         }
155
156         for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) {
157                 if (chip_addr[i] < 0x03 || chip_addr[i] > 0x77) {
158                         printk(KERN_ERR "i2c-stub: Invalid chip address "
159                                "0x%02x\n", chip_addr[i]);
160                         return -EINVAL;
161                 }
162
163                 printk(KERN_INFO "i2c-stub: Virtual chip at 0x%02x\n",
164                        chip_addr[i]);
165         }
166
167         /* Allocate memory for all chips at once */
168         stub_chips = kzalloc(i * sizeof(struct stub_chip), GFP_KERNEL);
169         if (!stub_chips) {
170                 printk(KERN_ERR "i2c-stub: Out of memory\n");
171                 return -ENOMEM;
172         }
173
174         ret = i2c_add_adapter(&stub_adapter);
175         if (ret)
176                 kfree(stub_chips);
177         return ret;
178 }
179
180 static void __exit i2c_stub_exit(void)
181 {
182         i2c_del_adapter(&stub_adapter);
183         kfree(stub_chips);
184 }
185
186 MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
187 MODULE_DESCRIPTION("I2C stub driver");
188 MODULE_LICENSE("GPL");
189
190 module_init(i2c_stub_init);
191 module_exit(i2c_stub_exit);
192