i2c / ACPI: add ACPI enumeration support
[linux-3.10.git] / drivers / i2c / i2c-stub.c
1 /*
2     i2c-stub.c - I2C/SMBus chip emulator
3
4     Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com>
5     Copyright (C) 2007, 2012 Jean Delvare <khali@linux-fr.org>
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 #define STUB_FUNC (I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE | \
33                    I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA | \
34                    I2C_FUNC_SMBUS_I2C_BLOCK)
35
36 static unsigned short chip_addr[MAX_CHIPS];
37 module_param_array(chip_addr, ushort, NULL, S_IRUGO);
38 MODULE_PARM_DESC(chip_addr,
39                  "Chip addresses (up to 10, between 0x03 and 0x77)");
40
41 static unsigned long functionality = STUB_FUNC;
42 module_param(functionality, ulong, S_IRUGO | S_IWUSR);
43 MODULE_PARM_DESC(functionality, "Override functionality bitfield");
44
45 struct stub_chip {
46         u8 pointer;
47         u16 words[256];         /* Byte operations use the LSB as per SMBus
48                                    specification */
49 };
50
51 static struct stub_chip *stub_chips;
52
53 /* Return negative errno on error. */
54 static s32 stub_xfer(struct i2c_adapter *adap, u16 addr, unsigned short flags,
55         char read_write, u8 command, int size, union i2c_smbus_data *data)
56 {
57         s32 ret;
58         int i, len;
59         struct stub_chip *chip = NULL;
60
61         /* Search for the right chip */
62         for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) {
63                 if (addr == chip_addr[i]) {
64                         chip = stub_chips + i;
65                         break;
66                 }
67         }
68         if (!chip)
69                 return -ENODEV;
70
71         switch (size) {
72
73         case I2C_SMBUS_QUICK:
74                 dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr);
75                 ret = 0;
76                 break;
77
78         case I2C_SMBUS_BYTE:
79                 if (read_write == I2C_SMBUS_WRITE) {
80                         chip->pointer = command;
81                         dev_dbg(&adap->dev,
82                                 "smbus byte - addr 0x%02x, wrote 0x%02x.\n",
83                                 addr, command);
84                 } else {
85                         data->byte = chip->words[chip->pointer++] & 0xff;
86                         dev_dbg(&adap->dev,
87                                 "smbus byte - addr 0x%02x, read  0x%02x.\n",
88                                 addr, data->byte);
89                 }
90
91                 ret = 0;
92                 break;
93
94         case I2C_SMBUS_BYTE_DATA:
95                 if (read_write == I2C_SMBUS_WRITE) {
96                         chip->words[command] &= 0xff00;
97                         chip->words[command] |= data->byte;
98                         dev_dbg(&adap->dev,
99                                 "smbus byte data - addr 0x%02x, wrote 0x%02x at 0x%02x.\n",
100                                 addr, data->byte, command);
101                 } else {
102                         data->byte = chip->words[command] & 0xff;
103                         dev_dbg(&adap->dev,
104                                 "smbus byte data - addr 0x%02x, read  0x%02x at 0x%02x.\n",
105                                 addr, data->byte, command);
106                 }
107                 chip->pointer = command + 1;
108
109                 ret = 0;
110                 break;
111
112         case I2C_SMBUS_WORD_DATA:
113                 if (read_write == I2C_SMBUS_WRITE) {
114                         chip->words[command] = data->word;
115                         dev_dbg(&adap->dev,
116                                 "smbus word data - addr 0x%02x, wrote 0x%04x at 0x%02x.\n",
117                                 addr, data->word, command);
118                 } else {
119                         data->word = chip->words[command];
120                         dev_dbg(&adap->dev,
121                                 "smbus word data - addr 0x%02x, read  0x%04x at 0x%02x.\n",
122                                 addr, data->word, command);
123                 }
124
125                 ret = 0;
126                 break;
127
128         case I2C_SMBUS_I2C_BLOCK_DATA:
129                 len = data->block[0];
130                 if (read_write == I2C_SMBUS_WRITE) {
131                         for (i = 0; i < len; i++) {
132                                 chip->words[command + i] &= 0xff00;
133                                 chip->words[command + i] |= data->block[1 + i];
134                         }
135                         dev_dbg(&adap->dev,
136                                 "i2c block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n",
137                                 addr, len, command);
138                 } else {
139                         for (i = 0; i < len; i++) {
140                                 data->block[1 + i] =
141                                         chip->words[command + i] & 0xff;
142                         }
143                         dev_dbg(&adap->dev,
144                                 "i2c block data - addr 0x%02x, read  %d bytes at 0x%02x.\n",
145                                 addr, len, command);
146                 }
147
148                 ret = 0;
149                 break;
150
151         default:
152                 dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n");
153                 ret = -EOPNOTSUPP;
154                 break;
155         } /* switch (size) */
156
157         return ret;
158 }
159
160 static u32 stub_func(struct i2c_adapter *adapter)
161 {
162         return STUB_FUNC & functionality;
163 }
164
165 static const struct i2c_algorithm smbus_algorithm = {
166         .functionality  = stub_func,
167         .smbus_xfer     = stub_xfer,
168 };
169
170 static struct i2c_adapter stub_adapter = {
171         .owner          = THIS_MODULE,
172         .class          = I2C_CLASS_HWMON | I2C_CLASS_SPD,
173         .algo           = &smbus_algorithm,
174         .name           = "SMBus stub driver",
175 };
176
177 static int __init i2c_stub_init(void)
178 {
179         int i, ret;
180
181         if (!chip_addr[0]) {
182                 pr_err("i2c-stub: Please specify a chip address\n");
183                 return -ENODEV;
184         }
185
186         for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) {
187                 if (chip_addr[i] < 0x03 || chip_addr[i] > 0x77) {
188                         pr_err("i2c-stub: Invalid chip address 0x%02x\n",
189                                chip_addr[i]);
190                         return -EINVAL;
191                 }
192
193                 pr_info("i2c-stub: Virtual chip at 0x%02x\n", chip_addr[i]);
194         }
195
196         /* Allocate memory for all chips at once */
197         stub_chips = kzalloc(i * sizeof(struct stub_chip), GFP_KERNEL);
198         if (!stub_chips) {
199                 pr_err("i2c-stub: Out of memory\n");
200                 return -ENOMEM;
201         }
202
203         ret = i2c_add_adapter(&stub_adapter);
204         if (ret)
205                 kfree(stub_chips);
206         return ret;
207 }
208
209 static void __exit i2c_stub_exit(void)
210 {
211         i2c_del_adapter(&stub_adapter);
212         kfree(stub_chips);
213 }
214
215 MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
216 MODULE_DESCRIPTION("I2C stub driver");
217 MODULE_LICENSE("GPL");
218
219 module_init(i2c_stub_init);
220 module_exit(i2c_stub_exit);