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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Jean Delvare569be442008-01-27 18:14:45 +01002 i2c-stub.c - I2C/SMBus chip emulator
Linus Torvalds1da177e2005-04-16 15:20:36 -07003
4 Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com>
Jean Delvare2408c172014-07-10 12:56:59 +02005 Copyright (C) 2007-2014 Jean Delvare <jdelvare@suse.de>
Linus Torvalds1da177e2005-04-16 15:20:36 -07006
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.
Linus Torvalds1da177e2005-04-16 15:20:36 -070016*/
17
18#define DEBUG 1
19
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <linux/init.h>
21#include <linux/module.h>
22#include <linux/kernel.h>
Jean Delvare9d90c1f2007-10-13 23:56:31 +020023#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024#include <linux/errno.h>
25#include <linux/i2c.h>
Guenter Roeck6f16b752014-07-17 09:56:03 -070026#include <linux/list.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070027
Jean Delvare9d90c1f2007-10-13 23:56:31 +020028#define MAX_CHIPS 10
Guenter Roeck6f16b752014-07-17 09:56:03 -070029
30/*
31 * Support for I2C_FUNC_SMBUS_BLOCK_DATA is disabled by default and must
32 * be enabled explicitly by setting the I2C_FUNC_SMBUS_BLOCK_DATA bits
33 * in the 'functionality' module parameter.
34 */
35#define STUB_FUNC_DEFAULT \
36 (I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE | \
37 I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA | \
38 I2C_FUNC_SMBUS_I2C_BLOCK)
39
40#define STUB_FUNC_ALL \
41 (STUB_FUNC_DEFAULT | I2C_FUNC_SMBUS_BLOCK_DATA)
Jean Delvare7a8d29c2006-08-13 23:46:44 +020042
Jean Delvare9d90c1f2007-10-13 23:56:31 +020043static unsigned short chip_addr[MAX_CHIPS];
44module_param_array(chip_addr, ushort, NULL, S_IRUGO);
45MODULE_PARM_DESC(chip_addr,
Jean Delvare85d69312008-04-29 23:11:37 +020046 "Chip addresses (up to 10, between 0x03 and 0x77)");
Jean Delvare9d90c1f2007-10-13 23:56:31 +020047
Guenter Roeck6f16b752014-07-17 09:56:03 -070048static unsigned long functionality = STUB_FUNC_DEFAULT;
Jean Delvare38f41f22009-12-06 17:06:29 +010049module_param(functionality, ulong, S_IRUGO | S_IWUSR);
50MODULE_PARM_DESC(functionality, "Override functionality bitfield");
51
Jean Delvare2408c172014-07-10 12:56:59 +020052/* Some chips have banked register ranges */
53
54static u8 bank_reg[MAX_CHIPS];
55module_param_array(bank_reg, byte, NULL, S_IRUGO);
56MODULE_PARM_DESC(bank_reg, "Bank register");
57
58static u8 bank_mask[MAX_CHIPS];
59module_param_array(bank_mask, byte, NULL, S_IRUGO);
60MODULE_PARM_DESC(bank_mask, "Bank value mask");
61
62static u8 bank_start[MAX_CHIPS];
63module_param_array(bank_start, byte, NULL, S_IRUGO);
64MODULE_PARM_DESC(bank_start, "First banked register");
65
66static u8 bank_end[MAX_CHIPS];
67module_param_array(bank_end, byte, NULL, S_IRUGO);
68MODULE_PARM_DESC(bank_end, "Last banked register");
69
Guenter Roeck6f16b752014-07-17 09:56:03 -070070struct smbus_block_data {
71 struct list_head node;
72 u8 command;
73 u8 len;
74 u8 block[I2C_SMBUS_BLOCK_MAX];
75};
76
Jean Delvare9d90c1f2007-10-13 23:56:31 +020077struct stub_chip {
78 u8 pointer;
Jean Delvare569be442008-01-27 18:14:45 +010079 u16 words[256]; /* Byte operations use the LSB as per SMBus
80 specification */
Guenter Roeck6f16b752014-07-17 09:56:03 -070081 struct list_head smbus_blocks;
Jean Delvare2408c172014-07-10 12:56:59 +020082
83 /* For chips with banks, extra registers are allocated dynamically */
84 u8 bank_reg;
85 u8 bank_shift;
86 u8 bank_mask;
87 u8 bank_sel; /* Currently selected bank */
88 u8 bank_start;
89 u8 bank_end;
90 u16 bank_size;
91 u16 *bank_words; /* Room for bank_mask * bank_size registers */
Jean Delvare9d90c1f2007-10-13 23:56:31 +020092};
93
94static struct stub_chip *stub_chips;
Jean Delvare1dff5982014-07-10 12:45:11 +020095static int stub_chips_nr;
Linus Torvalds1da177e2005-04-16 15:20:36 -070096
Guenter Roeck6f16b752014-07-17 09:56:03 -070097static struct smbus_block_data *stub_find_block(struct device *dev,
98 struct stub_chip *chip,
99 u8 command, bool create)
100{
101 struct smbus_block_data *b, *rb = NULL;
102
103 list_for_each_entry(b, &chip->smbus_blocks, node) {
104 if (b->command == command) {
105 rb = b;
106 break;
107 }
108 }
109 if (rb == NULL && create) {
110 rb = devm_kzalloc(dev, sizeof(*rb), GFP_KERNEL);
111 if (rb == NULL)
112 return rb;
113 rb->command = command;
114 list_add(&rb->node, &chip->smbus_blocks);
115 }
116 return rb;
117}
118
Jean Delvare2408c172014-07-10 12:56:59 +0200119static u16 *stub_get_wordp(struct stub_chip *chip, u8 offset)
120{
121 if (chip->bank_sel &&
122 offset >= chip->bank_start && offset <= chip->bank_end)
123 return chip->bank_words +
124 (chip->bank_sel - 1) * chip->bank_size +
125 offset - chip->bank_start;
126 else
127 return chip->words + offset;
128}
129
David Brownell97140342008-07-14 22:38:25 +0200130/* Return negative errno on error. */
Jean Delvare31d178b2012-10-28 21:37:00 +0100131static s32 stub_xfer(struct i2c_adapter *adap, u16 addr, unsigned short flags,
132 char read_write, u8 command, int size, union i2c_smbus_data *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133{
134 s32 ret;
Jean Delvare47103172009-12-06 17:06:28 +0100135 int i, len;
Jean Delvare9d90c1f2007-10-13 23:56:31 +0200136 struct stub_chip *chip = NULL;
Guenter Roeck6f16b752014-07-17 09:56:03 -0700137 struct smbus_block_data *b;
Jean Delvare2408c172014-07-10 12:56:59 +0200138 u16 *wordp;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139
Jean Delvare9d90c1f2007-10-13 23:56:31 +0200140 /* Search for the right chip */
Jean Delvare1dff5982014-07-10 12:45:11 +0200141 for (i = 0; i < stub_chips_nr; i++) {
Jean Delvare9d90c1f2007-10-13 23:56:31 +0200142 if (addr == chip_addr[i]) {
143 chip = stub_chips + i;
144 break;
145 }
146 }
147 if (!chip)
Jean Delvare7a8d29c2006-08-13 23:46:44 +0200148 return -ENODEV;
149
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 switch (size) {
151
152 case I2C_SMBUS_QUICK:
153 dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr);
154 ret = 0;
155 break;
156
157 case I2C_SMBUS_BYTE:
158 if (read_write == I2C_SMBUS_WRITE) {
Jean Delvare9d90c1f2007-10-13 23:56:31 +0200159 chip->pointer = command;
Jean Delvare31d178b2012-10-28 21:37:00 +0100160 dev_dbg(&adap->dev,
161 "smbus byte - addr 0x%02x, wrote 0x%02x.\n",
162 addr, command);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 } else {
Jean Delvare2408c172014-07-10 12:56:59 +0200164 wordp = stub_get_wordp(chip, chip->pointer++);
165 data->byte = *wordp & 0xff;
Jean Delvare31d178b2012-10-28 21:37:00 +0100166 dev_dbg(&adap->dev,
167 "smbus byte - addr 0x%02x, read 0x%02x.\n",
168 addr, data->byte);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169 }
170
171 ret = 0;
172 break;
173
174 case I2C_SMBUS_BYTE_DATA:
Jean Delvare2408c172014-07-10 12:56:59 +0200175 wordp = stub_get_wordp(chip, command);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 if (read_write == I2C_SMBUS_WRITE) {
Jean Delvare2408c172014-07-10 12:56:59 +0200177 *wordp &= 0xff00;
178 *wordp |= data->byte;
Jean Delvare31d178b2012-10-28 21:37:00 +0100179 dev_dbg(&adap->dev,
180 "smbus byte data - addr 0x%02x, wrote 0x%02x at 0x%02x.\n",
181 addr, data->byte, command);
Jean Delvare2408c172014-07-10 12:56:59 +0200182
183 /* Set the bank as needed */
184 if (chip->bank_words && command == chip->bank_reg) {
185 chip->bank_sel =
186 (data->byte >> chip->bank_shift)
187 & chip->bank_mask;
188 dev_dbg(&adap->dev,
189 "switching to bank %u.\n",
190 chip->bank_sel);
191 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192 } else {
Jean Delvare2408c172014-07-10 12:56:59 +0200193 data->byte = *wordp & 0xff;
Jean Delvare31d178b2012-10-28 21:37:00 +0100194 dev_dbg(&adap->dev,
195 "smbus byte data - addr 0x%02x, read 0x%02x at 0x%02x.\n",
196 addr, data->byte, command);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197 }
Jean Delvare9d90c1f2007-10-13 23:56:31 +0200198 chip->pointer = command + 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199
200 ret = 0;
201 break;
202
203 case I2C_SMBUS_WORD_DATA:
Jean Delvare2408c172014-07-10 12:56:59 +0200204 wordp = stub_get_wordp(chip, command);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205 if (read_write == I2C_SMBUS_WRITE) {
Jean Delvare2408c172014-07-10 12:56:59 +0200206 *wordp = data->word;
Jean Delvare31d178b2012-10-28 21:37:00 +0100207 dev_dbg(&adap->dev,
208 "smbus word data - addr 0x%02x, wrote 0x%04x at 0x%02x.\n",
209 addr, data->word, command);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 } else {
Jean Delvare2408c172014-07-10 12:56:59 +0200211 data->word = *wordp;
Jean Delvare31d178b2012-10-28 21:37:00 +0100212 dev_dbg(&adap->dev,
213 "smbus word data - addr 0x%02x, read 0x%04x at 0x%02x.\n",
214 addr, data->word, command);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215 }
216
217 ret = 0;
218 break;
219
Jean Delvare47103172009-12-06 17:06:28 +0100220 case I2C_SMBUS_I2C_BLOCK_DATA:
Jean Delvare2408c172014-07-10 12:56:59 +0200221 /*
222 * We ignore banks here, because banked chips don't use I2C
223 * block transfers
224 */
Jean Delvare0f6ba0d2014-07-13 17:17:17 +0200225 if (data->block[0] > 256 - command) /* Avoid overrun */
226 data->block[0] = 256 - command;
Jean Delvare47103172009-12-06 17:06:28 +0100227 len = data->block[0];
228 if (read_write == I2C_SMBUS_WRITE) {
229 for (i = 0; i < len; i++) {
230 chip->words[command + i] &= 0xff00;
231 chip->words[command + i] |= data->block[1 + i];
232 }
Jean Delvare31d178b2012-10-28 21:37:00 +0100233 dev_dbg(&adap->dev,
234 "i2c block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n",
235 addr, len, command);
Jean Delvare47103172009-12-06 17:06:28 +0100236 } else {
237 for (i = 0; i < len; i++) {
238 data->block[1 + i] =
239 chip->words[command + i] & 0xff;
240 }
Jean Delvare31d178b2012-10-28 21:37:00 +0100241 dev_dbg(&adap->dev,
242 "i2c block data - addr 0x%02x, read %d bytes at 0x%02x.\n",
243 addr, len, command);
Jean Delvare47103172009-12-06 17:06:28 +0100244 }
245
246 ret = 0;
247 break;
248
Guenter Roeck6f16b752014-07-17 09:56:03 -0700249 case I2C_SMBUS_BLOCK_DATA:
Jean Delvare2408c172014-07-10 12:56:59 +0200250 /*
251 * We ignore banks here, because chips typically don't use both
252 * banks and SMBus block transfers
253 */
Guenter Roeck6f16b752014-07-17 09:56:03 -0700254 b = stub_find_block(&adap->dev, chip, command, false);
255 if (read_write == I2C_SMBUS_WRITE) {
256 len = data->block[0];
257 if (len == 0 || len > I2C_SMBUS_BLOCK_MAX) {
258 ret = -EINVAL;
259 break;
260 }
261 if (b == NULL) {
262 b = stub_find_block(&adap->dev, chip, command,
263 true);
264 if (b == NULL) {
265 ret = -ENOMEM;
266 break;
267 }
268 }
269 /* Largest write sets read block length */
270 if (len > b->len)
271 b->len = len;
272 for (i = 0; i < len; i++)
273 b->block[i] = data->block[i + 1];
274 /* update for byte and word commands */
275 chip->words[command] = (b->block[0] << 8) | b->len;
276 dev_dbg(&adap->dev,
277 "smbus block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n",
278 addr, len, command);
279 } else {
280 if (b == NULL) {
281 dev_dbg(&adap->dev,
282 "SMBus block read command without prior block write not supported\n");
283 ret = -EOPNOTSUPP;
284 break;
285 }
286 len = b->len;
287 data->block[0] = len;
288 for (i = 0; i < len; i++)
289 data->block[i + 1] = b->block[i];
290 dev_dbg(&adap->dev,
291 "smbus block data - addr 0x%02x, read %d bytes at 0x%02x.\n",
292 addr, len, command);
293 }
294
295 ret = 0;
296 break;
297
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298 default:
299 dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n");
David Brownell97140342008-07-14 22:38:25 +0200300 ret = -EOPNOTSUPP;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 break;
302 } /* switch (size) */
303
304 return ret;
305}
306
307static u32 stub_func(struct i2c_adapter *adapter)
308{
Guenter Roeck6f16b752014-07-17 09:56:03 -0700309 return STUB_FUNC_ALL & functionality;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310}
311
Jean Delvare8f9082c2006-09-03 22:39:46 +0200312static const struct i2c_algorithm smbus_algorithm = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313 .functionality = stub_func,
314 .smbus_xfer = stub_xfer,
315};
316
317static struct i2c_adapter stub_adapter = {
318 .owner = THIS_MODULE,
Jean Delvare3401b2f2008-07-14 22:38:29 +0200319 .class = I2C_CLASS_HWMON | I2C_CLASS_SPD,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320 .algo = &smbus_algorithm,
321 .name = "SMBus stub driver",
322};
323
Jean Delvare2408c172014-07-10 12:56:59 +0200324static int __init i2c_stub_allocate_banks(int i)
325{
326 struct stub_chip *chip = stub_chips + i;
327
328 chip->bank_reg = bank_reg[i];
329 chip->bank_start = bank_start[i];
330 chip->bank_end = bank_end[i];
331 chip->bank_size = bank_end[i] - bank_start[i] + 1;
332
333 /* We assume that all bits in the mask are contiguous */
334 chip->bank_mask = bank_mask[i];
335 while (!(chip->bank_mask & 1)) {
336 chip->bank_shift++;
337 chip->bank_mask >>= 1;
338 }
339
340 chip->bank_words = kzalloc(chip->bank_mask * chip->bank_size *
341 sizeof(u16), GFP_KERNEL);
342 if (!chip->bank_words)
343 return -ENOMEM;
344
345 pr_debug("i2c-stub: Allocated %u banks of %u words each (registers 0x%02x to 0x%02x)\n",
346 chip->bank_mask, chip->bank_size, chip->bank_start,
347 chip->bank_end);
348
349 return 0;
350}
351
352static void i2c_stub_free(void)
353{
354 int i;
355
356 for (i = 0; i < stub_chips_nr; i++)
357 kfree(stub_chips[i].bank_words);
358 kfree(stub_chips);
359}
360
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361static int __init i2c_stub_init(void)
362{
Jean Delvare9d90c1f2007-10-13 23:56:31 +0200363 int i, ret;
364
365 if (!chip_addr[0]) {
Jean Delvare31d178b2012-10-28 21:37:00 +0100366 pr_err("i2c-stub: Please specify a chip address\n");
Jean Delvare7a8d29c2006-08-13 23:46:44 +0200367 return -ENODEV;
368 }
Jean Delvare9d90c1f2007-10-13 23:56:31 +0200369
370 for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) {
371 if (chip_addr[i] < 0x03 || chip_addr[i] > 0x77) {
Jean Delvare31d178b2012-10-28 21:37:00 +0100372 pr_err("i2c-stub: Invalid chip address 0x%02x\n",
373 chip_addr[i]);
Jean Delvare9d90c1f2007-10-13 23:56:31 +0200374 return -EINVAL;
375 }
376
Jean Delvare31d178b2012-10-28 21:37:00 +0100377 pr_info("i2c-stub: Virtual chip at 0x%02x\n", chip_addr[i]);
Jean Delvare7a8d29c2006-08-13 23:46:44 +0200378 }
379
Jean Delvare9d90c1f2007-10-13 23:56:31 +0200380 /* Allocate memory for all chips at once */
Jean Delvare1dff5982014-07-10 12:45:11 +0200381 stub_chips_nr = i;
382 stub_chips = kcalloc(stub_chips_nr, sizeof(struct stub_chip),
383 GFP_KERNEL);
Jean Delvare9d90c1f2007-10-13 23:56:31 +0200384 if (!stub_chips) {
Jean Delvare31d178b2012-10-28 21:37:00 +0100385 pr_err("i2c-stub: Out of memory\n");
Jean Delvare9d90c1f2007-10-13 23:56:31 +0200386 return -ENOMEM;
387 }
Jean Delvare2408c172014-07-10 12:56:59 +0200388 for (i = 0; i < stub_chips_nr; i++) {
Guenter Roeck6f16b752014-07-17 09:56:03 -0700389 INIT_LIST_HEAD(&stub_chips[i].smbus_blocks);
Jean Delvare9d90c1f2007-10-13 23:56:31 +0200390
Jean Delvare2408c172014-07-10 12:56:59 +0200391 /* Allocate extra memory for banked register ranges */
392 if (bank_mask[i]) {
393 ret = i2c_stub_allocate_banks(i);
394 if (ret)
395 goto fail_free;
396 }
397 }
398
Jean Delvare9d90c1f2007-10-13 23:56:31 +0200399 ret = i2c_add_adapter(&stub_adapter);
400 if (ret)
Jean Delvare2408c172014-07-10 12:56:59 +0200401 goto fail_free;
402
403 return 0;
404
405 fail_free:
406 i2c_stub_free();
Jean Delvare9d90c1f2007-10-13 23:56:31 +0200407 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408}
409
410static void __exit i2c_stub_exit(void)
411{
412 i2c_del_adapter(&stub_adapter);
Jean Delvare2408c172014-07-10 12:56:59 +0200413 i2c_stub_free();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414}
415
416MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
417MODULE_DESCRIPTION("I2C stub driver");
418MODULE_LICENSE("GPL");
419
420module_init(i2c_stub_init);
421module_exit(i2c_stub_exit);