Commit | Line | Data |
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c942fddf | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
1da177e4 | 2 | /* |
569be443 | 3 | i2c-stub.c - I2C/SMBus chip emulator |
1da177e4 LT |
4 | |
5 | Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com> | |
2408c17f | 6 | Copyright (C) 2007-2014 Jean Delvare <jdelvare@suse.de> |
1da177e4 | 7 | |
1da177e4 LT |
8 | */ |
9 | ||
d4400567 | 10 | #define DEBUG 1 |
6c427787 | 11 | #define pr_fmt(fmt) "i2c-stub: " fmt |
1da177e4 | 12 | |
1da177e4 LT |
13 | #include <linux/errno.h> |
14 | #include <linux/i2c.h> | |
9f8f53a6 WS |
15 | #include <linux/init.h> |
16 | #include <linux/kernel.h> | |
6f16b75a | 17 | #include <linux/list.h> |
9f8f53a6 WS |
18 | #include <linux/module.h> |
19 | #include <linux/slab.h> | |
1da177e4 | 20 | |
9d90c1fd | 21 | #define MAX_CHIPS 10 |
6f16b75a GR |
22 | |
23 | /* | |
24 | * Support for I2C_FUNC_SMBUS_BLOCK_DATA is disabled by default and must | |
25 | * be enabled explicitly by setting the I2C_FUNC_SMBUS_BLOCK_DATA bits | |
26 | * in the 'functionality' module parameter. | |
27 | */ | |
28 | #define STUB_FUNC_DEFAULT \ | |
29 | (I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE | \ | |
30 | I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA | \ | |
31 | I2C_FUNC_SMBUS_I2C_BLOCK) | |
32 | ||
33 | #define STUB_FUNC_ALL \ | |
34 | (STUB_FUNC_DEFAULT | I2C_FUNC_SMBUS_BLOCK_DATA) | |
7a8d29ce | 35 | |
9d90c1fd JD |
36 | static unsigned short chip_addr[MAX_CHIPS]; |
37 | module_param_array(chip_addr, ushort, NULL, S_IRUGO); | |
38 | MODULE_PARM_DESC(chip_addr, | |
85d6931c | 39 | "Chip addresses (up to 10, between 0x03 and 0x77)"); |
9d90c1fd | 40 | |
6f16b75a | 41 | static unsigned long functionality = STUB_FUNC_DEFAULT; |
38f41f28 JD |
42 | module_param(functionality, ulong, S_IRUGO | S_IWUSR); |
43 | MODULE_PARM_DESC(functionality, "Override functionality bitfield"); | |
44 | ||
2408c17f JD |
45 | /* Some chips have banked register ranges */ |
46 | ||
47 | static u8 bank_reg[MAX_CHIPS]; | |
48 | module_param_array(bank_reg, byte, NULL, S_IRUGO); | |
49 | MODULE_PARM_DESC(bank_reg, "Bank register"); | |
50 | ||
51 | static u8 bank_mask[MAX_CHIPS]; | |
52 | module_param_array(bank_mask, byte, NULL, S_IRUGO); | |
53 | MODULE_PARM_DESC(bank_mask, "Bank value mask"); | |
54 | ||
55 | static u8 bank_start[MAX_CHIPS]; | |
56 | module_param_array(bank_start, byte, NULL, S_IRUGO); | |
57 | MODULE_PARM_DESC(bank_start, "First banked register"); | |
58 | ||
59 | static u8 bank_end[MAX_CHIPS]; | |
60 | module_param_array(bank_end, byte, NULL, S_IRUGO); | |
61 | MODULE_PARM_DESC(bank_end, "Last banked register"); | |
62 | ||
6f16b75a GR |
63 | struct smbus_block_data { |
64 | struct list_head node; | |
65 | u8 command; | |
66 | u8 len; | |
67 | u8 block[I2C_SMBUS_BLOCK_MAX]; | |
68 | }; | |
69 | ||
9d90c1fd JD |
70 | struct stub_chip { |
71 | u8 pointer; | |
569be443 JD |
72 | u16 words[256]; /* Byte operations use the LSB as per SMBus |
73 | specification */ | |
6f16b75a | 74 | struct list_head smbus_blocks; |
2408c17f JD |
75 | |
76 | /* For chips with banks, extra registers are allocated dynamically */ | |
77 | u8 bank_reg; | |
78 | u8 bank_shift; | |
79 | u8 bank_mask; | |
80 | u8 bank_sel; /* Currently selected bank */ | |
81 | u8 bank_start; | |
82 | u8 bank_end; | |
83 | u16 bank_size; | |
84 | u16 *bank_words; /* Room for bank_mask * bank_size registers */ | |
9d90c1fd JD |
85 | }; |
86 | ||
87 | static struct stub_chip *stub_chips; | |
1dff5983 | 88 | static int stub_chips_nr; |
1da177e4 | 89 | |
6f16b75a GR |
90 | static struct smbus_block_data *stub_find_block(struct device *dev, |
91 | struct stub_chip *chip, | |
92 | u8 command, bool create) | |
93 | { | |
94 | struct smbus_block_data *b, *rb = NULL; | |
95 | ||
96 | list_for_each_entry(b, &chip->smbus_blocks, node) { | |
97 | if (b->command == command) { | |
98 | rb = b; | |
99 | break; | |
100 | } | |
101 | } | |
102 | if (rb == NULL && create) { | |
103 | rb = devm_kzalloc(dev, sizeof(*rb), GFP_KERNEL); | |
104 | if (rb == NULL) | |
105 | return rb; | |
106 | rb->command = command; | |
107 | list_add(&rb->node, &chip->smbus_blocks); | |
108 | } | |
109 | return rb; | |
110 | } | |
111 | ||
2408c17f JD |
112 | static u16 *stub_get_wordp(struct stub_chip *chip, u8 offset) |
113 | { | |
114 | if (chip->bank_sel && | |
115 | offset >= chip->bank_start && offset <= chip->bank_end) | |
116 | return chip->bank_words + | |
117 | (chip->bank_sel - 1) * chip->bank_size + | |
118 | offset - chip->bank_start; | |
119 | else | |
120 | return chip->words + offset; | |
121 | } | |
122 | ||
97140342 | 123 | /* Return negative errno on error. */ |
31d178bf JD |
124 | static s32 stub_xfer(struct i2c_adapter *adap, u16 addr, unsigned short flags, |
125 | char read_write, u8 command, int size, union i2c_smbus_data *data) | |
1da177e4 LT |
126 | { |
127 | s32 ret; | |
47103178 | 128 | int i, len; |
9d90c1fd | 129 | struct stub_chip *chip = NULL; |
6f16b75a | 130 | struct smbus_block_data *b; |
2408c17f | 131 | u16 *wordp; |
9d90c1fd JD |
132 | |
133 | /* Search for the right chip */ | |
1dff5983 | 134 | for (i = 0; i < stub_chips_nr; i++) { |
9d90c1fd JD |
135 | if (addr == chip_addr[i]) { |
136 | chip = stub_chips + i; | |
137 | break; | |
138 | } | |
139 | } | |
140 | if (!chip) | |
7a8d29ce JD |
141 | return -ENODEV; |
142 | ||
1da177e4 LT |
143 | switch (size) { |
144 | ||
145 | case I2C_SMBUS_QUICK: | |
146 | dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr); | |
147 | ret = 0; | |
148 | break; | |
149 | ||
150 | case I2C_SMBUS_BYTE: | |
151 | if (read_write == I2C_SMBUS_WRITE) { | |
9d90c1fd | 152 | chip->pointer = command; |
31d178bf JD |
153 | dev_dbg(&adap->dev, |
154 | "smbus byte - addr 0x%02x, wrote 0x%02x.\n", | |
155 | addr, command); | |
1da177e4 | 156 | } else { |
2408c17f JD |
157 | wordp = stub_get_wordp(chip, chip->pointer++); |
158 | data->byte = *wordp & 0xff; | |
31d178bf JD |
159 | dev_dbg(&adap->dev, |
160 | "smbus byte - addr 0x%02x, read 0x%02x.\n", | |
161 | addr, data->byte); | |
1da177e4 LT |
162 | } |
163 | ||
164 | ret = 0; | |
165 | break; | |
166 | ||
167 | case I2C_SMBUS_BYTE_DATA: | |
2408c17f | 168 | wordp = stub_get_wordp(chip, command); |
1da177e4 | 169 | if (read_write == I2C_SMBUS_WRITE) { |
2408c17f JD |
170 | *wordp &= 0xff00; |
171 | *wordp |= data->byte; | |
31d178bf JD |
172 | dev_dbg(&adap->dev, |
173 | "smbus byte data - addr 0x%02x, wrote 0x%02x at 0x%02x.\n", | |
174 | addr, data->byte, command); | |
2408c17f JD |
175 | |
176 | /* Set the bank as needed */ | |
177 | if (chip->bank_words && command == chip->bank_reg) { | |
178 | chip->bank_sel = | |
179 | (data->byte >> chip->bank_shift) | |
180 | & chip->bank_mask; | |
181 | dev_dbg(&adap->dev, | |
182 | "switching to bank %u.\n", | |
183 | chip->bank_sel); | |
184 | } | |
1da177e4 | 185 | } else { |
2408c17f | 186 | data->byte = *wordp & 0xff; |
31d178bf JD |
187 | dev_dbg(&adap->dev, |
188 | "smbus byte data - addr 0x%02x, read 0x%02x at 0x%02x.\n", | |
189 | addr, data->byte, command); | |
1da177e4 | 190 | } |
9d90c1fd | 191 | chip->pointer = command + 1; |
1da177e4 LT |
192 | |
193 | ret = 0; | |
194 | break; | |
195 | ||
196 | case I2C_SMBUS_WORD_DATA: | |
2408c17f | 197 | wordp = stub_get_wordp(chip, command); |
1da177e4 | 198 | if (read_write == I2C_SMBUS_WRITE) { |
2408c17f | 199 | *wordp = data->word; |
31d178bf JD |
200 | dev_dbg(&adap->dev, |
201 | "smbus word data - addr 0x%02x, wrote 0x%04x at 0x%02x.\n", | |
202 | addr, data->word, command); | |
1da177e4 | 203 | } else { |
2408c17f | 204 | data->word = *wordp; |
31d178bf JD |
205 | dev_dbg(&adap->dev, |
206 | "smbus word data - addr 0x%02x, read 0x%04x at 0x%02x.\n", | |
207 | addr, data->word, command); | |
1da177e4 LT |
208 | } |
209 | ||
210 | ret = 0; | |
211 | break; | |
212 | ||
47103178 | 213 | case I2C_SMBUS_I2C_BLOCK_DATA: |
2408c17f JD |
214 | /* |
215 | * We ignore banks here, because banked chips don't use I2C | |
216 | * block transfers | |
217 | */ | |
0f6ba0d1 JD |
218 | if (data->block[0] > 256 - command) /* Avoid overrun */ |
219 | data->block[0] = 256 - command; | |
47103178 JD |
220 | len = data->block[0]; |
221 | if (read_write == I2C_SMBUS_WRITE) { | |
222 | for (i = 0; i < len; i++) { | |
223 | chip->words[command + i] &= 0xff00; | |
224 | chip->words[command + i] |= data->block[1 + i]; | |
225 | } | |
31d178bf JD |
226 | dev_dbg(&adap->dev, |
227 | "i2c block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n", | |
228 | addr, len, command); | |
47103178 JD |
229 | } else { |
230 | for (i = 0; i < len; i++) { | |
231 | data->block[1 + i] = | |
232 | chip->words[command + i] & 0xff; | |
233 | } | |
31d178bf JD |
234 | dev_dbg(&adap->dev, |
235 | "i2c block data - addr 0x%02x, read %d bytes at 0x%02x.\n", | |
236 | addr, len, command); | |
47103178 JD |
237 | } |
238 | ||
239 | ret = 0; | |
240 | break; | |
241 | ||
6f16b75a | 242 | case I2C_SMBUS_BLOCK_DATA: |
2408c17f JD |
243 | /* |
244 | * We ignore banks here, because chips typically don't use both | |
245 | * banks and SMBus block transfers | |
246 | */ | |
6f16b75a GR |
247 | b = stub_find_block(&adap->dev, chip, command, false); |
248 | if (read_write == I2C_SMBUS_WRITE) { | |
249 | len = data->block[0]; | |
250 | if (len == 0 || len > I2C_SMBUS_BLOCK_MAX) { | |
251 | ret = -EINVAL; | |
252 | break; | |
253 | } | |
254 | if (b == NULL) { | |
255 | b = stub_find_block(&adap->dev, chip, command, | |
256 | true); | |
257 | if (b == NULL) { | |
258 | ret = -ENOMEM; | |
259 | break; | |
260 | } | |
261 | } | |
262 | /* Largest write sets read block length */ | |
263 | if (len > b->len) | |
264 | b->len = len; | |
265 | for (i = 0; i < len; i++) | |
266 | b->block[i] = data->block[i + 1]; | |
267 | /* update for byte and word commands */ | |
268 | chip->words[command] = (b->block[0] << 8) | b->len; | |
269 | dev_dbg(&adap->dev, | |
270 | "smbus block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n", | |
271 | addr, len, command); | |
272 | } else { | |
273 | if (b == NULL) { | |
274 | dev_dbg(&adap->dev, | |
275 | "SMBus block read command without prior block write not supported\n"); | |
276 | ret = -EOPNOTSUPP; | |
277 | break; | |
278 | } | |
279 | len = b->len; | |
280 | data->block[0] = len; | |
281 | for (i = 0; i < len; i++) | |
282 | data->block[i + 1] = b->block[i]; | |
283 | dev_dbg(&adap->dev, | |
284 | "smbus block data - addr 0x%02x, read %d bytes at 0x%02x.\n", | |
285 | addr, len, command); | |
286 | } | |
287 | ||
288 | ret = 0; | |
289 | break; | |
290 | ||
1da177e4 LT |
291 | default: |
292 | dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n"); | |
97140342 | 293 | ret = -EOPNOTSUPP; |
1da177e4 LT |
294 | break; |
295 | } /* switch (size) */ | |
296 | ||
297 | return ret; | |
298 | } | |
299 | ||
300 | static u32 stub_func(struct i2c_adapter *adapter) | |
301 | { | |
6f16b75a | 302 | return STUB_FUNC_ALL & functionality; |
1da177e4 LT |
303 | } |
304 | ||
8f9082c5 | 305 | static const struct i2c_algorithm smbus_algorithm = { |
1da177e4 LT |
306 | .functionality = stub_func, |
307 | .smbus_xfer = stub_xfer, | |
308 | }; | |
309 | ||
310 | static struct i2c_adapter stub_adapter = { | |
311 | .owner = THIS_MODULE, | |
3401b2ff | 312 | .class = I2C_CLASS_HWMON | I2C_CLASS_SPD, |
1da177e4 LT |
313 | .algo = &smbus_algorithm, |
314 | .name = "SMBus stub driver", | |
315 | }; | |
316 | ||
2408c17f JD |
317 | static int __init i2c_stub_allocate_banks(int i) |
318 | { | |
319 | struct stub_chip *chip = stub_chips + i; | |
320 | ||
321 | chip->bank_reg = bank_reg[i]; | |
322 | chip->bank_start = bank_start[i]; | |
323 | chip->bank_end = bank_end[i]; | |
324 | chip->bank_size = bank_end[i] - bank_start[i] + 1; | |
325 | ||
326 | /* We assume that all bits in the mask are contiguous */ | |
327 | chip->bank_mask = bank_mask[i]; | |
328 | while (!(chip->bank_mask & 1)) { | |
329 | chip->bank_shift++; | |
330 | chip->bank_mask >>= 1; | |
331 | } | |
332 | ||
6396bb22 KC |
333 | chip->bank_words = kcalloc(chip->bank_mask * chip->bank_size, |
334 | sizeof(u16), | |
335 | GFP_KERNEL); | |
2408c17f JD |
336 | if (!chip->bank_words) |
337 | return -ENOMEM; | |
338 | ||
6c427787 | 339 | pr_debug("Allocated %u banks of %u words each (registers 0x%02x to 0x%02x)\n", |
2408c17f JD |
340 | chip->bank_mask, chip->bank_size, chip->bank_start, |
341 | chip->bank_end); | |
342 | ||
343 | return 0; | |
344 | } | |
345 | ||
346 | static void i2c_stub_free(void) | |
347 | { | |
348 | int i; | |
349 | ||
350 | for (i = 0; i < stub_chips_nr; i++) | |
351 | kfree(stub_chips[i].bank_words); | |
352 | kfree(stub_chips); | |
353 | } | |
354 | ||
1da177e4 LT |
355 | static int __init i2c_stub_init(void) |
356 | { | |
9d90c1fd JD |
357 | int i, ret; |
358 | ||
359 | if (!chip_addr[0]) { | |
6c427787 | 360 | pr_err("Please specify a chip address\n"); |
7a8d29ce JD |
361 | return -ENODEV; |
362 | } | |
9d90c1fd JD |
363 | |
364 | for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) { | |
365 | if (chip_addr[i] < 0x03 || chip_addr[i] > 0x77) { | |
6c427787 | 366 | pr_err("Invalid chip address 0x%02x\n", |
31d178bf | 367 | chip_addr[i]); |
9d90c1fd JD |
368 | return -EINVAL; |
369 | } | |
370 | ||
6c427787 | 371 | pr_info("Virtual chip at 0x%02x\n", chip_addr[i]); |
7a8d29ce JD |
372 | } |
373 | ||
9d90c1fd | 374 | /* Allocate memory for all chips at once */ |
1dff5983 JD |
375 | stub_chips_nr = i; |
376 | stub_chips = kcalloc(stub_chips_nr, sizeof(struct stub_chip), | |
377 | GFP_KERNEL); | |
6c427787 | 378 | if (!stub_chips) |
9d90c1fd | 379 | return -ENOMEM; |
6c427787 | 380 | |
2408c17f | 381 | for (i = 0; i < stub_chips_nr; i++) { |
6f16b75a | 382 | INIT_LIST_HEAD(&stub_chips[i].smbus_blocks); |
9d90c1fd | 383 | |
2408c17f JD |
384 | /* Allocate extra memory for banked register ranges */ |
385 | if (bank_mask[i]) { | |
386 | ret = i2c_stub_allocate_banks(i); | |
387 | if (ret) | |
388 | goto fail_free; | |
389 | } | |
390 | } | |
391 | ||
9d90c1fd JD |
392 | ret = i2c_add_adapter(&stub_adapter); |
393 | if (ret) | |
2408c17f JD |
394 | goto fail_free; |
395 | ||
396 | return 0; | |
397 | ||
398 | fail_free: | |
399 | i2c_stub_free(); | |
9d90c1fd | 400 | return ret; |
1da177e4 LT |
401 | } |
402 | ||
403 | static void __exit i2c_stub_exit(void) | |
404 | { | |
405 | i2c_del_adapter(&stub_adapter); | |
2408c17f | 406 | i2c_stub_free(); |
1da177e4 LT |
407 | } |
408 | ||
409 | MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>"); | |
410 | MODULE_DESCRIPTION("I2C stub driver"); | |
411 | MODULE_LICENSE("GPL"); | |
412 | ||
413 | module_init(i2c_stub_init); | |
414 | module_exit(i2c_stub_exit); |