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1 | /* | |
2 | i2c-stub.c - I2C/SMBus chip emulator | |
3 | ||
4 | Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com> | |
5 | Copyright (C) 2007-2014 Jean Delvare <jdelvare@suse.de> | |
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 | ||
18 | #define DEBUG 1 | |
19 | #define pr_fmt(fmt) "i2c-stub: " fmt | |
20 | ||
21 | #include <linux/errno.h> | |
22 | #include <linux/i2c.h> | |
23 | #include <linux/init.h> | |
24 | #include <linux/kernel.h> | |
25 | #include <linux/list.h> | |
26 | #include <linux/module.h> | |
27 | #include <linux/slab.h> | |
28 | ||
29 | #define MAX_CHIPS 10 | |
30 | ||
31 | /* | |
32 | * Support for I2C_FUNC_SMBUS_BLOCK_DATA is disabled by default and must | |
33 | * be enabled explicitly by setting the I2C_FUNC_SMBUS_BLOCK_DATA bits | |
34 | * in the 'functionality' module parameter. | |
35 | */ | |
36 | #define STUB_FUNC_DEFAULT \ | |
37 | (I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE | \ | |
38 | I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA | \ | |
39 | I2C_FUNC_SMBUS_I2C_BLOCK) | |
40 | ||
41 | #define STUB_FUNC_ALL \ | |
42 | (STUB_FUNC_DEFAULT | I2C_FUNC_SMBUS_BLOCK_DATA) | |
43 | ||
44 | static unsigned short chip_addr[MAX_CHIPS]; | |
45 | module_param_array(chip_addr, ushort, NULL, S_IRUGO); | |
46 | MODULE_PARM_DESC(chip_addr, | |
47 | "Chip addresses (up to 10, between 0x03 and 0x77)"); | |
48 | ||
49 | static unsigned long functionality = STUB_FUNC_DEFAULT; | |
50 | module_param(functionality, ulong, S_IRUGO | S_IWUSR); | |
51 | MODULE_PARM_DESC(functionality, "Override functionality bitfield"); | |
52 | ||
53 | /* Some chips have banked register ranges */ | |
54 | ||
55 | static u8 bank_reg[MAX_CHIPS]; | |
56 | module_param_array(bank_reg, byte, NULL, S_IRUGO); | |
57 | MODULE_PARM_DESC(bank_reg, "Bank register"); | |
58 | ||
59 | static u8 bank_mask[MAX_CHIPS]; | |
60 | module_param_array(bank_mask, byte, NULL, S_IRUGO); | |
61 | MODULE_PARM_DESC(bank_mask, "Bank value mask"); | |
62 | ||
63 | static u8 bank_start[MAX_CHIPS]; | |
64 | module_param_array(bank_start, byte, NULL, S_IRUGO); | |
65 | MODULE_PARM_DESC(bank_start, "First banked register"); | |
66 | ||
67 | static u8 bank_end[MAX_CHIPS]; | |
68 | module_param_array(bank_end, byte, NULL, S_IRUGO); | |
69 | MODULE_PARM_DESC(bank_end, "Last banked register"); | |
70 | ||
71 | struct smbus_block_data { | |
72 | struct list_head node; | |
73 | u8 command; | |
74 | u8 len; | |
75 | u8 block[I2C_SMBUS_BLOCK_MAX]; | |
76 | }; | |
77 | ||
78 | struct stub_chip { | |
79 | u8 pointer; | |
80 | u16 words[256]; /* Byte operations use the LSB as per SMBus | |
81 | specification */ | |
82 | struct list_head smbus_blocks; | |
83 | ||
84 | /* For chips with banks, extra registers are allocated dynamically */ | |
85 | u8 bank_reg; | |
86 | u8 bank_shift; | |
87 | u8 bank_mask; | |
88 | u8 bank_sel; /* Currently selected bank */ | |
89 | u8 bank_start; | |
90 | u8 bank_end; | |
91 | u16 bank_size; | |
92 | u16 *bank_words; /* Room for bank_mask * bank_size registers */ | |
93 | }; | |
94 | ||
95 | static struct stub_chip *stub_chips; | |
96 | static int stub_chips_nr; | |
97 | ||
98 | static struct smbus_block_data *stub_find_block(struct device *dev, | |
99 | struct stub_chip *chip, | |
100 | u8 command, bool create) | |
101 | { | |
102 | struct smbus_block_data *b, *rb = NULL; | |
103 | ||
104 | list_for_each_entry(b, &chip->smbus_blocks, node) { | |
105 | if (b->command == command) { | |
106 | rb = b; | |
107 | break; | |
108 | } | |
109 | } | |
110 | if (rb == NULL && create) { | |
111 | rb = devm_kzalloc(dev, sizeof(*rb), GFP_KERNEL); | |
112 | if (rb == NULL) | |
113 | return rb; | |
114 | rb->command = command; | |
115 | list_add(&rb->node, &chip->smbus_blocks); | |
116 | } | |
117 | return rb; | |
118 | } | |
119 | ||
120 | static u16 *stub_get_wordp(struct stub_chip *chip, u8 offset) | |
121 | { | |
122 | if (chip->bank_sel && | |
123 | offset >= chip->bank_start && offset <= chip->bank_end) | |
124 | return chip->bank_words + | |
125 | (chip->bank_sel - 1) * chip->bank_size + | |
126 | offset - chip->bank_start; | |
127 | else | |
128 | return chip->words + offset; | |
129 | } | |
130 | ||
131 | /* Return negative errno on error. */ | |
132 | static s32 stub_xfer(struct i2c_adapter *adap, u16 addr, unsigned short flags, | |
133 | char read_write, u8 command, int size, union i2c_smbus_data *data) | |
134 | { | |
135 | s32 ret; | |
136 | int i, len; | |
137 | struct stub_chip *chip = NULL; | |
138 | struct smbus_block_data *b; | |
139 | u16 *wordp; | |
140 | ||
141 | /* Search for the right chip */ | |
142 | for (i = 0; i < stub_chips_nr; i++) { | |
143 | if (addr == chip_addr[i]) { | |
144 | chip = stub_chips + i; | |
145 | break; | |
146 | } | |
147 | } | |
148 | if (!chip) | |
149 | return -ENODEV; | |
150 | ||
151 | switch (size) { | |
152 | ||
153 | case I2C_SMBUS_QUICK: | |
154 | dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr); | |
155 | ret = 0; | |
156 | break; | |
157 | ||
158 | case I2C_SMBUS_BYTE: | |
159 | if (read_write == I2C_SMBUS_WRITE) { | |
160 | chip->pointer = command; | |
161 | dev_dbg(&adap->dev, | |
162 | "smbus byte - addr 0x%02x, wrote 0x%02x.\n", | |
163 | addr, command); | |
164 | } else { | |
165 | wordp = stub_get_wordp(chip, chip->pointer++); | |
166 | data->byte = *wordp & 0xff; | |
167 | dev_dbg(&adap->dev, | |
168 | "smbus byte - addr 0x%02x, read 0x%02x.\n", | |
169 | addr, data->byte); | |
170 | } | |
171 | ||
172 | ret = 0; | |
173 | break; | |
174 | ||
175 | case I2C_SMBUS_BYTE_DATA: | |
176 | wordp = stub_get_wordp(chip, command); | |
177 | if (read_write == I2C_SMBUS_WRITE) { | |
178 | *wordp &= 0xff00; | |
179 | *wordp |= data->byte; | |
180 | dev_dbg(&adap->dev, | |
181 | "smbus byte data - addr 0x%02x, wrote 0x%02x at 0x%02x.\n", | |
182 | addr, data->byte, command); | |
183 | ||
184 | /* Set the bank as needed */ | |
185 | if (chip->bank_words && command == chip->bank_reg) { | |
186 | chip->bank_sel = | |
187 | (data->byte >> chip->bank_shift) | |
188 | & chip->bank_mask; | |
189 | dev_dbg(&adap->dev, | |
190 | "switching to bank %u.\n", | |
191 | chip->bank_sel); | |
192 | } | |
193 | } else { | |
194 | data->byte = *wordp & 0xff; | |
195 | dev_dbg(&adap->dev, | |
196 | "smbus byte data - addr 0x%02x, read 0x%02x at 0x%02x.\n", | |
197 | addr, data->byte, command); | |
198 | } | |
199 | chip->pointer = command + 1; | |
200 | ||
201 | ret = 0; | |
202 | break; | |
203 | ||
204 | case I2C_SMBUS_WORD_DATA: | |
205 | wordp = stub_get_wordp(chip, command); | |
206 | if (read_write == I2C_SMBUS_WRITE) { | |
207 | *wordp = data->word; | |
208 | dev_dbg(&adap->dev, | |
209 | "smbus word data - addr 0x%02x, wrote 0x%04x at 0x%02x.\n", | |
210 | addr, data->word, command); | |
211 | } else { | |
212 | data->word = *wordp; | |
213 | dev_dbg(&adap->dev, | |
214 | "smbus word data - addr 0x%02x, read 0x%04x at 0x%02x.\n", | |
215 | addr, data->word, command); | |
216 | } | |
217 | ||
218 | ret = 0; | |
219 | break; | |
220 | ||
221 | case I2C_SMBUS_I2C_BLOCK_DATA: | |
222 | /* | |
223 | * We ignore banks here, because banked chips don't use I2C | |
224 | * block transfers | |
225 | */ | |
226 | if (data->block[0] > 256 - command) /* Avoid overrun */ | |
227 | data->block[0] = 256 - command; | |
228 | len = data->block[0]; | |
229 | if (read_write == I2C_SMBUS_WRITE) { | |
230 | for (i = 0; i < len; i++) { | |
231 | chip->words[command + i] &= 0xff00; | |
232 | chip->words[command + i] |= data->block[1 + i]; | |
233 | } | |
234 | dev_dbg(&adap->dev, | |
235 | "i2c block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n", | |
236 | addr, len, command); | |
237 | } else { | |
238 | for (i = 0; i < len; i++) { | |
239 | data->block[1 + i] = | |
240 | chip->words[command + i] & 0xff; | |
241 | } | |
242 | dev_dbg(&adap->dev, | |
243 | "i2c block data - addr 0x%02x, read %d bytes at 0x%02x.\n", | |
244 | addr, len, command); | |
245 | } | |
246 | ||
247 | ret = 0; | |
248 | break; | |
249 | ||
250 | case I2C_SMBUS_BLOCK_DATA: | |
251 | /* | |
252 | * We ignore banks here, because chips typically don't use both | |
253 | * banks and SMBus block transfers | |
254 | */ | |
255 | b = stub_find_block(&adap->dev, chip, command, false); | |
256 | if (read_write == I2C_SMBUS_WRITE) { | |
257 | len = data->block[0]; | |
258 | if (len == 0 || len > I2C_SMBUS_BLOCK_MAX) { | |
259 | ret = -EINVAL; | |
260 | break; | |
261 | } | |
262 | if (b == NULL) { | |
263 | b = stub_find_block(&adap->dev, chip, command, | |
264 | true); | |
265 | if (b == NULL) { | |
266 | ret = -ENOMEM; | |
267 | break; | |
268 | } | |
269 | } | |
270 | /* Largest write sets read block length */ | |
271 | if (len > b->len) | |
272 | b->len = len; | |
273 | for (i = 0; i < len; i++) | |
274 | b->block[i] = data->block[i + 1]; | |
275 | /* update for byte and word commands */ | |
276 | chip->words[command] = (b->block[0] << 8) | b->len; | |
277 | dev_dbg(&adap->dev, | |
278 | "smbus block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n", | |
279 | addr, len, command); | |
280 | } else { | |
281 | if (b == NULL) { | |
282 | dev_dbg(&adap->dev, | |
283 | "SMBus block read command without prior block write not supported\n"); | |
284 | ret = -EOPNOTSUPP; | |
285 | break; | |
286 | } | |
287 | len = b->len; | |
288 | data->block[0] = len; | |
289 | for (i = 0; i < len; i++) | |
290 | data->block[i + 1] = b->block[i]; | |
291 | dev_dbg(&adap->dev, | |
292 | "smbus block data - addr 0x%02x, read %d bytes at 0x%02x.\n", | |
293 | addr, len, command); | |
294 | } | |
295 | ||
296 | ret = 0; | |
297 | break; | |
298 | ||
299 | default: | |
300 | dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n"); | |
301 | ret = -EOPNOTSUPP; | |
302 | break; | |
303 | } /* switch (size) */ | |
304 | ||
305 | return ret; | |
306 | } | |
307 | ||
308 | static u32 stub_func(struct i2c_adapter *adapter) | |
309 | { | |
310 | return STUB_FUNC_ALL & functionality; | |
311 | } | |
312 | ||
313 | static const struct i2c_algorithm smbus_algorithm = { | |
314 | .functionality = stub_func, | |
315 | .smbus_xfer = stub_xfer, | |
316 | }; | |
317 | ||
318 | static struct i2c_adapter stub_adapter = { | |
319 | .owner = THIS_MODULE, | |
320 | .class = I2C_CLASS_HWMON | I2C_CLASS_SPD, | |
321 | .algo = &smbus_algorithm, | |
322 | .name = "SMBus stub driver", | |
323 | }; | |
324 | ||
325 | static int __init i2c_stub_allocate_banks(int i) | |
326 | { | |
327 | struct stub_chip *chip = stub_chips + i; | |
328 | ||
329 | chip->bank_reg = bank_reg[i]; | |
330 | chip->bank_start = bank_start[i]; | |
331 | chip->bank_end = bank_end[i]; | |
332 | chip->bank_size = bank_end[i] - bank_start[i] + 1; | |
333 | ||
334 | /* We assume that all bits in the mask are contiguous */ | |
335 | chip->bank_mask = bank_mask[i]; | |
336 | while (!(chip->bank_mask & 1)) { | |
337 | chip->bank_shift++; | |
338 | chip->bank_mask >>= 1; | |
339 | } | |
340 | ||
341 | chip->bank_words = kzalloc(chip->bank_mask * chip->bank_size * | |
342 | sizeof(u16), GFP_KERNEL); | |
343 | if (!chip->bank_words) | |
344 | return -ENOMEM; | |
345 | ||
346 | pr_debug("Allocated %u banks of %u words each (registers 0x%02x to 0x%02x)\n", | |
347 | chip->bank_mask, chip->bank_size, chip->bank_start, | |
348 | chip->bank_end); | |
349 | ||
350 | return 0; | |
351 | } | |
352 | ||
353 | static void i2c_stub_free(void) | |
354 | { | |
355 | int i; | |
356 | ||
357 | for (i = 0; i < stub_chips_nr; i++) | |
358 | kfree(stub_chips[i].bank_words); | |
359 | kfree(stub_chips); | |
360 | } | |
361 | ||
362 | static int __init i2c_stub_init(void) | |
363 | { | |
364 | int i, ret; | |
365 | ||
366 | if (!chip_addr[0]) { | |
367 | pr_err("Please specify a chip address\n"); | |
368 | return -ENODEV; | |
369 | } | |
370 | ||
371 | for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) { | |
372 | if (chip_addr[i] < 0x03 || chip_addr[i] > 0x77) { | |
373 | pr_err("Invalid chip address 0x%02x\n", | |
374 | chip_addr[i]); | |
375 | return -EINVAL; | |
376 | } | |
377 | ||
378 | pr_info("Virtual chip at 0x%02x\n", chip_addr[i]); | |
379 | } | |
380 | ||
381 | /* Allocate memory for all chips at once */ | |
382 | stub_chips_nr = i; | |
383 | stub_chips = kcalloc(stub_chips_nr, sizeof(struct stub_chip), | |
384 | GFP_KERNEL); | |
385 | if (!stub_chips) | |
386 | return -ENOMEM; | |
387 | ||
388 | for (i = 0; i < stub_chips_nr; i++) { | |
389 | INIT_LIST_HEAD(&stub_chips[i].smbus_blocks); | |
390 | ||
391 | /* 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 | ||
399 | ret = i2c_add_adapter(&stub_adapter); | |
400 | if (ret) | |
401 | goto fail_free; | |
402 | ||
403 | return 0; | |
404 | ||
405 | fail_free: | |
406 | i2c_stub_free(); | |
407 | return ret; | |
408 | } | |
409 | ||
410 | static void __exit i2c_stub_exit(void) | |
411 | { | |
412 | i2c_del_adapter(&stub_adapter); | |
413 | i2c_stub_free(); | |
414 | } | |
415 | ||
416 | MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>"); | |
417 | MODULE_DESCRIPTION("I2C stub driver"); | |
418 | MODULE_LICENSE("GPL"); | |
419 | ||
420 | module_init(i2c_stub_init); | |
421 | module_exit(i2c_stub_exit); |