GNU Linux-libre 4.4.289-gnu1
[releases.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) 2007-2014 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
20 #include <linux/init.h>
21 #include <linux/module.h>
22 #include <linux/kernel.h>
23 #include <linux/slab.h>
24 #include <linux/errno.h>
25 #include <linux/i2c.h>
26 #include <linux/list.h>
27
28 #define MAX_CHIPS 10
29
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)
42
43 static unsigned short chip_addr[MAX_CHIPS];
44 module_param_array(chip_addr, ushort, NULL, S_IRUGO);
45 MODULE_PARM_DESC(chip_addr,
46                  "Chip addresses (up to 10, between 0x03 and 0x77)");
47
48 static unsigned long functionality = STUB_FUNC_DEFAULT;
49 module_param(functionality, ulong, S_IRUGO | S_IWUSR);
50 MODULE_PARM_DESC(functionality, "Override functionality bitfield");
51
52 /* Some chips have banked register ranges */
53
54 static u8 bank_reg[MAX_CHIPS];
55 module_param_array(bank_reg, byte, NULL, S_IRUGO);
56 MODULE_PARM_DESC(bank_reg, "Bank register");
57
58 static u8 bank_mask[MAX_CHIPS];
59 module_param_array(bank_mask, byte, NULL, S_IRUGO);
60 MODULE_PARM_DESC(bank_mask, "Bank value mask");
61
62 static u8 bank_start[MAX_CHIPS];
63 module_param_array(bank_start, byte, NULL, S_IRUGO);
64 MODULE_PARM_DESC(bank_start, "First banked register");
65
66 static u8 bank_end[MAX_CHIPS];
67 module_param_array(bank_end, byte, NULL, S_IRUGO);
68 MODULE_PARM_DESC(bank_end, "Last banked register");
69
70 struct smbus_block_data {
71         struct list_head node;
72         u8 command;
73         u8 len;
74         u8 block[I2C_SMBUS_BLOCK_MAX];
75 };
76
77 struct stub_chip {
78         u8 pointer;
79         u16 words[256];         /* Byte operations use the LSB as per SMBus
80                                    specification */
81         struct list_head smbus_blocks;
82
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 */
92 };
93
94 static struct stub_chip *stub_chips;
95 static int stub_chips_nr;
96
97 static 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
119 static 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
130 /* Return negative errno on error. */
131 static 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)
133 {
134         s32 ret;
135         int i, len;
136         struct stub_chip *chip = NULL;
137         struct smbus_block_data *b;
138         u16 *wordp;
139
140         /* Search for the right chip */
141         for (i = 0; i < stub_chips_nr; i++) {
142                 if (addr == chip_addr[i]) {
143                         chip = stub_chips + i;
144                         break;
145                 }
146         }
147         if (!chip)
148                 return -ENODEV;
149
150         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) {
159                         chip->pointer = command;
160                         dev_dbg(&adap->dev,
161                                 "smbus byte - addr 0x%02x, wrote 0x%02x.\n",
162                                 addr, command);
163                 } else {
164                         wordp = stub_get_wordp(chip, chip->pointer++);
165                         data->byte = *wordp & 0xff;
166                         dev_dbg(&adap->dev,
167                                 "smbus byte - addr 0x%02x, read  0x%02x.\n",
168                                 addr, data->byte);
169                 }
170
171                 ret = 0;
172                 break;
173
174         case I2C_SMBUS_BYTE_DATA:
175                 wordp = stub_get_wordp(chip, command);
176                 if (read_write == I2C_SMBUS_WRITE) {
177                         *wordp &= 0xff00;
178                         *wordp |= data->byte;
179                         dev_dbg(&adap->dev,
180                                 "smbus byte data - addr 0x%02x, wrote 0x%02x at 0x%02x.\n",
181                                 addr, data->byte, command);
182
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                         }
192                 } else {
193                         data->byte = *wordp & 0xff;
194                         dev_dbg(&adap->dev,
195                                 "smbus byte data - addr 0x%02x, read  0x%02x at 0x%02x.\n",
196                                 addr, data->byte, command);
197                 }
198                 chip->pointer = command + 1;
199
200                 ret = 0;
201                 break;
202
203         case I2C_SMBUS_WORD_DATA:
204                 wordp = stub_get_wordp(chip, command);
205                 if (read_write == I2C_SMBUS_WRITE) {
206                         *wordp = data->word;
207                         dev_dbg(&adap->dev,
208                                 "smbus word data - addr 0x%02x, wrote 0x%04x at 0x%02x.\n",
209                                 addr, data->word, command);
210                 } else {
211                         data->word = *wordp;
212                         dev_dbg(&adap->dev,
213                                 "smbus word data - addr 0x%02x, read  0x%04x at 0x%02x.\n",
214                                 addr, data->word, command);
215                 }
216
217                 ret = 0;
218                 break;
219
220         case I2C_SMBUS_I2C_BLOCK_DATA:
221                 /*
222                  * We ignore banks here, because banked chips don't use I2C
223                  * block transfers
224                  */
225                 if (data->block[0] > 256 - command)     /* Avoid overrun */
226                         data->block[0] = 256 - command;
227                 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                         }
233                         dev_dbg(&adap->dev,
234                                 "i2c block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n",
235                                 addr, len, command);
236                 } else {
237                         for (i = 0; i < len; i++) {
238                                 data->block[1 + i] =
239                                         chip->words[command + i] & 0xff;
240                         }
241                         dev_dbg(&adap->dev,
242                                 "i2c block data - addr 0x%02x, read  %d bytes at 0x%02x.\n",
243                                 addr, len, command);
244                 }
245
246                 ret = 0;
247                 break;
248
249         case I2C_SMBUS_BLOCK_DATA:
250                 /*
251                  * We ignore banks here, because chips typically don't use both
252                  * banks and SMBus block transfers
253                  */
254                 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
298         default:
299                 dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n");
300                 ret = -EOPNOTSUPP;
301                 break;
302         } /* switch (size) */
303
304         return ret;
305 }
306
307 static u32 stub_func(struct i2c_adapter *adapter)
308 {
309         return STUB_FUNC_ALL & functionality;
310 }
311
312 static const struct i2c_algorithm smbus_algorithm = {
313         .functionality  = stub_func,
314         .smbus_xfer     = stub_xfer,
315 };
316
317 static struct i2c_adapter stub_adapter = {
318         .owner          = THIS_MODULE,
319         .class          = I2C_CLASS_HWMON | I2C_CLASS_SPD,
320         .algo           = &smbus_algorithm,
321         .name           = "SMBus stub driver",
322 };
323
324 static 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
352 static 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
361 static int __init i2c_stub_init(void)
362 {
363         int i, ret;
364
365         if (!chip_addr[0]) {
366                 pr_err("i2c-stub: Please specify a chip address\n");
367                 return -ENODEV;
368         }
369
370         for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) {
371                 if (chip_addr[i] < 0x03 || chip_addr[i] > 0x77) {
372                         pr_err("i2c-stub: Invalid chip address 0x%02x\n",
373                                chip_addr[i]);
374                         return -EINVAL;
375                 }
376
377                 pr_info("i2c-stub: Virtual chip at 0x%02x\n", chip_addr[i]);
378         }
379
380         /* Allocate memory for all chips at once */
381         stub_chips_nr = i;
382         stub_chips = kcalloc(stub_chips_nr, sizeof(struct stub_chip),
383                              GFP_KERNEL);
384         if (!stub_chips) {
385                 pr_err("i2c-stub: Out of memory\n");
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);