Merge tag 'ntb-5.3' of git://github.com/jonmason/ntb
[linux-2.6-microblaze.git] / drivers / i2c / i2c-stub.c
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3     i2c-stub.c - I2C/SMBus chip emulator
4
5     Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com>
6     Copyright (C) 2007-2014 Jean Delvare <jdelvare@suse.de>
7
8 */
9
10 #define DEBUG 1
11 #define pr_fmt(fmt) "i2c-stub: " fmt
12
13 #include <linux/errno.h>
14 #include <linux/i2c.h>
15 #include <linux/init.h>
16 #include <linux/kernel.h>
17 #include <linux/list.h>
18 #include <linux/module.h>
19 #include <linux/slab.h>
20
21 #define MAX_CHIPS 10
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)
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_DEFAULT;
42 module_param(functionality, ulong, S_IRUGO | S_IWUSR);
43 MODULE_PARM_DESC(functionality, "Override functionality bitfield");
44
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
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
70 struct stub_chip {
71         u8 pointer;
72         u16 words[256];         /* Byte operations use the LSB as per SMBus
73                                    specification */
74         struct list_head smbus_blocks;
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 */
85 };
86
87 static struct stub_chip *stub_chips;
88 static int stub_chips_nr;
89
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
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
123 /* Return negative errno on error. */
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)
126 {
127         s32 ret;
128         int i, len;
129         struct stub_chip *chip = NULL;
130         struct smbus_block_data *b;
131         u16 *wordp;
132
133         /* Search for the right chip */
134         for (i = 0; i < stub_chips_nr; i++) {
135                 if (addr == chip_addr[i]) {
136                         chip = stub_chips + i;
137                         break;
138                 }
139         }
140         if (!chip)
141                 return -ENODEV;
142
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) {
152                         chip->pointer = command;
153                         dev_dbg(&adap->dev,
154                                 "smbus byte - addr 0x%02x, wrote 0x%02x.\n",
155                                 addr, command);
156                 } else {
157                         wordp = stub_get_wordp(chip, chip->pointer++);
158                         data->byte = *wordp & 0xff;
159                         dev_dbg(&adap->dev,
160                                 "smbus byte - addr 0x%02x, read  0x%02x.\n",
161                                 addr, data->byte);
162                 }
163
164                 ret = 0;
165                 break;
166
167         case I2C_SMBUS_BYTE_DATA:
168                 wordp = stub_get_wordp(chip, command);
169                 if (read_write == I2C_SMBUS_WRITE) {
170                         *wordp &= 0xff00;
171                         *wordp |= data->byte;
172                         dev_dbg(&adap->dev,
173                                 "smbus byte data - addr 0x%02x, wrote 0x%02x at 0x%02x.\n",
174                                 addr, data->byte, command);
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                         }
185                 } else {
186                         data->byte = *wordp & 0xff;
187                         dev_dbg(&adap->dev,
188                                 "smbus byte data - addr 0x%02x, read  0x%02x at 0x%02x.\n",
189                                 addr, data->byte, command);
190                 }
191                 chip->pointer = command + 1;
192
193                 ret = 0;
194                 break;
195
196         case I2C_SMBUS_WORD_DATA:
197                 wordp = stub_get_wordp(chip, command);
198                 if (read_write == I2C_SMBUS_WRITE) {
199                         *wordp = data->word;
200                         dev_dbg(&adap->dev,
201                                 "smbus word data - addr 0x%02x, wrote 0x%04x at 0x%02x.\n",
202                                 addr, data->word, command);
203                 } else {
204                         data->word = *wordp;
205                         dev_dbg(&adap->dev,
206                                 "smbus word data - addr 0x%02x, read  0x%04x at 0x%02x.\n",
207                                 addr, data->word, command);
208                 }
209
210                 ret = 0;
211                 break;
212
213         case I2C_SMBUS_I2C_BLOCK_DATA:
214                 /*
215                  * We ignore banks here, because banked chips don't use I2C
216                  * block transfers
217                  */
218                 if (data->block[0] > 256 - command)     /* Avoid overrun */
219                         data->block[0] = 256 - command;
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                         }
226                         dev_dbg(&adap->dev,
227                                 "i2c block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n",
228                                 addr, len, command);
229                 } else {
230                         for (i = 0; i < len; i++) {
231                                 data->block[1 + i] =
232                                         chip->words[command + i] & 0xff;
233                         }
234                         dev_dbg(&adap->dev,
235                                 "i2c block data - addr 0x%02x, read  %d bytes at 0x%02x.\n",
236                                 addr, len, command);
237                 }
238
239                 ret = 0;
240                 break;
241
242         case I2C_SMBUS_BLOCK_DATA:
243                 /*
244                  * We ignore banks here, because chips typically don't use both
245                  * banks and SMBus block transfers
246                  */
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
291         default:
292                 dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n");
293                 ret = -EOPNOTSUPP;
294                 break;
295         } /* switch (size) */
296
297         return ret;
298 }
299
300 static u32 stub_func(struct i2c_adapter *adapter)
301 {
302         return STUB_FUNC_ALL & functionality;
303 }
304
305 static const struct i2c_algorithm smbus_algorithm = {
306         .functionality  = stub_func,
307         .smbus_xfer     = stub_xfer,
308 };
309
310 static struct i2c_adapter stub_adapter = {
311         .owner          = THIS_MODULE,
312         .class          = I2C_CLASS_HWMON | I2C_CLASS_SPD,
313         .algo           = &smbus_algorithm,
314         .name           = "SMBus stub driver",
315 };
316
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
333         chip->bank_words = kcalloc(chip->bank_mask * chip->bank_size,
334                                    sizeof(u16),
335                                    GFP_KERNEL);
336         if (!chip->bank_words)
337                 return -ENOMEM;
338
339         pr_debug("Allocated %u banks of %u words each (registers 0x%02x to 0x%02x)\n",
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
355 static int __init i2c_stub_init(void)
356 {
357         int i, ret;
358
359         if (!chip_addr[0]) {
360                 pr_err("Please specify a chip address\n");
361                 return -ENODEV;
362         }
363
364         for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) {
365                 if (chip_addr[i] < 0x03 || chip_addr[i] > 0x77) {
366                         pr_err("Invalid chip address 0x%02x\n",
367                                chip_addr[i]);
368                         return -EINVAL;
369                 }
370
371                 pr_info("Virtual chip at 0x%02x\n", chip_addr[i]);
372         }
373
374         /* Allocate memory for all chips at once */
375         stub_chips_nr = i;
376         stub_chips = kcalloc(stub_chips_nr, sizeof(struct stub_chip),
377                              GFP_KERNEL);
378         if (!stub_chips)
379                 return -ENOMEM;
380
381         for (i = 0; i < stub_chips_nr; i++) {
382                 INIT_LIST_HEAD(&stub_chips[i].smbus_blocks);
383
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
392         ret = i2c_add_adapter(&stub_adapter);
393         if (ret)
394                 goto fail_free;
395
396         return 0;
397
398  fail_free:
399         i2c_stub_free();
400         return ret;
401 }
402
403 static void __exit i2c_stub_exit(void)
404 {
405         i2c_del_adapter(&stub_adapter);
406         i2c_stub_free();
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);