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