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18#define DEBUG 1
19
20#include <linux/errno.h>
21#include <linux/i2c.h>
22#include <linux/init.h>
23#include <linux/kernel.h>
24#include <linux/list.h>
25#include <linux/module.h>
26#include <linux/slab.h>
27
28#define MAX_CHIPS 10
29
30
31
32
33
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
43static unsigned short chip_addr[MAX_CHIPS];
44module_param_array(chip_addr, ushort, NULL, S_IRUGO);
45MODULE_PARM_DESC(chip_addr,
46 "Chip addresses (up to 10, between 0x03 and 0x77)");
47
48static unsigned long functionality = STUB_FUNC_DEFAULT;
49module_param(functionality, ulong, S_IRUGO | S_IWUSR);
50MODULE_PARM_DESC(functionality, "Override functionality bitfield");
51
52
53
54static u8 bank_reg[MAX_CHIPS];
55module_param_array(bank_reg, byte, NULL, S_IRUGO);
56MODULE_PARM_DESC(bank_reg, "Bank register");
57
58static u8 bank_mask[MAX_CHIPS];
59module_param_array(bank_mask, byte, NULL, S_IRUGO);
60MODULE_PARM_DESC(bank_mask, "Bank value mask");
61
62static u8 bank_start[MAX_CHIPS];
63module_param_array(bank_start, byte, NULL, S_IRUGO);
64MODULE_PARM_DESC(bank_start, "First banked register");
65
66static u8 bank_end[MAX_CHIPS];
67module_param_array(bank_end, byte, NULL, S_IRUGO);
68MODULE_PARM_DESC(bank_end, "Last banked register");
69
70struct smbus_block_data {
71 struct list_head node;
72 u8 command;
73 u8 len;
74 u8 block[I2C_SMBUS_BLOCK_MAX];
75};
76
77struct stub_chip {
78 u8 pointer;
79 u16 words[256];
80
81 struct list_head smbus_blocks;
82
83
84 u8 bank_reg;
85 u8 bank_shift;
86 u8 bank_mask;
87 u8 bank_sel;
88 u8 bank_start;
89 u8 bank_end;
90 u16 bank_size;
91 u16 *bank_words;
92};
93
94static struct stub_chip *stub_chips;
95static int stub_chips_nr;
96
97static 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
119static 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
131static 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
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
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
223
224
225 if (data->block[0] > 256 - command)
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
252
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
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
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 }
303
304 return ret;
305}
306
307static u32 stub_func(struct i2c_adapter *adapter)
308{
309 return STUB_FUNC_ALL & functionality;
310}
311
312static const struct i2c_algorithm smbus_algorithm = {
313 .functionality = stub_func,
314 .smbus_xfer = stub_xfer,
315};
316
317static 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
324static 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
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
352static 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
361static 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
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
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
410static void __exit i2c_stub_exit(void)
411{
412 i2c_del_adapter(&stub_adapter);
413 i2c_stub_free();
414}
415
416MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
417MODULE_DESCRIPTION("I2C stub driver");
418MODULE_LICENSE("GPL");
419
420module_init(i2c_stub_init);
421module_exit(i2c_stub_exit);
422
