2 i2c-stub.c - I2C/SMBus chip emulator
4 Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com>
5 Copyright (C) 2007-2014 Jean Delvare <jdelvare@suse.de>
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.
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.
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>
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.
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)
40 #define STUB_FUNC_ALL \
41 (STUB_FUNC_DEFAULT | I2C_FUNC_SMBUS_BLOCK_DATA)
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)");
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");
52 /* Some chips have banked register ranges */
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");
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");
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");
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");
70 struct smbus_block_data {
71 struct list_head node;
74 u8 block[I2C_SMBUS_BLOCK_MAX];
79 u16 words[256]; /* Byte operations use the LSB as per SMBus
81 struct list_head smbus_blocks;
83 /* For chips with banks, extra registers are allocated dynamically */
87 u8 bank_sel; /* Currently selected bank */
91 u16 *bank_words; /* Room for bank_mask * bank_size registers */
94 static struct stub_chip *stub_chips;
95 static int stub_chips_nr;
97 static struct smbus_block_data *stub_find_block(struct device *dev,
98 struct stub_chip *chip,
99 u8 command, bool create)
101 struct smbus_block_data *b, *rb = NULL;
103 list_for_each_entry(b, &chip->smbus_blocks, node) {
104 if (b->command == command) {
109 if (rb == NULL && create) {
110 rb = devm_kzalloc(dev, sizeof(*rb), GFP_KERNEL);
113 rb->command = command;
114 list_add(&rb->node, &chip->smbus_blocks);
119 static u16 *stub_get_wordp(struct stub_chip *chip, u8 offset)
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;
127 return chip->words + offset;
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)
136 struct stub_chip *chip = NULL;
137 struct smbus_block_data *b;
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;
152 case I2C_SMBUS_QUICK:
153 dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr);
158 if (read_write == I2C_SMBUS_WRITE) {
159 chip->pointer = command;
161 "smbus byte - addr 0x%02x, wrote 0x%02x.\n",
164 wordp = stub_get_wordp(chip, chip->pointer++);
165 data->byte = *wordp & 0xff;
167 "smbus byte - addr 0x%02x, read 0x%02x.\n",
174 case I2C_SMBUS_BYTE_DATA:
175 wordp = stub_get_wordp(chip, command);
176 if (read_write == I2C_SMBUS_WRITE) {
178 *wordp |= data->byte;
180 "smbus byte data - addr 0x%02x, wrote 0x%02x at 0x%02x.\n",
181 addr, data->byte, command);
183 /* Set the bank as needed */
184 if (chip->bank_words && command == chip->bank_reg) {
186 (data->byte >> chip->bank_shift)
189 "switching to bank %u.\n",
193 data->byte = *wordp & 0xff;
195 "smbus byte data - addr 0x%02x, read 0x%02x at 0x%02x.\n",
196 addr, data->byte, command);
198 chip->pointer = command + 1;
203 case I2C_SMBUS_WORD_DATA:
204 wordp = stub_get_wordp(chip, command);
205 if (read_write == I2C_SMBUS_WRITE) {
208 "smbus word data - addr 0x%02x, wrote 0x%04x at 0x%02x.\n",
209 addr, data->word, command);
213 "smbus word data - addr 0x%02x, read 0x%04x at 0x%02x.\n",
214 addr, data->word, command);
220 case I2C_SMBUS_I2C_BLOCK_DATA:
222 * We ignore banks here, because banked chips don't use I2C
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];
234 "i2c block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n",
237 for (i = 0; i < len; i++) {
239 chip->words[command + i] & 0xff;
242 "i2c block data - addr 0x%02x, read %d bytes at 0x%02x.\n",
249 case I2C_SMBUS_BLOCK_DATA:
251 * We ignore banks here, because chips typically don't use both
252 * banks and SMBus block transfers
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) {
262 b = stub_find_block(&adap->dev, chip, command,
269 /* Largest write sets read block length */
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;
277 "smbus block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n",
282 "SMBus block read command without prior block write not supported\n");
287 data->block[0] = len;
288 for (i = 0; i < len; i++)
289 data->block[i + 1] = b->block[i];
291 "smbus block data - addr 0x%02x, read %d bytes at 0x%02x.\n",
299 dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n");
302 } /* switch (size) */
307 static u32 stub_func(struct i2c_adapter *adapter)
309 return STUB_FUNC_ALL & functionality;
312 static const struct i2c_algorithm smbus_algorithm = {
313 .functionality = stub_func,
314 .smbus_xfer = stub_xfer,
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",
324 static int __init i2c_stub_allocate_banks(int i)
326 struct stub_chip *chip = stub_chips + i;
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;
333 /* We assume that all bits in the mask are contiguous */
334 chip->bank_mask = bank_mask[i];
335 while (!(chip->bank_mask & 1)) {
337 chip->bank_mask >>= 1;
340 chip->bank_words = kzalloc(chip->bank_mask * chip->bank_size *
341 sizeof(u16), GFP_KERNEL);
342 if (!chip->bank_words)
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,
352 static void i2c_stub_free(void)
356 for (i = 0; i < stub_chips_nr; i++)
357 kfree(stub_chips[i].bank_words);
361 static int __init i2c_stub_init(void)
366 pr_err("i2c-stub: Please specify a chip address\n");
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",
377 pr_info("i2c-stub: Virtual chip at 0x%02x\n", chip_addr[i]);
380 /* Allocate memory for all chips at once */
382 stub_chips = kcalloc(stub_chips_nr, sizeof(struct stub_chip),
385 pr_err("i2c-stub: Out of memory\n");
388 for (i = 0; i < stub_chips_nr; i++) {
389 INIT_LIST_HEAD(&stub_chips[i].smbus_blocks);
391 /* Allocate extra memory for banked register ranges */
393 ret = i2c_stub_allocate_banks(i);
399 ret = i2c_add_adapter(&stub_adapter);
410 static void __exit i2c_stub_exit(void)
412 i2c_del_adapter(&stub_adapter);
416 MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
417 MODULE_DESCRIPTION("I2C stub driver");
418 MODULE_LICENSE("GPL");
420 module_init(i2c_stub_init);
421 module_exit(i2c_stub_exit);