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i2c.c
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1 /*
2  * Generic i2c interface for ALSA
3  *
4  * (c) 1998 Gerd Knorr <[email protected]>
5  * Modified for the ALSA driver by Jaroslav Kysela <[email protected]>
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  * You should have received a copy of the GNU General Public License
18  * along with this program; if not, write to the Free Software
19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20  *
21  */
22 
23 #include <linux/init.h>
24 #include <linux/slab.h>
25 #include <linux/module.h>
26 #include <linux/string.h>
27 #include <linux/errno.h>
28 #include <sound/core.h>
29 #include <sound/i2c.h>
30 
31 MODULE_AUTHOR("Jaroslav Kysela <[email protected]>");
32 MODULE_DESCRIPTION("Generic i2c interface for ALSA");
33 MODULE_LICENSE("GPL");
34 
35 static int snd_i2c_bit_sendbytes(struct snd_i2c_device *device,
36  unsigned char *bytes, int count);
37 static int snd_i2c_bit_readbytes(struct snd_i2c_device *device,
38  unsigned char *bytes, int count);
39 static int snd_i2c_bit_probeaddr(struct snd_i2c_bus *bus,
40  unsigned short addr);
41 
42 static struct snd_i2c_ops snd_i2c_bit_ops = {
43  .sendbytes = snd_i2c_bit_sendbytes,
44  .readbytes = snd_i2c_bit_readbytes,
45  .probeaddr = snd_i2c_bit_probeaddr,
46 };
47 
48 static int snd_i2c_bus_free(struct snd_i2c_bus *bus)
49 {
50  struct snd_i2c_bus *slave;
51  struct snd_i2c_device *device;
52 
53  if (snd_BUG_ON(!bus))
54  return -EINVAL;
55  while (!list_empty(&bus->devices)) {
56  device = snd_i2c_device(bus->devices.next);
57  snd_i2c_device_free(device);
58  }
59  if (bus->master)
60  list_del(&bus->buses);
61  else {
62  while (!list_empty(&bus->buses)) {
63  slave = snd_i2c_slave_bus(bus->buses.next);
64  snd_device_free(bus->card, slave);
65  }
66  }
67  if (bus->private_free)
68  bus->private_free(bus);
69  kfree(bus);
70  return 0;
71 }
72 
73 static int snd_i2c_bus_dev_free(struct snd_device *device)
74 {
75  struct snd_i2c_bus *bus = device->device_data;
76  return snd_i2c_bus_free(bus);
77 }
78 
79 int snd_i2c_bus_create(struct snd_card *card, const char *name,
80  struct snd_i2c_bus *master, struct snd_i2c_bus **ri2c)
81 {
82  struct snd_i2c_bus *bus;
83  int err;
84  static struct snd_device_ops ops = {
85  .dev_free = snd_i2c_bus_dev_free,
86  };
87 
88  *ri2c = NULL;
89  bus = kzalloc(sizeof(*bus), GFP_KERNEL);
90  if (bus == NULL)
91  return -ENOMEM;
92  mutex_init(&bus->lock_mutex);
93  INIT_LIST_HEAD(&bus->devices);
94  INIT_LIST_HEAD(&bus->buses);
95  bus->card = card;
96  bus->ops = &snd_i2c_bit_ops;
97  if (master) {
98  list_add_tail(&bus->buses, &master->buses);
99  bus->master = master;
100  }
101  strlcpy(bus->name, name, sizeof(bus->name));
102  err = snd_device_new(card, SNDRV_DEV_BUS, bus, &ops);
103  if (err < 0) {
104  snd_i2c_bus_free(bus);
105  return err;
106  }
107  *ri2c = bus;
108  return 0;
109 }
110 
112 
113 int snd_i2c_device_create(struct snd_i2c_bus *bus, const char *name,
114  unsigned char addr, struct snd_i2c_device **rdevice)
115 {
116  struct snd_i2c_device *device;
117 
118  *rdevice = NULL;
119  if (snd_BUG_ON(!bus))
120  return -EINVAL;
121  device = kzalloc(sizeof(*device), GFP_KERNEL);
122  if (device == NULL)
123  return -ENOMEM;
124  device->addr = addr;
125  strlcpy(device->name, name, sizeof(device->name));
126  list_add_tail(&device->list, &bus->devices);
127  device->bus = bus;
128  *rdevice = device;
129  return 0;
130 }
131 
133 
135 {
136  if (device->bus)
137  list_del(&device->list);
138  if (device->private_free)
139  device->private_free(device);
140  kfree(device);
141  return 0;
142 }
143 
145 
146 int snd_i2c_sendbytes(struct snd_i2c_device *device, unsigned char *bytes, int count)
147 {
148  return device->bus->ops->sendbytes(device, bytes, count);
149 }
150 
152 
153 int snd_i2c_readbytes(struct snd_i2c_device *device, unsigned char *bytes, int count)
154 {
155  return device->bus->ops->readbytes(device, bytes, count);
156 }
157 
159 
160 int snd_i2c_probeaddr(struct snd_i2c_bus *bus, unsigned short addr)
161 {
162  return bus->ops->probeaddr(bus, addr);
163 }
164 
166 
167 /*
168  * bit-operations
169  */
170 
171 static inline void snd_i2c_bit_hw_start(struct snd_i2c_bus *bus)
172 {
173  if (bus->hw_ops.bit->start)
174  bus->hw_ops.bit->start(bus);
175 }
176 
177 static inline void snd_i2c_bit_hw_stop(struct snd_i2c_bus *bus)
178 {
179  if (bus->hw_ops.bit->stop)
180  bus->hw_ops.bit->stop(bus);
181 }
182 
183 static void snd_i2c_bit_direction(struct snd_i2c_bus *bus, int clock, int data)
184 {
185  if (bus->hw_ops.bit->direction)
186  bus->hw_ops.bit->direction(bus, clock, data);
187 }
188 
189 static void snd_i2c_bit_set(struct snd_i2c_bus *bus, int clock, int data)
190 {
191  bus->hw_ops.bit->setlines(bus, clock, data);
192 }
193 
194 #if 0
195 static int snd_i2c_bit_clock(struct snd_i2c_bus *bus)
196 {
197  if (bus->hw_ops.bit->getclock)
198  return bus->hw_ops.bit->getclock(bus);
199  return -ENXIO;
200 }
201 #endif
202 
203 static int snd_i2c_bit_data(struct snd_i2c_bus *bus, int ack)
204 {
205  return bus->hw_ops.bit->getdata(bus, ack);
206 }
207 
208 static void snd_i2c_bit_start(struct snd_i2c_bus *bus)
209 {
210  snd_i2c_bit_hw_start(bus);
211  snd_i2c_bit_direction(bus, 1, 1); /* SCL - wr, SDA - wr */
212  snd_i2c_bit_set(bus, 1, 1);
213  snd_i2c_bit_set(bus, 1, 0);
214  snd_i2c_bit_set(bus, 0, 0);
215 }
216 
217 static void snd_i2c_bit_stop(struct snd_i2c_bus *bus)
218 {
219  snd_i2c_bit_set(bus, 0, 0);
220  snd_i2c_bit_set(bus, 1, 0);
221  snd_i2c_bit_set(bus, 1, 1);
222  snd_i2c_bit_hw_stop(bus);
223 }
224 
225 static void snd_i2c_bit_send(struct snd_i2c_bus *bus, int data)
226 {
227  snd_i2c_bit_set(bus, 0, data);
228  snd_i2c_bit_set(bus, 1, data);
229  snd_i2c_bit_set(bus, 0, data);
230 }
231 
232 static int snd_i2c_bit_ack(struct snd_i2c_bus *bus)
233 {
234  int ack;
235 
236  snd_i2c_bit_set(bus, 0, 1);
237  snd_i2c_bit_set(bus, 1, 1);
238  snd_i2c_bit_direction(bus, 1, 0); /* SCL - wr, SDA - rd */
239  ack = snd_i2c_bit_data(bus, 1);
240  snd_i2c_bit_direction(bus, 1, 1); /* SCL - wr, SDA - wr */
241  snd_i2c_bit_set(bus, 0, 1);
242  return ack ? -EIO : 0;
243 }
244 
245 static int snd_i2c_bit_sendbyte(struct snd_i2c_bus *bus, unsigned char data)
246 {
247  int i, err;
248 
249  for (i = 7; i >= 0; i--)
250  snd_i2c_bit_send(bus, !!(data & (1 << i)));
251  err = snd_i2c_bit_ack(bus);
252  if (err < 0)
253  return err;
254  return 0;
255 }
256 
257 static int snd_i2c_bit_readbyte(struct snd_i2c_bus *bus, int last)
258 {
259  int i;
260  unsigned char data = 0;
261 
262  snd_i2c_bit_set(bus, 0, 1);
263  snd_i2c_bit_direction(bus, 1, 0); /* SCL - wr, SDA - rd */
264  for (i = 7; i >= 0; i--) {
265  snd_i2c_bit_set(bus, 1, 1);
266  if (snd_i2c_bit_data(bus, 0))
267  data |= (1 << i);
268  snd_i2c_bit_set(bus, 0, 1);
269  }
270  snd_i2c_bit_direction(bus, 1, 1); /* SCL - wr, SDA - wr */
271  snd_i2c_bit_send(bus, !!last);
272  return data;
273 }
274 
275 static int snd_i2c_bit_sendbytes(struct snd_i2c_device *device,
276  unsigned char *bytes, int count)
277 {
278  struct snd_i2c_bus *bus = device->bus;
279  int err, res = 0;
280 
281  if (device->flags & SND_I2C_DEVICE_ADDRTEN)
282  return -EIO; /* not yet implemented */
283  snd_i2c_bit_start(bus);
284  err = snd_i2c_bit_sendbyte(bus, device->addr << 1);
285  if (err < 0) {
286  snd_i2c_bit_hw_stop(bus);
287  return err;
288  }
289  while (count-- > 0) {
290  err = snd_i2c_bit_sendbyte(bus, *bytes++);
291  if (err < 0) {
292  snd_i2c_bit_hw_stop(bus);
293  return err;
294  }
295  res++;
296  }
297  snd_i2c_bit_stop(bus);
298  return res;
299 }
300 
301 static int snd_i2c_bit_readbytes(struct snd_i2c_device *device,
302  unsigned char *bytes, int count)
303 {
304  struct snd_i2c_bus *bus = device->bus;
305  int err, res = 0;
306 
307  if (device->flags & SND_I2C_DEVICE_ADDRTEN)
308  return -EIO; /* not yet implemented */
309  snd_i2c_bit_start(bus);
310  err = snd_i2c_bit_sendbyte(bus, (device->addr << 1) | 1);
311  if (err < 0) {
312  snd_i2c_bit_hw_stop(bus);
313  return err;
314  }
315  while (count-- > 0) {
316  err = snd_i2c_bit_readbyte(bus, count == 0);
317  if (err < 0) {
318  snd_i2c_bit_hw_stop(bus);
319  return err;
320  }
321  *bytes++ = (unsigned char)err;
322  res++;
323  }
324  snd_i2c_bit_stop(bus);
325  return res;
326 }
327 
328 static int snd_i2c_bit_probeaddr(struct snd_i2c_bus *bus, unsigned short addr)
329 {
330  int err;
331 
332  if (addr & 0x8000) /* 10-bit address */
333  return -EIO; /* not yet implemented */
334  if (addr & 0x7f80) /* invalid address */
335  return -EINVAL;
336  snd_i2c_bit_start(bus);
337  err = snd_i2c_bit_sendbyte(bus, addr << 1);
338  snd_i2c_bit_stop(bus);
339  return err;
340 }
341 
342 
343 static int __init alsa_i2c_init(void)
344 {
345  return 0;
346 }
347 
348 static void __exit alsa_i2c_exit(void)
349 {
350 }
351 
352 module_init(alsa_i2c_init)
353 module_exit(alsa_i2c_exit)