Root/sound/i2c/i2c.c

1/*
2 * Generic i2c interface for ALSA
3 *
4 * (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>
5 * Modified for the ALSA driver by Jaroslav Kysela <perex@perex.cz>
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
31MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
32MODULE_DESCRIPTION("Generic i2c interface for ALSA");
33MODULE_LICENSE("GPL");
34
35static int snd_i2c_bit_sendbytes(struct snd_i2c_device *device,
36                 unsigned char *bytes, int count);
37static int snd_i2c_bit_readbytes(struct snd_i2c_device *device,
38                 unsigned char *bytes, int count);
39static int snd_i2c_bit_probeaddr(struct snd_i2c_bus *bus,
40                 unsigned short addr);
41
42static 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
48static 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
73static 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
79int 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
111EXPORT_SYMBOL(snd_i2c_bus_create);
112
113int 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
132EXPORT_SYMBOL(snd_i2c_device_create);
133
134int snd_i2c_device_free(struct snd_i2c_device *device)
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
144EXPORT_SYMBOL(snd_i2c_device_free);
145
146int 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
151EXPORT_SYMBOL(snd_i2c_sendbytes);
152
153int 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
158EXPORT_SYMBOL(snd_i2c_readbytes);
159
160int snd_i2c_probeaddr(struct snd_i2c_bus *bus, unsigned short addr)
161{
162    return bus->ops->probeaddr(bus, addr);
163}
164
165EXPORT_SYMBOL(snd_i2c_probeaddr);
166
167/*
168 * bit-operations
169 */
170
171static 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
177static 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
183static 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
189static 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
195static 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
203static int snd_i2c_bit_data(struct snd_i2c_bus *bus, int ack)
204{
205    return bus->hw_ops.bit->getdata(bus, ack);
206}
207
208static 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
217static 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
225static 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
232static 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
245static 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
257static 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
275static 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
301static 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
328static 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
343static int __init alsa_i2c_init(void)
344{
345    return 0;
346}
347
348static void __exit alsa_i2c_exit(void)
349{
350}
351
352module_init(alsa_i2c_init)
353module_exit(alsa_i2c_exit)
354

Archive Download this file



interactive