xref: /openbmc/linux/sound/i2c/i2c.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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@suse.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 <sound/driver.h>
24 #include <linux/init.h>
25 #include <linux/slab.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 <perex@suse.cz>");
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 	snd_assert(bus != NULL, return -EINVAL);
54 	while (!list_empty(&bus->devices)) {
55 		device = snd_i2c_device(bus->devices.next);
56 		snd_i2c_device_free(device);
57 	}
58 	if (bus->master)
59 		list_del(&bus->buses);
60 	else {
61 		while (!list_empty(&bus->buses)) {
62 			slave = snd_i2c_slave_bus(bus->buses.next);
63 			snd_device_free(bus->card, slave);
64 		}
65 	}
66 	if (bus->private_free)
67 		bus->private_free(bus);
68 	kfree(bus);
69 	return 0;
70 }
71 
72 static int snd_i2c_bus_dev_free(struct snd_device *device)
73 {
74 	struct snd_i2c_bus *bus = device->device_data;
75 	return snd_i2c_bus_free(bus);
76 }
77 
78 int snd_i2c_bus_create(struct snd_card *card, const char *name,
79 		       struct snd_i2c_bus *master, struct snd_i2c_bus **ri2c)
80 {
81 	struct snd_i2c_bus *bus;
82 	int err;
83 	static struct snd_device_ops ops = {
84 		.dev_free =	snd_i2c_bus_dev_free,
85 	};
86 
87 	*ri2c = NULL;
88 	bus = kzalloc(sizeof(*bus), GFP_KERNEL);
89 	if (bus == NULL)
90 		return -ENOMEM;
91 	mutex_init(&bus->lock_mutex);
92 	INIT_LIST_HEAD(&bus->devices);
93 	INIT_LIST_HEAD(&bus->buses);
94 	bus->card = card;
95 	bus->ops = &snd_i2c_bit_ops;
96 	if (master) {
97 		list_add_tail(&bus->buses, &master->buses);
98 		bus->master = master;
99 	}
100 	strlcpy(bus->name, name, sizeof(bus->name));
101 	if ((err = snd_device_new(card, SNDRV_DEV_BUS, bus, &ops)) < 0) {
102 		snd_i2c_bus_free(bus);
103 		return err;
104 	}
105 	*ri2c = bus;
106 	return 0;
107 }
108 
109 EXPORT_SYMBOL(snd_i2c_bus_create);
110 
111 int snd_i2c_device_create(struct snd_i2c_bus *bus, const char *name,
112 			  unsigned char addr, struct snd_i2c_device **rdevice)
113 {
114 	struct snd_i2c_device *device;
115 
116 	*rdevice = NULL;
117 	snd_assert(bus != NULL, return -EINVAL);
118 	device = kzalloc(sizeof(*device), GFP_KERNEL);
119 	if (device == NULL)
120 		return -ENOMEM;
121 	device->addr = addr;
122 	strlcpy(device->name, name, sizeof(device->name));
123 	list_add_tail(&device->list, &bus->devices);
124 	device->bus = bus;
125 	*rdevice = device;
126 	return 0;
127 }
128 
129 EXPORT_SYMBOL(snd_i2c_device_create);
130 
131 int snd_i2c_device_free(struct snd_i2c_device *device)
132 {
133 	if (device->bus)
134 		list_del(&device->list);
135 	if (device->private_free)
136 		device->private_free(device);
137 	kfree(device);
138 	return 0;
139 }
140 
141 EXPORT_SYMBOL(snd_i2c_device_free);
142 
143 int snd_i2c_sendbytes(struct snd_i2c_device *device, unsigned char *bytes, int count)
144 {
145 	return device->bus->ops->sendbytes(device, bytes, count);
146 }
147 
148 EXPORT_SYMBOL(snd_i2c_sendbytes);
149 
150 int snd_i2c_readbytes(struct snd_i2c_device *device, unsigned char *bytes, int count)
151 {
152 	return device->bus->ops->readbytes(device, bytes, count);
153 }
154 
155 EXPORT_SYMBOL(snd_i2c_readbytes);
156 
157 int snd_i2c_probeaddr(struct snd_i2c_bus *bus, unsigned short addr)
158 {
159 	return bus->ops->probeaddr(bus, addr);
160 }
161 
162 EXPORT_SYMBOL(snd_i2c_probeaddr);
163 
164 /*
165  *  bit-operations
166  */
167 
168 static inline void snd_i2c_bit_hw_start(struct snd_i2c_bus *bus)
169 {
170 	if (bus->hw_ops.bit->start)
171 		bus->hw_ops.bit->start(bus);
172 }
173 
174 static inline void snd_i2c_bit_hw_stop(struct snd_i2c_bus *bus)
175 {
176 	if (bus->hw_ops.bit->stop)
177 		bus->hw_ops.bit->stop(bus);
178 }
179 
180 static void snd_i2c_bit_direction(struct snd_i2c_bus *bus, int clock, int data)
181 {
182 	if (bus->hw_ops.bit->direction)
183 		bus->hw_ops.bit->direction(bus, clock, data);
184 }
185 
186 static void snd_i2c_bit_set(struct snd_i2c_bus *bus, int clock, int data)
187 {
188 	bus->hw_ops.bit->setlines(bus, clock, data);
189 }
190 
191 #if 0
192 static int snd_i2c_bit_clock(struct snd_i2c_bus *bus)
193 {
194 	if (bus->hw_ops.bit->getclock)
195 		return bus->hw_ops.bit->getclock(bus);
196 	return -ENXIO;
197 }
198 #endif
199 
200 static int snd_i2c_bit_data(struct snd_i2c_bus *bus, int ack)
201 {
202 	return bus->hw_ops.bit->getdata(bus, ack);
203 }
204 
205 static void snd_i2c_bit_start(struct snd_i2c_bus *bus)
206 {
207 	snd_i2c_bit_hw_start(bus);
208 	snd_i2c_bit_direction(bus, 1, 1);	/* SCL - wr, SDA - wr */
209 	snd_i2c_bit_set(bus, 1, 1);
210 	snd_i2c_bit_set(bus, 1, 0);
211 	snd_i2c_bit_set(bus, 0, 0);
212 }
213 
214 static void snd_i2c_bit_stop(struct snd_i2c_bus *bus)
215 {
216 	snd_i2c_bit_set(bus, 0, 0);
217 	snd_i2c_bit_set(bus, 1, 0);
218 	snd_i2c_bit_set(bus, 1, 1);
219 	snd_i2c_bit_hw_stop(bus);
220 }
221 
222 static void snd_i2c_bit_send(struct snd_i2c_bus *bus, int data)
223 {
224 	snd_i2c_bit_set(bus, 0, data);
225 	snd_i2c_bit_set(bus, 1, data);
226 	snd_i2c_bit_set(bus, 0, data);
227 }
228 
229 static int snd_i2c_bit_ack(struct snd_i2c_bus *bus)
230 {
231 	int ack;
232 
233 	snd_i2c_bit_set(bus, 0, 1);
234 	snd_i2c_bit_set(bus, 1, 1);
235 	snd_i2c_bit_direction(bus, 1, 0);	/* SCL - wr, SDA - rd */
236 	ack = snd_i2c_bit_data(bus, 1);
237 	snd_i2c_bit_direction(bus, 1, 1);	/* SCL - wr, SDA - wr */
238 	snd_i2c_bit_set(bus, 0, 1);
239 	return ack ? -EIO : 0;
240 }
241 
242 static int snd_i2c_bit_sendbyte(struct snd_i2c_bus *bus, unsigned char data)
243 {
244 	int i, err;
245 
246 	for (i = 7; i >= 0; i--)
247 		snd_i2c_bit_send(bus, !!(data & (1 << i)));
248 	if ((err = snd_i2c_bit_ack(bus)) < 0)
249 		return err;
250 	return 0;
251 }
252 
253 static int snd_i2c_bit_readbyte(struct snd_i2c_bus *bus, int last)
254 {
255 	int i;
256 	unsigned char data = 0;
257 
258 	snd_i2c_bit_set(bus, 0, 1);
259 	snd_i2c_bit_direction(bus, 1, 0);	/* SCL - wr, SDA - rd */
260 	for (i = 7; i >= 0; i--) {
261 		snd_i2c_bit_set(bus, 1, 1);
262 		if (snd_i2c_bit_data(bus, 0))
263 			data |= (1 << i);
264 		snd_i2c_bit_set(bus, 0, 1);
265 	}
266 	snd_i2c_bit_direction(bus, 1, 1);	/* SCL - wr, SDA - wr */
267 	snd_i2c_bit_send(bus, !!last);
268 	return data;
269 }
270 
271 static int snd_i2c_bit_sendbytes(struct snd_i2c_device *device,
272 				 unsigned char *bytes, int count)
273 {
274 	struct snd_i2c_bus *bus = device->bus;
275 	int err, res = 0;
276 
277 	if (device->flags & SND_I2C_DEVICE_ADDRTEN)
278 		return -EIO;		/* not yet implemented */
279 	snd_i2c_bit_start(bus);
280 	if ((err = snd_i2c_bit_sendbyte(bus, device->addr << 1)) < 0) {
281 		snd_i2c_bit_hw_stop(bus);
282 		return err;
283 	}
284 	while (count-- > 0) {
285 		if ((err = snd_i2c_bit_sendbyte(bus, *bytes++)) < 0) {
286 			snd_i2c_bit_hw_stop(bus);
287 			return err;
288 		}
289 		res++;
290 	}
291 	snd_i2c_bit_stop(bus);
292 	return res;
293 }
294 
295 static int snd_i2c_bit_readbytes(struct snd_i2c_device *device,
296 				 unsigned char *bytes, int count)
297 {
298 	struct snd_i2c_bus *bus = device->bus;
299 	int err, res = 0;
300 
301 	if (device->flags & SND_I2C_DEVICE_ADDRTEN)
302 		return -EIO;		/* not yet implemented */
303 	snd_i2c_bit_start(bus);
304 	if ((err = snd_i2c_bit_sendbyte(bus, (device->addr << 1) | 1)) < 0) {
305 		snd_i2c_bit_hw_stop(bus);
306 		return err;
307 	}
308 	while (count-- > 0) {
309 		if ((err = snd_i2c_bit_readbyte(bus, count == 0)) < 0) {
310 			snd_i2c_bit_hw_stop(bus);
311 			return err;
312 		}
313 		*bytes++ = (unsigned char)err;
314 		res++;
315 	}
316 	snd_i2c_bit_stop(bus);
317 	return res;
318 }
319 
320 static int snd_i2c_bit_probeaddr(struct snd_i2c_bus *bus, unsigned short addr)
321 {
322 	int err;
323 
324 	if (addr & 0x8000)	/* 10-bit address */
325 		return -EIO;	/* not yet implemented */
326 	if (addr & 0x7f80)	/* invalid address */
327 		return -EINVAL;
328 	snd_i2c_bit_start(bus);
329 	err = snd_i2c_bit_sendbyte(bus, addr << 1);
330 	snd_i2c_bit_stop(bus);
331 	return err;
332 }
333 
334 
335 static int __init alsa_i2c_init(void)
336 {
337 	return 0;
338 }
339 
340 static void __exit alsa_i2c_exit(void)
341 {
342 }
343 
344 module_init(alsa_i2c_init)
345 module_exit(alsa_i2c_exit)
346