xref: /openbmc/linux/sound/i2c/i2c.c (revision f42b3800)
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/string.h>
26 #include <linux/errno.h>
27 #include <sound/core.h>
28 #include <sound/i2c.h>
29 
30 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
31 MODULE_DESCRIPTION("Generic i2c interface for ALSA");
32 MODULE_LICENSE("GPL");
33 
34 static int snd_i2c_bit_sendbytes(struct snd_i2c_device *device,
35 				 unsigned char *bytes, int count);
36 static int snd_i2c_bit_readbytes(struct snd_i2c_device *device,
37 				 unsigned char *bytes, int count);
38 static int snd_i2c_bit_probeaddr(struct snd_i2c_bus *bus,
39 				 unsigned short addr);
40 
41 static struct snd_i2c_ops snd_i2c_bit_ops = {
42 	.sendbytes = snd_i2c_bit_sendbytes,
43 	.readbytes = snd_i2c_bit_readbytes,
44 	.probeaddr = snd_i2c_bit_probeaddr,
45 };
46 
47 static int snd_i2c_bus_free(struct snd_i2c_bus *bus)
48 {
49 	struct snd_i2c_bus *slave;
50 	struct snd_i2c_device *device;
51 
52 	snd_assert(bus != NULL, return -EINVAL);
53 	while (!list_empty(&bus->devices)) {
54 		device = snd_i2c_device(bus->devices.next);
55 		snd_i2c_device_free(device);
56 	}
57 	if (bus->master)
58 		list_del(&bus->buses);
59 	else {
60 		while (!list_empty(&bus->buses)) {
61 			slave = snd_i2c_slave_bus(bus->buses.next);
62 			snd_device_free(bus->card, slave);
63 		}
64 	}
65 	if (bus->private_free)
66 		bus->private_free(bus);
67 	kfree(bus);
68 	return 0;
69 }
70 
71 static int snd_i2c_bus_dev_free(struct snd_device *device)
72 {
73 	struct snd_i2c_bus *bus = device->device_data;
74 	return snd_i2c_bus_free(bus);
75 }
76 
77 int snd_i2c_bus_create(struct snd_card *card, const char *name,
78 		       struct snd_i2c_bus *master, struct snd_i2c_bus **ri2c)
79 {
80 	struct snd_i2c_bus *bus;
81 	int err;
82 	static struct snd_device_ops ops = {
83 		.dev_free =	snd_i2c_bus_dev_free,
84 	};
85 
86 	*ri2c = NULL;
87 	bus = kzalloc(sizeof(*bus), GFP_KERNEL);
88 	if (bus == NULL)
89 		return -ENOMEM;
90 	mutex_init(&bus->lock_mutex);
91 	INIT_LIST_HEAD(&bus->devices);
92 	INIT_LIST_HEAD(&bus->buses);
93 	bus->card = card;
94 	bus->ops = &snd_i2c_bit_ops;
95 	if (master) {
96 		list_add_tail(&bus->buses, &master->buses);
97 		bus->master = master;
98 	}
99 	strlcpy(bus->name, name, sizeof(bus->name));
100 	if ((err = snd_device_new(card, SNDRV_DEV_BUS, bus, &ops)) < 0) {
101 		snd_i2c_bus_free(bus);
102 		return err;
103 	}
104 	*ri2c = bus;
105 	return 0;
106 }
107 
108 EXPORT_SYMBOL(snd_i2c_bus_create);
109 
110 int snd_i2c_device_create(struct snd_i2c_bus *bus, const char *name,
111 			  unsigned char addr, struct snd_i2c_device **rdevice)
112 {
113 	struct snd_i2c_device *device;
114 
115 	*rdevice = NULL;
116 	snd_assert(bus != NULL, return -EINVAL);
117 	device = kzalloc(sizeof(*device), GFP_KERNEL);
118 	if (device == NULL)
119 		return -ENOMEM;
120 	device->addr = addr;
121 	strlcpy(device->name, name, sizeof(device->name));
122 	list_add_tail(&device->list, &bus->devices);
123 	device->bus = bus;
124 	*rdevice = device;
125 	return 0;
126 }
127 
128 EXPORT_SYMBOL(snd_i2c_device_create);
129 
130 int snd_i2c_device_free(struct snd_i2c_device *device)
131 {
132 	if (device->bus)
133 		list_del(&device->list);
134 	if (device->private_free)
135 		device->private_free(device);
136 	kfree(device);
137 	return 0;
138 }
139 
140 EXPORT_SYMBOL(snd_i2c_device_free);
141 
142 int snd_i2c_sendbytes(struct snd_i2c_device *device, unsigned char *bytes, int count)
143 {
144 	return device->bus->ops->sendbytes(device, bytes, count);
145 }
146 
147 EXPORT_SYMBOL(snd_i2c_sendbytes);
148 
149 int snd_i2c_readbytes(struct snd_i2c_device *device, unsigned char *bytes, int count)
150 {
151 	return device->bus->ops->readbytes(device, bytes, count);
152 }
153 
154 EXPORT_SYMBOL(snd_i2c_readbytes);
155 
156 int snd_i2c_probeaddr(struct snd_i2c_bus *bus, unsigned short addr)
157 {
158 	return bus->ops->probeaddr(bus, addr);
159 }
160 
161 EXPORT_SYMBOL(snd_i2c_probeaddr);
162 
163 /*
164  *  bit-operations
165  */
166 
167 static inline void snd_i2c_bit_hw_start(struct snd_i2c_bus *bus)
168 {
169 	if (bus->hw_ops.bit->start)
170 		bus->hw_ops.bit->start(bus);
171 }
172 
173 static inline void snd_i2c_bit_hw_stop(struct snd_i2c_bus *bus)
174 {
175 	if (bus->hw_ops.bit->stop)
176 		bus->hw_ops.bit->stop(bus);
177 }
178 
179 static void snd_i2c_bit_direction(struct snd_i2c_bus *bus, int clock, int data)
180 {
181 	if (bus->hw_ops.bit->direction)
182 		bus->hw_ops.bit->direction(bus, clock, data);
183 }
184 
185 static void snd_i2c_bit_set(struct snd_i2c_bus *bus, int clock, int data)
186 {
187 	bus->hw_ops.bit->setlines(bus, clock, data);
188 }
189 
190 #if 0
191 static int snd_i2c_bit_clock(struct snd_i2c_bus *bus)
192 {
193 	if (bus->hw_ops.bit->getclock)
194 		return bus->hw_ops.bit->getclock(bus);
195 	return -ENXIO;
196 }
197 #endif
198 
199 static int snd_i2c_bit_data(struct snd_i2c_bus *bus, int ack)
200 {
201 	return bus->hw_ops.bit->getdata(bus, ack);
202 }
203 
204 static void snd_i2c_bit_start(struct snd_i2c_bus *bus)
205 {
206 	snd_i2c_bit_hw_start(bus);
207 	snd_i2c_bit_direction(bus, 1, 1);	/* SCL - wr, SDA - wr */
208 	snd_i2c_bit_set(bus, 1, 1);
209 	snd_i2c_bit_set(bus, 1, 0);
210 	snd_i2c_bit_set(bus, 0, 0);
211 }
212 
213 static void snd_i2c_bit_stop(struct snd_i2c_bus *bus)
214 {
215 	snd_i2c_bit_set(bus, 0, 0);
216 	snd_i2c_bit_set(bus, 1, 0);
217 	snd_i2c_bit_set(bus, 1, 1);
218 	snd_i2c_bit_hw_stop(bus);
219 }
220 
221 static void snd_i2c_bit_send(struct snd_i2c_bus *bus, int data)
222 {
223 	snd_i2c_bit_set(bus, 0, data);
224 	snd_i2c_bit_set(bus, 1, data);
225 	snd_i2c_bit_set(bus, 0, data);
226 }
227 
228 static int snd_i2c_bit_ack(struct snd_i2c_bus *bus)
229 {
230 	int ack;
231 
232 	snd_i2c_bit_set(bus, 0, 1);
233 	snd_i2c_bit_set(bus, 1, 1);
234 	snd_i2c_bit_direction(bus, 1, 0);	/* SCL - wr, SDA - rd */
235 	ack = snd_i2c_bit_data(bus, 1);
236 	snd_i2c_bit_direction(bus, 1, 1);	/* SCL - wr, SDA - wr */
237 	snd_i2c_bit_set(bus, 0, 1);
238 	return ack ? -EIO : 0;
239 }
240 
241 static int snd_i2c_bit_sendbyte(struct snd_i2c_bus *bus, unsigned char data)
242 {
243 	int i, err;
244 
245 	for (i = 7; i >= 0; i--)
246 		snd_i2c_bit_send(bus, !!(data & (1 << i)));
247 	if ((err = snd_i2c_bit_ack(bus)) < 0)
248 		return err;
249 	return 0;
250 }
251 
252 static int snd_i2c_bit_readbyte(struct snd_i2c_bus *bus, int last)
253 {
254 	int i;
255 	unsigned char data = 0;
256 
257 	snd_i2c_bit_set(bus, 0, 1);
258 	snd_i2c_bit_direction(bus, 1, 0);	/* SCL - wr, SDA - rd */
259 	for (i = 7; i >= 0; i--) {
260 		snd_i2c_bit_set(bus, 1, 1);
261 		if (snd_i2c_bit_data(bus, 0))
262 			data |= (1 << i);
263 		snd_i2c_bit_set(bus, 0, 1);
264 	}
265 	snd_i2c_bit_direction(bus, 1, 1);	/* SCL - wr, SDA - wr */
266 	snd_i2c_bit_send(bus, !!last);
267 	return data;
268 }
269 
270 static int snd_i2c_bit_sendbytes(struct snd_i2c_device *device,
271 				 unsigned char *bytes, int count)
272 {
273 	struct snd_i2c_bus *bus = device->bus;
274 	int err, res = 0;
275 
276 	if (device->flags & SND_I2C_DEVICE_ADDRTEN)
277 		return -EIO;		/* not yet implemented */
278 	snd_i2c_bit_start(bus);
279 	if ((err = snd_i2c_bit_sendbyte(bus, device->addr << 1)) < 0) {
280 		snd_i2c_bit_hw_stop(bus);
281 		return err;
282 	}
283 	while (count-- > 0) {
284 		if ((err = snd_i2c_bit_sendbyte(bus, *bytes++)) < 0) {
285 			snd_i2c_bit_hw_stop(bus);
286 			return err;
287 		}
288 		res++;
289 	}
290 	snd_i2c_bit_stop(bus);
291 	return res;
292 }
293 
294 static int snd_i2c_bit_readbytes(struct snd_i2c_device *device,
295 				 unsigned char *bytes, int count)
296 {
297 	struct snd_i2c_bus *bus = device->bus;
298 	int err, res = 0;
299 
300 	if (device->flags & SND_I2C_DEVICE_ADDRTEN)
301 		return -EIO;		/* not yet implemented */
302 	snd_i2c_bit_start(bus);
303 	if ((err = snd_i2c_bit_sendbyte(bus, (device->addr << 1) | 1)) < 0) {
304 		snd_i2c_bit_hw_stop(bus);
305 		return err;
306 	}
307 	while (count-- > 0) {
308 		if ((err = snd_i2c_bit_readbyte(bus, count == 0)) < 0) {
309 			snd_i2c_bit_hw_stop(bus);
310 			return err;
311 		}
312 		*bytes++ = (unsigned char)err;
313 		res++;
314 	}
315 	snd_i2c_bit_stop(bus);
316 	return res;
317 }
318 
319 static int snd_i2c_bit_probeaddr(struct snd_i2c_bus *bus, unsigned short addr)
320 {
321 	int err;
322 
323 	if (addr & 0x8000)	/* 10-bit address */
324 		return -EIO;	/* not yet implemented */
325 	if (addr & 0x7f80)	/* invalid address */
326 		return -EINVAL;
327 	snd_i2c_bit_start(bus);
328 	err = snd_i2c_bit_sendbyte(bus, addr << 1);
329 	snd_i2c_bit_stop(bus);
330 	return err;
331 }
332 
333 
334 static int __init alsa_i2c_init(void)
335 {
336 	return 0;
337 }
338 
339 static void __exit alsa_i2c_exit(void)
340 {
341 }
342 
343 module_init(alsa_i2c_init)
344 module_exit(alsa_i2c_exit)
345