xref: /openbmc/linux/sound/i2c/i2c.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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(snd_i2c_device_t *device, unsigned char *bytes, int count);
36 static int snd_i2c_bit_readbytes(snd_i2c_device_t *device, unsigned char *bytes, int count);
37 static int snd_i2c_bit_probeaddr(snd_i2c_bus_t *bus, unsigned short addr);
38 
39 static snd_i2c_ops_t snd_i2c_bit_ops = {
40 	.sendbytes = snd_i2c_bit_sendbytes,
41 	.readbytes = snd_i2c_bit_readbytes,
42 	.probeaddr = snd_i2c_bit_probeaddr,
43 };
44 
45 static int snd_i2c_bus_free(snd_i2c_bus_t *bus)
46 {
47 	snd_i2c_bus_t *slave;
48 	snd_i2c_device_t *device;
49 
50 	snd_assert(bus != NULL, return -EINVAL);
51 	while (!list_empty(&bus->devices)) {
52 		device = snd_i2c_device(bus->devices.next);
53 		snd_i2c_device_free(device);
54 	}
55 	if (bus->master)
56 		list_del(&bus->buses);
57 	else {
58 		while (!list_empty(&bus->buses)) {
59 			slave = snd_i2c_slave_bus(bus->buses.next);
60 			snd_device_free(bus->card, slave);
61 		}
62 	}
63 	if (bus->private_free)
64 		bus->private_free(bus);
65 	kfree(bus);
66 	return 0;
67 }
68 
69 static int snd_i2c_bus_dev_free(snd_device_t *device)
70 {
71 	snd_i2c_bus_t *bus = device->device_data;
72 	return snd_i2c_bus_free(bus);
73 }
74 
75 int snd_i2c_bus_create(snd_card_t *card, const char *name, snd_i2c_bus_t *master, snd_i2c_bus_t **ri2c)
76 {
77 	snd_i2c_bus_t *bus;
78 	int err;
79 	static snd_device_ops_t ops = {
80 		.dev_free =	snd_i2c_bus_dev_free,
81 	};
82 
83 	*ri2c = NULL;
84 	bus = kzalloc(sizeof(*bus), GFP_KERNEL);
85 	if (bus == NULL)
86 		return -ENOMEM;
87 	init_MUTEX(&bus->lock_mutex);
88 	INIT_LIST_HEAD(&bus->devices);
89 	INIT_LIST_HEAD(&bus->buses);
90 	bus->card = card;
91 	bus->ops = &snd_i2c_bit_ops;
92 	if (master) {
93 		list_add_tail(&bus->buses, &master->buses);
94 		bus->master = master;
95 	}
96 	strlcpy(bus->name, name, sizeof(bus->name));
97 	if ((err = snd_device_new(card, SNDRV_DEV_BUS, bus, &ops)) < 0) {
98 		snd_i2c_bus_free(bus);
99 		return err;
100 	}
101 	*ri2c = bus;
102 	return 0;
103 }
104 
105 int snd_i2c_device_create(snd_i2c_bus_t *bus, const char *name, unsigned char addr, snd_i2c_device_t **rdevice)
106 {
107 	snd_i2c_device_t *device;
108 
109 	*rdevice = NULL;
110 	snd_assert(bus != NULL, return -EINVAL);
111 	device = kzalloc(sizeof(*device), GFP_KERNEL);
112 	if (device == NULL)
113 		return -ENOMEM;
114 	device->addr = addr;
115 	strlcpy(device->name, name, sizeof(device->name));
116 	list_add_tail(&device->list, &bus->devices);
117 	device->bus = bus;
118 	*rdevice = device;
119 	return 0;
120 }
121 
122 int snd_i2c_device_free(snd_i2c_device_t *device)
123 {
124 	if (device->bus)
125 		list_del(&device->list);
126 	if (device->private_free)
127 		device->private_free(device);
128 	kfree(device);
129 	return 0;
130 }
131 
132 int snd_i2c_sendbytes(snd_i2c_device_t *device, unsigned char *bytes, int count)
133 {
134 	return device->bus->ops->sendbytes(device, bytes, count);
135 }
136 
137 
138 int snd_i2c_readbytes(snd_i2c_device_t *device, unsigned char *bytes, int count)
139 {
140 	return device->bus->ops->readbytes(device, bytes, count);
141 }
142 
143 int snd_i2c_probeaddr(snd_i2c_bus_t *bus, unsigned short addr)
144 {
145 	return bus->ops->probeaddr(bus, addr);
146 }
147 
148 /*
149  *  bit-operations
150  */
151 
152 static inline void snd_i2c_bit_hw_start(snd_i2c_bus_t *bus)
153 {
154 	if (bus->hw_ops.bit->start)
155 		bus->hw_ops.bit->start(bus);
156 }
157 
158 static inline void snd_i2c_bit_hw_stop(snd_i2c_bus_t *bus)
159 {
160 	if (bus->hw_ops.bit->stop)
161 		bus->hw_ops.bit->stop(bus);
162 }
163 
164 static void snd_i2c_bit_direction(snd_i2c_bus_t *bus, int clock, int data)
165 {
166 	if (bus->hw_ops.bit->direction)
167 		bus->hw_ops.bit->direction(bus, clock, data);
168 }
169 
170 static void snd_i2c_bit_set(snd_i2c_bus_t *bus, int clock, int data)
171 {
172 	bus->hw_ops.bit->setlines(bus, clock, data);
173 }
174 
175 #if 0
176 static int snd_i2c_bit_clock(snd_i2c_bus_t *bus)
177 {
178 	if (bus->hw_ops.bit->getclock)
179 		return bus->hw_ops.bit->getclock(bus);
180 	return -ENXIO;
181 }
182 #endif
183 
184 static int snd_i2c_bit_data(snd_i2c_bus_t *bus, int ack)
185 {
186 	return bus->hw_ops.bit->getdata(bus, ack);
187 }
188 
189 static void snd_i2c_bit_start(snd_i2c_bus_t *bus)
190 {
191 	snd_i2c_bit_hw_start(bus);
192 	snd_i2c_bit_direction(bus, 1, 1);	/* SCL - wr, SDA - wr */
193 	snd_i2c_bit_set(bus, 1, 1);
194 	snd_i2c_bit_set(bus, 1, 0);
195 	snd_i2c_bit_set(bus, 0, 0);
196 }
197 
198 static void snd_i2c_bit_stop(snd_i2c_bus_t *bus)
199 {
200 	snd_i2c_bit_set(bus, 0, 0);
201 	snd_i2c_bit_set(bus, 1, 0);
202 	snd_i2c_bit_set(bus, 1, 1);
203 	snd_i2c_bit_hw_stop(bus);
204 }
205 
206 static void snd_i2c_bit_send(snd_i2c_bus_t *bus, int data)
207 {
208 	snd_i2c_bit_set(bus, 0, data);
209 	snd_i2c_bit_set(bus, 1, data);
210 	snd_i2c_bit_set(bus, 0, data);
211 }
212 
213 static int snd_i2c_bit_ack(snd_i2c_bus_t *bus)
214 {
215 	int ack;
216 
217 	snd_i2c_bit_set(bus, 0, 1);
218 	snd_i2c_bit_set(bus, 1, 1);
219 	snd_i2c_bit_direction(bus, 1, 0);	/* SCL - wr, SDA - rd */
220 	ack = snd_i2c_bit_data(bus, 1);
221 	snd_i2c_bit_direction(bus, 1, 1);	/* SCL - wr, SDA - wr */
222 	snd_i2c_bit_set(bus, 0, 1);
223 	return ack ? -EIO : 0;
224 }
225 
226 static int snd_i2c_bit_sendbyte(snd_i2c_bus_t *bus, unsigned char data)
227 {
228 	int i, err;
229 
230 	for (i = 7; i >= 0; i--)
231 		snd_i2c_bit_send(bus, !!(data & (1 << i)));
232 	if ((err = snd_i2c_bit_ack(bus)) < 0)
233 		return err;
234 	return 0;
235 }
236 
237 static int snd_i2c_bit_readbyte(snd_i2c_bus_t *bus, int last)
238 {
239 	int i;
240 	unsigned char data = 0;
241 
242 	snd_i2c_bit_set(bus, 0, 1);
243 	snd_i2c_bit_direction(bus, 1, 0);	/* SCL - wr, SDA - rd */
244 	for (i = 7; i >= 0; i--) {
245 		snd_i2c_bit_set(bus, 1, 1);
246 		if (snd_i2c_bit_data(bus, 0))
247 			data |= (1 << i);
248 		snd_i2c_bit_set(bus, 0, 1);
249 	}
250 	snd_i2c_bit_direction(bus, 1, 1);	/* SCL - wr, SDA - wr */
251 	snd_i2c_bit_send(bus, !!last);
252 	return data;
253 }
254 
255 static int snd_i2c_bit_sendbytes(snd_i2c_device_t *device, unsigned char *bytes, int count)
256 {
257 	snd_i2c_bus_t *bus = device->bus;
258 	int err, res = 0;
259 
260 	if (device->flags & SND_I2C_DEVICE_ADDRTEN)
261 		return -EIO;		/* not yet implemented */
262 	snd_i2c_bit_start(bus);
263 	if ((err = snd_i2c_bit_sendbyte(bus, device->addr << 1)) < 0) {
264 		snd_i2c_bit_hw_stop(bus);
265 		return err;
266 	}
267 	while (count-- > 0) {
268 		if ((err = snd_i2c_bit_sendbyte(bus, *bytes++)) < 0) {
269 			snd_i2c_bit_hw_stop(bus);
270 			return err;
271 		}
272 		res++;
273 	}
274 	snd_i2c_bit_stop(bus);
275 	return res;
276 }
277 
278 static int snd_i2c_bit_readbytes(snd_i2c_device_t *device, unsigned char *bytes, int count)
279 {
280 	snd_i2c_bus_t *bus = device->bus;
281 	int err, res = 0;
282 
283 	if (device->flags & SND_I2C_DEVICE_ADDRTEN)
284 		return -EIO;		/* not yet implemented */
285 	snd_i2c_bit_start(bus);
286 	if ((err = snd_i2c_bit_sendbyte(bus, (device->addr << 1) | 1)) < 0) {
287 		snd_i2c_bit_hw_stop(bus);
288 		return err;
289 	}
290 	while (count-- > 0) {
291 		if ((err = snd_i2c_bit_readbyte(bus, count == 0)) < 0) {
292 			snd_i2c_bit_hw_stop(bus);
293 			return err;
294 		}
295 		*bytes++ = (unsigned char)err;
296 		res++;
297 	}
298 	snd_i2c_bit_stop(bus);
299 	return res;
300 }
301 
302 static int snd_i2c_bit_probeaddr(snd_i2c_bus_t *bus, unsigned short addr)
303 {
304 	int err;
305 
306 	if (addr & 0x8000)	/* 10-bit address */
307 		return -EIO;	/* not yet implemented */
308 	if (addr & 0x7f80)	/* invalid address */
309 		return -EINVAL;
310 	snd_i2c_bit_start(bus);
311 	err = snd_i2c_bit_sendbyte(bus, addr << 1);
312 	snd_i2c_bit_stop(bus);
313 	return err;
314 }
315 
316 EXPORT_SYMBOL(snd_i2c_bus_create);
317 EXPORT_SYMBOL(snd_i2c_device_create);
318 EXPORT_SYMBOL(snd_i2c_device_free);
319 EXPORT_SYMBOL(snd_i2c_sendbytes);
320 EXPORT_SYMBOL(snd_i2c_readbytes);
321 EXPORT_SYMBOL(snd_i2c_probeaddr);
322 
323 static int __init alsa_i2c_init(void)
324 {
325 	return 0;
326 }
327 
328 static void __exit alsa_i2c_exit(void)
329 {
330 }
331 
332 module_init(alsa_i2c_init)
333 module_exit(alsa_i2c_exit)
334