xref: /openbmc/linux/sound/i2c/i2c.c (revision b868a02e) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *   Generic i2c interface for ALSA
4  *
5  *   (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>
6  *   Modified for the ALSA driver by Jaroslav Kysela <perex@perex.cz>
7  */
8 
9 #include <linux/init.h>
10 #include <linux/slab.h>
11 #include <linux/module.h>
12 #include <linux/string.h>
13 #include <linux/errno.h>
14 #include <sound/core.h>
15 #include <sound/i2c.h>
16 
17 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
18 MODULE_DESCRIPTION("Generic i2c interface for ALSA");
19 MODULE_LICENSE("GPL");
20 
21 static int snd_i2c_bit_sendbytes(struct snd_i2c_device *device,
22 				 unsigned char *bytes, int count);
23 static int snd_i2c_bit_readbytes(struct snd_i2c_device *device,
24 				 unsigned char *bytes, int count);
25 static int snd_i2c_bit_probeaddr(struct snd_i2c_bus *bus,
26 				 unsigned short addr);
27 
28 static const struct snd_i2c_ops snd_i2c_bit_ops = {
29 	.sendbytes = snd_i2c_bit_sendbytes,
30 	.readbytes = snd_i2c_bit_readbytes,
31 	.probeaddr = snd_i2c_bit_probeaddr,
32 };
33 
34 static int snd_i2c_bus_free(struct snd_i2c_bus *bus)
35 {
36 	struct snd_i2c_bus *slave;
37 	struct snd_i2c_device *device;
38 
39 	if (snd_BUG_ON(!bus))
40 		return -EINVAL;
41 	while (!list_empty(&bus->devices)) {
42 		device = snd_i2c_device(bus->devices.next);
43 		snd_i2c_device_free(device);
44 	}
45 	if (bus->master)
46 		list_del(&bus->buses);
47 	else {
48 		while (!list_empty(&bus->buses)) {
49 			slave = snd_i2c_slave_bus(bus->buses.next);
50 			snd_device_free(bus->card, slave);
51 		}
52 	}
53 	if (bus->private_free)
54 		bus->private_free(bus);
55 	kfree(bus);
56 	return 0;
57 }
58 
59 static int snd_i2c_bus_dev_free(struct snd_device *device)
60 {
61 	struct snd_i2c_bus *bus = device->device_data;
62 	return snd_i2c_bus_free(bus);
63 }
64 
65 int snd_i2c_bus_create(struct snd_card *card, const char *name,
66 		       struct snd_i2c_bus *master, struct snd_i2c_bus **ri2c)
67 {
68 	struct snd_i2c_bus *bus;
69 	int err;
70 	static const struct snd_device_ops ops = {
71 		.dev_free =	snd_i2c_bus_dev_free,
72 	};
73 
74 	*ri2c = NULL;
75 	bus = kzalloc(sizeof(*bus), GFP_KERNEL);
76 	if (bus == NULL)
77 		return -ENOMEM;
78 	mutex_init(&bus->lock_mutex);
79 	INIT_LIST_HEAD(&bus->devices);
80 	INIT_LIST_HEAD(&bus->buses);
81 	bus->card = card;
82 	bus->ops = &snd_i2c_bit_ops;
83 	if (master) {
84 		list_add_tail(&bus->buses, &master->buses);
85 		bus->master = master;
86 	}
87 	strscpy(bus->name, name, sizeof(bus->name));
88 	err = snd_device_new(card, SNDRV_DEV_BUS, bus, &ops);
89 	if (err < 0) {
90 		snd_i2c_bus_free(bus);
91 		return err;
92 	}
93 	*ri2c = bus;
94 	return 0;
95 }
96 
97 EXPORT_SYMBOL(snd_i2c_bus_create);
98 
99 int snd_i2c_device_create(struct snd_i2c_bus *bus, const char *name,
100 			  unsigned char addr, struct snd_i2c_device **rdevice)
101 {
102 	struct snd_i2c_device *device;
103 
104 	*rdevice = NULL;
105 	if (snd_BUG_ON(!bus))
106 		return -EINVAL;
107 	device = kzalloc(sizeof(*device), GFP_KERNEL);
108 	if (device == NULL)
109 		return -ENOMEM;
110 	device->addr = addr;
111 	strscpy(device->name, name, sizeof(device->name));
112 	list_add_tail(&device->list, &bus->devices);
113 	device->bus = bus;
114 	*rdevice = device;
115 	return 0;
116 }
117 
118 EXPORT_SYMBOL(snd_i2c_device_create);
119 
120 int snd_i2c_device_free(struct snd_i2c_device *device)
121 {
122 	if (device->bus)
123 		list_del(&device->list);
124 	if (device->private_free)
125 		device->private_free(device);
126 	kfree(device);
127 	return 0;
128 }
129 
130 EXPORT_SYMBOL(snd_i2c_device_free);
131 
132 int snd_i2c_sendbytes(struct snd_i2c_device *device, unsigned char *bytes, int count)
133 {
134 	return device->bus->ops->sendbytes(device, bytes, count);
135 }
136 
137 EXPORT_SYMBOL(snd_i2c_sendbytes);
138 
139 int snd_i2c_readbytes(struct snd_i2c_device *device, unsigned char *bytes, int count)
140 {
141 	return device->bus->ops->readbytes(device, bytes, count);
142 }
143 
144 EXPORT_SYMBOL(snd_i2c_readbytes);
145 
146 int snd_i2c_probeaddr(struct snd_i2c_bus *bus, unsigned short addr)
147 {
148 	return bus->ops->probeaddr(bus, addr);
149 }
150 
151 EXPORT_SYMBOL(snd_i2c_probeaddr);
152 
153 /*
154  *  bit-operations
155  */
156 
157 static inline void snd_i2c_bit_hw_start(struct snd_i2c_bus *bus)
158 {
159 	if (bus->hw_ops.bit->start)
160 		bus->hw_ops.bit->start(bus);
161 }
162 
163 static inline void snd_i2c_bit_hw_stop(struct snd_i2c_bus *bus)
164 {
165 	if (bus->hw_ops.bit->stop)
166 		bus->hw_ops.bit->stop(bus);
167 }
168 
169 static void snd_i2c_bit_direction(struct snd_i2c_bus *bus, int clock, int data)
170 {
171 	if (bus->hw_ops.bit->direction)
172 		bus->hw_ops.bit->direction(bus, clock, data);
173 }
174 
175 static void snd_i2c_bit_set(struct snd_i2c_bus *bus, int clock, int data)
176 {
177 	bus->hw_ops.bit->setlines(bus, clock, data);
178 }
179 
180 #if 0
181 static int snd_i2c_bit_clock(struct snd_i2c_bus *bus)
182 {
183 	if (bus->hw_ops.bit->getclock)
184 		return bus->hw_ops.bit->getclock(bus);
185 	return -ENXIO;
186 }
187 #endif
188 
189 static int snd_i2c_bit_data(struct snd_i2c_bus *bus, int ack)
190 {
191 	return bus->hw_ops.bit->getdata(bus, ack);
192 }
193 
194 static void snd_i2c_bit_start(struct snd_i2c_bus *bus)
195 {
196 	snd_i2c_bit_hw_start(bus);
197 	snd_i2c_bit_direction(bus, 1, 1);	/* SCL - wr, SDA - wr */
198 	snd_i2c_bit_set(bus, 1, 1);
199 	snd_i2c_bit_set(bus, 1, 0);
200 	snd_i2c_bit_set(bus, 0, 0);
201 }
202 
203 static void snd_i2c_bit_stop(struct snd_i2c_bus *bus)
204 {
205 	snd_i2c_bit_set(bus, 0, 0);
206 	snd_i2c_bit_set(bus, 1, 0);
207 	snd_i2c_bit_set(bus, 1, 1);
208 	snd_i2c_bit_hw_stop(bus);
209 }
210 
211 static void snd_i2c_bit_send(struct snd_i2c_bus *bus, int data)
212 {
213 	snd_i2c_bit_set(bus, 0, data);
214 	snd_i2c_bit_set(bus, 1, data);
215 	snd_i2c_bit_set(bus, 0, data);
216 }
217 
218 static int snd_i2c_bit_ack(struct snd_i2c_bus *bus)
219 {
220 	int ack;
221 
222 	snd_i2c_bit_set(bus, 0, 1);
223 	snd_i2c_bit_set(bus, 1, 1);
224 	snd_i2c_bit_direction(bus, 1, 0);	/* SCL - wr, SDA - rd */
225 	ack = snd_i2c_bit_data(bus, 1);
226 	snd_i2c_bit_direction(bus, 1, 1);	/* SCL - wr, SDA - wr */
227 	snd_i2c_bit_set(bus, 0, 1);
228 	return ack ? -EIO : 0;
229 }
230 
231 static int snd_i2c_bit_sendbyte(struct snd_i2c_bus *bus, unsigned char data)
232 {
233 	int i, err;
234 
235 	for (i = 7; i >= 0; i--)
236 		snd_i2c_bit_send(bus, !!(data & (1 << i)));
237 	err = snd_i2c_bit_ack(bus);
238 	if (err < 0)
239 		return err;
240 	return 0;
241 }
242 
243 static int snd_i2c_bit_readbyte(struct snd_i2c_bus *bus, int last)
244 {
245 	int i;
246 	unsigned char data = 0;
247 
248 	snd_i2c_bit_set(bus, 0, 1);
249 	snd_i2c_bit_direction(bus, 1, 0);	/* SCL - wr, SDA - rd */
250 	for (i = 7; i >= 0; i--) {
251 		snd_i2c_bit_set(bus, 1, 1);
252 		if (snd_i2c_bit_data(bus, 0))
253 			data |= (1 << i);
254 		snd_i2c_bit_set(bus, 0, 1);
255 	}
256 	snd_i2c_bit_direction(bus, 1, 1);	/* SCL - wr, SDA - wr */
257 	snd_i2c_bit_send(bus, !!last);
258 	return data;
259 }
260 
261 static int snd_i2c_bit_sendbytes(struct snd_i2c_device *device,
262 				 unsigned char *bytes, int count)
263 {
264 	struct snd_i2c_bus *bus = device->bus;
265 	int err, res = 0;
266 
267 	if (device->flags & SND_I2C_DEVICE_ADDRTEN)
268 		return -EIO;		/* not yet implemented */
269 	snd_i2c_bit_start(bus);
270 	err = snd_i2c_bit_sendbyte(bus, device->addr << 1);
271 	if (err < 0) {
272 		snd_i2c_bit_hw_stop(bus);
273 		return err;
274 	}
275 	while (count-- > 0) {
276 		err = snd_i2c_bit_sendbyte(bus, *bytes++);
277 		if (err < 0) {
278 			snd_i2c_bit_hw_stop(bus);
279 			return err;
280 		}
281 		res++;
282 	}
283 	snd_i2c_bit_stop(bus);
284 	return res;
285 }
286 
287 static int snd_i2c_bit_readbytes(struct snd_i2c_device *device,
288 				 unsigned char *bytes, int count)
289 {
290 	struct snd_i2c_bus *bus = device->bus;
291 	int err, res = 0;
292 
293 	if (device->flags & SND_I2C_DEVICE_ADDRTEN)
294 		return -EIO;		/* not yet implemented */
295 	snd_i2c_bit_start(bus);
296 	err = snd_i2c_bit_sendbyte(bus, (device->addr << 1) | 1);
297 	if (err < 0) {
298 		snd_i2c_bit_hw_stop(bus);
299 		return err;
300 	}
301 	while (count-- > 0) {
302 		err = snd_i2c_bit_readbyte(bus, count == 0);
303 		if (err < 0) {
304 			snd_i2c_bit_hw_stop(bus);
305 			return err;
306 		}
307 		*bytes++ = (unsigned char)err;
308 		res++;
309 	}
310 	snd_i2c_bit_stop(bus);
311 	return res;
312 }
313 
314 static int snd_i2c_bit_probeaddr(struct snd_i2c_bus *bus, unsigned short addr)
315 {
316 	int err;
317 
318 	if (addr & 0x8000)	/* 10-bit address */
319 		return -EIO;	/* not yet implemented */
320 	if (addr & 0x7f80)	/* invalid address */
321 		return -EINVAL;
322 	snd_i2c_bit_start(bus);
323 	err = snd_i2c_bit_sendbyte(bus, addr << 1);
324 	snd_i2c_bit_stop(bus);
325 	return err;
326 }
327