1 /* $NetBSD: i2c_exec.c,v 1.10 2015/03/07 14:16:51 jmcneill Exp $ */
2
3 /*
4 * Copyright (c) 2003 Wasabi Systems, Inc.
5 * All rights reserved.
6 *
7 * Written by Jason R. Thorpe for Wasabi Systems, Inc.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. All advertising materials mentioning features or use of this software
18 * must display the following acknowledgement:
19 * This product includes software developed for the NetBSD Project by
20 * Wasabi Systems, Inc.
21 * 4. The name of Wasabi Systems, Inc. may not be used to endorse
22 * or promote products derived from this software without specific prior
23 * written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
27 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
28 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL WASABI SYSTEMS, INC
29 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
30 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
31 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
32 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
33 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
34 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
35 * POSSIBILITY OF SUCH DAMAGE.
36 */
37
38 #include <sys/cdefs.h>
39 __KERNEL_RCSID(0, "$NetBSD: i2c_exec.c,v 1.10 2015/03/07 14:16:51 jmcneill Exp $");
40
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/device.h>
44 #include <sys/module.h>
45 #include <sys/event.h>
46 #include <sys/conf.h>
47
48 #define _I2C_PRIVATE
49 #include <dev/i2c/i2cvar.h>
50
51 static uint8_t iic_smbus_crc8(uint16_t);
52 static uint8_t iic_smbus_pec(int, uint8_t *, uint8_t *);
53
54 static int i2cexec_modcmd(modcmd_t, void *);
55
56 /*
57 * iic_exec:
58 *
59 * Simplified I2C client interface engine.
60 *
61 * This and the SMBus routines are the preferred interface for
62 * client access to I2C/SMBus, since many automated controllers
63 * do not provide access to the low-level primitives of the I2C
64 * bus protocol.
65 */
66 int
iic_exec(i2c_tag_t tag,i2c_op_t op,i2c_addr_t addr,const void * vcmd,size_t cmdlen,void * vbuf,size_t buflen,int flags)67 iic_exec(i2c_tag_t tag, i2c_op_t op, i2c_addr_t addr, const void *vcmd,
68 size_t cmdlen, void *vbuf, size_t buflen, int flags)
69 {
70 const uint8_t *cmd = vcmd;
71 uint8_t *buf = vbuf;
72 int error;
73 size_t len;
74
75 if ((flags & I2C_F_PEC) && cmdlen > 0 && tag->ic_exec != NULL) {
76 uint8_t data[33]; /* XXX */
77 uint8_t b[3];
78
79 b[0] = addr << 1;
80 b[1] = cmd[0];
81
82 switch (buflen) {
83 case 0:
84 data[0] = iic_smbus_pec(2, b, NULL);
85 buflen++;
86 break;
87 case 1:
88 b[2] = buf[0];
89 data[0] = iic_smbus_pec(3, b, NULL);
90 data[1] = b[2];
91 buflen++;
92 break;
93 case 2:
94 break;
95 default:
96 KASSERT(buflen+1 < sizeof(data));
97 memcpy(data, vbuf, buflen);
98 data[buflen] = iic_smbus_pec(2, b, data);
99 buflen++;
100 break;
101 }
102
103 return ((*tag->ic_exec)(tag->ic_cookie, op, addr, cmd,
104 cmdlen, data, buflen, flags));
105 }
106
107 /*
108 * Defer to the controller if it provides an exec function. Use
109 * it if it does.
110 */
111 if (tag->ic_exec != NULL)
112 return ((*tag->ic_exec)(tag->ic_cookie, op, addr, cmd,
113 cmdlen, buf, buflen, flags));
114
115 if ((len = cmdlen) != 0) {
116 if ((error = iic_initiate_xfer(tag, addr, flags)) != 0)
117 goto bad;
118 while (len--) {
119 if ((error = iic_write_byte(tag, *cmd++, flags)) != 0)
120 goto bad;
121 }
122 } else if (buflen == 0) {
123 /*
124 * This is a quick_read()/quick_write() command with
125 * neither command nor data bytes
126 */
127 if (I2C_OP_STOP_P(op))
128 flags |= I2C_F_STOP;
129 if (I2C_OP_READ_P(op))
130 flags |= I2C_F_READ;
131 if ((error = iic_initiate_xfer(tag, addr, flags)) != 0)
132 goto bad;
133 }
134
135 if (I2C_OP_READ_P(op))
136 flags |= I2C_F_READ;
137
138 len = buflen;
139 while (len--) {
140 if (len == 0 && I2C_OP_STOP_P(op))
141 flags |= I2C_F_STOP;
142 if (I2C_OP_READ_P(op)) {
143 /* Send REPEATED START. */
144 if ((len + 1) == buflen &&
145 (error = iic_initiate_xfer(tag, addr, flags)) != 0)
146 goto bad;
147 /* NACK on last byte. */
148 if (len == 0)
149 flags |= I2C_F_LAST;
150 if ((error = iic_read_byte(tag, buf++, flags)) != 0)
151 goto bad;
152 } else {
153 /* Maybe send START. */
154 if ((len + 1) == buflen && cmdlen == 0 &&
155 (error = iic_initiate_xfer(tag, addr, flags)) != 0)
156 goto bad;
157 if ((error = iic_write_byte(tag, *buf++, flags)) != 0)
158 goto bad;
159 }
160 }
161
162 return (0);
163 bad:
164 iic_send_stop(tag, flags);
165 return (error);
166 }
167
168 /*
169 * iic_smbus_write_byte:
170 *
171 * Perform an SMBus "write byte" operation.
172 */
173 int
iic_smbus_write_byte(i2c_tag_t tag,i2c_addr_t addr,uint8_t cmd,uint8_t val,int flags)174 iic_smbus_write_byte(i2c_tag_t tag, i2c_addr_t addr, uint8_t cmd,
175 uint8_t val, int flags)
176 {
177
178 return (iic_exec(tag, I2C_OP_WRITE_WITH_STOP, addr, &cmd, 1,
179 &val, 1, flags));
180 }
181
182 /*
183 * iic_smbus_write_word:
184 *
185 * Perform an SMBus "write word" operation.
186 */
187 int
iic_smbus_write_word(i2c_tag_t tag,i2c_addr_t addr,uint8_t cmd,uint16_t val,int flags)188 iic_smbus_write_word(i2c_tag_t tag, i2c_addr_t addr, uint8_t cmd,
189 uint16_t val, int flags)
190 {
191 uint8_t vbuf[2];
192
193 vbuf[0] = val & 0xff;
194 vbuf[1] = (val >> 8) & 0xff;
195
196 return (iic_exec(tag, I2C_OP_WRITE_WITH_STOP, addr, &cmd, 1,
197 vbuf, 2, flags));
198 }
199
200 /*
201 * iic_smbus_read_byte:
202 *
203 * Perform an SMBus "read byte" operation.
204 */
205 int
iic_smbus_read_byte(i2c_tag_t tag,i2c_addr_t addr,uint8_t cmd,uint8_t * valp,int flags)206 iic_smbus_read_byte(i2c_tag_t tag, i2c_addr_t addr, uint8_t cmd,
207 uint8_t *valp, int flags)
208 {
209
210 return (iic_exec(tag, I2C_OP_READ_WITH_STOP, addr, &cmd, 1,
211 valp, 1, flags));
212 }
213
214 /*
215 * iic_smbus_read_word:
216 *
217 * Perform an SMBus "read word" operation.
218 */
219 int
iic_smbus_read_word(i2c_tag_t tag,i2c_addr_t addr,uint8_t cmd,uint16_t * valp,int flags)220 iic_smbus_read_word(i2c_tag_t tag, i2c_addr_t addr, uint8_t cmd,
221 uint16_t *valp, int flags)
222 {
223
224 return (iic_exec(tag, I2C_OP_READ_WITH_STOP, addr, &cmd, 1,
225 (uint8_t *)valp, 2, flags));
226 }
227
228 /*
229 * iic_smbus_receive_byte:
230 *
231 * Perform an SMBus "receive byte" operation.
232 */
233 int
iic_smbus_receive_byte(i2c_tag_t tag,i2c_addr_t addr,uint8_t * valp,int flags)234 iic_smbus_receive_byte(i2c_tag_t tag, i2c_addr_t addr, uint8_t *valp,
235 int flags)
236 {
237
238 return (iic_exec(tag, I2C_OP_READ_WITH_STOP, addr, NULL, 0,
239 valp, 1, flags));
240 }
241
242 /*
243 * iic_smbus_send_byte:
244 *
245 * Perform an SMBus "send byte" operation.
246 */
247 int
iic_smbus_send_byte(i2c_tag_t tag,i2c_addr_t addr,uint8_t val,int flags)248 iic_smbus_send_byte(i2c_tag_t tag, i2c_addr_t addr, uint8_t val, int flags)
249 {
250
251 return (iic_exec(tag, I2C_OP_WRITE_WITH_STOP, addr, NULL, 0,
252 &val, 1, flags));
253 }
254
255 /*
256 * iic_smbus_quick_read:
257 *
258 * Perform an SMBus "quick read" operation.
259 */
260 int
iic_smbus_quick_read(i2c_tag_t tag,i2c_addr_t addr,int flags)261 iic_smbus_quick_read(i2c_tag_t tag, i2c_addr_t addr, int flags)
262 {
263
264 return (iic_exec(tag, I2C_OP_READ_WITH_STOP, addr, NULL, 0,
265 NULL, 0, flags));
266 }
267
268 /*
269 * iic_smbus_quick_write:
270 *
271 * Perform an SMBus "quick write" operation.
272 */
273 int
iic_smbus_quick_write(i2c_tag_t tag,i2c_addr_t addr,int flags)274 iic_smbus_quick_write(i2c_tag_t tag, i2c_addr_t addr, int flags)
275 {
276
277 return (iic_exec(tag, I2C_OP_WRITE_WITH_STOP, addr, NULL, 0,
278 NULL, 0, flags));
279 }
280
281 /*
282 * iic_smbus_block_read:
283 *
284 * Perform an SMBus "block read" operation.
285 */
286 int
iic_smbus_block_read(i2c_tag_t tag,i2c_addr_t addr,uint8_t cmd,uint8_t * vbuf,size_t buflen,int flags)287 iic_smbus_block_read(i2c_tag_t tag, i2c_addr_t addr, uint8_t cmd,
288 uint8_t *vbuf, size_t buflen, int flags)
289 {
290
291 return (iic_exec(tag, I2C_OP_READ_BLOCK, addr, &cmd, 1,
292 vbuf, buflen, flags));
293 }
294
295 /*
296 * iic_smbus_block_write:
297 *
298 * Perform an SMBus "block write" operation.
299 */
300 int
iic_smbus_block_write(i2c_tag_t tag,i2c_addr_t addr,uint8_t cmd,uint8_t * vbuf,size_t buflen,int flags)301 iic_smbus_block_write(i2c_tag_t tag, i2c_addr_t addr, uint8_t cmd,
302 uint8_t *vbuf, size_t buflen, int flags)
303 {
304
305 return (iic_exec(tag, I2C_OP_WRITE_BLOCK, addr, &cmd, 1,
306 vbuf, buflen, flags));
307 }
308
309 /*
310 * iic_smbus_crc8
311 *
312 * Private helper for calculating packet error checksum
313 */
314 static uint8_t
iic_smbus_crc8(uint16_t data)315 iic_smbus_crc8(uint16_t data)
316 {
317 int i;
318
319 for (i = 0; i < 8; i++) {
320 if (data & 0x8000)
321 data = data ^ (0x1070U << 3);
322 data = data << 1;
323 }
324
325 return (uint8_t)(data >> 8);
326 }
327
328 /*
329 * iic_smbus_pec
330 *
331 * Private function for calculating packet error checking on SMBus
332 * packets.
333 */
334 static uint8_t
iic_smbus_pec(int count,uint8_t * s,uint8_t * r)335 iic_smbus_pec(int count, uint8_t *s, uint8_t *r)
336 {
337 int i;
338 uint8_t crc = 0;
339
340 for (i = 0; i < count; i++)
341 crc = iic_smbus_crc8((crc ^ s[i]) << 8);
342 if (r != NULL)
343 for (i = 0; i <= r[0]; i++)
344 crc = iic_smbus_crc8((crc ^ r[i]) << 8);
345
346 return crc;
347 }
348
349 MODULE(MODULE_CLASS_MISC, i2cexec, NULL);
350
351 static int
i2cexec_modcmd(modcmd_t cmd,void * opaque)352 i2cexec_modcmd(modcmd_t cmd, void *opaque)
353 {
354 switch (cmd) {
355 case MODULE_CMD_INIT:
356 case MODULE_CMD_FINI:
357 return 0;
358 break;
359 default:
360 return ENOTTY;
361 }
362 }
363