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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Evgeniy Polyakov77859252005-05-20 22:33:25 +04002 * w1_io.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07003 *
4 * Copyright (c) 2004 Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Evgeniy Polyakov77859252005-05-20 22:33:25 +04005 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07006 *
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#include <asm/io.h>
23
24#include <linux/delay.h>
25#include <linux/moduleparam.h>
Andrew Morton339f0722006-04-03 22:51:17 -070026#include <linux/module.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070027
28#include "w1.h"
29#include "w1_log.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070030
Adrian Bunka9fb1c72005-12-13 14:04:33 -080031static int w1_delay_parm = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -070032module_param_named(delay_coef, w1_delay_parm, int, 0);
33
34static u8 w1_crc8_table[] = {
35 0, 94, 188, 226, 97, 63, 221, 131, 194, 156, 126, 32, 163, 253, 31, 65,
36 157, 195, 33, 127, 252, 162, 64, 30, 95, 1, 227, 189, 62, 96, 130, 220,
37 35, 125, 159, 193, 66, 28, 254, 160, 225, 191, 93, 3, 128, 222, 60, 98,
38 190, 224, 2, 92, 223, 129, 99, 61, 124, 34, 192, 158, 29, 67, 161, 255,
39 70, 24, 250, 164, 39, 121, 155, 197, 132, 218, 56, 102, 229, 187, 89, 7,
40 219, 133, 103, 57, 186, 228, 6, 88, 25, 71, 165, 251, 120, 38, 196, 154,
41 101, 59, 217, 135, 4, 90, 184, 230, 167, 249, 27, 69, 198, 152, 122, 36,
42 248, 166, 68, 26, 153, 199, 37, 123, 58, 100, 134, 216, 91, 5, 231, 185,
43 140, 210, 48, 110, 237, 179, 81, 15, 78, 16, 242, 172, 47, 113, 147, 205,
44 17, 79, 173, 243, 112, 46, 204, 146, 211, 141, 111, 49, 178, 236, 14, 80,
45 175, 241, 19, 77, 206, 144, 114, 44, 109, 51, 209, 143, 12, 82, 176, 238,
46 50, 108, 142, 208, 83, 13, 239, 177, 240, 174, 76, 18, 145, 207, 45, 115,
47 202, 148, 118, 40, 171, 245, 23, 73, 8, 86, 180, 234, 105, 55, 213, 139,
48 87, 9, 235, 181, 54, 104, 138, 212, 149, 203, 41, 119, 244, 170, 72, 22,
49 233, 183, 85, 11, 136, 214, 52, 106, 43, 117, 151, 201, 74, 20, 246, 168,
50 116, 42, 200, 150, 21, 75, 169, 247, 182, 232, 10, 84, 215, 137, 107, 53
51};
52
Evgeniy Polyakov70d484b2006-04-24 10:46:14 +040053static void w1_delay(unsigned long tm)
Linus Torvalds1da177e2005-04-16 15:20:36 -070054{
55 udelay(tm * w1_delay_parm);
56}
57
Evgeniy Polyakovbe57ce22005-06-04 01:21:46 +040058static void w1_write_bit(struct w1_master *dev, int bit);
59static u8 w1_read_bit(struct w1_master *dev);
60
61/**
62 * Generates a write-0 or write-1 cycle and samples the level.
63 */
Evgeniy Polyakov70d484b2006-04-24 10:46:14 +040064static u8 w1_touch_bit(struct w1_master *dev, int bit)
Linus Torvalds1da177e2005-04-16 15:20:36 -070065{
66 if (dev->bus_master->touch_bit)
67 return dev->bus_master->touch_bit(dev->bus_master->data, bit);
Evgeniy Polyakovbe57ce22005-06-04 01:21:46 +040068 else if (bit)
Linus Torvalds1da177e2005-04-16 15:20:36 -070069 return w1_read_bit(dev);
Evgeniy Polyakovbe57ce22005-06-04 01:21:46 +040070 else {
71 w1_write_bit(dev, 0);
72 return(0);
73 }
Linus Torvalds1da177e2005-04-16 15:20:36 -070074}
75
Evgeniy Polyakovbe57ce22005-06-04 01:21:46 +040076/**
77 * Generates a write-0 or write-1 cycle.
78 * Only call if dev->bus_master->touch_bit is NULL
79 */
80static void w1_write_bit(struct w1_master *dev, int bit)
Linus Torvalds1da177e2005-04-16 15:20:36 -070081{
82 if (bit) {
83 dev->bus_master->write_bit(dev->bus_master->data, 0);
84 w1_delay(6);
85 dev->bus_master->write_bit(dev->bus_master->data, 1);
86 w1_delay(64);
87 } else {
88 dev->bus_master->write_bit(dev->bus_master->data, 0);
89 w1_delay(60);
90 dev->bus_master->write_bit(dev->bus_master->data, 1);
91 w1_delay(10);
92 }
93}
94
Evgeniy Polyakovbe57ce22005-06-04 01:21:46 +040095/**
David Fries6a158c02008-10-15 22:04:42 -070096 * Pre-write operation, currently only supporting strong pullups.
97 * Program the hardware for a strong pullup, if one has been requested and
98 * the hardware supports it.
99 *
100 * @param dev the master device
101 */
102static void w1_pre_write(struct w1_master *dev)
103{
104 if (dev->pullup_duration &&
105 dev->enable_pullup && dev->bus_master->set_pullup) {
106 dev->bus_master->set_pullup(dev->bus_master->data,
107 dev->pullup_duration);
108 }
109}
110
111/**
112 * Post-write operation, currently only supporting strong pullups.
113 * If a strong pullup was requested, clear it if the hardware supports
114 * them, or execute the delay otherwise, in either case clear the request.
115 *
116 * @param dev the master device
117 */
118static void w1_post_write(struct w1_master *dev)
119{
120 if (dev->pullup_duration) {
121 if (dev->enable_pullup && dev->bus_master->set_pullup)
122 dev->bus_master->set_pullup(dev->bus_master->data, 0);
123 else
124 msleep(dev->pullup_duration);
125 dev->pullup_duration = 0;
126 }
127}
128
129/**
Evgeniy Polyakovbe57ce22005-06-04 01:21:46 +0400130 * Writes 8 bits.
131 *
132 * @param dev the master device
133 * @param byte the byte to write
134 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135void w1_write_8(struct w1_master *dev, u8 byte)
136{
137 int i;
138
David Fries6a158c02008-10-15 22:04:42 -0700139 if (dev->bus_master->write_byte) {
140 w1_pre_write(dev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 dev->bus_master->write_byte(dev->bus_master->data, byte);
David Fries6a158c02008-10-15 22:04:42 -0700142 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 else
David Fries6a158c02008-10-15 22:04:42 -0700144 for (i = 0; i < 8; ++i) {
145 if (i == 7)
146 w1_pre_write(dev);
Evgeniy Polyakovbe57ce22005-06-04 01:21:46 +0400147 w1_touch_bit(dev, (byte >> i) & 0x1);
David Fries6a158c02008-10-15 22:04:42 -0700148 }
149 w1_post_write(dev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150}
Andrew Morton339f0722006-04-03 22:51:17 -0700151EXPORT_SYMBOL_GPL(w1_write_8);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152
Evgeniy Polyakovbe57ce22005-06-04 01:21:46 +0400153
154/**
155 * Generates a write-1 cycle and samples the level.
156 * Only call if dev->bus_master->touch_bit is NULL
157 */
158static u8 w1_read_bit(struct w1_master *dev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159{
160 int result;
161
162 dev->bus_master->write_bit(dev->bus_master->data, 0);
163 w1_delay(6);
164 dev->bus_master->write_bit(dev->bus_master->data, 1);
165 w1_delay(9);
166
167 result = dev->bus_master->read_bit(dev->bus_master->data);
168 w1_delay(55);
169
170 return result & 0x1;
171}
172
Evgeniy Polyakovbe57ce22005-06-04 01:21:46 +0400173/**
Evgeniy Polyakov6b729862005-06-04 01:30:43 +0400174 * Does a triplet - used for searching ROM addresses.
175 * Return bits:
176 * bit 0 = id_bit
177 * bit 1 = comp_bit
178 * bit 2 = dir_taken
179 * If both bits 0 & 1 are set, the search should be restarted.
180 *
181 * @param dev the master device
182 * @param bdir the bit to write if both id_bit and comp_bit are 0
183 * @return bit fields - see above
184 */
185u8 w1_triplet(struct w1_master *dev, int bdir)
186{
187 if ( dev->bus_master->triplet )
188 return(dev->bus_master->triplet(dev->bus_master->data, bdir));
189 else {
190 u8 id_bit = w1_touch_bit(dev, 1);
191 u8 comp_bit = w1_touch_bit(dev, 1);
192 u8 retval;
193
194 if ( id_bit && comp_bit )
195 return(0x03); /* error */
196
197 if ( !id_bit && !comp_bit ) {
198 /* Both bits are valid, take the direction given */
199 retval = bdir ? 0x04 : 0;
200 } else {
201 /* Only one bit is valid, take that direction */
202 bdir = id_bit;
203 retval = id_bit ? 0x05 : 0x02;
204 }
205
206 if ( dev->bus_master->touch_bit )
207 w1_touch_bit(dev, bdir);
208 else
209 w1_write_bit(dev, bdir);
210 return(retval);
211 }
212}
213
214/**
Evgeniy Polyakovbe57ce22005-06-04 01:21:46 +0400215 * Reads 8 bits.
216 *
217 * @param dev the master device
218 * @return the byte read
219 */
Madhusudhan Chikkature34e453d2008-11-12 13:27:08 -0800220u8 w1_read_8(struct w1_master *dev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221{
222 int i;
223 u8 res = 0;
224
225 if (dev->bus_master->read_byte)
226 res = dev->bus_master->read_byte(dev->bus_master->data);
227 else
228 for (i = 0; i < 8; ++i)
Evgeniy Polyakovbe57ce22005-06-04 01:21:46 +0400229 res |= (w1_touch_bit(dev,1) << i);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230
231 return res;
232}
Madhusudhan Chikkature34e453d2008-11-12 13:27:08 -0800233EXPORT_SYMBOL_GPL(w1_read_8);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234
Evgeniy Polyakovbe57ce22005-06-04 01:21:46 +0400235/**
236 * Writes a series of bytes.
237 *
238 * @param dev the master device
239 * @param buf pointer to the data to write
240 * @param len the number of bytes to write
241 * @return the byte read
242 */
243void w1_write_block(struct w1_master *dev, const u8 *buf, int len)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244{
245 int i;
246
David Fries6a158c02008-10-15 22:04:42 -0700247 if (dev->bus_master->write_block) {
248 w1_pre_write(dev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249 dev->bus_master->write_block(dev->bus_master->data, buf, len);
David Fries6a158c02008-10-15 22:04:42 -0700250 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251 else
252 for (i = 0; i < len; ++i)
David Fries6a158c02008-10-15 22:04:42 -0700253 w1_write_8(dev, buf[i]); /* calls w1_pre_write */
254 w1_post_write(dev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255}
Andrew Morton339f0722006-04-03 22:51:17 -0700256EXPORT_SYMBOL_GPL(w1_write_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257
Evgeniy Polyakovbe57ce22005-06-04 01:21:46 +0400258/**
259 * Reads a series of bytes.
260 *
261 * @param dev the master device
262 * @param buf pointer to the buffer to fill
263 * @param len the number of bytes to read
264 * @return the number of bytes read
265 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266u8 w1_read_block(struct w1_master *dev, u8 *buf, int len)
267{
268 int i;
269 u8 ret;
270
271 if (dev->bus_master->read_block)
272 ret = dev->bus_master->read_block(dev->bus_master->data, buf, len);
273 else {
274 for (i = 0; i < len; ++i)
275 buf[i] = w1_read_8(dev);
276 ret = len;
277 }
278
279 return ret;
280}
Andrew Morton339f0722006-04-03 22:51:17 -0700281EXPORT_SYMBOL_GPL(w1_read_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282
Evgeniy Polyakovbe57ce22005-06-04 01:21:46 +0400283/**
284 * Issues a reset bus sequence.
285 *
286 * @param dev The bus master pointer
287 * @return 0=Device present, 1=No device present or error
288 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289int w1_reset_bus(struct w1_master *dev)
290{
Evgeniy Polyakovbe57ce22005-06-04 01:21:46 +0400291 int result;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292
293 if (dev->bus_master->reset_bus)
294 result = dev->bus_master->reset_bus(dev->bus_master->data) & 0x1;
295 else {
296 dev->bus_master->write_bit(dev->bus_master->data, 0);
David Fries8e3dae22008-10-15 22:05:01 -0700297 /* minimum 480, max ? us
298 * be nice and sleep, except 18b20 spec lists 960us maximum,
299 * so until we can sleep with microsecond accuracy, spin.
300 * Feel free to come up with some other way to give up the
301 * cpu for such a short amount of time AND get it back in
302 * the maximum amount of time.
303 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304 w1_delay(480);
305 dev->bus_master->write_bit(dev->bus_master->data, 1);
306 w1_delay(70);
307
308 result = dev->bus_master->read_bit(dev->bus_master->data) & 0x1;
David Fries8e3dae22008-10-15 22:05:01 -0700309 /* minmum 70 (above) + 410 = 480 us
310 * There aren't any timing requirements between a reset and
311 * the following transactions. Sleeping is safe here.
312 */
313 /* w1_delay(410); min required time */
314 msleep(1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315 }
316
317 return result;
318}
Andrew Morton339f0722006-04-03 22:51:17 -0700319EXPORT_SYMBOL_GPL(w1_reset_bus);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320
321u8 w1_calc_crc8(u8 * data, int len)
322{
323 u8 crc = 0;
324
325 while (len--)
326 crc = w1_crc8_table[crc ^ *data++];
327
328 return crc;
329}
Andrew Morton339f0722006-04-03 22:51:17 -0700330EXPORT_SYMBOL_GPL(w1_calc_crc8);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331
Evgeniy Polyakov12003372006-03-23 19:11:58 +0300332void w1_search_devices(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333{
334 dev->attempts++;
335 if (dev->bus_master->search)
David Friesc30c9b12008-10-15 22:04:38 -0700336 dev->bus_master->search(dev->bus_master->data, dev,
337 search_type, cb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338 else
Evgeniy Polyakov12003372006-03-23 19:11:58 +0300339 w1_search(dev, search_type, cb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340}
341
Evgeniy Polyakovea7d8f62005-08-11 17:27:49 +0400342/**
343 * Resets the bus and then selects the slave by sending either a skip rom
344 * or a rom match.
345 * The w1 master lock must be held.
346 *
347 * @param sl the slave to select
348 * @return 0=success, anything else=error
349 */
350int w1_reset_select_slave(struct w1_slave *sl)
351{
352 if (w1_reset_bus(sl->master))
353 return -1;
354
355 if (sl->master->slave_count == 1)
356 w1_write_8(sl->master, W1_SKIP_ROM);
357 else {
358 u8 match[9] = {W1_MATCH_ROM, };
359 memcpy(&match[1], (u8 *)&sl->reg_num, 8);
360 w1_write_block(sl->master, match, 9);
361 }
362 return 0;
363}
Andrew Morton339f0722006-04-03 22:51:17 -0700364EXPORT_SYMBOL_GPL(w1_reset_select_slave);
David Fries6a158c02008-10-15 22:04:42 -0700365
366/**
367 * Put out a strong pull-up of the specified duration after the next write
368 * operation. Not all hardware supports strong pullups. Hardware that
369 * doesn't support strong pullups will sleep for the given time after the
370 * write operation without a strong pullup. This is a one shot request for
371 * the next write, specifying zero will clear a previous request.
372 * The w1 master lock must be held.
373 *
374 * @param delay time in milliseconds
375 * @return 0=success, anything else=error
376 */
377void w1_next_pullup(struct w1_master *dev, int delay)
378{
379 dev->pullup_duration = delay;
380}
381EXPORT_SYMBOL_GPL(w1_next_pullup);