BUG_ON() Conversion in mm/mmap.c
[linux-2.6.22.y-op.git] / drivers / w1 / w1_io.c
blobf7f7e8bec30eb9312adf50ffe07e995259c2db00
1 /*
2 * w1_io.c
4 * Copyright (c) 2004 Evgeniy Polyakov <johnpol@2ka.mipt.ru>
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.
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.
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
22 #include <asm/io.h>
24 #include <linux/delay.h>
25 #include <linux/moduleparam.h>
27 #include "w1.h"
28 #include "w1_log.h"
29 #include "w1_io.h"
31 static int w1_delay_parm = 1;
32 module_param_named(delay_coef, w1_delay_parm, int, 0);
34 static 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
53 void w1_delay(unsigned long tm)
55 udelay(tm * w1_delay_parm);
58 static void w1_write_bit(struct w1_master *dev, int bit);
59 static u8 w1_read_bit(struct w1_master *dev);
61 /**
62 * Generates a write-0 or write-1 cycle and samples the level.
64 u8 w1_touch_bit(struct w1_master *dev, int bit)
66 if (dev->bus_master->touch_bit)
67 return dev->bus_master->touch_bit(dev->bus_master->data, bit);
68 else if (bit)
69 return w1_read_bit(dev);
70 else {
71 w1_write_bit(dev, 0);
72 return(0);
76 /**
77 * Generates a write-0 or write-1 cycle.
78 * Only call if dev->bus_master->touch_bit is NULL
80 static void w1_write_bit(struct w1_master *dev, int bit)
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);
95 /**
96 * Writes 8 bits.
98 * @param dev the master device
99 * @param byte the byte to write
101 void w1_write_8(struct w1_master *dev, u8 byte)
103 int i;
105 if (dev->bus_master->write_byte)
106 dev->bus_master->write_byte(dev->bus_master->data, byte);
107 else
108 for (i = 0; i < 8; ++i)
109 w1_touch_bit(dev, (byte >> i) & 0x1);
114 * Generates a write-1 cycle and samples the level.
115 * Only call if dev->bus_master->touch_bit is NULL
117 static u8 w1_read_bit(struct w1_master *dev)
119 int result;
121 dev->bus_master->write_bit(dev->bus_master->data, 0);
122 w1_delay(6);
123 dev->bus_master->write_bit(dev->bus_master->data, 1);
124 w1_delay(9);
126 result = dev->bus_master->read_bit(dev->bus_master->data);
127 w1_delay(55);
129 return result & 0x1;
133 * Does a triplet - used for searching ROM addresses.
134 * Return bits:
135 * bit 0 = id_bit
136 * bit 1 = comp_bit
137 * bit 2 = dir_taken
138 * If both bits 0 & 1 are set, the search should be restarted.
140 * @param dev the master device
141 * @param bdir the bit to write if both id_bit and comp_bit are 0
142 * @return bit fields - see above
144 u8 w1_triplet(struct w1_master *dev, int bdir)
146 if ( dev->bus_master->triplet )
147 return(dev->bus_master->triplet(dev->bus_master->data, bdir));
148 else {
149 u8 id_bit = w1_touch_bit(dev, 1);
150 u8 comp_bit = w1_touch_bit(dev, 1);
151 u8 retval;
153 if ( id_bit && comp_bit )
154 return(0x03); /* error */
156 if ( !id_bit && !comp_bit ) {
157 /* Both bits are valid, take the direction given */
158 retval = bdir ? 0x04 : 0;
159 } else {
160 /* Only one bit is valid, take that direction */
161 bdir = id_bit;
162 retval = id_bit ? 0x05 : 0x02;
165 if ( dev->bus_master->touch_bit )
166 w1_touch_bit(dev, bdir);
167 else
168 w1_write_bit(dev, bdir);
169 return(retval);
174 * Reads 8 bits.
176 * @param dev the master device
177 * @return the byte read
179 u8 w1_read_8(struct w1_master * dev)
181 int i;
182 u8 res = 0;
184 if (dev->bus_master->read_byte)
185 res = dev->bus_master->read_byte(dev->bus_master->data);
186 else
187 for (i = 0; i < 8; ++i)
188 res |= (w1_touch_bit(dev,1) << i);
190 return res;
194 * Writes a series of bytes.
196 * @param dev the master device
197 * @param buf pointer to the data to write
198 * @param len the number of bytes to write
199 * @return the byte read
201 void w1_write_block(struct w1_master *dev, const u8 *buf, int len)
203 int i;
205 if (dev->bus_master->write_block)
206 dev->bus_master->write_block(dev->bus_master->data, buf, len);
207 else
208 for (i = 0; i < len; ++i)
209 w1_write_8(dev, buf[i]);
213 * Reads a series of bytes.
215 * @param dev the master device
216 * @param buf pointer to the buffer to fill
217 * @param len the number of bytes to read
218 * @return the number of bytes read
220 u8 w1_read_block(struct w1_master *dev, u8 *buf, int len)
222 int i;
223 u8 ret;
225 if (dev->bus_master->read_block)
226 ret = dev->bus_master->read_block(dev->bus_master->data, buf, len);
227 else {
228 for (i = 0; i < len; ++i)
229 buf[i] = w1_read_8(dev);
230 ret = len;
233 return ret;
237 * Issues a reset bus sequence.
239 * @param dev The bus master pointer
240 * @return 0=Device present, 1=No device present or error
242 int w1_reset_bus(struct w1_master *dev)
244 int result;
246 if (dev->bus_master->reset_bus)
247 result = dev->bus_master->reset_bus(dev->bus_master->data) & 0x1;
248 else {
249 dev->bus_master->write_bit(dev->bus_master->data, 0);
250 w1_delay(480);
251 dev->bus_master->write_bit(dev->bus_master->data, 1);
252 w1_delay(70);
254 result = dev->bus_master->read_bit(dev->bus_master->data) & 0x1;
255 w1_delay(410);
258 return result;
261 u8 w1_calc_crc8(u8 * data, int len)
263 u8 crc = 0;
265 while (len--)
266 crc = w1_crc8_table[crc ^ *data++];
268 return crc;
271 void w1_search_devices(struct w1_master *dev, w1_slave_found_callback cb)
273 dev->attempts++;
274 if (dev->bus_master->search)
275 dev->bus_master->search(dev->bus_master->data, cb);
276 else
277 w1_search(dev, cb);
281 * Resets the bus and then selects the slave by sending either a skip rom
282 * or a rom match.
283 * The w1 master lock must be held.
285 * @param sl the slave to select
286 * @return 0=success, anything else=error
288 int w1_reset_select_slave(struct w1_slave *sl)
290 if (w1_reset_bus(sl->master))
291 return -1;
293 if (sl->master->slave_count == 1)
294 w1_write_8(sl->master, W1_SKIP_ROM);
295 else {
296 u8 match[9] = {W1_MATCH_ROM, };
297 memcpy(&match[1], (u8 *)&sl->reg_num, 8);
298 w1_write_block(sl->master, match, 9);
300 return 0;
303 EXPORT_SYMBOL(w1_touch_bit);
304 EXPORT_SYMBOL(w1_write_8);
305 EXPORT_SYMBOL(w1_read_8);
306 EXPORT_SYMBOL(w1_reset_bus);
307 EXPORT_SYMBOL(w1_calc_crc8);
308 EXPORT_SYMBOL(w1_delay);
309 EXPORT_SYMBOL(w1_read_block);
310 EXPORT_SYMBOL(w1_write_block);
311 EXPORT_SYMBOL(w1_search_devices);
312 EXPORT_SYMBOL(w1_reset_select_slave);