w1_io.c revision 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 
1/*
2 * 	w1_io.c
3 *
4 * Copyright (c) 2004 Evgeniy Polyakov <johnpol@2ka.mipt.ru>
5 *
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#include <asm/io.h>
23
24#include <linux/delay.h>
25#include <linux/moduleparam.h>
26
27#include "w1.h"
28#include "w1_log.h"
29#include "w1_io.h"
30
31int w1_delay_parm = 1;
32module_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
53void w1_delay(unsigned long tm)
54{
55	udelay(tm * w1_delay_parm);
56}
57
58u8 w1_touch_bit(struct w1_master *dev, int bit)
59{
60	if (dev->bus_master->touch_bit)
61		return dev->bus_master->touch_bit(dev->bus_master->data, bit);
62	else
63		return w1_read_bit(dev);
64}
65
66void w1_write_bit(struct w1_master *dev, int bit)
67{
68	if (bit) {
69		dev->bus_master->write_bit(dev->bus_master->data, 0);
70		w1_delay(6);
71		dev->bus_master->write_bit(dev->bus_master->data, 1);
72		w1_delay(64);
73	} else {
74		dev->bus_master->write_bit(dev->bus_master->data, 0);
75		w1_delay(60);
76		dev->bus_master->write_bit(dev->bus_master->data, 1);
77		w1_delay(10);
78	}
79}
80
81void w1_write_8(struct w1_master *dev, u8 byte)
82{
83	int i;
84
85	if (dev->bus_master->write_byte)
86		dev->bus_master->write_byte(dev->bus_master->data, byte);
87	else
88		for (i = 0; i < 8; ++i)
89			w1_write_bit(dev, (byte >> i) & 0x1);
90}
91
92u8 w1_read_bit(struct w1_master *dev)
93{
94	int result;
95
96	dev->bus_master->write_bit(dev->bus_master->data, 0);
97	w1_delay(6);
98	dev->bus_master->write_bit(dev->bus_master->data, 1);
99	w1_delay(9);
100
101	result = dev->bus_master->read_bit(dev->bus_master->data);
102	w1_delay(55);
103
104	return result & 0x1;
105}
106
107u8 w1_read_8(struct w1_master * dev)
108{
109	int i;
110	u8 res = 0;
111
112	if (dev->bus_master->read_byte)
113		res = dev->bus_master->read_byte(dev->bus_master->data);
114	else
115		for (i = 0; i < 8; ++i)
116			res |= (w1_read_bit(dev) << i);
117
118	return res;
119}
120
121void w1_write_block(struct w1_master *dev, u8 *buf, int len)
122{
123	int i;
124
125	if (dev->bus_master->write_block)
126		dev->bus_master->write_block(dev->bus_master->data, buf, len);
127	else
128		for (i = 0; i < len; ++i)
129			w1_write_8(dev, buf[i]);
130}
131
132u8 w1_read_block(struct w1_master *dev, u8 *buf, int len)
133{
134	int i;
135	u8 ret;
136
137	if (dev->bus_master->read_block)
138		ret = dev->bus_master->read_block(dev->bus_master->data, buf, len);
139	else {
140		for (i = 0; i < len; ++i)
141			buf[i] = w1_read_8(dev);
142		ret = len;
143	}
144
145	return ret;
146}
147
148int w1_reset_bus(struct w1_master *dev)
149{
150	int result = 0;
151
152	if (dev->bus_master->reset_bus)
153		result = dev->bus_master->reset_bus(dev->bus_master->data) & 0x1;
154	else {
155		dev->bus_master->write_bit(dev->bus_master->data, 0);
156		w1_delay(480);
157		dev->bus_master->write_bit(dev->bus_master->data, 1);
158		w1_delay(70);
159
160		result = dev->bus_master->read_bit(dev->bus_master->data) & 0x1;
161		w1_delay(410);
162	}
163
164	return result;
165}
166
167u8 w1_calc_crc8(u8 * data, int len)
168{
169	u8 crc = 0;
170
171	while (len--)
172		crc = w1_crc8_table[crc ^ *data++];
173
174	return crc;
175}
176
177void w1_search_devices(struct w1_master *dev, w1_slave_found_callback cb)
178{
179	dev->attempts++;
180	if (dev->bus_master->search)
181		dev->bus_master->search(dev->bus_master->data, cb);
182	else
183		w1_search(dev);
184}
185
186EXPORT_SYMBOL(w1_write_bit);
187EXPORT_SYMBOL(w1_write_8);
188EXPORT_SYMBOL(w1_read_bit);
189EXPORT_SYMBOL(w1_read_8);
190EXPORT_SYMBOL(w1_reset_bus);
191EXPORT_SYMBOL(w1_calc_crc8);
192EXPORT_SYMBOL(w1_delay);
193EXPORT_SYMBOL(w1_read_block);
194EXPORT_SYMBOL(w1_write_block);
195EXPORT_SYMBOL(w1_search_devices);
196