/drivers/w1/slaves/w1_therm.c

  1/*
  2 *	w1_therm.c
  3 *
  4 * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
  5 *
  6 *
  7 * This program is free software; you can redistribute it and/or modify
  8 * it under the therms 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/types.h>
 23
 24#include <linux/kernel.h>
 25#include <linux/module.h>
 26#include <linux/moduleparam.h>
 27#include <linux/sched.h>
 28#include <linux/device.h>
 29#include <linux/types.h>
 30#include <linux/delay.h>
 31
 32#include "../w1.h"
 33#include "../w1_int.h"
 34#include "../w1_family.h"
 35
 36MODULE_LICENSE("GPL");
 37MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
 38MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol, temperature family.");
 39
 40/* Allow the strong pullup to be disabled, but default to enabled.
 41 * If it was disabled a parasite powered device might not get the require
 42 * current to do a temperature conversion.  If it is enabled parasite powered
 43 * devices have a better chance of getting the current required.
 44 */
 45static int w1_strong_pullup = 1;
 46module_param_named(strong_pullup, w1_strong_pullup, int, 0);
 47
 48static u8 bad_roms[][9] = {
 49				{0xaa, 0x00, 0x4b, 0x46, 0xff, 0xff, 0x0c, 0x10, 0x87},
 50				{}
 51			};
 52
 53static ssize_t w1_therm_read(struct device *device,
 54	struct device_attribute *attr, char *buf);
 55
 56static struct device_attribute w1_therm_attr =
 57	__ATTR(w1_slave, S_IRUGO, w1_therm_read, NULL);
 58
 59static int w1_therm_add_slave(struct w1_slave *sl)
 60{
 61	return device_create_file(&sl->dev, &w1_therm_attr);
 62}
 63
 64static void w1_therm_remove_slave(struct w1_slave *sl)
 65{
 66	device_remove_file(&sl->dev, &w1_therm_attr);
 67}
 68
 69static struct w1_family_ops w1_therm_fops = {
 70	.add_slave	= w1_therm_add_slave,
 71	.remove_slave	= w1_therm_remove_slave,
 72};
 73
 74static struct w1_family w1_therm_family_DS18S20 = {
 75	.fid = W1_THERM_DS18S20,
 76	.fops = &w1_therm_fops,
 77};
 78
 79static struct w1_family w1_therm_family_DS18B20 = {
 80	.fid = W1_THERM_DS18B20,
 81	.fops = &w1_therm_fops,
 82};
 83
 84static struct w1_family w1_therm_family_DS1822 = {
 85	.fid = W1_THERM_DS1822,
 86	.fops = &w1_therm_fops,
 87};
 88
 89static struct w1_family w1_therm_family_DS28EA00 = {
 90	.fid = W1_THERM_DS28EA00,
 91	.fops = &w1_therm_fops,
 92};
 93
 94struct w1_therm_family_converter
 95{
 96	u8			broken;
 97	u16			reserved;
 98	struct w1_family	*f;
 99	int			(*convert)(u8 rom[9]);
100};
101
102/* The return value is millidegrees Centigrade. */
103static inline int w1_DS18B20_convert_temp(u8 rom[9]);
104static inline int w1_DS18S20_convert_temp(u8 rom[9]);
105
106static struct w1_therm_family_converter w1_therm_families[] = {
107	{
108		.f		= &w1_therm_family_DS18S20,
109		.convert 	= w1_DS18S20_convert_temp
110	},
111	{
112		.f		= &w1_therm_family_DS1822,
113		.convert 	= w1_DS18B20_convert_temp
114	},
115	{
116		.f		= &w1_therm_family_DS18B20,
117		.convert 	= w1_DS18B20_convert_temp
118	},
119	{
120		.f		= &w1_therm_family_DS28EA00,
121		.convert	= w1_DS18B20_convert_temp
122	},
123};
124
125static inline int w1_DS18B20_convert_temp(u8 rom[9])
126{
127	s16 t = le16_to_cpup((__le16 *)rom);
128	return t*1000/16;
129}
130
131static inline int w1_DS18S20_convert_temp(u8 rom[9])
132{
133	int t, h;
134
135	if (!rom[7])
136		return 0;
137
138	if (rom[1] == 0)
139		t = ((s32)rom[0] >> 1)*1000;
140	else
141		t = 1000*(-1*(s32)(0x100-rom[0]) >> 1);
142
143	t -= 250;
144	h = 1000*((s32)rom[7] - (s32)rom[6]);
145	h /= (s32)rom[7];
146	t += h;
147
148	return t;
149}
150
151static inline int w1_convert_temp(u8 rom[9], u8 fid)
152{
153	int i;
154
155	for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i)
156		if (w1_therm_families[i].f->fid == fid)
157			return w1_therm_families[i].convert(rom);
158
159	return 0;
160}
161
162static int w1_therm_check_rom(u8 rom[9])
163{
164	int i;
165
166	for (i=0; i<sizeof(bad_roms)/9; ++i)
167		if (!memcmp(bad_roms[i], rom, 9))
168			return 1;
169
170	return 0;
171}
172
173static ssize_t w1_therm_read(struct device *device,
174	struct device_attribute *attr, char *buf)
175{
176	struct w1_slave *sl = dev_to_w1_slave(device);
177	struct w1_master *dev = sl->master;
178	u8 rom[9], crc, verdict;
179	int i, max_trying = 10;
180	ssize_t c = PAGE_SIZE;
181
182	mutex_lock(&dev->mutex);
183
184	memset(rom, 0, sizeof(rom));
185
186	verdict = 0;
187	crc = 0;
188
189	while (max_trying--) {
190		if (!w1_reset_select_slave(sl)) {
191			int count = 0;
192			unsigned int tm = 750;
193
194			/* 750ms strong pullup (or delay) after the convert */
195			if (w1_strong_pullup)
196				w1_next_pullup(dev, tm);
197			w1_write_8(dev, W1_CONVERT_TEMP);
198			if (!w1_strong_pullup)
199				msleep(tm);
200
201			if (!w1_reset_select_slave(sl)) {
202
203				w1_write_8(dev, W1_READ_SCRATCHPAD);
204				if ((count = w1_read_block(dev, rom, 9)) != 9) {
205					dev_warn(device, "w1_read_block() "
206						"returned %u instead of 9.\n",
207						count);
208				}
209
210				crc = w1_calc_crc8(rom, 8);
211
212				if (rom[8] == crc)
213					verdict = 1;
214			}
215		}
216
217		if (!w1_therm_check_rom(rom))
218			break;
219	}
220
221	for (i = 0; i < 9; ++i)
222		c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", rom[i]);
223	c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n",
224			   crc, (verdict) ? "YES" : "NO");
225	if (verdict)
226		memcpy(sl->rom, rom, sizeof(sl->rom));
227	else
228		dev_warn(device, "18S20 doesn't respond to CONVERT_TEMP.\n");
229
230	for (i = 0; i < 9; ++i)
231		c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", sl->rom[i]);
232
233	c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n",
234		w1_convert_temp(rom, sl->family->fid));
235	mutex_unlock(&dev->mutex);
236
237	return PAGE_SIZE - c;
238}
239
240static int __init w1_therm_init(void)
241{
242	int err, i;
243
244	for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) {
245		err = w1_register_family(w1_therm_families[i].f);
246		if (err)
247			w1_therm_families[i].broken = 1;
248	}
249
250	return 0;
251}
252
253static void __exit w1_therm_fini(void)
254{
255	int i;
256
257	for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i)
258		if (!w1_therm_families[i].broken)
259			w1_unregister_family(w1_therm_families[i].f);
260}
261
262module_init(w1_therm_init);
263module_exit(w1_therm_fini);