Annotation of sys/dev/onewire/owtemp.c, Revision 1.1.1.1
1.1 nbrk 1: /* $OpenBSD: owtemp.c,v 1.8 2007/06/24 05:34:35 dlg Exp $ */
2:
3: /*
4: * Copyright (c) 2006 Alexander Yurchenko <grange@openbsd.org>
5: *
6: * Permission to use, copy, modify, and distribute this software for any
7: * purpose with or without fee is hereby granted, provided that the above
8: * copyright notice and this permission notice appear in all copies.
9: *
10: * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11: * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12: * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13: * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14: * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15: * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16: * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17: */
18:
19: /*
20: * 1-Wire temperature family type device driver.
21: */
22:
23: #include <sys/param.h>
24: #include <sys/systm.h>
25: #include <sys/device.h>
26: #include <sys/kernel.h>
27: #include <sys/proc.h>
28: #include <sys/rwlock.h>
29: #include <sys/sensors.h>
30:
31: #include <dev/onewire/onewiredevs.h>
32: #include <dev/onewire/onewirereg.h>
33: #include <dev/onewire/onewirevar.h>
34:
35: /* Commands */
36: #define DS1920_CMD_CONVERT 0x44
37: #define DS1920_CMD_READ_SCRATCHPAD 0xbe
38:
39: /* Scratchpad layout */
40: #define DS1920_SP_TEMP_LSB 0
41: #define DS1920_SP_TEMP_MSB 1
42: #define DS1920_SP_TH 2
43: #define DS1920_SP_TL 3
44: #define DS1920_SP_COUNT_REMAIN 6
45: #define DS1920_SP_COUNT_PERC 7
46: #define DS1920_SP_CRC 8
47:
48: struct owtemp_softc {
49: struct device sc_dev;
50:
51: void * sc_onewire;
52: u_int64_t sc_rom;
53:
54: struct ksensor sc_sensor;
55: struct ksensordev sc_sensordev;
56: struct sensor_task *sc_sensortask;
57: struct rwlock sc_lock;
58: };
59:
60: int owtemp_match(struct device *, void *, void *);
61: void owtemp_attach(struct device *, struct device *, void *);
62: int owtemp_detach(struct device *, int);
63: int owtemp_activate(struct device *, enum devact);
64:
65: void owtemp_update(void *);
66:
67: struct cfattach owtemp_ca = {
68: sizeof(struct owtemp_softc),
69: owtemp_match,
70: owtemp_attach,
71: owtemp_detach,
72: owtemp_activate
73: };
74:
75: struct cfdriver owtemp_cd = {
76: NULL, "owtemp", DV_DULL
77: };
78:
79: static const struct onewire_matchfam owtemp_fams[] = {
80: { ONEWIRE_FAMILY_DS1920 }
81: };
82:
83: int
84: owtemp_match(struct device *parent, void *match, void *aux)
85: {
86: return (onewire_matchbyfam(aux, owtemp_fams,
87: sizeof(owtemp_fams) /sizeof(owtemp_fams[0])));
88: }
89:
90: void
91: owtemp_attach(struct device *parent, struct device *self, void *aux)
92: {
93: struct owtemp_softc *sc = (struct owtemp_softc *)self;
94: struct onewire_attach_args *oa = aux;
95:
96: sc->sc_onewire = oa->oa_onewire;
97: sc->sc_rom = oa->oa_rom;
98:
99: /* Initialize sensor */
100: strlcpy(sc->sc_sensordev.xname, sc->sc_dev.dv_xname,
101: sizeof(sc->sc_sensordev.xname));
102: sc->sc_sensor.type = SENSOR_TEMP;
103:
104: sc->sc_sensortask = sensor_task_register(sc, owtemp_update, 5);
105: if (sc->sc_sensortask == NULL) {
106: printf(": unable to register update task\n");
107: return;
108: }
109: sensor_attach(&sc->sc_sensordev, &sc->sc_sensor);
110: sensordev_install(&sc->sc_sensordev);
111:
112: rw_init(&sc->sc_lock, sc->sc_dev.dv_xname);
113: printf("\n");
114: }
115:
116: int
117: owtemp_detach(struct device *self, int flags)
118: {
119: struct owtemp_softc *sc = (struct owtemp_softc *)self;
120:
121: rw_enter_write(&sc->sc_lock);
122: sensordev_deinstall(&sc->sc_sensordev);
123: if (sc->sc_sensortask != NULL)
124: sensor_task_unregister(sc->sc_sensortask);
125: rw_exit_write(&sc->sc_lock);
126:
127: return (0);
128: }
129:
130: int
131: owtemp_activate(struct device *self, enum devact act)
132: {
133: return (0);
134: }
135:
136: void
137: owtemp_update(void *arg)
138: {
139: struct owtemp_softc *sc = arg;
140: u_int8_t data[9];
141: u_int16_t temp;
142: int count_perc, count_remain, val;
143:
144: rw_enter_write(&sc->sc_lock);
145: onewire_lock(sc->sc_onewire, 0);
146: if (onewire_reset(sc->sc_onewire) != 0)
147: goto done;
148: onewire_matchrom(sc->sc_onewire, sc->sc_rom);
149:
150: /*
151: * Start temperature conversion. The conversion takes up to 750ms.
152: * After sending the command, the data line must be held high for
153: * at least 750ms to provide power during the conversion process.
154: * As such, no other activity may take place on the 1-Wire bus for
155: * at least this period.
156: */
157: onewire_write_byte(sc->sc_onewire, DS1920_CMD_CONVERT);
158: tsleep(sc, PRIBIO, "owtemp", hz);
159:
160: if (onewire_reset(sc->sc_onewire) != 0)
161: goto done;
162: onewire_matchrom(sc->sc_onewire, sc->sc_rom);
163:
164: /*
165: * The result of the temperature measurement is placed in the
166: * first two bytes of the scratchpad.
167: */
168: onewire_write_byte(sc->sc_onewire, DS1920_CMD_READ_SCRATCHPAD);
169: onewire_read_block(sc->sc_onewire, data, 9);
170: if (onewire_crc(data, 8) == data[DS1920_SP_CRC]) {
171: temp = data[DS1920_SP_TEMP_MSB] << 8 |
172: data[DS1920_SP_TEMP_LSB];
173: count_perc = data[DS1920_SP_COUNT_PERC];
174: count_remain = data[DS1920_SP_COUNT_REMAIN];
175:
176: if (count_perc != 0) {
177: /* High resolution algorithm */
178: temp &= ~0x0001;
179: val = temp * 500000 - 250000 +
180: ((count_perc - count_remain) * 1000000) /
181: count_perc;
182: } else {
183: val = temp * 500000;
184: }
185: sc->sc_sensor.value = 273150000 + val;
186: }
187:
188: done:
189: onewire_unlock(sc->sc_onewire);
190: rw_exit_write(&sc->sc_lock);
191: }
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