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/* $OpenBSD: owtemp.c,v 1.5 2006/12/20 14:46:59 grange Exp $ */
/*
* Copyright (c) 2006 Alexander Yurchenko <grange@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* 1-Wire temperature family type device driver.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/device.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/rwlock.h>
#include <sys/sensors.h>
#include <dev/onewire/onewiredevs.h>
#include <dev/onewire/onewirereg.h>
#include <dev/onewire/onewirevar.h>
/* Commands */
#define DS1920_CMD_CONVERT 0x44
#define DS1920_CMD_READ_SCRATCHPAD 0xbe
/* Scratchpad layout */
#define DS1920_SP_TEMP_LSB 0
#define DS1920_SP_TEMP_MSB 1
#define DS1920_SP_TH 2
#define DS1920_SP_TL 3
#define DS1920_SP_COUNT_REMAIN 6
#define DS1920_SP_COUNT_PERC 7
#define DS1920_SP_CRC 8
struct owtemp_softc {
struct device sc_dev;
void * sc_onewire;
u_int64_t sc_rom;
struct sensor sc_sensor;
struct rwlock sc_lock;
};
int owtemp_match(struct device *, void *, void *);
void owtemp_attach(struct device *, struct device *, void *);
int owtemp_detach(struct device *, int);
int owtemp_activate(struct device *, enum devact);
void owtemp_update(void *);
struct cfattach owtemp_ca = {
sizeof(struct owtemp_softc),
owtemp_match,
owtemp_attach,
owtemp_detach,
owtemp_activate
};
struct cfdriver owtemp_cd = {
NULL, "owtemp", DV_DULL
};
static const struct onewire_matchfam owtemp_fams[] = {
{ ONEWIRE_FAMILY_DS1920 }
};
int
owtemp_match(struct device *parent, void *match, void *aux)
{
return (onewire_matchbyfam(aux, owtemp_fams,
sizeof(owtemp_fams) /sizeof(owtemp_fams[0])));
}
void
owtemp_attach(struct device *parent, struct device *self, void *aux)
{
struct owtemp_softc *sc = (struct owtemp_softc *)self;
struct onewire_attach_args *oa = aux;
sc->sc_onewire = oa->oa_onewire;
sc->sc_rom = oa->oa_rom;
/* Initialize sensor */
strlcpy(sc->sc_sensor.device, sc->sc_dev.dv_xname,
sizeof(sc->sc_sensor.device));
sc->sc_sensor.type = SENSOR_TEMP;
strlcpy(sc->sc_sensor.desc, "Temp", sizeof(sc->sc_sensor.desc));
if (sensor_task_register(sc, owtemp_update, 5)) {
printf(": unable to register update task\n");
return;
}
sensor_add(&sc->sc_sensor);
rw_init(&sc->sc_lock, sc->sc_dev.dv_xname);
printf("\n");
}
int
owtemp_detach(struct device *self, int flags)
{
struct owtemp_softc *sc = (struct owtemp_softc *)self;
rw_enter_write(&sc->sc_lock);
sensor_del(&sc->sc_sensor);
sensor_task_unregister(sc);
rw_exit_write(&sc->sc_lock);
return (0);
}
int
owtemp_activate(struct device *self, enum devact act)
{
return (0);
}
void
owtemp_update(void *arg)
{
struct owtemp_softc *sc = arg;
u_int8_t data[9];
u_int16_t temp;
int count_perc, count_remain, val;
rw_enter_write(&sc->sc_lock);
onewire_lock(sc->sc_onewire, 0);
if (onewire_reset(sc->sc_onewire) != 0)
goto done;
onewire_matchrom(sc->sc_onewire, sc->sc_rom);
/*
* Start temperature conversion. The conversion takes up to 750ms.
* After sending the command, the data line must be held high for
* at least 750ms to provide power during the conversion process.
* As such, no other activity may take place on the 1-Wire bus for
* at least this period.
*/
onewire_write_byte(sc->sc_onewire, DS1920_CMD_CONVERT);
tsleep(sc, PRIBIO, "owtemp", hz);
if (onewire_reset(sc->sc_onewire) != 0)
goto done;
onewire_matchrom(sc->sc_onewire, sc->sc_rom);
/*
* The result of the temperature measurement is placed in the
* first two bytes of the scratchpad.
*/
onewire_write_byte(sc->sc_onewire, DS1920_CMD_READ_SCRATCHPAD);
onewire_read_block(sc->sc_onewire, data, 9);
if (onewire_crc(data, 8) == data[DS1920_SP_CRC]) {
temp = data[DS1920_SP_TEMP_MSB] << 8 |
data[DS1920_SP_TEMP_LSB];
count_perc = data[DS1920_SP_COUNT_PERC];
count_remain = data[DS1920_SP_COUNT_REMAIN];
if (count_perc != 0) {
/* High resolution algorithm */
temp &= ~0x0001;
val = temp * 500000 - 250000 +
((count_perc - count_remain) * 1000000) /
count_perc;
} else {
val = temp * 500000;
}
sc->sc_sensor.value = 273150000 + val;
}
done:
onewire_unlock(sc->sc_onewire);
rw_exit_write(&sc->sc_lock);
}
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