/*-
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2016 Michael Zhilin <mizhka@freebsd.org> All rights reserved.
* Copyright (c) 2019 Ian Lepore <ian@freebsd.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* GPIOTHS - Temp/Humidity sensor over GPIO.
*
* This is driver for Temperature & Humidity sensor which provides digital
* output over single-wire protocol from embedded 8-bit microcontroller.
* Note that it uses a custom single-wire protocol, it is not 1-wire(tm).
*
* This driver supports the following chips:
* DHT11: Temp 0c to 50c +-2.0c, Humidity 20% to 90% +-5%
* DHT12: Temp -20c to 60c +-0.5c, Humidity 20% to 95% +-5%
* DHT21: Temp -40c to 80c +-0.3c, Humidity 0% to 100% +-3%
* DHT22: Temp -40c to 80c +-0.3c, Humidity 0% to 100% +-2%
* AM2301: Same as DHT21, but also supports i2c interface.
* AM2302: Same as DHT22, but also supports i2c interface.
*
* Temp/Humidity sensor can't be discovered automatically, please specify hints
* as part of loader or kernel configuration:
* hint.gpioths.0.at="gpiobus0"
* hint.gpioths.0.pins=<PIN>
*
* Or configure via FDT data.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/bus.h>
#include <sys/gpio.h>
#include <sys/module.h>
#include <sys/errno.h>
#include <sys/systm.h>
#include <sys/sysctl.h>
#include <sys/taskqueue.h>
#include <dev/gpio/gpiobusvar.h>
#ifdef FDT
#include <dev/ofw/ofw_bus.h>
#include <dev/ofw/ofw_bus_subr.h>
static struct ofw_compat_data compat_data[] = {
{"dht11", true},
{NULL, false}
};
OFWBUS_PNP_INFO(compat_data);
SIMPLEBUS_PNP_INFO(compat_data);
#endif /* FDT */
#define PIN_IDX 0 /* Use the first/only configured pin. */
#define GPIOTHS_POLLTIME 5 /* in seconds */
#define GPIOTHS_DHT_STARTCYCLE 20000 /* 20ms = 20000us */
#define GPIOTHS_DHT_TIMEOUT 1000 /* 1ms = 1000us */
#define GPIOTHS_DHT_CYCLES 41
#define GPIOTHS_DHT_ONEBYTEMASK 0xFF
struct gpioths_softc {
device_t dev;
gpio_pin_t pin;
int temp;
int hum;
int fails;
struct timeout_task task;
bool detaching;
};
static int
gpioths_probe(device_t dev)
{
int rv;
/*
* By default we only bid to attach if specifically added by our parent
* (usually via hint.gpioths.#.at=busname). On FDT systems we bid as
* the default driver based on being configured in the FDT data.
*/
rv = BUS_PROBE_NOWILDCARD;
#ifdef FDT
if (ofw_bus_status_okay(dev) &&
ofw_bus_search_compatible(dev, compat_data)->ocd_data)
rv = BUS_PROBE_DEFAULT;
#endif
device_set_desc(dev, "DHT11/DHT22 Temperature and Humidity Sensor");
return (rv);
}
static int
gpioths_dht_timeuntil(struct gpioths_softc *sc, bool lev, uint32_t *time)
{
bool cur_level;
int i;
for (i = 0; i < GPIOTHS_DHT_TIMEOUT; i++) {
gpio_pin_is_active(sc->pin, &cur_level);
if (cur_level == lev) {
if (time != NULL)
*time = i;
return (0);
}
DELAY(1);
}
/* Timeout */
return (ETIMEDOUT);
}
static void
gpioths_dht_initread(struct gpioths_softc *sc)
{
/*
* According to specifications we need to drive the data line low for at
* least 20ms then drive it high, to wake up the chip and signal it to
* send a measurement. After sending this start signal, we switch the
* pin back to input so the device can begin talking to us.
*/
gpio_pin_setflags(sc->pin, GPIO_PIN_OUTPUT);
gpio_pin_set_active(sc->pin, false);
pause_sbt("gpioths", ustosbt(GPIOTHS_DHT_STARTCYCLE), C_PREL(2), 0);
gpio_pin_set_active(sc->pin, true);
gpio_pin_setflags(sc->pin, GPIO_PIN_INPUT);
}
static int
gpioths_dht_readbytes(struct gpioths_softc *sc)
{
uint32_t calibrations[GPIOTHS_DHT_CYCLES];
uint32_t intervals[GPIOTHS_DHT_CYCLES];
uint32_t err, avglen, value;
uint8_t crc, calc;
int i, negmul, offset, size, tmphi, tmplo;
gpioths_dht_initread(sc);
err = gpioths_dht_timeuntil(sc, false, NULL);
if (err) {
device_printf(sc->dev, "err(START) = %d\n", err);
goto error;
}
/* reading - 41 cycles */
for (i = 0; i < GPIOTHS_DHT_CYCLES; i++) {
err = gpioths_dht_timeuntil(sc, true, &calibrations[i]);
if (err) {
device_printf(sc->dev, "err(CAL, %d) = %d\n", i, err);
goto error;
}
err = gpioths_dht_timeuntil(sc, false, &intervals[i]);
if (err) {
device_printf(sc->dev, "err(INTERVAL, %d) = %d\n", i, err);
goto error;
}
}
/* Calculate average data calibration cycle length */
avglen = 0;
for (i = 1; i < GPIOTHS_DHT_CYCLES; i++)
avglen += calibrations[i];
avglen = avglen / (GPIOTHS_DHT_CYCLES - 1);
/* Calculate data */
value = 0;
offset = 1;
size = sizeof(value) * 8;
for (i = offset; i < size + offset; i++) {
value <<= 1;
if (intervals[i] > avglen)
value += 1;
}
/* Calculate CRC */
crc = 0;
offset = sizeof(value) * 8 + 1;
size = sizeof(crc) * 8;
for (i = offset; i < size + offset; i++) {
crc <<= 1;
if (intervals[i] > avglen)
crc += 1;
}
calc = 0;
for (i = 0; i < sizeof(value); i++)
calc += (value >> (8*i)) & GPIOTHS_DHT_ONEBYTEMASK;
#ifdef GPIOTHS_DEBUG
/* Debug bits */
for (i = 0; i < GPIOTHS_DHT_CYCLES; i++)
device_printf(sc->dev, "%d: %d %d\n", i, calibrations[i],
intervals[i]);
device_printf(sc->dev, "len=%d, data=%x, crc=%x/%x\n", avglen, value, crc,
calc);
#endif /* GPIOTHS_DEBUG */
/* CRC check */
if (calc != crc) {
err = -1;
goto error;
}
/*
* For DHT11/12, the values are split into 8 bits of integer and 8 bits
* of fractional tenths. On DHT11 the fraction bytes are always zero.
* On DHT12 the sign bit is in the high bit of the fraction byte.
* - DHT11: 0HHHHHHH 00000000 00TTTTTT 00000000
* - DHT12: 0HHHHHHH 0000hhhh 00TTTTTT s000tttt
*
* For DHT21/21, the values are are encoded in 16 bits each, with the
* temperature sign bit in the high bit. The values are tenths of a
* degree C and tenths of a percent RH.
* - DHT21: 000000HH HHHHHHHH s00000TT TTTTTTTT
* - DHT22: 000000HH HHHHHHHH s00000TT TTTTTTTT
*
* For all devices, some bits are always zero because of the range of
* values supported by the device.
*
* We figure out how to decode things based on the high byte of the
* humidity. A DHT21/22 cannot report a value greater than 3 in
* the upper bits of its 16-bit humidity. A DHT11/12 should not report
* a value lower than 20. To allow for the possibility that a device
* could report a value slightly out of its sensitivity range, we split
* the difference and say if the value is greater than 10 it must be a
* DHT11/12 (that would be a humidity over 256% on a DHT21/22).
*/
#define DK_OFFSET 2731 /* Offset between K and C, in decikelvins. */
if ((value >> 24) > 10) {
/* DHT11 or DHT12 */
tmphi = (value >> 8) & 0x3f;
tmplo = value & 0x0f;
negmul = (value & 0x80) ? -1 : 1;
sc->temp = DK_OFFSET + (negmul * (tmphi * 10 + tmplo));
sc->hum = (value >> 24) & 0x7f;
} else {
/* DHT21 or DHT22 */
negmul = (value & 0x8000) ? -1 : 1;
sc->temp = DK_OFFSET + (negmul * (value & 0x03ff));
sc->hum = ((value >> 16) & 0x03ff) / 10;
}
sc->fails = 0;
#ifdef GPIOTHS_DEBUG
/* Debug bits */
device_printf(dev, "fails=%d, temp=%d, hum=%d\n", sc->fails,
sc->temp, sc->hum);
#endif /* GPIOTHS_DEBUG */
return (0);
error:
sc->fails++;
return (err);
}
static void
gpioths_poll(void *arg, int pending __unused)
{
struct gpioths_softc *sc;
sc = (struct gpioths_softc *)arg;
gpioths_dht_readbytes(sc);
if (!sc->detaching)
taskqueue_enqueue_timeout_sbt(taskqueue_thread, &sc->task,
GPIOTHS_POLLTIME * SBT_1S, 0, C_PREL(3));
}
static int
gpioths_attach(device_t dev)
{
struct gpioths_softc *sc;
struct sysctl_ctx_list *ctx;
struct sysctl_oid *tree;
int err;
sc = device_get_softc(dev);
ctx = device_get_sysctl_ctx(dev);
tree = device_get_sysctl_tree(dev);
sc->dev = dev;
TIMEOUT_TASK_INIT(taskqueue_thread, &sc->task, 0, gpioths_poll, sc);
#ifdef FDT
/* Try to configure our pin from fdt data on fdt-based systems. */
err = gpio_pin_get_by_ofw_idx(dev, ofw_bus_get_node(dev), PIN_IDX,
&sc->pin);
#else
err = ENOENT;
#endif
/*
* If we didn't get configured by fdt data and our parent is gpiobus,
* see if we can be configured by the bus (allows hinted attachment even
* on fdt-based systems).
*/
if (err != 0 &&
strcmp("gpiobus", device_get_name(device_get_parent(dev))) == 0)
err = gpio_pin_get_by_child_index(dev, PIN_IDX, &sc->pin);
/* If we didn't get configured by either method, whine and punt. */
if (err != 0) {
device_printf(sc->dev,
"cannot acquire gpio pin (config error)\n");
return (err);
}
/*
* Ensure we have control of our pin, and preset the data line to its
* idle condition (high). Leave the line in input mode, relying on the
* external pullup to keep the line high while idle.
*/
err = gpio_pin_setflags(sc->pin, GPIO_PIN_OUTPUT);
if (err != 0) {
device_printf(dev, "gpio_pin_setflags(OUT) = %d\n", err);
return (err);
}
err = gpio_pin_set_active(sc->pin, true);
if (err != 0) {
device_printf(dev, "gpio_pin_set_active(false) = %d\n", err);
return (err);
}
err = gpio_pin_setflags(sc->pin, GPIO_PIN_INPUT);
if (err != 0) {
device_printf(dev, "gpio_pin_setflags(IN) = %d\n", err);
return (err);
}
/*
* Do an initial read so we have correct values for reporting before
* registering the sysctls that can access those values. This also
* schedules the periodic polling the driver does every few seconds to
* update the sysctl variables.
*/
gpioths_poll(sc, 0);
sysctl_add_oid(ctx, SYSCTL_CHILDREN(tree), OID_AUTO, "temperature", \
CTLFLAG_RD | CTLTYPE_INT | CTLFLAG_MPSAFE,
&sc->temp, 0, sysctl_handle_int, "IK", "temperature", NULL);
SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO, "humidity",
CTLFLAG_RD, &sc->hum, 0, "relative humidity(%)");
SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO, "fails",
CTLFLAG_RD, &sc->fails, 0,
"failures since last successful read");
return (0);
}
static int
gpioths_detach(device_t dev)
{
struct gpioths_softc *sc;
sc = device_get_softc(dev);
gpio_pin_release(sc->pin);
sc->detaching = true;
while (taskqueue_cancel_timeout(taskqueue_thread, &sc->task, NULL) != 0)
taskqueue_drain_timeout(taskqueue_thread, &sc->task);
return (0);
}
/* Driver bits */
static device_method_t gpioths_methods[] = {
/* Device interface */
DEVMETHOD(device_probe, gpioths_probe),
DEVMETHOD(device_attach, gpioths_attach),
DEVMETHOD(device_detach, gpioths_detach),
DEVMETHOD_END
};
DEFINE_CLASS_0(gpioths, gpioths_driver, gpioths_methods, sizeof(struct gpioths_softc));
#ifdef FDT
DRIVER_MODULE(gpioths, simplebus, gpioths_driver, 0, 0);
#endif
DRIVER_MODULE(gpioths, gpiobus, gpioths_driver, 0, 0);
MODULE_DEPEND(gpioths, gpiobus, 1, 1, 1);