1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2016 Michael Zhilin <mizhka@freebsd.org> All rights reserved.
5 * Copyright (c) 2019 Ian Lepore <ian@freebsd.org>
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 /*
30 * GPIOTHS - Temp/Humidity sensor over GPIO.
31 *
32 * This is driver for Temperature & Humidity sensor which provides digital
33 * output over single-wire protocol from embedded 8-bit microcontroller.
34 * Note that it uses a custom single-wire protocol, it is not 1-wire(tm).
35 *
36 * This driver supports the following chips:
37 * DHT11: Temp 0c to 50c +-2.0c, Humidity 20% to 90% +-5%
38 * DHT12: Temp -20c to 60c +-0.5c, Humidity 20% to 95% +-5%
39 * DHT21: Temp -40c to 80c +-0.3c, Humidity 0% to 100% +-3%
40 * DHT22: Temp -40c to 80c +-0.3c, Humidity 0% to 100% +-2%
41 * AM2301: Same as DHT21, but also supports i2c interface.
42 * AM2302: Same as DHT22, but also supports i2c interface.
43 *
44 * Temp/Humidity sensor can't be discovered automatically, please specify hints
45 * as part of loader or kernel configuration:
46 * hint.gpioths.0.at="gpiobus0"
47 * hint.gpioths.0.pins=<PIN>
48 *
49 * Or configure via FDT data.
50 */
51
52 #include <sys/param.h>
53 #include <sys/kernel.h>
54 #include <sys/bus.h>
55 #include <sys/gpio.h>
56 #include <sys/module.h>
57 #include <sys/errno.h>
58 #include <sys/systm.h>
59 #include <sys/sysctl.h>
60 #include <sys/taskqueue.h>
61
62 #include <dev/gpio/gpiobusvar.h>
63
64 #ifdef FDT
65 #include <dev/ofw/ofw_bus.h>
66 #include <dev/ofw/ofw_bus_subr.h>
67
68 static struct ofw_compat_data compat_data[] = {
69 {"dht11", true},
70 {NULL, false}
71 };
72 OFWBUS_PNP_INFO(compat_data);
73 SIMPLEBUS_PNP_INFO(compat_data);
74 #endif /* FDT */
75
76 #define PIN_IDX 0 /* Use the first/only configured pin. */
77
78 #define GPIOTHS_POLLTIME 5 /* in seconds */
79
80 #define GPIOTHS_DHT_STARTCYCLE 20000 /* 20ms = 20000us */
81 #define GPIOTHS_DHT_TIMEOUT 1000 /* 1ms = 1000us */
82 #define GPIOTHS_DHT_CYCLES 41
83 #define GPIOTHS_DHT_ONEBYTEMASK 0xFF
84
85 struct gpioths_softc {
86 device_t dev;
87 gpio_pin_t pin;
88 int temp;
89 int hum;
90 int fails;
91 struct timeout_task task;
92 bool detaching;
93 };
94
95 static int
gpioths_probe(device_t dev)96 gpioths_probe(device_t dev)
97 {
98 int rv;
99
100 /*
101 * By default we only bid to attach if specifically added by our parent
102 * (usually via hint.gpioths.#.at=busname). On FDT systems we bid as
103 * the default driver based on being configured in the FDT data.
104 */
105 rv = BUS_PROBE_NOWILDCARD;
106
107 #ifdef FDT
108 if (ofw_bus_status_okay(dev) &&
109 ofw_bus_search_compatible(dev, compat_data)->ocd_data)
110 rv = BUS_PROBE_DEFAULT;
111 #endif
112
113 device_set_desc(dev, "DHT11/DHT22 Temperature and Humidity Sensor");
114
115 return (rv);
116 }
117
118 static int
gpioths_dht_timeuntil(struct gpioths_softc * sc,bool lev,uint32_t * time)119 gpioths_dht_timeuntil(struct gpioths_softc *sc, bool lev, uint32_t *time)
120 {
121 bool cur_level;
122 int i;
123
124 for (i = 0; i < GPIOTHS_DHT_TIMEOUT; i++) {
125 gpio_pin_is_active(sc->pin, &cur_level);
126 if (cur_level == lev) {
127 if (time != NULL)
128 *time = i;
129 return (0);
130 }
131 DELAY(1);
132 }
133
134 /* Timeout */
135 return (ETIMEDOUT);
136 }
137
138 static void
gpioths_dht_initread(struct gpioths_softc * sc)139 gpioths_dht_initread(struct gpioths_softc *sc)
140 {
141
142 /*
143 * According to specifications we need to drive the data line low for at
144 * least 20ms then drive it high, to wake up the chip and signal it to
145 * send a measurement. After sending this start signal, we switch the
146 * pin back to input so the device can begin talking to us.
147 */
148 gpio_pin_setflags(sc->pin, GPIO_PIN_OUTPUT);
149 gpio_pin_set_active(sc->pin, false);
150 pause_sbt("gpioths", ustosbt(GPIOTHS_DHT_STARTCYCLE), C_PREL(2), 0);
151 gpio_pin_set_active(sc->pin, true);
152 gpio_pin_setflags(sc->pin, GPIO_PIN_INPUT);
153 }
154
155 static int
gpioths_dht_readbytes(struct gpioths_softc * sc)156 gpioths_dht_readbytes(struct gpioths_softc *sc)
157 {
158 uint32_t calibrations[GPIOTHS_DHT_CYCLES];
159 uint32_t intervals[GPIOTHS_DHT_CYCLES];
160 uint32_t err, avglen, value;
161 uint8_t crc, calc;
162 int i, negmul, offset, size, tmphi, tmplo;
163
164 gpioths_dht_initread(sc);
165
166 err = gpioths_dht_timeuntil(sc, false, NULL);
167 if (err) {
168 device_printf(sc->dev, "err(START) = %d\n", err);
169 goto error;
170 }
171
172 /* reading - 41 cycles */
173 for (i = 0; i < GPIOTHS_DHT_CYCLES; i++) {
174 err = gpioths_dht_timeuntil(sc, true, &calibrations[i]);
175 if (err) {
176 device_printf(sc->dev, "err(CAL, %d) = %d\n", i, err);
177 goto error;
178 }
179 err = gpioths_dht_timeuntil(sc, false, &intervals[i]);
180 if (err) {
181 device_printf(sc->dev, "err(INTERVAL, %d) = %d\n", i, err);
182 goto error;
183 }
184 }
185
186 /* Calculate average data calibration cycle length */
187 avglen = 0;
188 for (i = 1; i < GPIOTHS_DHT_CYCLES; i++)
189 avglen += calibrations[i];
190
191 avglen = avglen / (GPIOTHS_DHT_CYCLES - 1);
192
193 /* Calculate data */
194 value = 0;
195 offset = 1;
196 size = sizeof(value) * 8;
197 for (i = offset; i < size + offset; i++) {
198 value <<= 1;
199 if (intervals[i] > avglen)
200 value += 1;
201 }
202
203 /* Calculate CRC */
204 crc = 0;
205 offset = sizeof(value) * 8 + 1;
206 size = sizeof(crc) * 8;
207 for (i = offset; i < size + offset; i++) {
208 crc <<= 1;
209 if (intervals[i] > avglen)
210 crc += 1;
211 }
212
213 calc = 0;
214 for (i = 0; i < sizeof(value); i++)
215 calc += (value >> (8*i)) & GPIOTHS_DHT_ONEBYTEMASK;
216
217 #ifdef GPIOTHS_DEBUG
218 /* Debug bits */
219 for (i = 0; i < GPIOTHS_DHT_CYCLES; i++)
220 device_printf(sc->dev, "%d: %d %d\n", i, calibrations[i],
221 intervals[i]);
222
223 device_printf(sc->dev, "len=%d, data=%x, crc=%x/%x\n", avglen, value, crc,
224 calc);
225 #endif /* GPIOTHS_DEBUG */
226
227 /* CRC check */
228 if (calc != crc) {
229 err = -1;
230 goto error;
231 }
232
233 /*
234 * For DHT11/12, the values are split into 8 bits of integer and 8 bits
235 * of fractional tenths. On DHT11 the fraction bytes are always zero.
236 * On DHT12 the sign bit is in the high bit of the fraction byte.
237 * - DHT11: 0HHHHHHH 00000000 00TTTTTT 00000000
238 * - DHT12: 0HHHHHHH 0000hhhh 00TTTTTT s000tttt
239 *
240 * For DHT21/21, the values are are encoded in 16 bits each, with the
241 * temperature sign bit in the high bit. The values are tenths of a
242 * degree C and tenths of a percent RH.
243 * - DHT21: 000000HH HHHHHHHH s00000TT TTTTTTTT
244 * - DHT22: 000000HH HHHHHHHH s00000TT TTTTTTTT
245 *
246 * For all devices, some bits are always zero because of the range of
247 * values supported by the device.
248 *
249 * We figure out how to decode things based on the high byte of the
250 * humidity. A DHT21/22 cannot report a value greater than 3 in
251 * the upper bits of its 16-bit humidity. A DHT11/12 should not report
252 * a value lower than 20. To allow for the possibility that a device
253 * could report a value slightly out of its sensitivity range, we split
254 * the difference and say if the value is greater than 10 it must be a
255 * DHT11/12 (that would be a humidity over 256% on a DHT21/22).
256 */
257 #define DK_OFFSET 2731 /* Offset between K and C, in decikelvins. */
258 if ((value >> 24) > 10) {
259 /* DHT11 or DHT12 */
260 tmphi = (value >> 8) & 0x3f;
261 tmplo = value & 0x0f;
262 negmul = (value & 0x80) ? -1 : 1;
263 sc->temp = DK_OFFSET + (negmul * (tmphi * 10 + tmplo));
264 sc->hum = (value >> 24) & 0x7f;
265 } else {
266 /* DHT21 or DHT22 */
267 negmul = (value & 0x8000) ? -1 : 1;
268 sc->temp = DK_OFFSET + (negmul * (value & 0x03ff));
269 sc->hum = ((value >> 16) & 0x03ff) / 10;
270 }
271
272 sc->fails = 0;
273
274 #ifdef GPIOTHS_DEBUG
275 /* Debug bits */
276 device_printf(dev, "fails=%d, temp=%d, hum=%d\n", sc->fails,
277 sc->temp, sc->hum);
278 #endif /* GPIOTHS_DEBUG */
279
280 return (0);
281 error:
282 sc->fails++;
283 return (err);
284 }
285
286 static void
gpioths_poll(void * arg,int pending __unused)287 gpioths_poll(void *arg, int pending __unused)
288 {
289 struct gpioths_softc *sc;
290
291 sc = (struct gpioths_softc *)arg;
292
293 gpioths_dht_readbytes(sc);
294 if (!sc->detaching)
295 taskqueue_enqueue_timeout_sbt(taskqueue_thread, &sc->task,
296 GPIOTHS_POLLTIME * SBT_1S, 0, C_PREL(3));
297 }
298
299 static int
gpioths_attach(device_t dev)300 gpioths_attach(device_t dev)
301 {
302 struct gpioths_softc *sc;
303 struct sysctl_ctx_list *ctx;
304 struct sysctl_oid *tree;
305 int err;
306
307 sc = device_get_softc(dev);
308 ctx = device_get_sysctl_ctx(dev);
309 tree = device_get_sysctl_tree(dev);
310
311 sc->dev = dev;
312
313 TIMEOUT_TASK_INIT(taskqueue_thread, &sc->task, 0, gpioths_poll, sc);
314
315 #ifdef FDT
316 /* Try to configure our pin from fdt data on fdt-based systems. */
317 err = gpio_pin_get_by_ofw_idx(dev, ofw_bus_get_node(dev), PIN_IDX,
318 &sc->pin);
319 #else
320 err = ENOENT;
321 #endif
322 /*
323 * If we didn't get configured by fdt data and our parent is gpiobus,
324 * see if we can be configured by the bus (allows hinted attachment even
325 * on fdt-based systems).
326 */
327 if (err != 0 &&
328 strcmp("gpiobus", device_get_name(device_get_parent(dev))) == 0)
329 err = gpio_pin_get_by_child_index(dev, PIN_IDX, &sc->pin);
330
331 /* If we didn't get configured by either method, whine and punt. */
332 if (err != 0) {
333 device_printf(sc->dev,
334 "cannot acquire gpio pin (config error)\n");
335 return (err);
336 }
337
338 /*
339 * Ensure we have control of our pin, and preset the data line to its
340 * idle condition (high). Leave the line in input mode, relying on the
341 * external pullup to keep the line high while idle.
342 */
343 err = gpio_pin_setflags(sc->pin, GPIO_PIN_OUTPUT);
344 if (err != 0) {
345 device_printf(dev, "gpio_pin_setflags(OUT) = %d\n", err);
346 return (err);
347 }
348 err = gpio_pin_set_active(sc->pin, true);
349 if (err != 0) {
350 device_printf(dev, "gpio_pin_set_active(false) = %d\n", err);
351 return (err);
352 }
353 err = gpio_pin_setflags(sc->pin, GPIO_PIN_INPUT);
354 if (err != 0) {
355 device_printf(dev, "gpio_pin_setflags(IN) = %d\n", err);
356 return (err);
357 }
358
359 /*
360 * Do an initial read so we have correct values for reporting before
361 * registering the sysctls that can access those values. This also
362 * schedules the periodic polling the driver does every few seconds to
363 * update the sysctl variables.
364 */
365 gpioths_poll(sc, 0);
366
367 sysctl_add_oid(ctx, SYSCTL_CHILDREN(tree), OID_AUTO, "temperature", \
368 CTLFLAG_RD | CTLTYPE_INT | CTLFLAG_MPSAFE,
369 &sc->temp, 0, sysctl_handle_int, "IK", "temperature", NULL);
370
371 SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO, "humidity",
372 CTLFLAG_RD, &sc->hum, 0, "relative humidity(%)");
373
374 SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO, "fails",
375 CTLFLAG_RD, &sc->fails, 0,
376 "failures since last successful read");
377
378 return (0);
379 }
380
381 static int
gpioths_detach(device_t dev)382 gpioths_detach(device_t dev)
383 {
384 struct gpioths_softc *sc;
385
386 sc = device_get_softc(dev);
387 gpio_pin_release(sc->pin);
388 sc->detaching = true;
389 while (taskqueue_cancel_timeout(taskqueue_thread, &sc->task, NULL) != 0)
390 taskqueue_drain_timeout(taskqueue_thread, &sc->task);
391
392 return (0);
393 }
394
395 /* Driver bits */
396 static device_method_t gpioths_methods[] = {
397 /* Device interface */
398 DEVMETHOD(device_probe, gpioths_probe),
399 DEVMETHOD(device_attach, gpioths_attach),
400 DEVMETHOD(device_detach, gpioths_detach),
401
402 DEVMETHOD_END
403 };
404
405 DEFINE_CLASS_0(gpioths, gpioths_driver, gpioths_methods, sizeof(struct gpioths_softc));
406
407 #ifdef FDT
408 DRIVER_MODULE(gpioths, simplebus, gpioths_driver, 0, 0);
409 #endif
410
411 DRIVER_MODULE(gpioths, gpiobus, gpioths_driver, 0, 0);
412 MODULE_DEPEND(gpioths, gpiobus, 1, 1, 1);
413