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/cdefs.h> 53 #include <sys/param.h> 54 #include <sys/kernel.h> 55 #include <sys/bus.h> 56 #include <sys/gpio.h> 57 #include <sys/module.h> 58 #include <sys/errno.h> 59 #include <sys/systm.h> 60 #include <sys/sysctl.h> 61 #include <sys/taskqueue.h> 62 63 #include <dev/gpio/gpiobusvar.h> 64 65 #ifdef FDT 66 #include <dev/ofw/ofw_bus.h> 67 #include <dev/ofw/ofw_bus_subr.h> 68 69 static struct ofw_compat_data compat_data[] = { 70 {"dht11", true}, 71 {NULL, false} 72 }; 73 OFWBUS_PNP_INFO(compat_data); 74 SIMPLEBUS_PNP_INFO(compat_data); 75 #endif /* FDT */ 76 77 #define PIN_IDX 0 /* Use the first/only configured pin. */ 78 79 #define GPIOTHS_POLLTIME 5 /* in seconds */ 80 81 #define GPIOTHS_DHT_STARTCYCLE 20000 /* 20ms = 20000us */ 82 #define GPIOTHS_DHT_TIMEOUT 1000 /* 1ms = 1000us */ 83 #define GPIOTHS_DHT_CYCLES 41 84 #define GPIOTHS_DHT_ONEBYTEMASK 0xFF 85 86 struct gpioths_softc { 87 device_t dev; 88 gpio_pin_t pin; 89 int temp; 90 int hum; 91 int fails; 92 struct timeout_task task; 93 bool detaching; 94 }; 95 96 static int 97 gpioths_probe(device_t dev) 98 { 99 int rv; 100 101 /* 102 * By default we only bid to attach if specifically added by our parent 103 * (usually via hint.gpioths.#.at=busname). On FDT systems we bid as 104 * the default driver based on being configured in the FDT data. 105 */ 106 rv = BUS_PROBE_NOWILDCARD; 107 108 #ifdef FDT 109 if (ofw_bus_status_okay(dev) && 110 ofw_bus_search_compatible(dev, compat_data)->ocd_data) 111 rv = BUS_PROBE_DEFAULT; 112 #endif 113 114 device_set_desc(dev, "DHT11/DHT22 Temperature and Humidity Sensor"); 115 116 return (rv); 117 } 118 119 static int 120 gpioths_dht_timeuntil(struct gpioths_softc *sc, bool lev, uint32_t *time) 121 { 122 bool cur_level; 123 int i; 124 125 for (i = 0; i < GPIOTHS_DHT_TIMEOUT; i++) { 126 gpio_pin_is_active(sc->pin, &cur_level); 127 if (cur_level == lev) { 128 if (time != NULL) 129 *time = i; 130 return (0); 131 } 132 DELAY(1); 133 } 134 135 /* Timeout */ 136 return (ETIMEDOUT); 137 } 138 139 static void 140 gpioths_dht_initread(struct gpioths_softc *sc) 141 { 142 143 /* 144 * According to specifications we need to drive the data line low for at 145 * least 20ms then drive it high, to wake up the chip and signal it to 146 * send a measurement. After sending this start signal, we switch the 147 * pin back to input so the device can begin talking to us. 148 */ 149 gpio_pin_setflags(sc->pin, GPIO_PIN_OUTPUT); 150 gpio_pin_set_active(sc->pin, false); 151 pause_sbt("gpioths", ustosbt(GPIOTHS_DHT_STARTCYCLE), C_PREL(2), 0); 152 gpio_pin_set_active(sc->pin, true); 153 gpio_pin_setflags(sc->pin, GPIO_PIN_INPUT); 154 } 155 156 static int 157 gpioths_dht_readbytes(struct gpioths_softc *sc) 158 { 159 uint32_t calibrations[GPIOTHS_DHT_CYCLES]; 160 uint32_t intervals[GPIOTHS_DHT_CYCLES]; 161 uint32_t err, avglen, value; 162 uint8_t crc, calc; 163 int i, negmul, offset, size, tmphi, tmplo; 164 165 gpioths_dht_initread(sc); 166 167 err = gpioths_dht_timeuntil(sc, false, NULL); 168 if (err) { 169 device_printf(sc->dev, "err(START) = %d\n", err); 170 goto error; 171 } 172 173 /* reading - 41 cycles */ 174 for (i = 0; i < GPIOTHS_DHT_CYCLES; i++) { 175 err = gpioths_dht_timeuntil(sc, true, &calibrations[i]); 176 if (err) { 177 device_printf(sc->dev, "err(CAL, %d) = %d\n", i, err); 178 goto error; 179 } 180 err = gpioths_dht_timeuntil(sc, false, &intervals[i]); 181 if (err) { 182 device_printf(sc->dev, "err(INTERVAL, %d) = %d\n", i, err); 183 goto error; 184 } 185 } 186 187 /* Calculate average data calibration cycle length */ 188 avglen = 0; 189 for (i = 1; i < GPIOTHS_DHT_CYCLES; i++) 190 avglen += calibrations[i]; 191 192 avglen = avglen / (GPIOTHS_DHT_CYCLES - 1); 193 194 /* Calculate data */ 195 value = 0; 196 offset = 1; 197 size = sizeof(value) * 8; 198 for (i = offset; i < size + offset; i++) { 199 value <<= 1; 200 if (intervals[i] > avglen) 201 value += 1; 202 } 203 204 /* Calculate CRC */ 205 crc = 0; 206 offset = sizeof(value) * 8 + 1; 207 size = sizeof(crc) * 8; 208 for (i = offset; i < size + offset; i++) { 209 crc <<= 1; 210 if (intervals[i] > avglen) 211 crc += 1; 212 } 213 214 calc = 0; 215 for (i = 0; i < sizeof(value); i++) 216 calc += (value >> (8*i)) & GPIOTHS_DHT_ONEBYTEMASK; 217 218 #ifdef GPIOTHS_DEBUG 219 /* Debug bits */ 220 for (i = 0; i < GPIOTHS_DHT_CYCLES; i++) 221 device_printf(sc->dev, "%d: %d %d\n", i, calibrations[i], 222 intervals[i]); 223 224 device_printf(sc->dev, "len=%d, data=%x, crc=%x/%x\n", avglen, value, crc, 225 calc); 226 #endif /* GPIOTHS_DEBUG */ 227 228 /* CRC check */ 229 if (calc != crc) { 230 err = -1; 231 goto error; 232 } 233 234 /* 235 * For DHT11/12, the values are split into 8 bits of integer and 8 bits 236 * of fractional tenths. On DHT11 the fraction bytes are always zero. 237 * On DHT12 the sign bit is in the high bit of the fraction byte. 238 * - DHT11: 0HHHHHHH 00000000 00TTTTTT 00000000 239 * - DHT12: 0HHHHHHH 0000hhhh 00TTTTTT s000tttt 240 * 241 * For DHT21/21, the values are are encoded in 16 bits each, with the 242 * temperature sign bit in the high bit. The values are tenths of a 243 * degree C and tenths of a percent RH. 244 * - DHT21: 000000HH HHHHHHHH s00000TT TTTTTTTT 245 * - DHT22: 000000HH HHHHHHHH s00000TT TTTTTTTT 246 * 247 * For all devices, some bits are always zero because of the range of 248 * values supported by the device. 249 * 250 * We figure out how to decode things based on the high byte of the 251 * humidity. A DHT21/22 cannot report a value greater than 3 in 252 * the upper bits of its 16-bit humidity. A DHT11/12 should not report 253 * a value lower than 20. To allow for the possibility that a device 254 * could report a value slightly out of its sensitivity range, we split 255 * the difference and say if the value is greater than 10 it must be a 256 * DHT11/12 (that would be a humidity over 256% on a DHT21/22). 257 */ 258 #define DK_OFFSET 2731 /* Offset between K and C, in decikelvins. */ 259 if ((value >> 24) > 10) { 260 /* DHT11 or DHT12 */ 261 tmphi = (value >> 8) & 0x3f; 262 tmplo = value & 0x0f; 263 negmul = (value & 0x80) ? -1 : 1; 264 sc->temp = DK_OFFSET + (negmul * (tmphi * 10 + tmplo)); 265 sc->hum = (value >> 24) & 0x7f; 266 } else { 267 /* DHT21 or DHT22 */ 268 negmul = (value & 0x8000) ? -1 : 1; 269 sc->temp = DK_OFFSET + (negmul * (value & 0x03ff)); 270 sc->hum = ((value >> 16) & 0x03ff) / 10; 271 } 272 273 sc->fails = 0; 274 275 #ifdef GPIOTHS_DEBUG 276 /* Debug bits */ 277 device_printf(dev, "fails=%d, temp=%d, hum=%d\n", sc->fails, 278 sc->temp, sc->hum); 279 #endif /* GPIOTHS_DEBUG */ 280 281 return (0); 282 error: 283 sc->fails++; 284 return (err); 285 } 286 287 static void 288 gpioths_poll(void *arg, int pending __unused) 289 { 290 struct gpioths_softc *sc; 291 292 sc = (struct gpioths_softc *)arg; 293 294 gpioths_dht_readbytes(sc); 295 if (!sc->detaching) 296 taskqueue_enqueue_timeout_sbt(taskqueue_thread, &sc->task, 297 GPIOTHS_POLLTIME * SBT_1S, 0, C_PREL(3)); 298 } 299 300 static int 301 gpioths_attach(device_t dev) 302 { 303 struct gpioths_softc *sc; 304 struct sysctl_ctx_list *ctx; 305 struct sysctl_oid *tree; 306 int err; 307 308 sc = device_get_softc(dev); 309 ctx = device_get_sysctl_ctx(dev); 310 tree = device_get_sysctl_tree(dev); 311 312 sc->dev = dev; 313 314 TIMEOUT_TASK_INIT(taskqueue_thread, &sc->task, 0, gpioths_poll, sc); 315 316 #ifdef FDT 317 /* Try to configure our pin from fdt data on fdt-based systems. */ 318 err = gpio_pin_get_by_ofw_idx(dev, ofw_bus_get_node(dev), PIN_IDX, 319 &sc->pin); 320 #else 321 err = ENOENT; 322 #endif 323 /* 324 * If we didn't get configured by fdt data and our parent is gpiobus, 325 * see if we can be configured by the bus (allows hinted attachment even 326 * on fdt-based systems). 327 */ 328 if (err != 0 && 329 strcmp("gpiobus", device_get_name(device_get_parent(dev))) == 0) 330 err = gpio_pin_get_by_child_index(dev, PIN_IDX, &sc->pin); 331 332 /* If we didn't get configured by either method, whine and punt. */ 333 if (err != 0) { 334 device_printf(sc->dev, 335 "cannot acquire gpio pin (config error)\n"); 336 return (err); 337 } 338 339 /* 340 * Ensure we have control of our pin, and preset the data line to its 341 * idle condition (high). Leave the line in input mode, relying on the 342 * external pullup to keep the line high while idle. 343 */ 344 err = gpio_pin_setflags(sc->pin, GPIO_PIN_OUTPUT); 345 if (err != 0) { 346 device_printf(dev, "gpio_pin_setflags(OUT) = %d\n", err); 347 return (err); 348 } 349 err = gpio_pin_set_active(sc->pin, true); 350 if (err != 0) { 351 device_printf(dev, "gpio_pin_set_active(false) = %d\n", err); 352 return (err); 353 } 354 err = gpio_pin_setflags(sc->pin, GPIO_PIN_INPUT); 355 if (err != 0) { 356 device_printf(dev, "gpio_pin_setflags(IN) = %d\n", err); 357 return (err); 358 } 359 360 /* 361 * Do an initial read so we have correct values for reporting before 362 * registering the sysctls that can access those values. This also 363 * schedules the periodic polling the driver does every few seconds to 364 * update the sysctl variables. 365 */ 366 gpioths_poll(sc, 0); 367 368 sysctl_add_oid(ctx, SYSCTL_CHILDREN(tree), OID_AUTO, "temperature", \ 369 CTLFLAG_RD | CTLTYPE_INT | CTLFLAG_MPSAFE, 370 &sc->temp, 0, sysctl_handle_int, "IK", "temperature", NULL); 371 372 SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO, "humidity", 373 CTLFLAG_RD, &sc->hum, 0, "relative humidity(%)"); 374 375 SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO, "fails", 376 CTLFLAG_RD, &sc->fails, 0, 377 "failures since last successful read"); 378 379 return (0); 380 } 381 382 static int 383 gpioths_detach(device_t dev) 384 { 385 struct gpioths_softc *sc; 386 387 sc = device_get_softc(dev); 388 gpio_pin_release(sc->pin); 389 sc->detaching = true; 390 while (taskqueue_cancel_timeout(taskqueue_thread, &sc->task, NULL) != 0) 391 taskqueue_drain_timeout(taskqueue_thread, &sc->task); 392 393 return (0); 394 } 395 396 /* Driver bits */ 397 static device_method_t gpioths_methods[] = { 398 /* Device interface */ 399 DEVMETHOD(device_probe, gpioths_probe), 400 DEVMETHOD(device_attach, gpioths_attach), 401 DEVMETHOD(device_detach, gpioths_detach), 402 403 DEVMETHOD_END 404 }; 405 406 DEFINE_CLASS_0(gpioths, gpioths_driver, gpioths_methods, sizeof(struct gpioths_softc)); 407 408 #ifdef FDT 409 DRIVER_MODULE(gpioths, simplebus, gpioths_driver, 0, 0); 410 #endif 411 412 DRIVER_MODULE(gpioths, gpiobus, gpioths_driver, 0, 0); 413 MODULE_DEPEND(gpioths, gpiobus, 1, 1, 1); 414