1 /*- 2 * Copyright (c) 2015 M. Warner Losh <imp@freebsd.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD$"); 29 30 #include "opt_platform.h" 31 32 #include <sys/param.h> 33 #include <sys/systm.h> 34 #include <sys/bus.h> 35 #include <sys/gpio.h> 36 #include <sys/kernel.h> 37 #include <sys/lock.h> 38 #include <sys/malloc.h> 39 #include <sys/module.h> 40 #include <sys/mutex.h> 41 42 #ifdef FDT 43 #include <dev/fdt/fdt_common.h> 44 #include <dev/ofw/ofw_bus.h> 45 #include <dev/ofw/ofw_bus_subr.h> 46 #endif 47 48 #include <dev/gpio/gpiobusvar.h> 49 #include "gpiobus_if.h" 50 51 #include <dev/ow/owll.h> 52 53 #define OW_PIN 0 54 55 #define OWC_GPIOBUS_LOCK(_sc) mtx_lock(&(_sc)->sc_mtx) 56 #define OWC_GPIOBUS_UNLOCK(_sc) mtx_unlock(&(_sc)->sc_mtx) 57 #define OWC_GPIOBUS_LOCK_INIT(_sc) \ 58 mtx_init(&_sc->sc_mtx, device_get_nameunit(_sc->sc_dev), \ 59 "owc_gpiobus", MTX_DEF) 60 #define OWC_GPIOBUS_LOCK_DESTROY(_sc) mtx_destroy(&_sc->sc_mtx); 61 62 struct owc_gpiobus_softc 63 { 64 device_t sc_dev; 65 device_t sc_busdev; 66 struct mtx sc_mtx; 67 }; 68 69 static int owc_gpiobus_probe(device_t); 70 static int owc_gpiobus_attach(device_t); 71 static int owc_gpiobus_detach(device_t); 72 73 #ifdef FDT 74 static void 75 owc_gpiobus_identify(driver_t *driver, device_t bus) 76 { 77 phandle_t w1, root; 78 79 /* 80 * Find all the 1-wire bus pseudo-nodes that are 81 * at the top level of the FDT. Would be nice to 82 * somehow preserve the node name of these busses, 83 * but there's no good place to put it. The driver's 84 * name is used for the device name, and the 1-wire 85 * bus overwrites the description. 86 */ 87 root = OF_finddevice("/"); 88 if (root == 0) 89 return; 90 for (w1 = OF_child(root); w1 != 0; w1 = OF_peer(w1)) { 91 if (!fdt_is_compatible_strict(w1, "w1-gpio")) 92 continue; 93 if (!OF_hasprop(w1, "gpios")) 94 continue; 95 ofw_gpiobus_add_fdt_child(bus, driver->name, w1); 96 } 97 } 98 #endif 99 100 static int 101 owc_gpiobus_probe(device_t dev) 102 { 103 #ifdef FDT 104 if (!ofw_bus_status_okay(dev)) 105 return (ENXIO); 106 107 if (ofw_bus_is_compatible(dev, "w1-gpio")) { 108 device_set_desc(dev, "FDT GPIO attached one-wire bus"); 109 return (BUS_PROBE_DEFAULT); 110 } 111 112 return (ENXIO); 113 #else 114 device_set_desc(dev, "GPIO attached one-wire bus"); 115 return 0; 116 #endif 117 } 118 119 static int 120 owc_gpiobus_attach(device_t dev) 121 { 122 struct owc_gpiobus_softc *sc; 123 device_t *kids; 124 int nkid; 125 126 sc = device_get_softc(dev); 127 sc->sc_dev = dev; 128 sc->sc_busdev = device_get_parent(dev); 129 OWC_GPIOBUS_LOCK_INIT(sc); 130 nkid = 0; 131 if (device_get_children(dev, &kids, &nkid) == 0) 132 free(kids, M_TEMP); 133 if (nkid == 0) 134 device_add_child(dev, "ow", -1); 135 bus_generic_attach(dev); 136 137 return (0); 138 } 139 140 static int 141 owc_gpiobus_detach(device_t dev) 142 { 143 struct owc_gpiobus_softc *sc; 144 145 sc = device_get_softc(dev); 146 OWC_GPIOBUS_LOCK_DESTROY(sc); 147 bus_generic_detach(dev); 148 return (0); 149 } 150 151 /* 152 * In the diagrams below, R is driven by the resistor pullup, M is driven by the 153 * master, and S is driven by the slave / target. 154 */ 155 156 /* 157 * These macros let what why we're doing stuff shine in the code 158 * below, and let the how be confined to here. 159 */ 160 #define GETBUS(sc) GPIOBUS_ACQUIRE_BUS((sc)->sc_busdev, \ 161 (sc)->sc_dev, GPIOBUS_WAIT) 162 #define RELBUS(sc) GPIOBUS_RELEASE_BUS((sc)->sc_busdev, \ 163 (sc)->sc_dev) 164 #define OUTPIN(sc) GPIOBUS_PIN_SETFLAGS((sc)->sc_busdev, \ 165 (sc)->sc_dev, OW_PIN, GPIO_PIN_OUTPUT) 166 #define INPIN(sc) GPIOBUS_PIN_SETFLAGS((sc)->sc_busdev, \ 167 (sc)->sc_dev, OW_PIN, GPIO_PIN_INPUT) 168 #define GETPIN(sc, bit) GPIOBUS_PIN_GET((sc)->sc_busdev, \ 169 (sc)->sc_dev, OW_PIN, bit) 170 #define LOW(sc) GPIOBUS_PIN_SET((sc)->sc_busdev, \ 171 (sc)->sc_dev, OW_PIN, GPIO_PIN_LOW) 172 173 /* 174 * WRITE-ONE (see owll_if.m for timings) From Figure 4-1 AN-937 175 * 176 * |<---------tSLOT---->|<-tREC->| 177 * High RRRRM | RRRRRRRRRRRR|RRRRRRRRM 178 * M | R | | | M 179 * M| R | | | M 180 * Low MMMMMMM | | | MMMMMM... 181 * |<-tLOW1->| | | 182 * |<------15us--->| | 183 * |<--------60us---->| 184 */ 185 static int 186 owc_gpiobus_write_one(device_t dev, struct ow_timing *t) 187 { 188 struct owc_gpiobus_softc *sc; 189 int error; 190 191 sc = device_get_softc(dev); 192 error = GETBUS(sc); 193 if (error != 0) 194 return error; 195 196 critical_enter(); 197 198 /* Force low */ 199 OUTPIN(sc); 200 LOW(sc); 201 DELAY(t->t_low1); 202 203 /* Allow resistor to float line high */ 204 INPIN(sc); 205 DELAY(t->t_slot - t->t_low1 + t->t_rec); 206 207 critical_exit(); 208 209 RELBUS(sc); 210 211 return 0; 212 } 213 214 /* 215 * WRITE-ZERO (see owll_if.m for timings) From Figure 4-2 AN-937 216 * 217 * |<---------tSLOT------>|<-tREC->| 218 * High RRRRM | | |RRRRRRRM 219 * M | | R M 220 * M| | | |R M 221 * Low MMMMMMMMMMMMMMMMMMMMMR MMMMMM... 222 * |<--15us->| | | 223 * |<------60us--->| | 224 * |<-------tLOW0------>| 225 */ 226 static int 227 owc_gpiobus_write_zero(device_t dev, struct ow_timing *t) 228 { 229 struct owc_gpiobus_softc *sc; 230 int error; 231 232 sc = device_get_softc(dev); 233 error = GETBUS(sc); 234 if (error != 0) 235 return error; 236 237 critical_enter(); 238 239 /* Force low */ 240 OUTPIN(sc); 241 LOW(sc); 242 DELAY(t->t_low0); 243 244 /* Allow resistor to float line high */ 245 INPIN(sc); 246 DELAY(t->t_slot - t->t_low0 + t->t_rec); 247 248 critical_exit(); 249 250 RELBUS(sc); 251 252 return 0; 253 } 254 255 /* 256 * READ-DATA (see owll_if.m for timings) From Figure 4-3 AN-937 257 * 258 * |<---------tSLOT------>|<-tREC->| 259 * High RRRRM | rrrrrrrrrrrrrrrRRRRRRRM 260 * M | r | R M 261 * M| r | |R M 262 * Low MMMMMMMSSSSSSSSSSSSSSR MMMMMM... 263 * |<tLOWR>< sample > | 264 * |<------tRDV---->| | 265 * ->| |<-tRELEASE 266 * 267 * r -- allowed to pull high via the resitor when slave writes a 1-bit 268 * 269 */ 270 static int 271 owc_gpiobus_read_data(device_t dev, struct ow_timing *t, int *bit) 272 { 273 struct owc_gpiobus_softc *sc; 274 int error, sample; 275 sbintime_t then, now; 276 277 sc = device_get_softc(dev); 278 error = GETBUS(sc); 279 if (error != 0) 280 return error; 281 282 /* Force low for t_lowr microseconds */ 283 then = sbinuptime(); 284 OUTPIN(sc); 285 LOW(sc); 286 DELAY(t->t_lowr); 287 288 /* 289 * Slave is supposed to hold the line low for t_rdv microseconds for 0 290 * and immediately float it high for a 1. This is measured from the 291 * master's pushing the line low. 292 */ 293 INPIN(sc); 294 critical_enter(); 295 do { 296 now = sbinuptime(); 297 GETPIN(sc, &sample); 298 } while (sbttous(now - then) < t->t_rdv + 2 && sample == 0); 299 critical_exit(); 300 301 if (sbttons(now - then) < t->t_rdv * 1000) 302 *bit = 1; 303 else 304 *bit = 0; 305 306 /* Wait out the rest of t_slot */ 307 do { 308 now = sbinuptime(); 309 } while ((now - then) / SBT_1US < t->t_slot); 310 311 RELBUS(sc); 312 313 return 0; 314 } 315 316 /* 317 * RESET AND PRESENCE PULSE (see owll_if.m for timings) From Figure 4-4 AN-937 318 * 319 * |<---------tRSTH------------>| 320 * High RRRM | | RRRRRRRS | RRRR RRM 321 * M | |R| |S | R M 322 * M| R | | S |R M 323 * Low MMMMMMMM MMMMMM| | | SSSSSSSSSS MMMMMM 324 * |<----tRSTL--->| | |<-tPDL---->| 325 * | ->| |<-tR | | 326 * |<tPDH>| 327 * 328 * Note: for Regular Speed operations, tRSTL + tR should be less than 960us to 329 * avoid interferring with other devices on the bus 330 */ 331 static int 332 owc_gpiobus_reset_and_presence(device_t dev, struct ow_timing *t, int *bit) 333 { 334 struct owc_gpiobus_softc *sc; 335 int error; 336 int buf = -1; 337 338 sc = device_get_softc(dev); 339 error = GETBUS(sc); 340 if (error != 0) 341 return error; 342 343 344 /* 345 * Read the current state of the bus. The steady state of an idle bus is 346 * high. Badly wired buses that are missing the required pull up, or 347 * that have a short circuit to ground cause all kinds of mischief when 348 * we try to read them later. Return EIO and release the bus if the bus 349 * is currently low. 350 */ 351 INPIN(sc); 352 GETPIN(sc, &buf); 353 if (buf == 0) { 354 *bit = -1; 355 RELBUS(sc); 356 return EIO; 357 } 358 359 critical_enter(); 360 361 /* Force low */ 362 OUTPIN(sc); 363 LOW(sc); 364 DELAY(t->t_rstl); 365 366 /* Allow resistor to float line high and then wait for reset pulse */ 367 INPIN(sc); 368 DELAY(t->t_pdh + t->t_pdl / 2); 369 370 /* Read presence pulse */ 371 GETPIN(sc, &buf); 372 *bit = !!buf; 373 374 critical_exit(); 375 376 DELAY(t->t_rsth - (t->t_pdh + t->t_pdl / 2)); /* Timing not critical for this one */ 377 378 /* 379 * Read the state of the bus after we've waited past the end of the rest 380 * window. It should return to high. If it is low, then we have some 381 * problem and should abort the reset. 382 */ 383 GETPIN(sc, &buf); 384 if (buf == 0) { 385 *bit = -1; 386 RELBUS(sc); 387 return EIO; 388 } 389 390 RELBUS(sc); 391 392 return 0; 393 } 394 395 static devclass_t owc_gpiobus_devclass; 396 397 static device_method_t owc_gpiobus_methods[] = { 398 /* Device interface */ 399 #ifdef FDT 400 DEVMETHOD(device_identify, owc_gpiobus_identify), 401 #endif 402 DEVMETHOD(device_probe, owc_gpiobus_probe), 403 DEVMETHOD(device_attach, owc_gpiobus_attach), 404 DEVMETHOD(device_detach, owc_gpiobus_detach), 405 406 DEVMETHOD(owll_write_one, owc_gpiobus_write_one), 407 DEVMETHOD(owll_write_zero, owc_gpiobus_write_zero), 408 DEVMETHOD(owll_read_data, owc_gpiobus_read_data), 409 DEVMETHOD(owll_reset_and_presence, owc_gpiobus_reset_and_presence), 410 { 0, 0 } 411 }; 412 413 static driver_t owc_gpiobus_driver = { 414 "owc", 415 owc_gpiobus_methods, 416 sizeof(struct owc_gpiobus_softc), 417 }; 418 419 DRIVER_MODULE(owc_gpiobus_fdt, gpiobus, owc_gpiobus_driver, owc_gpiobus_devclass, 0, 0); 420 MODULE_DEPEND(owc_gpiobus_fdt, ow, 1, 1, 1); 421