bcm2835_rng.c revision 331889
1/* 2 * Copyright (c) 2015, 2016, Stephen J. Kiernan 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 29__FBSDID("$FreeBSD: stable/11/sys/arm/broadcom/bcm2835/bcm2835_rng.c 331889 2018-04-02 21:48:29Z gonzo $"); 30 31#include <sys/param.h> 32#include <sys/kernel.h> 33#include <sys/lock.h> 34#include <sys/malloc.h> 35#include <sys/module.h> 36#include <sys/random.h> 37#include <sys/sbuf.h> 38#include <sys/sysctl.h> 39#include <sys/selinfo.h> 40#include <sys/systm.h> 41#include <sys/bus.h> 42#include <sys/rman.h> 43 44#include <machine/bus.h> 45#include <machine/resource.h> 46 47#include <dev/ofw/openfirm.h> 48#include <dev/ofw/ofw_bus.h> 49#include <dev/ofw/ofw_bus_subr.h> 50 51#include <dev/random/randomdev.h> 52#include <dev/random/random_harvestq.h> 53 54#if !defined(BCM2835_RNG_USE_CALLOUT) 55#define BCM2835_RNG_USE_INTERRUPT 56#endif 57 58static device_attach_t bcm2835_rng_attach; 59static device_detach_t bcm2835_rng_detach; 60static device_probe_t bcm2835_rng_probe; 61 62#define RNG_CTRL 0x00 /* RNG Control Register */ 63#define RNG_COMBLK1_OSC 0x003f0000 /* Combiner Blk 1 Oscillator */ 64#define RNG_COMBLK1_OSC_SHIFT 16 65#define RNG_COMBLK2_OSC 0x0fc00000 /* Combiner Blk 2 Oscillator */ 66#define RNG_COMBLK2_OSC_SHIFT 22 67#define RNG_JCLK_BYP_DIV_CNT 0x0000ff00 /* Jitter clk bypass divider 68 count */ 69#define RNG_JCLK_BYP_DIV_CNT_SHIFT 8 70#define RNG_JCLK_BYP_SRC 0x00000020 /* Jitter clk bypass source */ 71#define RNG_JCLK_BYP_SEL 0x00000010 /* Jitter clk bypass select */ 72#define RNG_RBG2X 0x00000002 /* RBG 2X SPEED */ 73#define RNG_RBGEN_BIT 0x00000001 /* Enable RNG bit */ 74 75#define RNG_STATUS 0x04 /* RNG status register */ 76#define RND_VAL_SHIFT 24 /* Shift for valid words */ 77#define RND_VAL_MASK 0x000000ff /* Number valid words mask */ 78#define RND_VAL_WARM_CNT 0x40000 /* RNG Warm Up count */ 79#define RND_WARM_CNT 0xfffff /* RNG Warm Up Count mask */ 80 81#define RNG_DATA 0x08 /* RNG Data Register */ 82#define RNG_FF_THRES 0x0c 83#define RNG_FF_THRES_MASK 0x0000001f 84 85#define RNG_INT_MASK 0x10 86#define RNG_INT_OFF_BIT 0x00000001 87 88#define RNG_FF_DEFAULT 0x10 /* FIFO threshold default */ 89 90#define RNG_FIFO_WORDS (RNG_FF_DEFAULT / sizeof(uint32_t)) 91 92#define RNG_NUM_OSCILLATORS 6 93#define RNG_STALL_COUNT_DEFAULT 10 94 95struct bcm2835_rng_softc { 96 device_t sc_dev; 97 struct resource * sc_mem_res; 98 struct resource * sc_irq_res; 99 void * sc_intr_hdl; 100#if defined(BCM2835_RNG_USE_CALLOUT) || defined(BCM2835_RNG_USE_INTERRUPT) 101 uint32_t sc_buf[RNG_FIFO_WORDS]; 102#endif 103#if defined(BCM2835_RNG_USE_CALLOUT) 104 struct callout sc_rngto; 105 int sc_rnghz; 106#endif 107 int sc_stall_count; 108 int sc_rbg2x; 109 long sc_underrun; 110}; 111 112static __inline void 113bcm2835_rng_stat_inc_underrun(struct bcm2835_rng_softc *sc) 114{ 115 116 atomic_add_long(&sc->sc_underrun, 1); 117} 118 119static __inline uint32_t 120bcm2835_rng_read4(struct bcm2835_rng_softc *sc, bus_size_t off) 121{ 122 123 return bus_read_4(sc->sc_mem_res, off); 124} 125 126static __inline void 127bcm2835_rng_read_multi4(struct bcm2835_rng_softc *sc, bus_size_t off, 128 uint32_t *datap, bus_size_t count) 129{ 130 131 bus_read_multi_4(sc->sc_mem_res, off, datap, count); 132} 133 134static __inline void 135bcm2835_rng_write4(struct bcm2835_rng_softc *sc, bus_size_t off, uint32_t val) 136{ 137 138 bus_write_4(sc->sc_mem_res, off, val); 139} 140 141static void 142bcm2835_rng_dump_registers(struct bcm2835_rng_softc *sc, struct sbuf *sbp) 143{ 144 uint32_t comblk2_osc, comblk1_osc, jclk_byp_div, val; 145 int i; 146 147 /* Display RNG control register contents */ 148 val = bcm2835_rng_read4(sc, RNG_CTRL); 149 sbuf_printf(sbp, "RNG_CTRL (%08x)\n", val); 150 151 comblk2_osc = (val & RNG_COMBLK2_OSC) >> RNG_COMBLK2_OSC_SHIFT; 152 sbuf_printf(sbp, " RNG_COMBLK2_OSC (%02x)\n", comblk2_osc); 153 for (i = 0; i < RNG_NUM_OSCILLATORS; i++) 154 if ((comblk2_osc & (1 << i)) == 0) 155 sbuf_printf(sbp, " Oscillator %d enabled\n", i + 1); 156 157 comblk1_osc = (val & RNG_COMBLK1_OSC) >> RNG_COMBLK1_OSC_SHIFT; 158 sbuf_printf(sbp, " RNG_COMBLK1_OSC (%02x)\n", comblk1_osc); 159 for (i = 0; i < RNG_NUM_OSCILLATORS; i++) 160 if ((comblk1_osc & (1 << i)) == 0) 161 sbuf_printf(sbp, " Oscillator %d enabled\n", i + 1); 162 163 jclk_byp_div = (val & RNG_JCLK_BYP_DIV_CNT) >> 164 RNG_JCLK_BYP_DIV_CNT_SHIFT; 165 sbuf_printf(sbp, 166 " RNG_JCLK_BYP_DIV_CNT (%02x)\n APB clock frequency / %d\n", 167 jclk_byp_div, 2 * (jclk_byp_div + 1)); 168 169 sbuf_printf(sbp, " RNG_JCLK_BYP_SRC:\n %s\n", 170 (val & RNG_JCLK_BYP_SRC) ? "Use divided down APB clock" : 171 "Use RNG clock (APB clock)"); 172 173 sbuf_printf(sbp, " RNG_JCLK_BYP_SEL:\n %s\n", 174 (val & RNG_JCLK_BYP_SEL) ? "Bypass internal jitter clock" : 175 "Use internal jitter clock"); 176 177 if ((val & RNG_RBG2X) != 0) 178 sbuf_cat(sbp, " RNG_RBG2X: RNG 2X SPEED enabled\n"); 179 180 if ((val & RNG_RBGEN_BIT) != 0) 181 sbuf_cat(sbp, " RNG_RBGEN_BIT: RBG enabled\n"); 182 183 /* Display RNG status register contents */ 184 val = bcm2835_rng_read4(sc, RNG_STATUS); 185 sbuf_printf(sbp, "RNG_CTRL (%08x)\n", val); 186 sbuf_printf(sbp, " RND_VAL: %02x\n", 187 (val >> RND_VAL_SHIFT) & RND_VAL_MASK); 188 sbuf_printf(sbp, " RND_WARM_CNT: %05x\n", val & RND_WARM_CNT); 189 190 /* Display FIFO threshold register contents */ 191 val = bcm2835_rng_read4(sc, RNG_FF_THRES); 192 sbuf_printf(sbp, "RNG_FF_THRES: %05x\n", val & RNG_FF_THRES_MASK); 193 194 /* Display interrupt mask register contents */ 195 val = bcm2835_rng_read4(sc, RNG_INT_MASK); 196 sbuf_printf(sbp, "RNG_INT_MASK: interrupt %s\n", 197 ((val & RNG_INT_OFF_BIT) != 0) ? "disabled" : "enabled"); 198} 199 200static void 201bcm2835_rng_disable_intr(struct bcm2835_rng_softc *sc) 202{ 203 uint32_t mask; 204 205 /* Set the interrupt off bit in the interrupt mask register */ 206 mask = bcm2835_rng_read4(sc, RNG_INT_MASK); 207 mask |= RNG_INT_OFF_BIT; 208 bcm2835_rng_write4(sc, RNG_INT_MASK, mask); 209} 210 211#if defined(BCM2835_RNG_USE_INTERRUPT) 212static void 213bcm2835_rng_enable_intr(struct bcm2835_rng_softc *sc) 214{ 215 uint32_t mask; 216 217 /* Clear the interrupt off bit in the interrupt mask register */ 218 mask = bcm2835_rng_read4(sc, RNG_INT_MASK); 219 mask &= ~RNG_INT_OFF_BIT; 220 bcm2835_rng_write4(sc, RNG_INT_MASK, mask); 221} 222#endif 223 224static void 225bcm2835_rng_start(struct bcm2835_rng_softc *sc) 226{ 227 uint32_t ctrl; 228 229 /* Disable the interrupt */ 230 bcm2835_rng_disable_intr(sc); 231 232 /* Set the warmup count */ 233 bcm2835_rng_write4(sc, RNG_STATUS, RND_VAL_WARM_CNT); 234 235 /* Enable the RNG */ 236 ctrl = bcm2835_rng_read4(sc, RNG_CTRL); 237 ctrl |= RNG_RBGEN_BIT; 238 if (sc->sc_rbg2x) 239 ctrl |= RNG_RBG2X; 240 bcm2835_rng_write4(sc, RNG_CTRL, ctrl); 241 242#if defined(BCM2835_RNG_USE_INTERRUPT) 243 /* Enable the interrupt */ 244 bcm2835_rng_enable_intr(sc); 245#endif 246} 247 248static void 249bcm2835_rng_stop(struct bcm2835_rng_softc *sc) 250{ 251 uint32_t ctrl; 252 253 /* Disable the RNG */ 254 ctrl = bcm2835_rng_read4(sc, RNG_CTRL); 255 ctrl &= ~RNG_RBGEN_BIT; 256 bcm2835_rng_write4(sc, RNG_CTRL, ctrl); 257} 258 259static void 260bcm2835_rng_harvest(struct bcm2835_rng_softc *sc) 261{ 262 uint32_t *dest; 263 uint32_t status; 264 u_int cnt, nread, num_avail, num_words; 265 int seen_underrun, num_stalls; 266 267 dest = sc->sc_buf; 268 nread = num_words = 0; 269 seen_underrun = num_stalls = 0; 270 for (cnt = sizeof(sc->sc_buf) / sizeof(uint32_t); cnt > 0; 271 cnt -= num_words) { 272 /* Read status register to find out how many words available */ 273 status = bcm2835_rng_read4(sc, RNG_STATUS); 274 num_avail = (status >> RND_VAL_SHIFT) & RND_VAL_MASK; 275 276 /* If we have none... */ 277 if (num_avail == 0) { 278 bcm2835_rng_stat_inc_underrun(sc); 279 if (++seen_underrun >= sc->sc_stall_count) { 280 if (num_stalls++ > 0) { 281 device_printf(sc->sc_dev, 282 "RNG stalled, disabling device\n"); 283 bcm2835_rng_stop(sc); 284 break; 285 } else { 286 device_printf(sc->sc_dev, 287 "Too many underruns, resetting\n"); 288 bcm2835_rng_stop(sc); 289 bcm2835_rng_start(sc); 290 seen_underrun = 0; 291 } 292 } 293 /* Try again */ 294 continue; 295 } 296 297 CTR2(KTR_DEV, "%s: %d words available in RNG FIFO", 298 device_get_nameunit(sc->sc_dev), num_avail); 299 300 /* Pull MIN(num_avail, cnt) words from the FIFO */ 301 num_words = (num_avail > cnt) ? cnt : num_avail; 302 bcm2835_rng_read_multi4(sc, RNG_DATA, dest, 303 num_words); 304 dest += num_words; 305 nread += num_words; 306 } 307 308 cnt = nread * sizeof(uint32_t); 309 if (cnt > 0) 310 random_harvest_queue(sc->sc_buf, cnt, cnt * NBBY / 2, 311 RANDOM_PURE_BROADCOM); 312 313#if defined(BCM2835_RNG_USE_CALLOUT) 314 callout_reset(&sc->sc_rngto, sc->sc_rnghz, bcm2835_rng_harvest, sc); 315#endif 316} 317 318static int 319sysctl_bcm2835_rng_2xspeed(SYSCTL_HANDLER_ARGS) 320{ 321 struct bcm2835_rng_softc *sc = arg1; 322 int error, rbg2x; 323 324 rbg2x = sc->sc_rbg2x; 325 error = sysctl_handle_int(oidp, &rbg2x, 0, req); 326 if (error) 327 return (error); 328 if (req->newptr == NULL) 329 return (error); 330 if (rbg2x == sc->sc_rbg2x) 331 return (0); 332 333 /* Reset the RNG */ 334 bcm2835_rng_stop(sc); 335 sc->sc_rbg2x = rbg2x; 336 bcm2835_rng_start(sc); 337 338 return (0); 339} 340 341#ifdef BCM2835_RNG_DEBUG_REGISTERS 342static int 343sysctl_bcm2835_rng_dump(SYSCTL_HANDLER_ARGS) 344{ 345 struct sbuf sb; 346 struct bcm2835_rng_softc *sc = arg1; 347 int error; 348 349 error = sysctl_wire_old_buffer(req, 0); 350 if (error != 0) 351 return (error); 352 sbuf_new_for_sysctl(&sb, NULL, 128, req); 353 bcm2835_rng_dump_registers(sc, &sb); 354 error = sbuf_finish(&sb); 355 sbuf_delete(&sb); 356 return (error); 357} 358#endif 359 360static int 361bcm2835_rng_probe(device_t dev) 362{ 363 364 if (!ofw_bus_status_okay(dev)) 365 return (ENXIO); 366 367 if (!ofw_bus_is_compatible(dev, "broadcom,bcm2835-rng")) 368 return (ENXIO); 369 370 device_set_desc(dev, "Broadcom BCM2835 RNG"); 371 372 return (BUS_PROBE_DEFAULT); 373} 374 375static int 376bcm2835_rng_attach(device_t dev) 377{ 378 struct bcm2835_rng_softc *sc; 379 struct sysctl_ctx_list *sysctl_ctx; 380 struct sysctl_oid *sysctl_tree; 381 int error, rid; 382 383 error = 0; 384 sc = device_get_softc(dev); 385 sc->sc_dev = dev; 386 sc->sc_stall_count = RNG_STALL_COUNT_DEFAULT; 387#ifdef BCM2835_RNG_USE_CALLOUT 388 /* Initialize callout */ 389 callout_init(&sc->sc_rngto, CALLOUT_MPSAFE); 390#endif 391 TUNABLE_INT_FETCH("bcmrng.2xspeed", &sc->sc_rbg2x); 392 TUNABLE_INT_FETCH("bcmrng.stall_count", &sc->sc_stall_count); 393 394 /* Allocate memory resources */ 395 rid = 0; 396 sc->sc_mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid, 397 RF_ACTIVE); 398 if (sc->sc_mem_res == NULL) { 399 bcm2835_rng_detach(dev); 400 return (ENXIO); 401 } 402 403#if defined(BCM2835_RNG_USE_INTERRUPT) 404 /* Allocate interrupt resource */ 405 rid = 0; 406 sc->sc_irq_res = bus_alloc_resource_any(dev, SYS_RES_IRQ, &rid, 407 RF_SHAREABLE | RF_ACTIVE); 408 if (sc->sc_irq_res == NULL) { 409 bcm2835_rng_detach(dev); 410 return (ENXIO); 411 } 412 413 /* Set up the interrupt handler */ 414 error = bus_setup_intr(dev, sc->sc_irq_res, INTR_TYPE_BIO | INTR_MPSAFE, 415 NULL, (driver_intr_t *)bcm2835_rng_harvest, sc, &sc->sc_intr_hdl); 416 if (error) { 417 device_printf(dev, "Failed to set up IRQ\n"); 418 sc->sc_intr_hdl = NULL; 419 bcm2835_rng_detach(dev); 420 return (error); 421 } 422#endif 423 424 /* Start the RNG */ 425 bcm2835_rng_start(sc); 426 427 /* Dump the registers if booting verbose */ 428 if (bootverbose) { 429 struct sbuf sb; 430 431 (void) sbuf_new(&sb, NULL, 256, 432 SBUF_AUTOEXTEND | SBUF_INCLUDENUL); 433 bcm2835_rng_dump_registers(sc, &sb); 434 sbuf_trim(&sb); 435 error = sbuf_finish(&sb); 436 if (error == 0) 437 device_printf(dev, "%s", sbuf_data(&sb)); 438 sbuf_delete(&sb); 439 } 440 441 sysctl_ctx = device_get_sysctl_ctx(dev); 442 sysctl_tree = device_get_sysctl_tree(dev); 443 SYSCTL_ADD_LONG(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, 444 "underrun", CTLFLAG_RD, &sc->sc_underrun, 445 "Number of FIFO underruns"); 446 SYSCTL_ADD_PROC(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, 447 "2xspeed", CTLTYPE_INT | CTLFLAG_RW, sc, 0, 448 sysctl_bcm2835_rng_2xspeed, "I", "Enable RBG 2X SPEED"); 449 SYSCTL_ADD_INT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, 450 "stall_count", CTLFLAG_RW, &sc->sc_stall_count, 451 RNG_STALL_COUNT_DEFAULT, "Number of underruns to assume RNG stall"); 452#ifdef BCM2835_RNG_DEBUG_REGISTERS 453 SYSCTL_ADD_PROC(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, 454 "dumpregs", CTLTYPE_STRING | CTLFLAG_RD, sc, 0, 455 sysctl_bcm2835_rng_dump, "S", "Dump RNG registers"); 456#endif 457 458#if defined(BCM2835_RNG_USE_CALLOUT) 459 /* Reset callout */ 460 if (hz >= 100) 461 sc->sc_rnghz = hz / 100; 462 else 463 sc->sc_rnghz = 1; 464 callout_reset(&sc->sc_rngto, sc->sc_rnghz, bcm2835_rng_harvest, sc); 465#endif 466 467 return (0); 468} 469 470static int 471bcm2835_rng_detach(device_t dev) 472{ 473 struct bcm2835_rng_softc *sc; 474#if defined(BCM2835_RNG_USE_INTERRUPT) 475 int error; 476#endif 477 478 sc = device_get_softc(dev); 479 480 /* Stop the RNG */ 481 bcm2835_rng_stop(sc); 482 483 /* Drain the callout it */ 484#if defined(BCM2835_RNG_USE_CALLOUT) 485 callout_drain(&sc->sc_rngto); 486#endif 487 488#if defined(BCM2835_RNG_USE_INTERRUPT) 489 /* Tear down the interrupt */ 490 if (sc->sc_irq_res && sc->sc_intr_hdl) { 491 error = bus_teardown_intr(dev, sc->sc_irq_res, sc->sc_intr_hdl); 492 if (error != 0) { 493 device_printf(dev, "could not tear down IRQ\n"); 494 return (error); 495 } 496 sc->sc_intr_hdl = NULL; 497 } 498 499 /* Release interrupt resource */ 500 if (sc->sc_irq_res) { 501 bus_release_resource(dev, SYS_RES_IRQ, 0, sc->sc_irq_res); 502 sc->sc_irq_res = NULL; 503 } 504#endif 505 506 /* Release memory resource */ 507 if (sc->sc_mem_res != NULL) 508 bus_release_resource(dev, SYS_RES_MEMORY, 0, sc->sc_mem_res); 509 510 return (0); 511} 512 513static device_method_t bcm2835_rng_methods[] = { 514 /* Device interface */ 515 DEVMETHOD(device_probe, bcm2835_rng_probe), 516 DEVMETHOD(device_attach, bcm2835_rng_attach), 517 DEVMETHOD(device_detach, bcm2835_rng_detach), 518 519 DEVMETHOD_END 520}; 521 522static driver_t bcm2835_rng_driver = { 523 "bcmrng", 524 bcm2835_rng_methods, 525 sizeof(struct bcm2835_rng_softc) 526}; 527static devclass_t bcm2835_rng_devclass; 528 529DRIVER_MODULE(bcm2835_rng, simplebus, bcm2835_rng_driver, 530 bcm2835_rng_devclass, 0, 0); 531DRIVER_MODULE(bcm2835_rng, ofwbus, bcm2835_rng_driver, bcm2835_rng_devclass, 0, 532 0); 533MODULE_VERSION(bcm2835_rng, 1); 534MODULE_DEPEND(bcm2835_rng, randomdev, 1, 1, 1); 535