1 /* 2 * "RTT as Real Time Clock" driver for AT91SAM9 SoC family 3 * 4 * (C) 2007 Michel Benoit 5 * 6 * Based on rtc-at91rm9200.c by Rick Bronson 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU General Public License 10 * as published by the Free Software Foundation; either version 11 * 2 of the License, or (at your option) any later version. 12 */ 13 14 #include <linux/module.h> 15 #include <linux/kernel.h> 16 #include <linux/platform_device.h> 17 #include <linux/time.h> 18 #include <linux/rtc.h> 19 #include <linux/interrupt.h> 20 #include <linux/ioctl.h> 21 #include <linux/slab.h> 22 23 #include <mach/board.h> 24 #include <mach/at91_rtt.h> 25 #include <mach/cpu.h> 26 27 28 /* 29 * This driver uses two configurable hardware resources that live in the 30 * AT91SAM9 backup power domain (intended to be powered at all times) 31 * to implement the Real Time Clock interfaces 32 * 33 * - A "Real-time Timer" (RTT) counts up in seconds from a base time. 34 * We can't assign the counter value (CRTV) ... but we can reset it. 35 * 36 * - One of the "General Purpose Backup Registers" (GPBRs) holds the 37 * base time, normally an offset from the beginning of the POSIX 38 * epoch (1970-Jan-1 00:00:00 UTC). Some systems also include the 39 * local timezone's offset. 40 * 41 * The RTC's value is the RTT counter plus that offset. The RTC's alarm 42 * is likewise a base (ALMV) plus that offset. 43 * 44 * Not all RTTs will be used as RTCs; some systems have multiple RTTs to 45 * choose from, or a "real" RTC module. All systems have multiple GPBR 46 * registers available, likewise usable for more than "RTC" support. 47 */ 48 49 /* 50 * We store ALARM_DISABLED in ALMV to record that no alarm is set. 51 * It's also the reset value for that field. 52 */ 53 #define ALARM_DISABLED ((u32)~0) 54 55 56 struct sam9_rtc { 57 void __iomem *rtt; 58 struct rtc_device *rtcdev; 59 u32 imr; 60 }; 61 62 #define rtt_readl(rtc, field) \ 63 __raw_readl((rtc)->rtt + AT91_RTT_ ## field) 64 #define rtt_writel(rtc, field, val) \ 65 __raw_writel((val), (rtc)->rtt + AT91_RTT_ ## field) 66 67 #define gpbr_readl(rtc) \ 68 at91_sys_read(AT91_GPBR + 4 * CONFIG_RTC_DRV_AT91SAM9_GPBR) 69 #define gpbr_writel(rtc, val) \ 70 at91_sys_write(AT91_GPBR + 4 * CONFIG_RTC_DRV_AT91SAM9_GPBR, (val)) 71 72 /* 73 * Read current time and date in RTC 74 */ 75 static int at91_rtc_readtime(struct device *dev, struct rtc_time *tm) 76 { 77 struct sam9_rtc *rtc = dev_get_drvdata(dev); 78 u32 secs, secs2; 79 u32 offset; 80 81 /* read current time offset */ 82 offset = gpbr_readl(rtc); 83 if (offset == 0) 84 return -EILSEQ; 85 86 /* reread the counter to help sync the two clock domains */ 87 secs = rtt_readl(rtc, VR); 88 secs2 = rtt_readl(rtc, VR); 89 if (secs != secs2) 90 secs = rtt_readl(rtc, VR); 91 92 rtc_time_to_tm(offset + secs, tm); 93 94 dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readtime", 95 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday, 96 tm->tm_hour, tm->tm_min, tm->tm_sec); 97 98 return 0; 99 } 100 101 /* 102 * Set current time and date in RTC 103 */ 104 static int at91_rtc_settime(struct device *dev, struct rtc_time *tm) 105 { 106 struct sam9_rtc *rtc = dev_get_drvdata(dev); 107 int err; 108 u32 offset, alarm, mr; 109 unsigned long secs; 110 111 dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "settime", 112 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday, 113 tm->tm_hour, tm->tm_min, tm->tm_sec); 114 115 err = rtc_tm_to_time(tm, &secs); 116 if (err != 0) 117 return err; 118 119 mr = rtt_readl(rtc, MR); 120 121 /* disable interrupts */ 122 rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN)); 123 124 /* read current time offset */ 125 offset = gpbr_readl(rtc); 126 127 /* store the new base time in a battery backup register */ 128 secs += 1; 129 gpbr_writel(rtc, secs); 130 131 /* adjust the alarm time for the new base */ 132 alarm = rtt_readl(rtc, AR); 133 if (alarm != ALARM_DISABLED) { 134 if (offset > secs) { 135 /* time jumped backwards, increase time until alarm */ 136 alarm += (offset - secs); 137 } else if ((alarm + offset) > secs) { 138 /* time jumped forwards, decrease time until alarm */ 139 alarm -= (secs - offset); 140 } else { 141 /* time jumped past the alarm, disable alarm */ 142 alarm = ALARM_DISABLED; 143 mr &= ~AT91_RTT_ALMIEN; 144 } 145 rtt_writel(rtc, AR, alarm); 146 } 147 148 /* reset the timer, and re-enable interrupts */ 149 rtt_writel(rtc, MR, mr | AT91_RTT_RTTRST); 150 151 return 0; 152 } 153 154 static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm) 155 { 156 struct sam9_rtc *rtc = dev_get_drvdata(dev); 157 struct rtc_time *tm = &alrm->time; 158 u32 alarm = rtt_readl(rtc, AR); 159 u32 offset; 160 161 offset = gpbr_readl(rtc); 162 if (offset == 0) 163 return -EILSEQ; 164 165 memset(alrm, 0, sizeof(*alrm)); 166 if (alarm != ALARM_DISABLED && offset != 0) { 167 rtc_time_to_tm(offset + alarm, tm); 168 169 dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readalarm", 170 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday, 171 tm->tm_hour, tm->tm_min, tm->tm_sec); 172 173 if (rtt_readl(rtc, MR) & AT91_RTT_ALMIEN) 174 alrm->enabled = 1; 175 } 176 177 return 0; 178 } 179 180 static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm) 181 { 182 struct sam9_rtc *rtc = dev_get_drvdata(dev); 183 struct rtc_time *tm = &alrm->time; 184 unsigned long secs; 185 u32 offset; 186 u32 mr; 187 int err; 188 189 err = rtc_tm_to_time(tm, &secs); 190 if (err != 0) 191 return err; 192 193 offset = gpbr_readl(rtc); 194 if (offset == 0) { 195 /* time is not set */ 196 return -EILSEQ; 197 } 198 mr = rtt_readl(rtc, MR); 199 rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN); 200 201 /* alarm in the past? finish and leave disabled */ 202 if (secs <= offset) { 203 rtt_writel(rtc, AR, ALARM_DISABLED); 204 return 0; 205 } 206 207 /* else set alarm and maybe enable it */ 208 rtt_writel(rtc, AR, secs - offset); 209 if (alrm->enabled) 210 rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN); 211 212 dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "setalarm", 213 tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, 214 tm->tm_min, tm->tm_sec); 215 216 return 0; 217 } 218 219 /* 220 * Handle commands from user-space 221 */ 222 static int at91_rtc_ioctl(struct device *dev, unsigned int cmd, 223 unsigned long arg) 224 { 225 struct sam9_rtc *rtc = dev_get_drvdata(dev); 226 int ret = 0; 227 u32 mr = rtt_readl(rtc, MR); 228 229 dev_dbg(dev, "ioctl: cmd=%08x, arg=%08lx, mr %08x\n", cmd, arg, mr); 230 231 switch (cmd) { 232 case RTC_AIE_OFF: /* alarm off */ 233 rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN); 234 break; 235 case RTC_AIE_ON: /* alarm on */ 236 rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN); 237 break; 238 case RTC_UIE_OFF: /* update off */ 239 rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN); 240 break; 241 case RTC_UIE_ON: /* update on */ 242 rtt_writel(rtc, MR, mr | AT91_RTT_RTTINCIEN); 243 break; 244 default: 245 ret = -ENOIOCTLCMD; 246 break; 247 } 248 249 return ret; 250 } 251 252 /* 253 * Provide additional RTC information in /proc/driver/rtc 254 */ 255 static int at91_rtc_proc(struct device *dev, struct seq_file *seq) 256 { 257 struct sam9_rtc *rtc = dev_get_drvdata(dev); 258 u32 mr = mr = rtt_readl(rtc, MR); 259 260 seq_printf(seq, "update_IRQ\t: %s\n", 261 (mr & AT91_RTT_RTTINCIEN) ? "yes" : "no"); 262 return 0; 263 } 264 265 /* 266 * IRQ handler for the RTC 267 */ 268 static irqreturn_t at91_rtc_interrupt(int irq, void *_rtc) 269 { 270 struct sam9_rtc *rtc = _rtc; 271 u32 sr, mr; 272 unsigned long events = 0; 273 274 /* Shared interrupt may be for another device. Note: reading 275 * SR clears it, so we must only read it in this irq handler! 276 */ 277 mr = rtt_readl(rtc, MR) & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); 278 sr = rtt_readl(rtc, SR) & (mr >> 16); 279 if (!sr) 280 return IRQ_NONE; 281 282 /* alarm status */ 283 if (sr & AT91_RTT_ALMS) 284 events |= (RTC_AF | RTC_IRQF); 285 286 /* timer update/increment */ 287 if (sr & AT91_RTT_RTTINC) 288 events |= (RTC_UF | RTC_IRQF); 289 290 rtc_update_irq(rtc->rtcdev, 1, events); 291 292 pr_debug("%s: num=%ld, events=0x%02lx\n", __func__, 293 events >> 8, events & 0x000000FF); 294 295 return IRQ_HANDLED; 296 } 297 298 static const struct rtc_class_ops at91_rtc_ops = { 299 .ioctl = at91_rtc_ioctl, 300 .read_time = at91_rtc_readtime, 301 .set_time = at91_rtc_settime, 302 .read_alarm = at91_rtc_readalarm, 303 .set_alarm = at91_rtc_setalarm, 304 .proc = at91_rtc_proc, 305 }; 306 307 /* 308 * Initialize and install RTC driver 309 */ 310 static int __init at91_rtc_probe(struct platform_device *pdev) 311 { 312 struct resource *r; 313 struct sam9_rtc *rtc; 314 int ret; 315 u32 mr; 316 317 r = platform_get_resource(pdev, IORESOURCE_MEM, 0); 318 if (!r) 319 return -ENODEV; 320 321 rtc = kzalloc(sizeof *rtc, GFP_KERNEL); 322 if (!rtc) 323 return -ENOMEM; 324 325 /* platform setup code should have handled this; sigh */ 326 if (!device_can_wakeup(&pdev->dev)) 327 device_init_wakeup(&pdev->dev, 1); 328 329 platform_set_drvdata(pdev, rtc); 330 rtc->rtt = (void __force __iomem *) (AT91_VA_BASE_SYS - AT91_BASE_SYS); 331 rtc->rtt += r->start; 332 333 mr = rtt_readl(rtc, MR); 334 335 /* unless RTT is counting at 1 Hz, re-initialize it */ 336 if ((mr & AT91_RTT_RTPRES) != AT91_SLOW_CLOCK) { 337 mr = AT91_RTT_RTTRST | (AT91_SLOW_CLOCK & AT91_RTT_RTPRES); 338 gpbr_writel(rtc, 0); 339 } 340 341 /* disable all interrupts (same as on shutdown path) */ 342 mr &= ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); 343 rtt_writel(rtc, MR, mr); 344 345 rtc->rtcdev = rtc_device_register(pdev->name, &pdev->dev, 346 &at91_rtc_ops, THIS_MODULE); 347 if (IS_ERR(rtc->rtcdev)) { 348 ret = PTR_ERR(rtc->rtcdev); 349 goto fail; 350 } 351 352 /* register irq handler after we know what name we'll use */ 353 ret = request_irq(AT91_ID_SYS, at91_rtc_interrupt, 354 IRQF_DISABLED | IRQF_SHARED, 355 dev_name(&rtc->rtcdev->dev), rtc); 356 if (ret) { 357 dev_dbg(&pdev->dev, "can't share IRQ %d?\n", AT91_ID_SYS); 358 rtc_device_unregister(rtc->rtcdev); 359 goto fail; 360 } 361 362 /* NOTE: sam9260 rev A silicon has a ROM bug which resets the 363 * RTT on at least some reboots. If you have that chip, you must 364 * initialize the time from some external source like a GPS, wall 365 * clock, discrete RTC, etc 366 */ 367 368 if (gpbr_readl(rtc) == 0) 369 dev_warn(&pdev->dev, "%s: SET TIME!\n", 370 dev_name(&rtc->rtcdev->dev)); 371 372 return 0; 373 374 fail: 375 platform_set_drvdata(pdev, NULL); 376 kfree(rtc); 377 return ret; 378 } 379 380 /* 381 * Disable and remove the RTC driver 382 */ 383 static int __exit at91_rtc_remove(struct platform_device *pdev) 384 { 385 struct sam9_rtc *rtc = platform_get_drvdata(pdev); 386 u32 mr = rtt_readl(rtc, MR); 387 388 /* disable all interrupts */ 389 rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN)); 390 free_irq(AT91_ID_SYS, rtc); 391 392 rtc_device_unregister(rtc->rtcdev); 393 394 platform_set_drvdata(pdev, NULL); 395 kfree(rtc); 396 return 0; 397 } 398 399 static void at91_rtc_shutdown(struct platform_device *pdev) 400 { 401 struct sam9_rtc *rtc = platform_get_drvdata(pdev); 402 u32 mr = rtt_readl(rtc, MR); 403 404 rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); 405 rtt_writel(rtc, MR, mr & ~rtc->imr); 406 } 407 408 #ifdef CONFIG_PM 409 410 /* AT91SAM9 RTC Power management control */ 411 412 static int at91_rtc_suspend(struct platform_device *pdev, 413 pm_message_t state) 414 { 415 struct sam9_rtc *rtc = platform_get_drvdata(pdev); 416 u32 mr = rtt_readl(rtc, MR); 417 418 /* 419 * This IRQ is shared with DBGU and other hardware which isn't 420 * necessarily a wakeup event source. 421 */ 422 rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); 423 if (rtc->imr) { 424 if (device_may_wakeup(&pdev->dev) && (mr & AT91_RTT_ALMIEN)) { 425 enable_irq_wake(AT91_ID_SYS); 426 /* don't let RTTINC cause wakeups */ 427 if (mr & AT91_RTT_RTTINCIEN) 428 rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN); 429 } else 430 rtt_writel(rtc, MR, mr & ~rtc->imr); 431 } 432 433 return 0; 434 } 435 436 static int at91_rtc_resume(struct platform_device *pdev) 437 { 438 struct sam9_rtc *rtc = platform_get_drvdata(pdev); 439 u32 mr; 440 441 if (rtc->imr) { 442 if (device_may_wakeup(&pdev->dev)) 443 disable_irq_wake(AT91_ID_SYS); 444 mr = rtt_readl(rtc, MR); 445 rtt_writel(rtc, MR, mr | rtc->imr); 446 } 447 448 return 0; 449 } 450 #else 451 #define at91_rtc_suspend NULL 452 #define at91_rtc_resume NULL 453 #endif 454 455 static struct platform_driver at91_rtc_driver = { 456 .driver.name = "rtc-at91sam9", 457 .driver.owner = THIS_MODULE, 458 .remove = __exit_p(at91_rtc_remove), 459 .shutdown = at91_rtc_shutdown, 460 .suspend = at91_rtc_suspend, 461 .resume = at91_rtc_resume, 462 }; 463 464 /* Chips can have more than one RTT module, and they can be used for more 465 * than just RTCs. So we can't just register as "the" RTT driver. 466 * 467 * A normal approach in such cases is to create a library to allocate and 468 * free the modules. Here we just use bus_find_device() as like such a 469 * library, binding directly ... no runtime "library" footprint is needed. 470 */ 471 static int __init at91_rtc_match(struct device *dev, void *v) 472 { 473 struct platform_device *pdev = to_platform_device(dev); 474 int ret; 475 476 /* continue searching if this isn't the RTT we need */ 477 if (strcmp("at91_rtt", pdev->name) != 0 478 || pdev->id != CONFIG_RTC_DRV_AT91SAM9_RTT) 479 goto fail; 480 481 /* else we found it ... but fail unless we can bind to the RTC driver */ 482 if (dev->driver) { 483 dev_dbg(dev, "busy, can't use as RTC!\n"); 484 goto fail; 485 } 486 dev->driver = &at91_rtc_driver.driver; 487 if (device_attach(dev) == 0) { 488 dev_dbg(dev, "can't attach RTC!\n"); 489 goto fail; 490 } 491 ret = at91_rtc_probe(pdev); 492 if (ret == 0) 493 return true; 494 495 dev_dbg(dev, "RTC probe err %d!\n", ret); 496 fail: 497 return false; 498 } 499 500 static int __init at91_rtc_init(void) 501 { 502 int status; 503 struct device *rtc; 504 505 status = platform_driver_register(&at91_rtc_driver); 506 if (status) 507 return status; 508 rtc = bus_find_device(&platform_bus_type, NULL, 509 NULL, at91_rtc_match); 510 if (!rtc) 511 platform_driver_unregister(&at91_rtc_driver); 512 return rtc ? 0 : -ENODEV; 513 } 514 module_init(at91_rtc_init); 515 516 static void __exit at91_rtc_exit(void) 517 { 518 platform_driver_unregister(&at91_rtc_driver); 519 } 520 module_exit(at91_rtc_exit); 521 522 523 MODULE_AUTHOR("Michel Benoit"); 524 MODULE_DESCRIPTION("RTC driver for Atmel AT91SAM9x"); 525 MODULE_LICENSE("GPL"); 526