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