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 static int at91_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled) 220 { 221 struct sam9_rtc *rtc = dev_get_drvdata(dev); 222 u32 mr = rtt_readl(rtc, MR); 223 224 dev_dbg(dev, "alarm_irq_enable: enabled=%08x, mr %08x\n", enabled, mr); 225 if (enabled) 226 rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN); 227 else 228 rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN); 229 return 0; 230 } 231 232 /* 233 * Provide additional RTC information in /proc/driver/rtc 234 */ 235 static int at91_rtc_proc(struct device *dev, struct seq_file *seq) 236 { 237 struct sam9_rtc *rtc = dev_get_drvdata(dev); 238 u32 mr = mr = rtt_readl(rtc, MR); 239 240 seq_printf(seq, "update_IRQ\t: %s\n", 241 (mr & AT91_RTT_RTTINCIEN) ? "yes" : "no"); 242 return 0; 243 } 244 245 /* 246 * IRQ handler for the RTC 247 */ 248 static irqreturn_t at91_rtc_interrupt(int irq, void *_rtc) 249 { 250 struct sam9_rtc *rtc = _rtc; 251 u32 sr, mr; 252 unsigned long events = 0; 253 254 /* Shared interrupt may be for another device. Note: reading 255 * SR clears it, so we must only read it in this irq handler! 256 */ 257 mr = rtt_readl(rtc, MR) & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); 258 sr = rtt_readl(rtc, SR) & (mr >> 16); 259 if (!sr) 260 return IRQ_NONE; 261 262 /* alarm status */ 263 if (sr & AT91_RTT_ALMS) 264 events |= (RTC_AF | RTC_IRQF); 265 266 /* timer update/increment */ 267 if (sr & AT91_RTT_RTTINC) 268 events |= (RTC_UF | RTC_IRQF); 269 270 rtc_update_irq(rtc->rtcdev, 1, events); 271 272 pr_debug("%s: num=%ld, events=0x%02lx\n", __func__, 273 events >> 8, events & 0x000000FF); 274 275 return IRQ_HANDLED; 276 } 277 278 static const struct rtc_class_ops at91_rtc_ops = { 279 .read_time = at91_rtc_readtime, 280 .set_time = at91_rtc_settime, 281 .read_alarm = at91_rtc_readalarm, 282 .set_alarm = at91_rtc_setalarm, 283 .proc = at91_rtc_proc, 284 .alarm_irq_enable = at91_rtc_alarm_irq_enable, 285 }; 286 287 /* 288 * Initialize and install RTC driver 289 */ 290 static int __init at91_rtc_probe(struct platform_device *pdev) 291 { 292 struct resource *r; 293 struct sam9_rtc *rtc; 294 int ret; 295 u32 mr; 296 297 r = platform_get_resource(pdev, IORESOURCE_MEM, 0); 298 if (!r) 299 return -ENODEV; 300 301 rtc = kzalloc(sizeof *rtc, GFP_KERNEL); 302 if (!rtc) 303 return -ENOMEM; 304 305 /* platform setup code should have handled this; sigh */ 306 if (!device_can_wakeup(&pdev->dev)) 307 device_init_wakeup(&pdev->dev, 1); 308 309 platform_set_drvdata(pdev, rtc); 310 rtc->rtt = ioremap(r->start, resource_size(r)); 311 if (!rtc->rtt) { 312 dev_err(&pdev->dev, "failed to map registers, aborting.\n"); 313 ret = -ENOMEM; 314 goto fail; 315 } 316 317 mr = rtt_readl(rtc, MR); 318 319 /* unless RTT is counting at 1 Hz, re-initialize it */ 320 if ((mr & AT91_RTT_RTPRES) != AT91_SLOW_CLOCK) { 321 mr = AT91_RTT_RTTRST | (AT91_SLOW_CLOCK & AT91_RTT_RTPRES); 322 gpbr_writel(rtc, 0); 323 } 324 325 /* disable all interrupts (same as on shutdown path) */ 326 mr &= ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); 327 rtt_writel(rtc, MR, mr); 328 329 rtc->rtcdev = rtc_device_register(pdev->name, &pdev->dev, 330 &at91_rtc_ops, THIS_MODULE); 331 if (IS_ERR(rtc->rtcdev)) { 332 ret = PTR_ERR(rtc->rtcdev); 333 goto fail_register; 334 } 335 336 /* register irq handler after we know what name we'll use */ 337 ret = request_irq(AT91_ID_SYS, at91_rtc_interrupt, 338 IRQF_DISABLED | IRQF_SHARED, 339 dev_name(&rtc->rtcdev->dev), rtc); 340 if (ret) { 341 dev_dbg(&pdev->dev, "can't share IRQ %d?\n", AT91_ID_SYS); 342 rtc_device_unregister(rtc->rtcdev); 343 goto fail; 344 } 345 346 /* NOTE: sam9260 rev A silicon has a ROM bug which resets the 347 * RTT on at least some reboots. If you have that chip, you must 348 * initialize the time from some external source like a GPS, wall 349 * clock, discrete RTC, etc 350 */ 351 352 if (gpbr_readl(rtc) == 0) 353 dev_warn(&pdev->dev, "%s: SET TIME!\n", 354 dev_name(&rtc->rtcdev->dev)); 355 356 return 0; 357 358 fail_register: 359 iounmap(rtc->rtt); 360 fail: 361 platform_set_drvdata(pdev, NULL); 362 kfree(rtc); 363 return ret; 364 } 365 366 /* 367 * Disable and remove the RTC driver 368 */ 369 static int __exit at91_rtc_remove(struct platform_device *pdev) 370 { 371 struct sam9_rtc *rtc = platform_get_drvdata(pdev); 372 u32 mr = rtt_readl(rtc, MR); 373 374 /* disable all interrupts */ 375 rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN)); 376 free_irq(AT91_ID_SYS, rtc); 377 378 rtc_device_unregister(rtc->rtcdev); 379 380 iounmap(rtc->rtt); 381 platform_set_drvdata(pdev, NULL); 382 kfree(rtc); 383 return 0; 384 } 385 386 static void at91_rtc_shutdown(struct platform_device *pdev) 387 { 388 struct sam9_rtc *rtc = platform_get_drvdata(pdev); 389 u32 mr = rtt_readl(rtc, MR); 390 391 rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); 392 rtt_writel(rtc, MR, mr & ~rtc->imr); 393 } 394 395 #ifdef CONFIG_PM 396 397 /* AT91SAM9 RTC Power management control */ 398 399 static int at91_rtc_suspend(struct platform_device *pdev, 400 pm_message_t state) 401 { 402 struct sam9_rtc *rtc = platform_get_drvdata(pdev); 403 u32 mr = rtt_readl(rtc, MR); 404 405 /* 406 * This IRQ is shared with DBGU and other hardware which isn't 407 * necessarily a wakeup event source. 408 */ 409 rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); 410 if (rtc->imr) { 411 if (device_may_wakeup(&pdev->dev) && (mr & AT91_RTT_ALMIEN)) { 412 enable_irq_wake(AT91_ID_SYS); 413 /* don't let RTTINC cause wakeups */ 414 if (mr & AT91_RTT_RTTINCIEN) 415 rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN); 416 } else 417 rtt_writel(rtc, MR, mr & ~rtc->imr); 418 } 419 420 return 0; 421 } 422 423 static int at91_rtc_resume(struct platform_device *pdev) 424 { 425 struct sam9_rtc *rtc = platform_get_drvdata(pdev); 426 u32 mr; 427 428 if (rtc->imr) { 429 if (device_may_wakeup(&pdev->dev)) 430 disable_irq_wake(AT91_ID_SYS); 431 mr = rtt_readl(rtc, MR); 432 rtt_writel(rtc, MR, mr | rtc->imr); 433 } 434 435 return 0; 436 } 437 #else 438 #define at91_rtc_suspend NULL 439 #define at91_rtc_resume NULL 440 #endif 441 442 static struct platform_driver at91_rtc_driver = { 443 .driver.name = "rtc-at91sam9", 444 .driver.owner = THIS_MODULE, 445 .remove = __exit_p(at91_rtc_remove), 446 .shutdown = at91_rtc_shutdown, 447 .suspend = at91_rtc_suspend, 448 .resume = at91_rtc_resume, 449 }; 450 451 /* Chips can have more than one RTT module, and they can be used for more 452 * than just RTCs. So we can't just register as "the" RTT driver. 453 * 454 * A normal approach in such cases is to create a library to allocate and 455 * free the modules. Here we just use bus_find_device() as like such a 456 * library, binding directly ... no runtime "library" footprint is needed. 457 */ 458 static int __init at91_rtc_match(struct device *dev, void *v) 459 { 460 struct platform_device *pdev = to_platform_device(dev); 461 int ret; 462 463 /* continue searching if this isn't the RTT we need */ 464 if (strcmp("at91_rtt", pdev->name) != 0 465 || pdev->id != CONFIG_RTC_DRV_AT91SAM9_RTT) 466 goto fail; 467 468 /* else we found it ... but fail unless we can bind to the RTC driver */ 469 if (dev->driver) { 470 dev_dbg(dev, "busy, can't use as RTC!\n"); 471 goto fail; 472 } 473 dev->driver = &at91_rtc_driver.driver; 474 if (device_attach(dev) == 0) { 475 dev_dbg(dev, "can't attach RTC!\n"); 476 goto fail; 477 } 478 ret = at91_rtc_probe(pdev); 479 if (ret == 0) 480 return true; 481 482 dev_dbg(dev, "RTC probe err %d!\n", ret); 483 fail: 484 return false; 485 } 486 487 static int __init at91_rtc_init(void) 488 { 489 int status; 490 struct device *rtc; 491 492 status = platform_driver_register(&at91_rtc_driver); 493 if (status) 494 return status; 495 rtc = bus_find_device(&platform_bus_type, NULL, 496 NULL, at91_rtc_match); 497 if (!rtc) 498 platform_driver_unregister(&at91_rtc_driver); 499 return rtc ? 0 : -ENODEV; 500 } 501 module_init(at91_rtc_init); 502 503 static void __exit at91_rtc_exit(void) 504 { 505 platform_driver_unregister(&at91_rtc_driver); 506 } 507 module_exit(at91_rtc_exit); 508 509 510 MODULE_AUTHOR("Michel Benoit"); 511 MODULE_DESCRIPTION("RTC driver for Atmel AT91SAM9x"); 512 MODULE_LICENSE("GPL"); 513