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 #include <linux/platform_data/atmel.h> 23 #include <linux/io.h> 24 25 #include <mach/at91_rtt.h> 26 #include <mach/cpu.h> 27 #include <mach/hardware.h> 28 29 /* 30 * This driver uses two configurable hardware resources that live in the 31 * AT91SAM9 backup power domain (intended to be powered at all times) 32 * to implement the Real Time Clock interfaces 33 * 34 * - A "Real-time Timer" (RTT) counts up in seconds from a base time. 35 * We can't assign the counter value (CRTV) ... but we can reset it. 36 * 37 * - One of the "General Purpose Backup Registers" (GPBRs) holds the 38 * base time, normally an offset from the beginning of the POSIX 39 * epoch (1970-Jan-1 00:00:00 UTC). Some systems also include the 40 * local timezone's offset. 41 * 42 * The RTC's value is the RTT counter plus that offset. The RTC's alarm 43 * is likewise a base (ALMV) plus that offset. 44 * 45 * Not all RTTs will be used as RTCs; some systems have multiple RTTs to 46 * choose from, or a "real" RTC module. All systems have multiple GPBR 47 * registers available, likewise usable for more than "RTC" support. 48 */ 49 50 /* 51 * We store ALARM_DISABLED in ALMV to record that no alarm is set. 52 * It's also the reset value for that field. 53 */ 54 #define ALARM_DISABLED ((u32)~0) 55 56 57 struct sam9_rtc { 58 void __iomem *rtt; 59 struct rtc_device *rtcdev; 60 u32 imr; 61 void __iomem *gpbr; 62 int irq; 63 }; 64 65 #define rtt_readl(rtc, field) \ 66 __raw_readl((rtc)->rtt + AT91_RTT_ ## field) 67 #define rtt_writel(rtc, field, val) \ 68 __raw_writel((val), (rtc)->rtt + AT91_RTT_ ## field) 69 70 #define gpbr_readl(rtc) \ 71 __raw_readl((rtc)->gpbr) 72 #define gpbr_writel(rtc, val) \ 73 __raw_writel((val), (rtc)->gpbr) 74 75 /* 76 * Read current time and date in RTC 77 */ 78 static int at91_rtc_readtime(struct device *dev, struct rtc_time *tm) 79 { 80 struct sam9_rtc *rtc = dev_get_drvdata(dev); 81 u32 secs, secs2; 82 u32 offset; 83 84 /* read current time offset */ 85 offset = gpbr_readl(rtc); 86 if (offset == 0) 87 return -EILSEQ; 88 89 /* reread the counter to help sync the two clock domains */ 90 secs = rtt_readl(rtc, VR); 91 secs2 = rtt_readl(rtc, VR); 92 if (secs != secs2) 93 secs = rtt_readl(rtc, VR); 94 95 rtc_time_to_tm(offset + secs, tm); 96 97 dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readtime", 98 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday, 99 tm->tm_hour, tm->tm_min, tm->tm_sec); 100 101 return 0; 102 } 103 104 /* 105 * Set current time and date in RTC 106 */ 107 static int at91_rtc_settime(struct device *dev, struct rtc_time *tm) 108 { 109 struct sam9_rtc *rtc = dev_get_drvdata(dev); 110 int err; 111 u32 offset, alarm, mr; 112 unsigned long secs; 113 114 dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "settime", 115 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday, 116 tm->tm_hour, tm->tm_min, tm->tm_sec); 117 118 err = rtc_tm_to_time(tm, &secs); 119 if (err != 0) 120 return err; 121 122 mr = rtt_readl(rtc, MR); 123 124 /* disable interrupts */ 125 rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN)); 126 127 /* read current time offset */ 128 offset = gpbr_readl(rtc); 129 130 /* store the new base time in a battery backup register */ 131 secs += 1; 132 gpbr_writel(rtc, secs); 133 134 /* adjust the alarm time for the new base */ 135 alarm = rtt_readl(rtc, AR); 136 if (alarm != ALARM_DISABLED) { 137 if (offset > secs) { 138 /* time jumped backwards, increase time until alarm */ 139 alarm += (offset - secs); 140 } else if ((alarm + offset) > secs) { 141 /* time jumped forwards, decrease time until alarm */ 142 alarm -= (secs - offset); 143 } else { 144 /* time jumped past the alarm, disable alarm */ 145 alarm = ALARM_DISABLED; 146 mr &= ~AT91_RTT_ALMIEN; 147 } 148 rtt_writel(rtc, AR, alarm); 149 } 150 151 /* reset the timer, and re-enable interrupts */ 152 rtt_writel(rtc, MR, mr | AT91_RTT_RTTRST); 153 154 return 0; 155 } 156 157 static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm) 158 { 159 struct sam9_rtc *rtc = dev_get_drvdata(dev); 160 struct rtc_time *tm = &alrm->time; 161 u32 alarm = rtt_readl(rtc, AR); 162 u32 offset; 163 164 offset = gpbr_readl(rtc); 165 if (offset == 0) 166 return -EILSEQ; 167 168 memset(alrm, 0, sizeof(*alrm)); 169 if (alarm != ALARM_DISABLED && offset != 0) { 170 rtc_time_to_tm(offset + alarm, tm); 171 172 dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readalarm", 173 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday, 174 tm->tm_hour, tm->tm_min, tm->tm_sec); 175 176 if (rtt_readl(rtc, MR) & AT91_RTT_ALMIEN) 177 alrm->enabled = 1; 178 } 179 180 return 0; 181 } 182 183 static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm) 184 { 185 struct sam9_rtc *rtc = dev_get_drvdata(dev); 186 struct rtc_time *tm = &alrm->time; 187 unsigned long secs; 188 u32 offset; 189 u32 mr; 190 int err; 191 192 err = rtc_tm_to_time(tm, &secs); 193 if (err != 0) 194 return err; 195 196 offset = gpbr_readl(rtc); 197 if (offset == 0) { 198 /* time is not set */ 199 return -EILSEQ; 200 } 201 mr = rtt_readl(rtc, MR); 202 rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN); 203 204 /* alarm in the past? finish and leave disabled */ 205 if (secs <= offset) { 206 rtt_writel(rtc, AR, ALARM_DISABLED); 207 return 0; 208 } 209 210 /* else set alarm and maybe enable it */ 211 rtt_writel(rtc, AR, secs - offset); 212 if (alrm->enabled) 213 rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN); 214 215 dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "setalarm", 216 tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, 217 tm->tm_min, tm->tm_sec); 218 219 return 0; 220 } 221 222 static int at91_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled) 223 { 224 struct sam9_rtc *rtc = dev_get_drvdata(dev); 225 u32 mr = rtt_readl(rtc, MR); 226 227 dev_dbg(dev, "alarm_irq_enable: enabled=%08x, mr %08x\n", enabled, mr); 228 if (enabled) 229 rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN); 230 else 231 rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN); 232 return 0; 233 } 234 235 /* 236 * Provide additional RTC information in /proc/driver/rtc 237 */ 238 static int at91_rtc_proc(struct device *dev, struct seq_file *seq) 239 { 240 struct sam9_rtc *rtc = dev_get_drvdata(dev); 241 u32 mr = mr = rtt_readl(rtc, MR); 242 243 seq_printf(seq, "update_IRQ\t: %s\n", 244 (mr & AT91_RTT_RTTINCIEN) ? "yes" : "no"); 245 return 0; 246 } 247 248 /* 249 * IRQ handler for the RTC 250 */ 251 static irqreturn_t at91_rtc_interrupt(int irq, void *_rtc) 252 { 253 struct sam9_rtc *rtc = _rtc; 254 u32 sr, mr; 255 unsigned long events = 0; 256 257 /* Shared interrupt may be for another device. Note: reading 258 * SR clears it, so we must only read it in this irq handler! 259 */ 260 mr = rtt_readl(rtc, MR) & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); 261 sr = rtt_readl(rtc, SR) & (mr >> 16); 262 if (!sr) 263 return IRQ_NONE; 264 265 /* alarm status */ 266 if (sr & AT91_RTT_ALMS) 267 events |= (RTC_AF | RTC_IRQF); 268 269 /* timer update/increment */ 270 if (sr & AT91_RTT_RTTINC) 271 events |= (RTC_UF | RTC_IRQF); 272 273 rtc_update_irq(rtc->rtcdev, 1, events); 274 275 pr_debug("%s: num=%ld, events=0x%02lx\n", __func__, 276 events >> 8, events & 0x000000FF); 277 278 return IRQ_HANDLED; 279 } 280 281 static const struct rtc_class_ops at91_rtc_ops = { 282 .read_time = at91_rtc_readtime, 283 .set_time = at91_rtc_settime, 284 .read_alarm = at91_rtc_readalarm, 285 .set_alarm = at91_rtc_setalarm, 286 .proc = at91_rtc_proc, 287 .alarm_irq_enable = at91_rtc_alarm_irq_enable, 288 }; 289 290 /* 291 * Initialize and install RTC driver 292 */ 293 static int at91_rtc_probe(struct platform_device *pdev) 294 { 295 struct resource *r, *r_gpbr; 296 struct sam9_rtc *rtc; 297 int ret, irq; 298 u32 mr; 299 300 r = platform_get_resource(pdev, IORESOURCE_MEM, 0); 301 r_gpbr = platform_get_resource(pdev, IORESOURCE_MEM, 1); 302 if (!r || !r_gpbr) { 303 dev_err(&pdev->dev, "need 2 ressources\n"); 304 return -ENODEV; 305 } 306 307 irq = platform_get_irq(pdev, 0); 308 if (irq < 0) { 309 dev_err(&pdev->dev, "failed to get interrupt resource\n"); 310 return irq; 311 } 312 313 rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL); 314 if (!rtc) 315 return -ENOMEM; 316 317 rtc->irq = irq; 318 319 /* platform setup code should have handled this; sigh */ 320 if (!device_can_wakeup(&pdev->dev)) 321 device_init_wakeup(&pdev->dev, 1); 322 323 platform_set_drvdata(pdev, rtc); 324 rtc->rtt = devm_ioremap(&pdev->dev, r->start, resource_size(r)); 325 if (!rtc->rtt) { 326 dev_err(&pdev->dev, "failed to map registers, aborting.\n"); 327 return -ENOMEM; 328 } 329 330 rtc->gpbr = devm_ioremap(&pdev->dev, r_gpbr->start, 331 resource_size(r_gpbr)); 332 if (!rtc->gpbr) { 333 dev_err(&pdev->dev, "failed to map gpbr registers, aborting.\n"); 334 return -ENOMEM; 335 } 336 337 mr = rtt_readl(rtc, MR); 338 339 /* unless RTT is counting at 1 Hz, re-initialize it */ 340 if ((mr & AT91_RTT_RTPRES) != AT91_SLOW_CLOCK) { 341 mr = AT91_RTT_RTTRST | (AT91_SLOW_CLOCK & AT91_RTT_RTPRES); 342 gpbr_writel(rtc, 0); 343 } 344 345 /* disable all interrupts (same as on shutdown path) */ 346 mr &= ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); 347 rtt_writel(rtc, MR, mr); 348 349 rtc->rtcdev = devm_rtc_device_register(&pdev->dev, pdev->name, 350 &at91_rtc_ops, THIS_MODULE); 351 if (IS_ERR(rtc->rtcdev)) 352 return PTR_ERR(rtc->rtcdev); 353 354 /* register irq handler after we know what name we'll use */ 355 ret = devm_request_irq(&pdev->dev, rtc->irq, at91_rtc_interrupt, 356 IRQF_SHARED, dev_name(&rtc->rtcdev->dev), rtc); 357 if (ret) { 358 dev_dbg(&pdev->dev, "can't share IRQ %d?\n", rtc->irq); 359 return ret; 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 } 374 375 /* 376 * Disable and remove the RTC driver 377 */ 378 static int at91_rtc_remove(struct platform_device *pdev) 379 { 380 struct sam9_rtc *rtc = platform_get_drvdata(pdev); 381 u32 mr = rtt_readl(rtc, MR); 382 383 /* disable all interrupts */ 384 rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN)); 385 386 return 0; 387 } 388 389 static void at91_rtc_shutdown(struct platform_device *pdev) 390 { 391 struct sam9_rtc *rtc = platform_get_drvdata(pdev); 392 u32 mr = rtt_readl(rtc, MR); 393 394 rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); 395 rtt_writel(rtc, MR, mr & ~rtc->imr); 396 } 397 398 #ifdef CONFIG_PM_SLEEP 399 400 /* AT91SAM9 RTC Power management control */ 401 402 static int at91_rtc_suspend(struct device *dev) 403 { 404 struct sam9_rtc *rtc = dev_get_drvdata(dev); 405 u32 mr = rtt_readl(rtc, MR); 406 407 /* 408 * This IRQ is shared with DBGU and other hardware which isn't 409 * necessarily a wakeup event source. 410 */ 411 rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); 412 if (rtc->imr) { 413 if (device_may_wakeup(dev) && (mr & AT91_RTT_ALMIEN)) { 414 enable_irq_wake(rtc->irq); 415 /* don't let RTTINC cause wakeups */ 416 if (mr & AT91_RTT_RTTINCIEN) 417 rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN); 418 } else 419 rtt_writel(rtc, MR, mr & ~rtc->imr); 420 } 421 422 return 0; 423 } 424 425 static int at91_rtc_resume(struct device *dev) 426 { 427 struct sam9_rtc *rtc = dev_get_drvdata(dev); 428 u32 mr; 429 430 if (rtc->imr) { 431 if (device_may_wakeup(dev)) 432 disable_irq_wake(rtc->irq); 433 mr = rtt_readl(rtc, MR); 434 rtt_writel(rtc, MR, mr | rtc->imr); 435 } 436 437 return 0; 438 } 439 #endif 440 441 static SIMPLE_DEV_PM_OPS(at91_rtc_pm_ops, at91_rtc_suspend, at91_rtc_resume); 442 443 static struct platform_driver at91_rtc_driver = { 444 .probe = at91_rtc_probe, 445 .remove = at91_rtc_remove, 446 .shutdown = at91_rtc_shutdown, 447 .driver = { 448 .name = "rtc-at91sam9", 449 .owner = THIS_MODULE, 450 .pm = &at91_rtc_pm_ops, 451 }, 452 }; 453 454 module_platform_driver(at91_rtc_driver); 455 456 MODULE_AUTHOR("Michel Benoit"); 457 MODULE_DESCRIPTION("RTC driver for Atmel AT91SAM9x"); 458 MODULE_LICENSE("GPL"); 459