1 /* 2 * Copyright 2008-2009 Freescale Semiconductor, Inc. All Rights Reserved. 3 * Copyright 2010 Orex Computed Radiography 4 */ 5 6 /* 7 * The code contained herein is licensed under the GNU General Public 8 * License. You may obtain a copy of the GNU General Public License 9 * Version 2 or later at the following locations: 10 * 11 * http://www.opensource.org/licenses/gpl-license.html 12 * http://www.gnu.org/copyleft/gpl.html 13 */ 14 15 /* based on rtc-mc13892.c */ 16 17 /* 18 * This driver uses the 47-bit 32 kHz counter in the Freescale DryIce block 19 * to implement a Linux RTC. Times and alarms are truncated to seconds. 20 * Since the RTC framework performs API locking via rtc->ops_lock the 21 * only simultaneous accesses we need to deal with is updating DryIce 22 * registers while servicing an alarm. 23 * 24 * Note that reading the DSR (DryIce Status Register) automatically clears 25 * the WCF (Write Complete Flag). All DryIce writes are synchronized to the 26 * LP (Low Power) domain and set the WCF upon completion. Writes to the 27 * DIER (DryIce Interrupt Enable Register) are the only exception. These 28 * occur at normal bus speeds and do not set WCF. Periodic interrupts are 29 * not supported by the hardware. 30 */ 31 32 #include <linux/io.h> 33 #include <linux/clk.h> 34 #include <linux/delay.h> 35 #include <linux/module.h> 36 #include <linux/platform_device.h> 37 #include <linux/rtc.h> 38 #include <linux/sched.h> 39 #include <linux/workqueue.h> 40 41 /* DryIce Register Definitions */ 42 43 #define DTCMR 0x00 /* Time Counter MSB Reg */ 44 #define DTCLR 0x04 /* Time Counter LSB Reg */ 45 46 #define DCAMR 0x08 /* Clock Alarm MSB Reg */ 47 #define DCALR 0x0c /* Clock Alarm LSB Reg */ 48 #define DCAMR_UNSET 0xFFFFFFFF /* doomsday - 1 sec */ 49 50 #define DCR 0x10 /* Control Reg */ 51 #define DCR_TCE (1 << 3) /* Time Counter Enable */ 52 53 #define DSR 0x14 /* Status Reg */ 54 #define DSR_WBF (1 << 10) /* Write Busy Flag */ 55 #define DSR_WNF (1 << 9) /* Write Next Flag */ 56 #define DSR_WCF (1 << 8) /* Write Complete Flag */ 57 #define DSR_WEF (1 << 7) /* Write Error Flag */ 58 #define DSR_CAF (1 << 4) /* Clock Alarm Flag */ 59 #define DSR_NVF (1 << 1) /* Non-Valid Flag */ 60 #define DSR_SVF (1 << 0) /* Security Violation Flag */ 61 62 #define DIER 0x18 /* Interrupt Enable Reg */ 63 #define DIER_WNIE (1 << 9) /* Write Next Interrupt Enable */ 64 #define DIER_WCIE (1 << 8) /* Write Complete Interrupt Enable */ 65 #define DIER_WEIE (1 << 7) /* Write Error Interrupt Enable */ 66 #define DIER_CAIE (1 << 4) /* Clock Alarm Interrupt Enable */ 67 68 /** 69 * struct imxdi_dev - private imxdi rtc data 70 * @pdev: pionter to platform dev 71 * @rtc: pointer to rtc struct 72 * @ioaddr: IO registers pointer 73 * @irq: dryice normal interrupt 74 * @clk: input reference clock 75 * @dsr: copy of the DSR register 76 * @irq_lock: interrupt enable register (DIER) lock 77 * @write_wait: registers write complete queue 78 * @write_mutex: serialize registers write 79 * @work: schedule alarm work 80 */ 81 struct imxdi_dev { 82 struct platform_device *pdev; 83 struct rtc_device *rtc; 84 void __iomem *ioaddr; 85 int irq; 86 struct clk *clk; 87 u32 dsr; 88 spinlock_t irq_lock; 89 wait_queue_head_t write_wait; 90 struct mutex write_mutex; 91 struct work_struct work; 92 }; 93 94 /* 95 * enable a dryice interrupt 96 */ 97 static void di_int_enable(struct imxdi_dev *imxdi, u32 intr) 98 { 99 unsigned long flags; 100 101 spin_lock_irqsave(&imxdi->irq_lock, flags); 102 __raw_writel(__raw_readl(imxdi->ioaddr + DIER) | intr, 103 imxdi->ioaddr + DIER); 104 spin_unlock_irqrestore(&imxdi->irq_lock, flags); 105 } 106 107 /* 108 * disable a dryice interrupt 109 */ 110 static void di_int_disable(struct imxdi_dev *imxdi, u32 intr) 111 { 112 unsigned long flags; 113 114 spin_lock_irqsave(&imxdi->irq_lock, flags); 115 __raw_writel(__raw_readl(imxdi->ioaddr + DIER) & ~intr, 116 imxdi->ioaddr + DIER); 117 spin_unlock_irqrestore(&imxdi->irq_lock, flags); 118 } 119 120 /* 121 * This function attempts to clear the dryice write-error flag. 122 * 123 * A dryice write error is similar to a bus fault and should not occur in 124 * normal operation. Clearing the flag requires another write, so the root 125 * cause of the problem may need to be fixed before the flag can be cleared. 126 */ 127 static void clear_write_error(struct imxdi_dev *imxdi) 128 { 129 int cnt; 130 131 dev_warn(&imxdi->pdev->dev, "WARNING: Register write error!\n"); 132 133 /* clear the write error flag */ 134 __raw_writel(DSR_WEF, imxdi->ioaddr + DSR); 135 136 /* wait for it to take effect */ 137 for (cnt = 0; cnt < 1000; cnt++) { 138 if ((__raw_readl(imxdi->ioaddr + DSR) & DSR_WEF) == 0) 139 return; 140 udelay(10); 141 } 142 dev_err(&imxdi->pdev->dev, 143 "ERROR: Cannot clear write-error flag!\n"); 144 } 145 146 /* 147 * Write a dryice register and wait until it completes. 148 * 149 * This function uses interrupts to determine when the 150 * write has completed. 151 */ 152 static int di_write_wait(struct imxdi_dev *imxdi, u32 val, int reg) 153 { 154 int ret; 155 int rc = 0; 156 157 /* serialize register writes */ 158 mutex_lock(&imxdi->write_mutex); 159 160 /* enable the write-complete interrupt */ 161 di_int_enable(imxdi, DIER_WCIE); 162 163 imxdi->dsr = 0; 164 165 /* do the register write */ 166 __raw_writel(val, imxdi->ioaddr + reg); 167 168 /* wait for the write to finish */ 169 ret = wait_event_interruptible_timeout(imxdi->write_wait, 170 imxdi->dsr & (DSR_WCF | DSR_WEF), msecs_to_jiffies(1)); 171 if (ret < 0) { 172 rc = ret; 173 goto out; 174 } else if (ret == 0) { 175 dev_warn(&imxdi->pdev->dev, 176 "Write-wait timeout " 177 "val = 0x%08x reg = 0x%08x\n", val, reg); 178 } 179 180 /* check for write error */ 181 if (imxdi->dsr & DSR_WEF) { 182 clear_write_error(imxdi); 183 rc = -EIO; 184 } 185 186 out: 187 mutex_unlock(&imxdi->write_mutex); 188 189 return rc; 190 } 191 192 /* 193 * read the seconds portion of the current time from the dryice time counter 194 */ 195 static int dryice_rtc_read_time(struct device *dev, struct rtc_time *tm) 196 { 197 struct imxdi_dev *imxdi = dev_get_drvdata(dev); 198 unsigned long now; 199 200 now = __raw_readl(imxdi->ioaddr + DTCMR); 201 rtc_time_to_tm(now, tm); 202 203 return 0; 204 } 205 206 /* 207 * set the seconds portion of dryice time counter and clear the 208 * fractional part. 209 */ 210 static int dryice_rtc_set_mmss(struct device *dev, unsigned long secs) 211 { 212 struct imxdi_dev *imxdi = dev_get_drvdata(dev); 213 int rc; 214 215 /* zero the fractional part first */ 216 rc = di_write_wait(imxdi, 0, DTCLR); 217 if (rc == 0) 218 rc = di_write_wait(imxdi, secs, DTCMR); 219 220 return rc; 221 } 222 223 static int dryice_rtc_alarm_irq_enable(struct device *dev, 224 unsigned int enabled) 225 { 226 struct imxdi_dev *imxdi = dev_get_drvdata(dev); 227 228 if (enabled) 229 di_int_enable(imxdi, DIER_CAIE); 230 else 231 di_int_disable(imxdi, DIER_CAIE); 232 233 return 0; 234 } 235 236 /* 237 * read the seconds portion of the alarm register. 238 * the fractional part of the alarm register is always zero. 239 */ 240 static int dryice_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm) 241 { 242 struct imxdi_dev *imxdi = dev_get_drvdata(dev); 243 u32 dcamr; 244 245 dcamr = __raw_readl(imxdi->ioaddr + DCAMR); 246 rtc_time_to_tm(dcamr, &alarm->time); 247 248 /* alarm is enabled if the interrupt is enabled */ 249 alarm->enabled = (__raw_readl(imxdi->ioaddr + DIER) & DIER_CAIE) != 0; 250 251 /* don't allow the DSR read to mess up DSR_WCF */ 252 mutex_lock(&imxdi->write_mutex); 253 254 /* alarm is pending if the alarm flag is set */ 255 alarm->pending = (__raw_readl(imxdi->ioaddr + DSR) & DSR_CAF) != 0; 256 257 mutex_unlock(&imxdi->write_mutex); 258 259 return 0; 260 } 261 262 /* 263 * set the seconds portion of dryice alarm register 264 */ 265 static int dryice_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm) 266 { 267 struct imxdi_dev *imxdi = dev_get_drvdata(dev); 268 unsigned long now; 269 unsigned long alarm_time; 270 int rc; 271 272 rc = rtc_tm_to_time(&alarm->time, &alarm_time); 273 if (rc) 274 return rc; 275 276 /* don't allow setting alarm in the past */ 277 now = __raw_readl(imxdi->ioaddr + DTCMR); 278 if (alarm_time < now) 279 return -EINVAL; 280 281 /* write the new alarm time */ 282 rc = di_write_wait(imxdi, (u32)alarm_time, DCAMR); 283 if (rc) 284 return rc; 285 286 if (alarm->enabled) 287 di_int_enable(imxdi, DIER_CAIE); /* enable alarm intr */ 288 else 289 di_int_disable(imxdi, DIER_CAIE); /* disable alarm intr */ 290 291 return 0; 292 } 293 294 static struct rtc_class_ops dryice_rtc_ops = { 295 .read_time = dryice_rtc_read_time, 296 .set_mmss = dryice_rtc_set_mmss, 297 .alarm_irq_enable = dryice_rtc_alarm_irq_enable, 298 .read_alarm = dryice_rtc_read_alarm, 299 .set_alarm = dryice_rtc_set_alarm, 300 }; 301 302 /* 303 * dryice "normal" interrupt handler 304 */ 305 static irqreturn_t dryice_norm_irq(int irq, void *dev_id) 306 { 307 struct imxdi_dev *imxdi = dev_id; 308 u32 dsr, dier; 309 irqreturn_t rc = IRQ_NONE; 310 311 dier = __raw_readl(imxdi->ioaddr + DIER); 312 313 /* handle write complete and write error cases */ 314 if ((dier & DIER_WCIE)) { 315 /*If the write wait queue is empty then there is no pending 316 operations. It means the interrupt is for DryIce -Security. 317 IRQ must be returned as none.*/ 318 if (list_empty_careful(&imxdi->write_wait.task_list)) 319 return rc; 320 321 /* DSR_WCF clears itself on DSR read */ 322 dsr = __raw_readl(imxdi->ioaddr + DSR); 323 if ((dsr & (DSR_WCF | DSR_WEF))) { 324 /* mask the interrupt */ 325 di_int_disable(imxdi, DIER_WCIE); 326 327 /* save the dsr value for the wait queue */ 328 imxdi->dsr |= dsr; 329 330 wake_up_interruptible(&imxdi->write_wait); 331 rc = IRQ_HANDLED; 332 } 333 } 334 335 /* handle the alarm case */ 336 if ((dier & DIER_CAIE)) { 337 /* DSR_WCF clears itself on DSR read */ 338 dsr = __raw_readl(imxdi->ioaddr + DSR); 339 if (dsr & DSR_CAF) { 340 /* mask the interrupt */ 341 di_int_disable(imxdi, DIER_CAIE); 342 343 /* finish alarm in user context */ 344 schedule_work(&imxdi->work); 345 rc = IRQ_HANDLED; 346 } 347 } 348 return rc; 349 } 350 351 /* 352 * post the alarm event from user context so it can sleep 353 * on the write completion. 354 */ 355 static void dryice_work(struct work_struct *work) 356 { 357 struct imxdi_dev *imxdi = container_of(work, 358 struct imxdi_dev, work); 359 360 /* dismiss the interrupt (ignore error) */ 361 di_write_wait(imxdi, DSR_CAF, DSR); 362 363 /* pass the alarm event to the rtc framework. */ 364 rtc_update_irq(imxdi->rtc, 1, RTC_AF | RTC_IRQF); 365 } 366 367 /* 368 * probe for dryice rtc device 369 */ 370 static int dryice_rtc_probe(struct platform_device *pdev) 371 { 372 struct resource *res; 373 struct imxdi_dev *imxdi; 374 int rc; 375 376 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 377 if (!res) 378 return -ENODEV; 379 380 imxdi = devm_kzalloc(&pdev->dev, sizeof(*imxdi), GFP_KERNEL); 381 if (!imxdi) 382 return -ENOMEM; 383 384 imxdi->pdev = pdev; 385 386 if (!devm_request_mem_region(&pdev->dev, res->start, resource_size(res), 387 pdev->name)) 388 return -EBUSY; 389 390 imxdi->ioaddr = devm_ioremap(&pdev->dev, res->start, 391 resource_size(res)); 392 if (imxdi->ioaddr == NULL) 393 return -ENOMEM; 394 395 imxdi->irq = platform_get_irq(pdev, 0); 396 if (imxdi->irq < 0) 397 return imxdi->irq; 398 399 init_waitqueue_head(&imxdi->write_wait); 400 401 INIT_WORK(&imxdi->work, dryice_work); 402 403 mutex_init(&imxdi->write_mutex); 404 405 imxdi->clk = clk_get(&pdev->dev, NULL); 406 if (IS_ERR(imxdi->clk)) 407 return PTR_ERR(imxdi->clk); 408 clk_prepare_enable(imxdi->clk); 409 410 /* 411 * Initialize dryice hardware 412 */ 413 414 /* mask all interrupts */ 415 __raw_writel(0, imxdi->ioaddr + DIER); 416 417 rc = devm_request_irq(&pdev->dev, imxdi->irq, dryice_norm_irq, 418 IRQF_SHARED, pdev->name, imxdi); 419 if (rc) { 420 dev_warn(&pdev->dev, "interrupt not available.\n"); 421 goto err; 422 } 423 424 /* put dryice into valid state */ 425 if (__raw_readl(imxdi->ioaddr + DSR) & DSR_NVF) { 426 rc = di_write_wait(imxdi, DSR_NVF | DSR_SVF, DSR); 427 if (rc) 428 goto err; 429 } 430 431 /* initialize alarm */ 432 rc = di_write_wait(imxdi, DCAMR_UNSET, DCAMR); 433 if (rc) 434 goto err; 435 rc = di_write_wait(imxdi, 0, DCALR); 436 if (rc) 437 goto err; 438 439 /* clear alarm flag */ 440 if (__raw_readl(imxdi->ioaddr + DSR) & DSR_CAF) { 441 rc = di_write_wait(imxdi, DSR_CAF, DSR); 442 if (rc) 443 goto err; 444 } 445 446 /* the timer won't count if it has never been written to */ 447 if (__raw_readl(imxdi->ioaddr + DTCMR) == 0) { 448 rc = di_write_wait(imxdi, 0, DTCMR); 449 if (rc) 450 goto err; 451 } 452 453 /* start keeping time */ 454 if (!(__raw_readl(imxdi->ioaddr + DCR) & DCR_TCE)) { 455 rc = di_write_wait(imxdi, 456 __raw_readl(imxdi->ioaddr + DCR) | DCR_TCE, 457 DCR); 458 if (rc) 459 goto err; 460 } 461 462 platform_set_drvdata(pdev, imxdi); 463 imxdi->rtc = rtc_device_register(pdev->name, &pdev->dev, 464 &dryice_rtc_ops, THIS_MODULE); 465 if (IS_ERR(imxdi->rtc)) { 466 rc = PTR_ERR(imxdi->rtc); 467 goto err; 468 } 469 470 return 0; 471 472 err: 473 clk_disable_unprepare(imxdi->clk); 474 clk_put(imxdi->clk); 475 476 return rc; 477 } 478 479 static int __devexit dryice_rtc_remove(struct platform_device *pdev) 480 { 481 struct imxdi_dev *imxdi = platform_get_drvdata(pdev); 482 483 flush_work(&imxdi->work); 484 485 /* mask all interrupts */ 486 __raw_writel(0, imxdi->ioaddr + DIER); 487 488 rtc_device_unregister(imxdi->rtc); 489 490 clk_disable_unprepare(imxdi->clk); 491 clk_put(imxdi->clk); 492 493 return 0; 494 } 495 496 static struct platform_driver dryice_rtc_driver = { 497 .driver = { 498 .name = "imxdi_rtc", 499 .owner = THIS_MODULE, 500 }, 501 .remove = __devexit_p(dryice_rtc_remove), 502 }; 503 504 static int __init dryice_rtc_init(void) 505 { 506 return platform_driver_probe(&dryice_rtc_driver, dryice_rtc_probe); 507 } 508 509 static void __exit dryice_rtc_exit(void) 510 { 511 platform_driver_unregister(&dryice_rtc_driver); 512 } 513 514 module_init(dryice_rtc_init); 515 module_exit(dryice_rtc_exit); 516 517 MODULE_AUTHOR("Freescale Semiconductor, Inc."); 518 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>"); 519 MODULE_DESCRIPTION("IMX DryIce Realtime Clock Driver (RTC)"); 520 MODULE_LICENSE("GPL"); 521