xref: /linux/drivers/rtc/rtc-imxdi.c (revision 0ea5c948cb64bab5bc7a5516774eb8536f05aa0d)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Copyright 2008-2009 Freescale Semiconductor, Inc. All Rights Reserved.
4  * Copyright 2010 Orex Computed Radiography
5  */
6 
7 /*
8  * This driver uses the 47-bit 32 kHz counter in the Freescale DryIce block
9  * to implement a Linux RTC. Times and alarms are truncated to seconds.
10  * Since the RTC framework performs API locking via rtc->ops_lock the
11  * only simultaneous accesses we need to deal with is updating DryIce
12  * registers while servicing an alarm.
13  *
14  * Note that reading the DSR (DryIce Status Register) automatically clears
15  * the WCF (Write Complete Flag). All DryIce writes are synchronized to the
16  * LP (Low Power) domain and set the WCF upon completion. Writes to the
17  * DIER (DryIce Interrupt Enable Register) are the only exception. These
18  * occur at normal bus speeds and do not set WCF.  Periodic interrupts are
19  * not supported by the hardware.
20  */
21 
22 #include <linux/io.h>
23 #include <linux/clk.h>
24 #include <linux/delay.h>
25 #include <linux/module.h>
26 #include <linux/platform_device.h>
27 #include <linux/pm_wakeirq.h>
28 #include <linux/rtc.h>
29 #include <linux/sched.h>
30 #include <linux/spinlock.h>
31 #include <linux/workqueue.h>
32 #include <linux/of.h>
33 
34 /* DryIce Register Definitions */
35 
36 #define DTCMR     0x00           /* Time Counter MSB Reg */
37 #define DTCLR     0x04           /* Time Counter LSB Reg */
38 
39 #define DCAMR     0x08           /* Clock Alarm MSB Reg */
40 #define DCALR     0x0c           /* Clock Alarm LSB Reg */
41 #define DCAMR_UNSET  0xFFFFFFFF  /* doomsday - 1 sec */
42 
43 #define DCR       0x10           /* Control Reg */
44 #define DCR_TDCHL (1 << 30)      /* Tamper-detect configuration hard lock */
45 #define DCR_TDCSL (1 << 29)      /* Tamper-detect configuration soft lock */
46 #define DCR_KSSL  (1 << 27)      /* Key-select soft lock */
47 #define DCR_MCHL  (1 << 20)      /* Monotonic-counter hard lock */
48 #define DCR_MCSL  (1 << 19)      /* Monotonic-counter soft lock */
49 #define DCR_TCHL  (1 << 18)      /* Timer-counter hard lock */
50 #define DCR_TCSL  (1 << 17)      /* Timer-counter soft lock */
51 #define DCR_FSHL  (1 << 16)      /* Failure state hard lock */
52 #define DCR_TCE   (1 << 3)       /* Time Counter Enable */
53 #define DCR_MCE   (1 << 2)       /* Monotonic Counter Enable */
54 
55 #define DSR       0x14           /* Status Reg */
56 #define DSR_WTD   (1 << 23)      /* Wire-mesh tamper detected */
57 #define DSR_ETBD  (1 << 22)      /* External tamper B detected */
58 #define DSR_ETAD  (1 << 21)      /* External tamper A detected */
59 #define DSR_EBD   (1 << 20)      /* External boot detected */
60 #define DSR_SAD   (1 << 19)      /* SCC alarm detected */
61 #define DSR_TTD   (1 << 18)      /* Temperature tamper detected */
62 #define DSR_CTD   (1 << 17)      /* Clock tamper detected */
63 #define DSR_VTD   (1 << 16)      /* Voltage tamper detected */
64 #define DSR_WBF   (1 << 10)      /* Write Busy Flag (synchronous) */
65 #define DSR_WNF   (1 << 9)       /* Write Next Flag (synchronous) */
66 #define DSR_WCF   (1 << 8)       /* Write Complete Flag (synchronous)*/
67 #define DSR_WEF   (1 << 7)       /* Write Error Flag */
68 #define DSR_CAF   (1 << 4)       /* Clock Alarm Flag */
69 #define DSR_MCO   (1 << 3)       /* monotonic counter overflow */
70 #define DSR_TCO   (1 << 2)       /* time counter overflow */
71 #define DSR_NVF   (1 << 1)       /* Non-Valid Flag */
72 #define DSR_SVF   (1 << 0)       /* Security Violation Flag */
73 
74 #define DIER      0x18           /* Interrupt Enable Reg (synchronous) */
75 #define DIER_WNIE (1 << 9)       /* Write Next Interrupt Enable */
76 #define DIER_WCIE (1 << 8)       /* Write Complete Interrupt Enable */
77 #define DIER_WEIE (1 << 7)       /* Write Error Interrupt Enable */
78 #define DIER_CAIE (1 << 4)       /* Clock Alarm Interrupt Enable */
79 #define DIER_SVIE (1 << 0)       /* Security-violation Interrupt Enable */
80 
81 #define DMCR      0x1c           /* DryIce Monotonic Counter Reg */
82 
83 #define DTCR      0x28           /* DryIce Tamper Configuration Reg */
84 #define DTCR_MOE  (1 << 9)       /* monotonic overflow enabled */
85 #define DTCR_TOE  (1 << 8)       /* time overflow enabled */
86 #define DTCR_WTE  (1 << 7)       /* wire-mesh tamper enabled */
87 #define DTCR_ETBE (1 << 6)       /* external B tamper enabled */
88 #define DTCR_ETAE (1 << 5)       /* external A tamper enabled */
89 #define DTCR_EBE  (1 << 4)       /* external boot tamper enabled */
90 #define DTCR_SAIE (1 << 3)       /* SCC enabled */
91 #define DTCR_TTE  (1 << 2)       /* temperature tamper enabled */
92 #define DTCR_CTE  (1 << 1)       /* clock tamper enabled */
93 #define DTCR_VTE  (1 << 0)       /* voltage tamper enabled */
94 
95 #define DGPR      0x3c           /* DryIce General Purpose Reg */
96 
97 /**
98  * struct imxdi_dev - private imxdi rtc data
99  * @pdev: pointer to platform dev
100  * @rtc: pointer to rtc struct
101  * @ioaddr: IO registers pointer
102  * @clk: input reference clock
103  * @dsr: copy of the DSR register
104  * @irq_lock: interrupt enable register (DIER) lock
105  * @write_wait: registers write complete queue
106  * @write_mutex: serialize registers write
107  * @work: schedule alarm work
108  */
109 struct imxdi_dev {
110 	struct platform_device *pdev;
111 	struct rtc_device *rtc;
112 	void __iomem *ioaddr;
113 	struct clk *clk;
114 	u32 dsr;
115 	spinlock_t irq_lock;
116 	wait_queue_head_t write_wait;
117 	struct mutex write_mutex;
118 	struct work_struct work;
119 };
120 
121 /* Some background:
122  *
123  * The DryIce unit is a complex security/tamper monitor device. To be able do
124  * its job in a useful manner it runs a bigger statemachine to bring it into
125  * security/tamper failure state and once again to bring it out of this state.
126  *
127  * This unit can be in one of three states:
128  *
129  * - "NON-VALID STATE"
130  *   always after the battery power was removed
131  * - "FAILURE STATE"
132  *   if one of the enabled security events has happened
133  * - "VALID STATE"
134  *   if the unit works as expected
135  *
136  * Everything stops when the unit enters the failure state including the RTC
137  * counter (to be able to detect the time the security event happened).
138  *
139  * The following events (when enabled) let the DryIce unit enter the failure
140  * state:
141  *
142  * - wire-mesh-tamper detect
143  * - external tamper B detect
144  * - external tamper A detect
145  * - temperature tamper detect
146  * - clock tamper detect
147  * - voltage tamper detect
148  * - RTC counter overflow
149  * - monotonic counter overflow
150  * - external boot
151  *
152  * If we find the DryIce unit in "FAILURE STATE" and the TDCHL cleared, we
153  * can only detect this state. In this case the unit is completely locked and
154  * must force a second "SYSTEM POR" to bring the DryIce into the
155  * "NON-VALID STATE" + "FAILURE STATE" where a recovery is possible.
156  * If the TDCHL is set in the "FAILURE STATE" we are out of luck. In this case
157  * a battery power cycle is required.
158  *
159  * In the "NON-VALID STATE" + "FAILURE STATE" we can clear the "FAILURE STATE"
160  * and recover the DryIce unit. By clearing the "NON-VALID STATE" as the last
161  * task, we bring back this unit into life.
162  */
163 
164 /*
165  * Do a write into the unit without interrupt support.
166  * We do not need to check the WEF here, because the only reason this kind of
167  * write error can happen is if we write to the unit twice within the 122 us
168  * interval. This cannot happen, since we are using this function only while
169  * setting up the unit.
170  */
di_write_busy_wait(const struct imxdi_dev * imxdi,u32 val,unsigned reg)171 static void di_write_busy_wait(const struct imxdi_dev *imxdi, u32 val,
172 			       unsigned reg)
173 {
174 	/* do the register write */
175 	writel(val, imxdi->ioaddr + reg);
176 
177 	/*
178 	 * now it takes four 32,768 kHz clock cycles to take
179 	 * the change into effect = 122 us
180 	 */
181 	usleep_range(130, 200);
182 }
183 
di_report_tamper_info(struct imxdi_dev * imxdi,u32 dsr)184 static void di_report_tamper_info(struct imxdi_dev *imxdi,  u32 dsr)
185 {
186 	u32 dtcr;
187 
188 	dtcr = readl(imxdi->ioaddr + DTCR);
189 
190 	dev_emerg(&imxdi->pdev->dev, "DryIce tamper event detected\n");
191 	/* the following flags force a transition into the "FAILURE STATE" */
192 	if (dsr & DSR_VTD)
193 		dev_emerg(&imxdi->pdev->dev, "%sVoltage Tamper Event\n",
194 			  dtcr & DTCR_VTE ? "" : "Spurious ");
195 
196 	if (dsr & DSR_CTD)
197 		dev_emerg(&imxdi->pdev->dev, "%s32768 Hz Clock Tamper Event\n",
198 			  dtcr & DTCR_CTE ? "" : "Spurious ");
199 
200 	if (dsr & DSR_TTD)
201 		dev_emerg(&imxdi->pdev->dev, "%sTemperature Tamper Event\n",
202 			  dtcr & DTCR_TTE ? "" : "Spurious ");
203 
204 	if (dsr & DSR_SAD)
205 		dev_emerg(&imxdi->pdev->dev,
206 			  "%sSecure Controller Alarm Event\n",
207 			  dtcr & DTCR_SAIE ? "" : "Spurious ");
208 
209 	if (dsr & DSR_EBD)
210 		dev_emerg(&imxdi->pdev->dev, "%sExternal Boot Tamper Event\n",
211 			  dtcr & DTCR_EBE ? "" : "Spurious ");
212 
213 	if (dsr & DSR_ETAD)
214 		dev_emerg(&imxdi->pdev->dev, "%sExternal Tamper A Event\n",
215 			  dtcr & DTCR_ETAE ? "" : "Spurious ");
216 
217 	if (dsr & DSR_ETBD)
218 		dev_emerg(&imxdi->pdev->dev, "%sExternal Tamper B Event\n",
219 			  dtcr & DTCR_ETBE ? "" : "Spurious ");
220 
221 	if (dsr & DSR_WTD)
222 		dev_emerg(&imxdi->pdev->dev, "%sWire-mesh Tamper Event\n",
223 			  dtcr & DTCR_WTE ? "" : "Spurious ");
224 
225 	if (dsr & DSR_MCO)
226 		dev_emerg(&imxdi->pdev->dev,
227 			  "%sMonotonic-counter Overflow Event\n",
228 			  dtcr & DTCR_MOE ? "" : "Spurious ");
229 
230 	if (dsr & DSR_TCO)
231 		dev_emerg(&imxdi->pdev->dev, "%sTimer-counter Overflow Event\n",
232 			  dtcr & DTCR_TOE ? "" : "Spurious ");
233 }
234 
di_what_is_to_be_done(struct imxdi_dev * imxdi,const char * power_supply)235 static void di_what_is_to_be_done(struct imxdi_dev *imxdi,
236 				  const char *power_supply)
237 {
238 	dev_emerg(&imxdi->pdev->dev, "Please cycle the %s power supply in order to get the DryIce/RTC unit working again\n",
239 		  power_supply);
240 }
241 
di_handle_failure_state(struct imxdi_dev * imxdi,u32 dsr)242 static int di_handle_failure_state(struct imxdi_dev *imxdi, u32 dsr)
243 {
244 	u32 dcr;
245 
246 	dev_dbg(&imxdi->pdev->dev, "DSR register reports: %08X\n", dsr);
247 
248 	/* report the cause */
249 	di_report_tamper_info(imxdi, dsr);
250 
251 	dcr = readl(imxdi->ioaddr + DCR);
252 
253 	if (dcr & DCR_FSHL) {
254 		/* we are out of luck */
255 		di_what_is_to_be_done(imxdi, "battery");
256 		return -ENODEV;
257 	}
258 	/*
259 	 * with the next SYSTEM POR we will transit from the "FAILURE STATE"
260 	 * into the "NON-VALID STATE" + "FAILURE STATE"
261 	 */
262 	di_what_is_to_be_done(imxdi, "main");
263 
264 	return -ENODEV;
265 }
266 
di_handle_valid_state(struct imxdi_dev * imxdi,u32 dsr)267 static int di_handle_valid_state(struct imxdi_dev *imxdi, u32 dsr)
268 {
269 	/* initialize alarm */
270 	di_write_busy_wait(imxdi, DCAMR_UNSET, DCAMR);
271 	di_write_busy_wait(imxdi, 0, DCALR);
272 
273 	/* clear alarm flag */
274 	if (dsr & DSR_CAF)
275 		di_write_busy_wait(imxdi, DSR_CAF, DSR);
276 
277 	return 0;
278 }
279 
di_handle_invalid_state(struct imxdi_dev * imxdi,u32 dsr)280 static int di_handle_invalid_state(struct imxdi_dev *imxdi, u32 dsr)
281 {
282 	u32 dcr, sec;
283 
284 	/*
285 	 * lets disable all sources which can force the DryIce unit into
286 	 * the "FAILURE STATE" for now
287 	 */
288 	di_write_busy_wait(imxdi, 0x00000000, DTCR);
289 	/* and lets protect them at runtime from any change */
290 	di_write_busy_wait(imxdi, DCR_TDCSL, DCR);
291 
292 	sec = readl(imxdi->ioaddr + DTCMR);
293 	if (sec != 0)
294 		dev_warn(&imxdi->pdev->dev,
295 			 "The security violation has happened at %u seconds\n",
296 			 sec);
297 	/*
298 	 * the timer cannot be set/modified if
299 	 * - the TCHL or TCSL bit is set in DCR
300 	 */
301 	dcr = readl(imxdi->ioaddr + DCR);
302 	if (!(dcr & DCR_TCE)) {
303 		if (dcr & DCR_TCHL) {
304 			/* we are out of luck */
305 			di_what_is_to_be_done(imxdi, "battery");
306 			return -ENODEV;
307 		}
308 		if (dcr & DCR_TCSL) {
309 			di_what_is_to_be_done(imxdi, "main");
310 			return -ENODEV;
311 		}
312 	}
313 	/*
314 	 * - the timer counter stops/is stopped if
315 	 *   - its overflow flag is set (TCO in DSR)
316 	 *      -> clear overflow bit to make it count again
317 	 *   - NVF is set in DSR
318 	 *      -> clear non-valid bit to make it count again
319 	 *   - its TCE (DCR) is cleared
320 	 *      -> set TCE to make it count
321 	 *   - it was never set before
322 	 *      -> write a time into it (required again if the NVF was set)
323 	 */
324 	/* state handled */
325 	di_write_busy_wait(imxdi, DSR_NVF, DSR);
326 	/* clear overflow flag */
327 	di_write_busy_wait(imxdi, DSR_TCO, DSR);
328 	/* enable the counter */
329 	di_write_busy_wait(imxdi, dcr | DCR_TCE, DCR);
330 	/* set and trigger it to make it count */
331 	di_write_busy_wait(imxdi, sec, DTCMR);
332 
333 	/* now prepare for the valid state */
334 	return di_handle_valid_state(imxdi, __raw_readl(imxdi->ioaddr + DSR));
335 }
336 
di_handle_invalid_and_failure_state(struct imxdi_dev * imxdi,u32 dsr)337 static int di_handle_invalid_and_failure_state(struct imxdi_dev *imxdi, u32 dsr)
338 {
339 	u32 dcr;
340 
341 	/*
342 	 * now we must first remove the tamper sources in order to get the
343 	 * device out of the "FAILURE STATE"
344 	 * To disable any of the following sources we need to modify the DTCR
345 	 */
346 	if (dsr & (DSR_WTD | DSR_ETBD | DSR_ETAD | DSR_EBD | DSR_SAD |
347 			DSR_TTD | DSR_CTD | DSR_VTD | DSR_MCO | DSR_TCO)) {
348 		dcr = __raw_readl(imxdi->ioaddr + DCR);
349 		if (dcr & DCR_TDCHL) {
350 			/*
351 			 * the tamper register is locked. We cannot disable the
352 			 * tamper detection. The TDCHL can only be reset by a
353 			 * DRYICE POR, but we cannot force a DRYICE POR in
354 			 * software because we are still in "FAILURE STATE".
355 			 * We need a DRYICE POR via battery power cycling....
356 			 */
357 			/*
358 			 * out of luck!
359 			 * we cannot disable them without a DRYICE POR
360 			 */
361 			di_what_is_to_be_done(imxdi, "battery");
362 			return -ENODEV;
363 		}
364 		if (dcr & DCR_TDCSL) {
365 			/* a soft lock can be removed by a SYSTEM POR */
366 			di_what_is_to_be_done(imxdi, "main");
367 			return -ENODEV;
368 		}
369 	}
370 
371 	/* disable all sources */
372 	di_write_busy_wait(imxdi, 0x00000000, DTCR);
373 
374 	/* clear the status bits now */
375 	di_write_busy_wait(imxdi, dsr & (DSR_WTD | DSR_ETBD | DSR_ETAD |
376 			DSR_EBD | DSR_SAD | DSR_TTD | DSR_CTD | DSR_VTD |
377 			DSR_MCO | DSR_TCO), DSR);
378 
379 	dsr = readl(imxdi->ioaddr + DSR);
380 	if ((dsr & ~(DSR_NVF | DSR_SVF | DSR_WBF | DSR_WNF |
381 			DSR_WCF | DSR_WEF)) != 0)
382 		dev_warn(&imxdi->pdev->dev,
383 			 "There are still some sources of pain in DSR: %08x!\n",
384 			 dsr & ~(DSR_NVF | DSR_SVF | DSR_WBF | DSR_WNF |
385 				 DSR_WCF | DSR_WEF));
386 
387 	/*
388 	 * now we are trying to clear the "Security-violation flag" to
389 	 * get the DryIce out of this state
390 	 */
391 	di_write_busy_wait(imxdi, DSR_SVF, DSR);
392 
393 	/* success? */
394 	dsr = readl(imxdi->ioaddr + DSR);
395 	if (dsr & DSR_SVF) {
396 		dev_crit(&imxdi->pdev->dev,
397 			 "Cannot clear the security violation flag. We are ending up in an endless loop!\n");
398 		/* last resort */
399 		di_what_is_to_be_done(imxdi, "battery");
400 		return -ENODEV;
401 	}
402 
403 	/*
404 	 * now we have left the "FAILURE STATE" and ending up in the
405 	 * "NON-VALID STATE" time to recover everything
406 	 */
407 	return di_handle_invalid_state(imxdi, dsr);
408 }
409 
di_handle_state(struct imxdi_dev * imxdi)410 static int di_handle_state(struct imxdi_dev *imxdi)
411 {
412 	int rc;
413 	u32 dsr;
414 
415 	dsr = readl(imxdi->ioaddr + DSR);
416 
417 	switch (dsr & (DSR_NVF | DSR_SVF)) {
418 	case DSR_NVF:
419 		dev_warn(&imxdi->pdev->dev, "Invalid stated unit detected\n");
420 		rc = di_handle_invalid_state(imxdi, dsr);
421 		break;
422 	case DSR_SVF:
423 		dev_warn(&imxdi->pdev->dev, "Failure stated unit detected\n");
424 		rc = di_handle_failure_state(imxdi, dsr);
425 		break;
426 	case DSR_NVF | DSR_SVF:
427 		dev_warn(&imxdi->pdev->dev,
428 			 "Failure+Invalid stated unit detected\n");
429 		rc = di_handle_invalid_and_failure_state(imxdi, dsr);
430 		break;
431 	default:
432 		dev_notice(&imxdi->pdev->dev, "Unlocked unit detected\n");
433 		rc = di_handle_valid_state(imxdi, dsr);
434 	}
435 
436 	return rc;
437 }
438 
439 /*
440  * enable a dryice interrupt
441  */
di_int_enable(struct imxdi_dev * imxdi,u32 intr)442 static void di_int_enable(struct imxdi_dev *imxdi, u32 intr)
443 {
444 	unsigned long flags;
445 
446 	spin_lock_irqsave(&imxdi->irq_lock, flags);
447 	writel(readl(imxdi->ioaddr + DIER) | intr,
448 	       imxdi->ioaddr + DIER);
449 	spin_unlock_irqrestore(&imxdi->irq_lock, flags);
450 }
451 
452 /*
453  * disable a dryice interrupt
454  */
di_int_disable(struct imxdi_dev * imxdi,u32 intr)455 static void di_int_disable(struct imxdi_dev *imxdi, u32 intr)
456 {
457 	unsigned long flags;
458 
459 	spin_lock_irqsave(&imxdi->irq_lock, flags);
460 	writel(readl(imxdi->ioaddr + DIER) & ~intr,
461 	       imxdi->ioaddr + DIER);
462 	spin_unlock_irqrestore(&imxdi->irq_lock, flags);
463 }
464 
465 /*
466  * This function attempts to clear the dryice write-error flag.
467  *
468  * A dryice write error is similar to a bus fault and should not occur in
469  * normal operation.  Clearing the flag requires another write, so the root
470  * cause of the problem may need to be fixed before the flag can be cleared.
471  */
clear_write_error(struct imxdi_dev * imxdi)472 static void clear_write_error(struct imxdi_dev *imxdi)
473 {
474 	int cnt;
475 
476 	dev_warn(&imxdi->pdev->dev, "WARNING: Register write error!\n");
477 
478 	/* clear the write error flag */
479 	writel(DSR_WEF, imxdi->ioaddr + DSR);
480 
481 	/* wait for it to take effect */
482 	for (cnt = 0; cnt < 1000; cnt++) {
483 		if ((readl(imxdi->ioaddr + DSR) & DSR_WEF) == 0)
484 			return;
485 		udelay(10);
486 	}
487 	dev_err(&imxdi->pdev->dev,
488 			"ERROR: Cannot clear write-error flag!\n");
489 }
490 
491 /*
492  * Write a dryice register and wait until it completes.
493  *
494  * This function uses interrupts to determine when the
495  * write has completed.
496  */
di_write_wait(struct imxdi_dev * imxdi,u32 val,int reg)497 static int di_write_wait(struct imxdi_dev *imxdi, u32 val, int reg)
498 {
499 	int ret;
500 	int rc = 0;
501 
502 	/* serialize register writes */
503 	mutex_lock(&imxdi->write_mutex);
504 
505 	/* enable the write-complete interrupt */
506 	di_int_enable(imxdi, DIER_WCIE);
507 
508 	imxdi->dsr = 0;
509 
510 	/* do the register write */
511 	writel(val, imxdi->ioaddr + reg);
512 
513 	/* wait for the write to finish */
514 	ret = wait_event_interruptible_timeout(imxdi->write_wait,
515 			imxdi->dsr & (DSR_WCF | DSR_WEF), msecs_to_jiffies(1));
516 	if (ret < 0) {
517 		rc = ret;
518 		goto out;
519 	} else if (ret == 0) {
520 		dev_warn(&imxdi->pdev->dev,
521 				"Write-wait timeout "
522 				"val = 0x%08x reg = 0x%08x\n", val, reg);
523 	}
524 
525 	/* check for write error */
526 	if (imxdi->dsr & DSR_WEF) {
527 		clear_write_error(imxdi);
528 		rc = -EIO;
529 	}
530 
531 out:
532 	mutex_unlock(&imxdi->write_mutex);
533 
534 	return rc;
535 }
536 
537 /*
538  * read the seconds portion of the current time from the dryice time counter
539  */
dryice_rtc_read_time(struct device * dev,struct rtc_time * tm)540 static int dryice_rtc_read_time(struct device *dev, struct rtc_time *tm)
541 {
542 	struct imxdi_dev *imxdi = dev_get_drvdata(dev);
543 	unsigned long now;
544 
545 	now = readl(imxdi->ioaddr + DTCMR);
546 	rtc_time64_to_tm(now, tm);
547 
548 	return 0;
549 }
550 
551 /*
552  * set the seconds portion of dryice time counter and clear the
553  * fractional part.
554  */
dryice_rtc_set_time(struct device * dev,struct rtc_time * tm)555 static int dryice_rtc_set_time(struct device *dev, struct rtc_time *tm)
556 {
557 	struct imxdi_dev *imxdi = dev_get_drvdata(dev);
558 	u32 dcr, dsr;
559 	int rc;
560 
561 	dcr = readl(imxdi->ioaddr + DCR);
562 	dsr = readl(imxdi->ioaddr + DSR);
563 
564 	if (!(dcr & DCR_TCE) || (dsr & DSR_SVF)) {
565 		if (dcr & DCR_TCHL) {
566 			/* we are even more out of luck */
567 			di_what_is_to_be_done(imxdi, "battery");
568 			return -EPERM;
569 		}
570 		if ((dcr & DCR_TCSL) || (dsr & DSR_SVF)) {
571 			/* we are out of luck for now */
572 			di_what_is_to_be_done(imxdi, "main");
573 			return -EPERM;
574 		}
575 	}
576 
577 	/* zero the fractional part first */
578 	rc = di_write_wait(imxdi, 0, DTCLR);
579 	if (rc != 0)
580 		return rc;
581 
582 	rc = di_write_wait(imxdi, rtc_tm_to_time64(tm), DTCMR);
583 	if (rc != 0)
584 		return rc;
585 
586 	return di_write_wait(imxdi, readl(imxdi->ioaddr + DCR) | DCR_TCE, DCR);
587 }
588 
dryice_rtc_alarm_irq_enable(struct device * dev,unsigned int enabled)589 static int dryice_rtc_alarm_irq_enable(struct device *dev,
590 		unsigned int enabled)
591 {
592 	struct imxdi_dev *imxdi = dev_get_drvdata(dev);
593 
594 	if (enabled)
595 		di_int_enable(imxdi, DIER_CAIE);
596 	else
597 		di_int_disable(imxdi, DIER_CAIE);
598 
599 	return 0;
600 }
601 
602 /*
603  * read the seconds portion of the alarm register.
604  * the fractional part of the alarm register is always zero.
605  */
dryice_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alarm)606 static int dryice_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
607 {
608 	struct imxdi_dev *imxdi = dev_get_drvdata(dev);
609 	u32 dcamr;
610 
611 	dcamr = readl(imxdi->ioaddr + DCAMR);
612 	rtc_time64_to_tm(dcamr, &alarm->time);
613 
614 	/* alarm is enabled if the interrupt is enabled */
615 	alarm->enabled = (readl(imxdi->ioaddr + DIER) & DIER_CAIE) != 0;
616 
617 	/* don't allow the DSR read to mess up DSR_WCF */
618 	mutex_lock(&imxdi->write_mutex);
619 
620 	/* alarm is pending if the alarm flag is set */
621 	alarm->pending = (readl(imxdi->ioaddr + DSR) & DSR_CAF) != 0;
622 
623 	mutex_unlock(&imxdi->write_mutex);
624 
625 	return 0;
626 }
627 
628 /*
629  * set the seconds portion of dryice alarm register
630  */
dryice_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alarm)631 static int dryice_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
632 {
633 	struct imxdi_dev *imxdi = dev_get_drvdata(dev);
634 	int rc;
635 
636 	/* write the new alarm time */
637 	rc = di_write_wait(imxdi, rtc_tm_to_time64(&alarm->time), DCAMR);
638 	if (rc)
639 		return rc;
640 
641 	if (alarm->enabled)
642 		di_int_enable(imxdi, DIER_CAIE);  /* enable alarm intr */
643 	else
644 		di_int_disable(imxdi, DIER_CAIE); /* disable alarm intr */
645 
646 	return 0;
647 }
648 
649 static const struct rtc_class_ops dryice_rtc_ops = {
650 	.read_time		= dryice_rtc_read_time,
651 	.set_time		= dryice_rtc_set_time,
652 	.alarm_irq_enable	= dryice_rtc_alarm_irq_enable,
653 	.read_alarm		= dryice_rtc_read_alarm,
654 	.set_alarm		= dryice_rtc_set_alarm,
655 };
656 
657 /*
658  * interrupt handler for dryice "normal" and security violation interrupt
659  */
dryice_irq(int irq,void * dev_id)660 static irqreturn_t dryice_irq(int irq, void *dev_id)
661 {
662 	struct imxdi_dev *imxdi = dev_id;
663 	u32 dsr, dier;
664 	irqreturn_t rc = IRQ_NONE;
665 
666 	dier = readl(imxdi->ioaddr + DIER);
667 	dsr = readl(imxdi->ioaddr + DSR);
668 
669 	/* handle the security violation event */
670 	if (dier & DIER_SVIE) {
671 		if (dsr & DSR_SVF) {
672 			/*
673 			 * Disable the interrupt when this kind of event has
674 			 * happened.
675 			 * There cannot be more than one event of this type,
676 			 * because it needs a complex state change
677 			 * including a main power cycle to get again out of
678 			 * this state.
679 			 */
680 			di_int_disable(imxdi, DIER_SVIE);
681 			/* report the violation */
682 			di_report_tamper_info(imxdi, dsr);
683 			rc = IRQ_HANDLED;
684 		}
685 	}
686 
687 	/* handle write complete and write error cases */
688 	if (dier & DIER_WCIE) {
689 		/*If the write wait queue is empty then there is no pending
690 		  operations. It means the interrupt is for DryIce -Security.
691 		  IRQ must be returned as none.*/
692 		if (list_empty_careful(&imxdi->write_wait.head))
693 			return rc;
694 
695 		/* DSR_WCF clears itself on DSR read */
696 		if (dsr & (DSR_WCF | DSR_WEF)) {
697 			/* mask the interrupt */
698 			di_int_disable(imxdi, DIER_WCIE);
699 
700 			/* save the dsr value for the wait queue */
701 			imxdi->dsr |= dsr;
702 
703 			wake_up_interruptible(&imxdi->write_wait);
704 			rc = IRQ_HANDLED;
705 		}
706 	}
707 
708 	/* handle the alarm case */
709 	if (dier & DIER_CAIE) {
710 		/* DSR_WCF clears itself on DSR read */
711 		if (dsr & DSR_CAF) {
712 			/* mask the interrupt */
713 			di_int_disable(imxdi, DIER_CAIE);
714 
715 			/* finish alarm in user context */
716 			schedule_work(&imxdi->work);
717 			rc = IRQ_HANDLED;
718 		}
719 	}
720 	return rc;
721 }
722 
723 /*
724  * post the alarm event from user context so it can sleep
725  * on the write completion.
726  */
dryice_work(struct work_struct * work)727 static void dryice_work(struct work_struct *work)
728 {
729 	struct imxdi_dev *imxdi = container_of(work,
730 			struct imxdi_dev, work);
731 
732 	/* dismiss the interrupt (ignore error) */
733 	di_write_wait(imxdi, DSR_CAF, DSR);
734 
735 	/* pass the alarm event to the rtc framework. */
736 	rtc_update_irq(imxdi->rtc, 1, RTC_AF | RTC_IRQF);
737 }
738 
739 /*
740  * probe for dryice rtc device
741  */
dryice_rtc_probe(struct platform_device * pdev)742 static int __init dryice_rtc_probe(struct platform_device *pdev)
743 {
744 	struct imxdi_dev *imxdi;
745 	int norm_irq, sec_irq;
746 	int rc;
747 
748 	imxdi = devm_kzalloc(&pdev->dev, sizeof(*imxdi), GFP_KERNEL);
749 	if (!imxdi)
750 		return -ENOMEM;
751 
752 	imxdi->pdev = pdev;
753 
754 	imxdi->ioaddr = devm_platform_ioremap_resource(pdev, 0);
755 	if (IS_ERR(imxdi->ioaddr))
756 		return PTR_ERR(imxdi->ioaddr);
757 
758 	spin_lock_init(&imxdi->irq_lock);
759 
760 	norm_irq = platform_get_irq(pdev, 0);
761 	if (norm_irq < 0)
762 		return norm_irq;
763 
764 	/* the 2nd irq is the security violation irq
765 	 * make this optional, don't break the device tree ABI
766 	 */
767 	sec_irq = platform_get_irq(pdev, 1);
768 	if (sec_irq <= 0)
769 		sec_irq = IRQ_NOTCONNECTED;
770 
771 	init_waitqueue_head(&imxdi->write_wait);
772 
773 	INIT_WORK(&imxdi->work, dryice_work);
774 
775 	mutex_init(&imxdi->write_mutex);
776 
777 	imxdi->rtc = devm_rtc_allocate_device(&pdev->dev);
778 	if (IS_ERR(imxdi->rtc))
779 		return PTR_ERR(imxdi->rtc);
780 
781 	imxdi->clk = devm_clk_get(&pdev->dev, NULL);
782 	if (IS_ERR(imxdi->clk))
783 		return PTR_ERR(imxdi->clk);
784 	rc = clk_prepare_enable(imxdi->clk);
785 	if (rc)
786 		return rc;
787 
788 	/*
789 	 * Initialize dryice hardware
790 	 */
791 
792 	/* mask all interrupts */
793 	writel(0, imxdi->ioaddr + DIER);
794 
795 	rc = di_handle_state(imxdi);
796 	if (rc != 0)
797 		goto err;
798 
799 	rc = devm_request_irq(&pdev->dev, norm_irq, dryice_irq,
800 			      IRQF_SHARED, pdev->name, imxdi);
801 	if (rc) {
802 		dev_warn(&pdev->dev, "interrupt not available.\n");
803 		goto err;
804 	}
805 
806 	rc = devm_request_irq(&pdev->dev, sec_irq, dryice_irq,
807 			      IRQF_SHARED, pdev->name, imxdi);
808 	if (rc) {
809 		dev_warn(&pdev->dev, "security violation interrupt not available.\n");
810 		/* this is not an error, see above */
811 	}
812 
813 	platform_set_drvdata(pdev, imxdi);
814 
815 	device_init_wakeup(&pdev->dev, true);
816 	dev_pm_set_wake_irq(&pdev->dev, norm_irq);
817 
818 	imxdi->rtc->ops = &dryice_rtc_ops;
819 	imxdi->rtc->range_max = U32_MAX;
820 
821 	rc = devm_rtc_register_device(imxdi->rtc);
822 	if (rc)
823 		goto err;
824 
825 	return 0;
826 
827 err:
828 	clk_disable_unprepare(imxdi->clk);
829 
830 	return rc;
831 }
832 
dryice_rtc_remove(struct platform_device * pdev)833 static void __exit dryice_rtc_remove(struct platform_device *pdev)
834 {
835 	struct imxdi_dev *imxdi = platform_get_drvdata(pdev);
836 
837 	flush_work(&imxdi->work);
838 
839 	/* mask all interrupts */
840 	writel(0, imxdi->ioaddr + DIER);
841 
842 	clk_disable_unprepare(imxdi->clk);
843 }
844 
845 static const struct of_device_id dryice_dt_ids[] = {
846 	{ .compatible = "fsl,imx25-rtc" },
847 	{ /* sentinel */ }
848 };
849 
850 MODULE_DEVICE_TABLE(of, dryice_dt_ids);
851 
852 /*
853  * dryice_rtc_remove() lives in .exit.text. For drivers registered via
854  * module_platform_driver_probe() this is ok because they cannot get unbound at
855  * runtime. So mark the driver struct with __refdata to prevent modpost
856  * triggering a section mismatch warning.
857  */
858 static struct platform_driver dryice_rtc_driver __refdata = {
859 	.driver = {
860 		   .name = "imxdi_rtc",
861 		   .of_match_table = dryice_dt_ids,
862 		   },
863 	.remove_new = __exit_p(dryice_rtc_remove),
864 };
865 
866 module_platform_driver_probe(dryice_rtc_driver, dryice_rtc_probe);
867 
868 MODULE_AUTHOR("Freescale Semiconductor, Inc.");
869 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
870 MODULE_DESCRIPTION("IMX DryIce Realtime Clock Driver (RTC)");
871 MODULE_LICENSE("GPL");
872