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Linux/drivers/rtc/rtc-mrst.c

  1 /*
  2  * rtc-mrst.c: Driver for Moorestown virtual RTC
  3  *
  4  * (C) Copyright 2009 Intel Corporation
  5  * Author: Jacob Pan (jacob.jun.pan@intel.com)
  6  *         Feng Tang (feng.tang@intel.com)
  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; version 2
 11  * of the License.
 12  *
 13  * Note:
 14  * VRTC is emulated by system controller firmware, the real HW
 15  * RTC is located in the PMIC device. SCU FW shadows PMIC RTC
 16  * in a memory mapped IO space that is visible to the host IA
 17  * processor.
 18  *
 19  * This driver is based upon drivers/rtc/rtc-cmos.c
 20  */
 21 
 22 /*
 23  * Note:
 24  *  * vRTC only supports binary mode and 24H mode
 25  *  * vRTC only support PIE and AIE, no UIE, and its PIE only happens
 26  *    at 23:59:59pm everyday, no support for adjustable frequency
 27  *  * Alarm function is also limited to hr/min/sec.
 28  */
 29 
 30 #include <linux/mod_devicetable.h>
 31 #include <linux/platform_device.h>
 32 #include <linux/interrupt.h>
 33 #include <linux/spinlock.h>
 34 #include <linux/kernel.h>
 35 #include <linux/module.h>
 36 #include <linux/init.h>
 37 #include <linux/sfi.h>
 38 
 39 #include <asm-generic/rtc.h>
 40 #include <asm/intel_scu_ipc.h>
 41 #include <asm/intel-mid.h>
 42 #include <asm/intel_mid_vrtc.h>
 43 
 44 struct mrst_rtc {
 45         struct rtc_device       *rtc;
 46         struct device           *dev;
 47         int                     irq;
 48         struct resource         *iomem;
 49 
 50         u8                      enabled_wake;
 51         u8                      suspend_ctrl;
 52 };
 53 
 54 static const char driver_name[] = "rtc_mrst";
 55 
 56 #define RTC_IRQMASK     (RTC_PF | RTC_AF)
 57 
 58 static inline int is_intr(u8 rtc_intr)
 59 {
 60         if (!(rtc_intr & RTC_IRQF))
 61                 return 0;
 62         return rtc_intr & RTC_IRQMASK;
 63 }
 64 
 65 static inline unsigned char vrtc_is_updating(void)
 66 {
 67         unsigned char uip;
 68         unsigned long flags;
 69 
 70         spin_lock_irqsave(&rtc_lock, flags);
 71         uip = (vrtc_cmos_read(RTC_FREQ_SELECT) & RTC_UIP);
 72         spin_unlock_irqrestore(&rtc_lock, flags);
 73         return uip;
 74 }
 75 
 76 /*
 77  * rtc_time's year contains the increment over 1900, but vRTC's YEAR
 78  * register can't be programmed to value larger than 0x64, so vRTC
 79  * driver chose to use 1972 (1970 is UNIX time start point) as the base,
 80  * and does the translation at read/write time.
 81  *
 82  * Why not just use 1970 as the offset? it's because using 1972 will
 83  * make it consistent in leap year setting for both vrtc and low-level
 84  * physical rtc devices. Then why not use 1960 as the offset? If we use
 85  * 1960, for a device's first use, its YEAR register is 0 and the system
 86  * year will be parsed as 1960 which is not a valid UNIX time and will
 87  * cause many applications to fail mysteriously.
 88  */
 89 static int mrst_read_time(struct device *dev, struct rtc_time *time)
 90 {
 91         unsigned long flags;
 92 
 93         if (vrtc_is_updating())
 94                 mdelay(20);
 95 
 96         spin_lock_irqsave(&rtc_lock, flags);
 97         time->tm_sec = vrtc_cmos_read(RTC_SECONDS);
 98         time->tm_min = vrtc_cmos_read(RTC_MINUTES);
 99         time->tm_hour = vrtc_cmos_read(RTC_HOURS);
100         time->tm_mday = vrtc_cmos_read(RTC_DAY_OF_MONTH);
101         time->tm_mon = vrtc_cmos_read(RTC_MONTH);
102         time->tm_year = vrtc_cmos_read(RTC_YEAR);
103         spin_unlock_irqrestore(&rtc_lock, flags);
104 
105         /* Adjust for the 1972/1900 */
106         time->tm_year += 72;
107         time->tm_mon--;
108         return rtc_valid_tm(time);
109 }
110 
111 static int mrst_set_time(struct device *dev, struct rtc_time *time)
112 {
113         int ret;
114         unsigned long flags;
115         unsigned char mon, day, hrs, min, sec;
116         unsigned int yrs;
117 
118         yrs = time->tm_year;
119         mon = time->tm_mon + 1;   /* tm_mon starts at zero */
120         day = time->tm_mday;
121         hrs = time->tm_hour;
122         min = time->tm_min;
123         sec = time->tm_sec;
124 
125         if (yrs < 72 || yrs > 138)
126                 return -EINVAL;
127         yrs -= 72;
128 
129         spin_lock_irqsave(&rtc_lock, flags);
130 
131         vrtc_cmos_write(yrs, RTC_YEAR);
132         vrtc_cmos_write(mon, RTC_MONTH);
133         vrtc_cmos_write(day, RTC_DAY_OF_MONTH);
134         vrtc_cmos_write(hrs, RTC_HOURS);
135         vrtc_cmos_write(min, RTC_MINUTES);
136         vrtc_cmos_write(sec, RTC_SECONDS);
137 
138         spin_unlock_irqrestore(&rtc_lock, flags);
139 
140         ret = intel_scu_ipc_simple_command(IPCMSG_VRTC, IPC_CMD_VRTC_SETTIME);
141         return ret;
142 }
143 
144 static int mrst_read_alarm(struct device *dev, struct rtc_wkalrm *t)
145 {
146         struct mrst_rtc *mrst = dev_get_drvdata(dev);
147         unsigned char rtc_control;
148 
149         if (mrst->irq <= 0)
150                 return -EIO;
151 
152         /* Basic alarms only support hour, minute, and seconds fields.
153          * Some also support day and month, for alarms up to a year in
154          * the future.
155          */
156         t->time.tm_mday = -1;
157         t->time.tm_mon = -1;
158         t->time.tm_year = -1;
159 
160         /* vRTC only supports binary mode */
161         spin_lock_irq(&rtc_lock);
162         t->time.tm_sec = vrtc_cmos_read(RTC_SECONDS_ALARM);
163         t->time.tm_min = vrtc_cmos_read(RTC_MINUTES_ALARM);
164         t->time.tm_hour = vrtc_cmos_read(RTC_HOURS_ALARM);
165 
166         rtc_control = vrtc_cmos_read(RTC_CONTROL);
167         spin_unlock_irq(&rtc_lock);
168 
169         t->enabled = !!(rtc_control & RTC_AIE);
170         t->pending = 0;
171 
172         return 0;
173 }
174 
175 static void mrst_checkintr(struct mrst_rtc *mrst, unsigned char rtc_control)
176 {
177         unsigned char   rtc_intr;
178 
179         /*
180          * NOTE after changing RTC_xIE bits we always read INTR_FLAGS;
181          * allegedly some older rtcs need that to handle irqs properly
182          */
183         rtc_intr = vrtc_cmos_read(RTC_INTR_FLAGS);
184         rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
185         if (is_intr(rtc_intr))
186                 rtc_update_irq(mrst->rtc, 1, rtc_intr);
187 }
188 
189 static void mrst_irq_enable(struct mrst_rtc *mrst, unsigned char mask)
190 {
191         unsigned char   rtc_control;
192 
193         /*
194          * Flush any pending IRQ status, notably for update irqs,
195          * before we enable new IRQs
196          */
197         rtc_control = vrtc_cmos_read(RTC_CONTROL);
198         mrst_checkintr(mrst, rtc_control);
199 
200         rtc_control |= mask;
201         vrtc_cmos_write(rtc_control, RTC_CONTROL);
202 
203         mrst_checkintr(mrst, rtc_control);
204 }
205 
206 static void mrst_irq_disable(struct mrst_rtc *mrst, unsigned char mask)
207 {
208         unsigned char   rtc_control;
209 
210         rtc_control = vrtc_cmos_read(RTC_CONTROL);
211         rtc_control &= ~mask;
212         vrtc_cmos_write(rtc_control, RTC_CONTROL);
213         mrst_checkintr(mrst, rtc_control);
214 }
215 
216 static int mrst_set_alarm(struct device *dev, struct rtc_wkalrm *t)
217 {
218         struct mrst_rtc *mrst = dev_get_drvdata(dev);
219         unsigned char hrs, min, sec;
220         int ret = 0;
221 
222         if (!mrst->irq)
223                 return -EIO;
224 
225         hrs = t->time.tm_hour;
226         min = t->time.tm_min;
227         sec = t->time.tm_sec;
228 
229         spin_lock_irq(&rtc_lock);
230         /* Next rtc irq must not be from previous alarm setting */
231         mrst_irq_disable(mrst, RTC_AIE);
232 
233         /* Update alarm */
234         vrtc_cmos_write(hrs, RTC_HOURS_ALARM);
235         vrtc_cmos_write(min, RTC_MINUTES_ALARM);
236         vrtc_cmos_write(sec, RTC_SECONDS_ALARM);
237 
238         spin_unlock_irq(&rtc_lock);
239 
240         ret = intel_scu_ipc_simple_command(IPCMSG_VRTC, IPC_CMD_VRTC_SETALARM);
241         if (ret)
242                 return ret;
243 
244         spin_lock_irq(&rtc_lock);
245         if (t->enabled)
246                 mrst_irq_enable(mrst, RTC_AIE);
247 
248         spin_unlock_irq(&rtc_lock);
249 
250         return 0;
251 }
252 
253 /* Currently, the vRTC doesn't support UIE ON/OFF */
254 static int mrst_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
255 {
256         struct mrst_rtc *mrst = dev_get_drvdata(dev);
257         unsigned long   flags;
258 
259         spin_lock_irqsave(&rtc_lock, flags);
260         if (enabled)
261                 mrst_irq_enable(mrst, RTC_AIE);
262         else
263                 mrst_irq_disable(mrst, RTC_AIE);
264         spin_unlock_irqrestore(&rtc_lock, flags);
265         return 0;
266 }
267 
268 
269 #if defined(CONFIG_RTC_INTF_PROC) || defined(CONFIG_RTC_INTF_PROC_MODULE)
270 
271 static int mrst_procfs(struct device *dev, struct seq_file *seq)
272 {
273         unsigned char   rtc_control, valid;
274 
275         spin_lock_irq(&rtc_lock);
276         rtc_control = vrtc_cmos_read(RTC_CONTROL);
277         valid = vrtc_cmos_read(RTC_VALID);
278         spin_unlock_irq(&rtc_lock);
279 
280         seq_printf(seq,
281                    "periodic_IRQ\t: %s\n"
282                    "alarm\t\t: %s\n"
283                    "BCD\t\t: no\n"
284                    "periodic_freq\t: daily (not adjustable)\n",
285                    (rtc_control & RTC_PIE) ? "on" : "off",
286                    (rtc_control & RTC_AIE) ? "on" : "off");
287 
288         return 0;
289 }
290 
291 #else
292 #define mrst_procfs     NULL
293 #endif
294 
295 static const struct rtc_class_ops mrst_rtc_ops = {
296         .read_time      = mrst_read_time,
297         .set_time       = mrst_set_time,
298         .read_alarm     = mrst_read_alarm,
299         .set_alarm      = mrst_set_alarm,
300         .proc           = mrst_procfs,
301         .alarm_irq_enable = mrst_rtc_alarm_irq_enable,
302 };
303 
304 static struct mrst_rtc  mrst_rtc;
305 
306 /*
307  * When vRTC IRQ is captured by SCU FW, FW will clear the AIE bit in
308  * Reg B, so no need for this driver to clear it
309  */
310 static irqreturn_t mrst_rtc_irq(int irq, void *p)
311 {
312         u8 irqstat;
313 
314         spin_lock(&rtc_lock);
315         /* This read will clear all IRQ flags inside Reg C */
316         irqstat = vrtc_cmos_read(RTC_INTR_FLAGS);
317         spin_unlock(&rtc_lock);
318 
319         irqstat &= RTC_IRQMASK | RTC_IRQF;
320         if (is_intr(irqstat)) {
321                 rtc_update_irq(p, 1, irqstat);
322                 return IRQ_HANDLED;
323         }
324         return IRQ_NONE;
325 }
326 
327 static int vrtc_mrst_do_probe(struct device *dev, struct resource *iomem,
328                               int rtc_irq)
329 {
330         int retval = 0;
331         unsigned char rtc_control;
332 
333         /* There can be only one ... */
334         if (mrst_rtc.dev)
335                 return -EBUSY;
336 
337         if (!iomem)
338                 return -ENODEV;
339 
340         iomem = request_mem_region(iomem->start, resource_size(iomem),
341                                    driver_name);
342         if (!iomem) {
343                 dev_dbg(dev, "i/o mem already in use.\n");
344                 return -EBUSY;
345         }
346 
347         mrst_rtc.irq = rtc_irq;
348         mrst_rtc.iomem = iomem;
349         mrst_rtc.dev = dev;
350         dev_set_drvdata(dev, &mrst_rtc);
351 
352         mrst_rtc.rtc = rtc_device_register(driver_name, dev,
353                                 &mrst_rtc_ops, THIS_MODULE);
354         if (IS_ERR(mrst_rtc.rtc)) {
355                 retval = PTR_ERR(mrst_rtc.rtc);
356                 goto cleanup0;
357         }
358 
359         rename_region(iomem, dev_name(&mrst_rtc.rtc->dev));
360 
361         spin_lock_irq(&rtc_lock);
362         mrst_irq_disable(&mrst_rtc, RTC_PIE | RTC_AIE);
363         rtc_control = vrtc_cmos_read(RTC_CONTROL);
364         spin_unlock_irq(&rtc_lock);
365 
366         if (!(rtc_control & RTC_24H) || (rtc_control & (RTC_DM_BINARY)))
367                 dev_dbg(dev, "TODO: support more than 24-hr BCD mode\n");
368 
369         if (rtc_irq) {
370                 retval = request_irq(rtc_irq, mrst_rtc_irq,
371                                 0, dev_name(&mrst_rtc.rtc->dev),
372                                 mrst_rtc.rtc);
373                 if (retval < 0) {
374                         dev_dbg(dev, "IRQ %d is already in use, err %d\n",
375                                 rtc_irq, retval);
376                         goto cleanup1;
377                 }
378         }
379         dev_dbg(dev, "initialised\n");
380         return 0;
381 
382 cleanup1:
383         rtc_device_unregister(mrst_rtc.rtc);
384 cleanup0:
385         mrst_rtc.dev = NULL;
386         release_mem_region(iomem->start, resource_size(iomem));
387         dev_err(dev, "rtc-mrst: unable to initialise\n");
388         return retval;
389 }
390 
391 static void rtc_mrst_do_shutdown(void)
392 {
393         spin_lock_irq(&rtc_lock);
394         mrst_irq_disable(&mrst_rtc, RTC_IRQMASK);
395         spin_unlock_irq(&rtc_lock);
396 }
397 
398 static void rtc_mrst_do_remove(struct device *dev)
399 {
400         struct mrst_rtc *mrst = dev_get_drvdata(dev);
401         struct resource *iomem;
402 
403         rtc_mrst_do_shutdown();
404 
405         if (mrst->irq)
406                 free_irq(mrst->irq, mrst->rtc);
407 
408         rtc_device_unregister(mrst->rtc);
409         mrst->rtc = NULL;
410 
411         iomem = mrst->iomem;
412         release_mem_region(iomem->start, resource_size(iomem));
413         mrst->iomem = NULL;
414 
415         mrst->dev = NULL;
416 }
417 
418 #ifdef CONFIG_PM_SLEEP
419 static int mrst_suspend(struct device *dev)
420 {
421         struct mrst_rtc *mrst = dev_get_drvdata(dev);
422         unsigned char   tmp;
423 
424         /* Only the alarm might be a wakeup event source */
425         spin_lock_irq(&rtc_lock);
426         mrst->suspend_ctrl = tmp = vrtc_cmos_read(RTC_CONTROL);
427         if (tmp & (RTC_PIE | RTC_AIE)) {
428                 unsigned char   mask;
429 
430                 if (device_may_wakeup(dev))
431                         mask = RTC_IRQMASK & ~RTC_AIE;
432                 else
433                         mask = RTC_IRQMASK;
434                 tmp &= ~mask;
435                 vrtc_cmos_write(tmp, RTC_CONTROL);
436 
437                 mrst_checkintr(mrst, tmp);
438         }
439         spin_unlock_irq(&rtc_lock);
440 
441         if (tmp & RTC_AIE) {
442                 mrst->enabled_wake = 1;
443                 enable_irq_wake(mrst->irq);
444         }
445 
446         dev_dbg(&mrst_rtc.rtc->dev, "suspend%s, ctrl %02x\n",
447                         (tmp & RTC_AIE) ? ", alarm may wake" : "",
448                         tmp);
449 
450         return 0;
451 }
452 
453 /*
454  * We want RTC alarms to wake us from the deep power saving state
455  */
456 static inline int mrst_poweroff(struct device *dev)
457 {
458         return mrst_suspend(dev);
459 }
460 
461 static int mrst_resume(struct device *dev)
462 {
463         struct mrst_rtc *mrst = dev_get_drvdata(dev);
464         unsigned char tmp = mrst->suspend_ctrl;
465 
466         /* Re-enable any irqs previously active */
467         if (tmp & RTC_IRQMASK) {
468                 unsigned char   mask;
469 
470                 if (mrst->enabled_wake) {
471                         disable_irq_wake(mrst->irq);
472                         mrst->enabled_wake = 0;
473                 }
474 
475                 spin_lock_irq(&rtc_lock);
476                 do {
477                         vrtc_cmos_write(tmp, RTC_CONTROL);
478 
479                         mask = vrtc_cmos_read(RTC_INTR_FLAGS);
480                         mask &= (tmp & RTC_IRQMASK) | RTC_IRQF;
481                         if (!is_intr(mask))
482                                 break;
483 
484                         rtc_update_irq(mrst->rtc, 1, mask);
485                         tmp &= ~RTC_AIE;
486                 } while (mask & RTC_AIE);
487                 spin_unlock_irq(&rtc_lock);
488         }
489 
490         dev_dbg(&mrst_rtc.rtc->dev, "resume, ctrl %02x\n", tmp);
491 
492         return 0;
493 }
494 
495 static SIMPLE_DEV_PM_OPS(mrst_pm_ops, mrst_suspend, mrst_resume);
496 #define MRST_PM_OPS (&mrst_pm_ops)
497 
498 #else
499 #define MRST_PM_OPS NULL
500 
501 static inline int mrst_poweroff(struct device *dev)
502 {
503         return -ENOSYS;
504 }
505 
506 #endif
507 
508 static int vrtc_mrst_platform_probe(struct platform_device *pdev)
509 {
510         return vrtc_mrst_do_probe(&pdev->dev,
511                         platform_get_resource(pdev, IORESOURCE_MEM, 0),
512                         platform_get_irq(pdev, 0));
513 }
514 
515 static int vrtc_mrst_platform_remove(struct platform_device *pdev)
516 {
517         rtc_mrst_do_remove(&pdev->dev);
518         return 0;
519 }
520 
521 static void vrtc_mrst_platform_shutdown(struct platform_device *pdev)
522 {
523         if (system_state == SYSTEM_POWER_OFF && !mrst_poweroff(&pdev->dev))
524                 return;
525 
526         rtc_mrst_do_shutdown();
527 }
528 
529 MODULE_ALIAS("platform:vrtc_mrst");
530 
531 static struct platform_driver vrtc_mrst_platform_driver = {
532         .probe          = vrtc_mrst_platform_probe,
533         .remove         = vrtc_mrst_platform_remove,
534         .shutdown       = vrtc_mrst_platform_shutdown,
535         .driver = {
536                 .name   = driver_name,
537                 .pm     = MRST_PM_OPS,
538         }
539 };
540 
541 module_platform_driver(vrtc_mrst_platform_driver);
542 
543 MODULE_AUTHOR("Jacob Pan; Feng Tang");
544 MODULE_DESCRIPTION("Driver for Moorestown virtual RTC");
545 MODULE_LICENSE("GPL");
546 

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