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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/mc146818rtc.h>
36#include <linux/module.h>
37#include <linux/init.h>
38#include <linux/sfi.h>
39
40#include <asm/intel_scu_ipc.h>
41#include <asm/intel-mid.h>
42#include <asm/intel_mid_vrtc.h>
43
44struct 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
54static const char driver_name[] = "rtc_mrst";
55
56#define RTC_IRQMASK (RTC_PF | RTC_AF)
57
58static 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
65static 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 */
89static 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
111static 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
144static 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 /* vRTC only supports binary mode */
153 spin_lock_irq(&rtc_lock);
154 t->time.tm_sec = vrtc_cmos_read(RTC_SECONDS_ALARM);
155 t->time.tm_min = vrtc_cmos_read(RTC_MINUTES_ALARM);
156 t->time.tm_hour = vrtc_cmos_read(RTC_HOURS_ALARM);
157
158 rtc_control = vrtc_cmos_read(RTC_CONTROL);
159 spin_unlock_irq(&rtc_lock);
160
161 t->enabled = !!(rtc_control & RTC_AIE);
162 t->pending = 0;
163
164 return 0;
165}
166
167static void mrst_checkintr(struct mrst_rtc *mrst, unsigned char rtc_control)
168{
169 unsigned char rtc_intr;
170
171 /*
172 * NOTE after changing RTC_xIE bits we always read INTR_FLAGS;
173 * allegedly some older rtcs need that to handle irqs properly
174 */
175 rtc_intr = vrtc_cmos_read(RTC_INTR_FLAGS);
176 rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
177 if (is_intr(rtc_intr))
178 rtc_update_irq(mrst->rtc, 1, rtc_intr);
179}
180
181static void mrst_irq_enable(struct mrst_rtc *mrst, unsigned char mask)
182{
183 unsigned char rtc_control;
184
185 /*
186 * Flush any pending IRQ status, notably for update irqs,
187 * before we enable new IRQs
188 */
189 rtc_control = vrtc_cmos_read(RTC_CONTROL);
190 mrst_checkintr(mrst, rtc_control);
191
192 rtc_control |= mask;
193 vrtc_cmos_write(rtc_control, RTC_CONTROL);
194
195 mrst_checkintr(mrst, rtc_control);
196}
197
198static void mrst_irq_disable(struct mrst_rtc *mrst, unsigned char mask)
199{
200 unsigned char rtc_control;
201
202 rtc_control = vrtc_cmos_read(RTC_CONTROL);
203 rtc_control &= ~mask;
204 vrtc_cmos_write(rtc_control, RTC_CONTROL);
205 mrst_checkintr(mrst, rtc_control);
206}
207
208static int mrst_set_alarm(struct device *dev, struct rtc_wkalrm *t)
209{
210 struct mrst_rtc *mrst = dev_get_drvdata(dev);
211 unsigned char hrs, min, sec;
212 int ret = 0;
213
214 if (!mrst->irq)
215 return -EIO;
216
217 hrs = t->time.tm_hour;
218 min = t->time.tm_min;
219 sec = t->time.tm_sec;
220
221 spin_lock_irq(&rtc_lock);
222 /* Next rtc irq must not be from previous alarm setting */
223 mrst_irq_disable(mrst, RTC_AIE);
224
225 /* Update alarm */
226 vrtc_cmos_write(hrs, RTC_HOURS_ALARM);
227 vrtc_cmos_write(min, RTC_MINUTES_ALARM);
228 vrtc_cmos_write(sec, RTC_SECONDS_ALARM);
229
230 spin_unlock_irq(&rtc_lock);
231
232 ret = intel_scu_ipc_simple_command(IPCMSG_VRTC, IPC_CMD_VRTC_SETALARM);
233 if (ret)
234 return ret;
235
236 spin_lock_irq(&rtc_lock);
237 if (t->enabled)
238 mrst_irq_enable(mrst, RTC_AIE);
239
240 spin_unlock_irq(&rtc_lock);
241
242 return 0;
243}
244
245/* Currently, the vRTC doesn't support UIE ON/OFF */
246static int mrst_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
247{
248 struct mrst_rtc *mrst = dev_get_drvdata(dev);
249 unsigned long flags;
250
251 spin_lock_irqsave(&rtc_lock, flags);
252 if (enabled)
253 mrst_irq_enable(mrst, RTC_AIE);
254 else
255 mrst_irq_disable(mrst, RTC_AIE);
256 spin_unlock_irqrestore(&rtc_lock, flags);
257 return 0;
258}
259
260
261#if IS_ENABLED(CONFIG_RTC_INTF_PROC)
262
263static int mrst_procfs(struct device *dev, struct seq_file *seq)
264{
265 unsigned char rtc_control, valid;
266
267 spin_lock_irq(&rtc_lock);
268 rtc_control = vrtc_cmos_read(RTC_CONTROL);
269 valid = vrtc_cmos_read(RTC_VALID);
270 spin_unlock_irq(&rtc_lock);
271
272 seq_printf(seq,
273 "periodic_IRQ\t: %s\n"
274 "alarm\t\t: %s\n"
275 "BCD\t\t: no\n"
276 "periodic_freq\t: daily (not adjustable)\n",
277 (rtc_control & RTC_PIE) ? "on" : "off",
278 (rtc_control & RTC_AIE) ? "on" : "off");
279
280 return 0;
281}
282
283#else
284#define mrst_procfs NULL
285#endif
286
287static const struct rtc_class_ops mrst_rtc_ops = {
288 .read_time = mrst_read_time,
289 .set_time = mrst_set_time,
290 .read_alarm = mrst_read_alarm,
291 .set_alarm = mrst_set_alarm,
292 .proc = mrst_procfs,
293 .alarm_irq_enable = mrst_rtc_alarm_irq_enable,
294};
295
296static struct mrst_rtc mrst_rtc;
297
298/*
299 * When vRTC IRQ is captured by SCU FW, FW will clear the AIE bit in
300 * Reg B, so no need for this driver to clear it
301 */
302static irqreturn_t mrst_rtc_irq(int irq, void *p)
303{
304 u8 irqstat;
305
306 spin_lock(&rtc_lock);
307 /* This read will clear all IRQ flags inside Reg C */
308 irqstat = vrtc_cmos_read(RTC_INTR_FLAGS);
309 spin_unlock(&rtc_lock);
310
311 irqstat &= RTC_IRQMASK | RTC_IRQF;
312 if (is_intr(irqstat)) {
313 rtc_update_irq(p, 1, irqstat);
314 return IRQ_HANDLED;
315 }
316 return IRQ_NONE;
317}
318
319static int vrtc_mrst_do_probe(struct device *dev, struct resource *iomem,
320 int rtc_irq)
321{
322 int retval = 0;
323 unsigned char rtc_control;
324
325 /* There can be only one ... */
326 if (mrst_rtc.dev)
327 return -EBUSY;
328
329 if (!iomem)
330 return -ENODEV;
331
332 iomem = request_mem_region(iomem->start, resource_size(iomem),
333 driver_name);
334 if (!iomem) {
335 dev_dbg(dev, "i/o mem already in use.\n");
336 return -EBUSY;
337 }
338
339 mrst_rtc.irq = rtc_irq;
340 mrst_rtc.iomem = iomem;
341 mrst_rtc.dev = dev;
342 dev_set_drvdata(dev, &mrst_rtc);
343
344 mrst_rtc.rtc = rtc_device_register(driver_name, dev,
345 &mrst_rtc_ops, THIS_MODULE);
346 if (IS_ERR(mrst_rtc.rtc)) {
347 retval = PTR_ERR(mrst_rtc.rtc);
348 goto cleanup0;
349 }
350
351 rename_region(iomem, dev_name(&mrst_rtc.rtc->dev));
352
353 spin_lock_irq(&rtc_lock);
354 mrst_irq_disable(&mrst_rtc, RTC_PIE | RTC_AIE);
355 rtc_control = vrtc_cmos_read(RTC_CONTROL);
356 spin_unlock_irq(&rtc_lock);
357
358 if (!(rtc_control & RTC_24H) || (rtc_control & (RTC_DM_BINARY)))
359 dev_dbg(dev, "TODO: support more than 24-hr BCD mode\n");
360
361 if (rtc_irq) {
362 retval = request_irq(rtc_irq, mrst_rtc_irq,
363 0, dev_name(&mrst_rtc.rtc->dev),
364 mrst_rtc.rtc);
365 if (retval < 0) {
366 dev_dbg(dev, "IRQ %d is already in use, err %d\n",
367 rtc_irq, retval);
368 goto cleanup1;
369 }
370 }
371 dev_dbg(dev, "initialised\n");
372 return 0;
373
374cleanup1:
375 rtc_device_unregister(mrst_rtc.rtc);
376cleanup0:
377 mrst_rtc.dev = NULL;
378 release_mem_region(iomem->start, resource_size(iomem));
379 dev_err(dev, "rtc-mrst: unable to initialise\n");
380 return retval;
381}
382
383static void rtc_mrst_do_shutdown(void)
384{
385 spin_lock_irq(&rtc_lock);
386 mrst_irq_disable(&mrst_rtc, RTC_IRQMASK);
387 spin_unlock_irq(&rtc_lock);
388}
389
390static void rtc_mrst_do_remove(struct device *dev)
391{
392 struct mrst_rtc *mrst = dev_get_drvdata(dev);
393 struct resource *iomem;
394
395 rtc_mrst_do_shutdown();
396
397 if (mrst->irq)
398 free_irq(mrst->irq, mrst->rtc);
399
400 rtc_device_unregister(mrst->rtc);
401 mrst->rtc = NULL;
402
403 iomem = mrst->iomem;
404 release_mem_region(iomem->start, resource_size(iomem));
405 mrst->iomem = NULL;
406
407 mrst->dev = NULL;
408}
409
410#ifdef CONFIG_PM_SLEEP
411static int mrst_suspend(struct device *dev)
412{
413 struct mrst_rtc *mrst = dev_get_drvdata(dev);
414 unsigned char tmp;
415
416 /* Only the alarm might be a wakeup event source */
417 spin_lock_irq(&rtc_lock);
418 mrst->suspend_ctrl = tmp = vrtc_cmos_read(RTC_CONTROL);
419 if (tmp & (RTC_PIE | RTC_AIE)) {
420 unsigned char mask;
421
422 if (device_may_wakeup(dev))
423 mask = RTC_IRQMASK & ~RTC_AIE;
424 else
425 mask = RTC_IRQMASK;
426 tmp &= ~mask;
427 vrtc_cmos_write(tmp, RTC_CONTROL);
428
429 mrst_checkintr(mrst, tmp);
430 }
431 spin_unlock_irq(&rtc_lock);
432
433 if (tmp & RTC_AIE) {
434 mrst->enabled_wake = 1;
435 enable_irq_wake(mrst->irq);
436 }
437
438 dev_dbg(&mrst_rtc.rtc->dev, "suspend%s, ctrl %02x\n",
439 (tmp & RTC_AIE) ? ", alarm may wake" : "",
440 tmp);
441
442 return 0;
443}
444
445/*
446 * We want RTC alarms to wake us from the deep power saving state
447 */
448static inline int mrst_poweroff(struct device *dev)
449{
450 return mrst_suspend(dev);
451}
452
453static int mrst_resume(struct device *dev)
454{
455 struct mrst_rtc *mrst = dev_get_drvdata(dev);
456 unsigned char tmp = mrst->suspend_ctrl;
457
458 /* Re-enable any irqs previously active */
459 if (tmp & RTC_IRQMASK) {
460 unsigned char mask;
461
462 if (mrst->enabled_wake) {
463 disable_irq_wake(mrst->irq);
464 mrst->enabled_wake = 0;
465 }
466
467 spin_lock_irq(&rtc_lock);
468 do {
469 vrtc_cmos_write(tmp, RTC_CONTROL);
470
471 mask = vrtc_cmos_read(RTC_INTR_FLAGS);
472 mask &= (tmp & RTC_IRQMASK) | RTC_IRQF;
473 if (!is_intr(mask))
474 break;
475
476 rtc_update_irq(mrst->rtc, 1, mask);
477 tmp &= ~RTC_AIE;
478 } while (mask & RTC_AIE);
479 spin_unlock_irq(&rtc_lock);
480 }
481
482 dev_dbg(&mrst_rtc.rtc->dev, "resume, ctrl %02x\n", tmp);
483
484 return 0;
485}
486
487static SIMPLE_DEV_PM_OPS(mrst_pm_ops, mrst_suspend, mrst_resume);
488#define MRST_PM_OPS (&mrst_pm_ops)
489
490#else
491#define MRST_PM_OPS NULL
492
493static inline int mrst_poweroff(struct device *dev)
494{
495 return -ENOSYS;
496}
497
498#endif
499
500static int vrtc_mrst_platform_probe(struct platform_device *pdev)
501{
502 return vrtc_mrst_do_probe(&pdev->dev,
503 platform_get_resource(pdev, IORESOURCE_MEM, 0),
504 platform_get_irq(pdev, 0));
505}
506
507static int vrtc_mrst_platform_remove(struct platform_device *pdev)
508{
509 rtc_mrst_do_remove(&pdev->dev);
510 return 0;
511}
512
513static void vrtc_mrst_platform_shutdown(struct platform_device *pdev)
514{
515 if (system_state == SYSTEM_POWER_OFF && !mrst_poweroff(&pdev->dev))
516 return;
517
518 rtc_mrst_do_shutdown();
519}
520
521MODULE_ALIAS("platform:vrtc_mrst");
522
523static struct platform_driver vrtc_mrst_platform_driver = {
524 .probe = vrtc_mrst_platform_probe,
525 .remove = vrtc_mrst_platform_remove,
526 .shutdown = vrtc_mrst_platform_shutdown,
527 .driver = {
528 .name = driver_name,
529 .pm = MRST_PM_OPS,
530 }
531};
532
533module_platform_driver(vrtc_mrst_platform_driver);
534
535MODULE_AUTHOR("Jacob Pan; Feng Tang");
536MODULE_DESCRIPTION("Driver for Moorestown virtual RTC");
537MODULE_LICENSE("GPL");