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
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	/* 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
175static 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
189static 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
206static 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
216static 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 */
254static 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
271static 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
295static 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
304static 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 */
310static 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
327static 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
382cleanup1:
383	rtc_device_unregister(mrst_rtc.rtc);
384cleanup0:
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
391static 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
398static 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
419static 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 */
456static inline int mrst_poweroff(struct device *dev)
457{
458	return mrst_suspend(dev);
459}
460
461static 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
495static 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
501static inline int mrst_poweroff(struct device *dev)
502{
503	return -ENOSYS;
504}
505
506#endif
507
508static 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
515static int vrtc_mrst_platform_remove(struct platform_device *pdev)
516{
517	rtc_mrst_do_remove(&pdev->dev);
518	return 0;
519}
520
521static 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
529MODULE_ALIAS("platform:vrtc_mrst");
530
531static 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
541module_platform_driver(vrtc_mrst_platform_driver);
542
543MODULE_AUTHOR("Jacob Pan; Feng Tang");
544MODULE_DESCRIPTION("Driver for Moorestown virtual RTC");
545MODULE_LICENSE("GPL");
546