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	return 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
289#else
290#define	mrst_procfs	NULL
291#endif
292
293static const struct rtc_class_ops mrst_rtc_ops = {
294	.read_time	= mrst_read_time,
295	.set_time	= mrst_set_time,
296	.read_alarm	= mrst_read_alarm,
297	.set_alarm	= mrst_set_alarm,
298	.proc		= mrst_procfs,
299	.alarm_irq_enable = mrst_rtc_alarm_irq_enable,
300};
301
302static struct mrst_rtc	mrst_rtc;
303
304/*
305 * When vRTC IRQ is captured by SCU FW, FW will clear the AIE bit in
306 * Reg B, so no need for this driver to clear it
307 */
308static irqreturn_t mrst_rtc_irq(int irq, void *p)
309{
310	u8 irqstat;
311
312	spin_lock(&rtc_lock);
313	/* This read will clear all IRQ flags inside Reg C */
314	irqstat = vrtc_cmos_read(RTC_INTR_FLAGS);
315	spin_unlock(&rtc_lock);
316
317	irqstat &= RTC_IRQMASK | RTC_IRQF;
318	if (is_intr(irqstat)) {
319		rtc_update_irq(p, 1, irqstat);
320		return IRQ_HANDLED;
321	}
322	return IRQ_NONE;
323}
324
325static int vrtc_mrst_do_probe(struct device *dev, struct resource *iomem,
326			      int rtc_irq)
327{
328	int retval = 0;
329	unsigned char rtc_control;
330
331	/* There can be only one ... */
332	if (mrst_rtc.dev)
333		return -EBUSY;
334
335	if (!iomem)
336		return -ENODEV;
337
338	iomem = request_mem_region(iomem->start, resource_size(iomem),
339				   driver_name);
340	if (!iomem) {
341		dev_dbg(dev, "i/o mem already in use.\n");
342		return -EBUSY;
343	}
344
345	mrst_rtc.irq = rtc_irq;
346	mrst_rtc.iomem = iomem;
347	mrst_rtc.dev = dev;
348	dev_set_drvdata(dev, &mrst_rtc);
349
350	mrst_rtc.rtc = rtc_device_register(driver_name, dev,
351				&mrst_rtc_ops, THIS_MODULE);
352	if (IS_ERR(mrst_rtc.rtc)) {
353		retval = PTR_ERR(mrst_rtc.rtc);
354		goto cleanup0;
355	}
356
357	rename_region(iomem, dev_name(&mrst_rtc.rtc->dev));
358
359	spin_lock_irq(&rtc_lock);
360	mrst_irq_disable(&mrst_rtc, RTC_PIE | RTC_AIE);
361	rtc_control = vrtc_cmos_read(RTC_CONTROL);
362	spin_unlock_irq(&rtc_lock);
363
364	if (!(rtc_control & RTC_24H) || (rtc_control & (RTC_DM_BINARY)))
365		dev_dbg(dev, "TODO: support more than 24-hr BCD mode\n");
366
367	if (rtc_irq) {
368		retval = request_irq(rtc_irq, mrst_rtc_irq,
369				0, dev_name(&mrst_rtc.rtc->dev),
370				mrst_rtc.rtc);
371		if (retval < 0) {
372			dev_dbg(dev, "IRQ %d is already in use, err %d\n",
373				rtc_irq, retval);
374			goto cleanup1;
375		}
376	}
377	dev_dbg(dev, "initialised\n");
378	return 0;
379
380cleanup1:
381	rtc_device_unregister(mrst_rtc.rtc);
382cleanup0:
383	mrst_rtc.dev = NULL;
384	release_mem_region(iomem->start, resource_size(iomem));
385	dev_err(dev, "rtc-mrst: unable to initialise\n");
386	return retval;
387}
388
389static void rtc_mrst_do_shutdown(void)
390{
391	spin_lock_irq(&rtc_lock);
392	mrst_irq_disable(&mrst_rtc, RTC_IRQMASK);
393	spin_unlock_irq(&rtc_lock);
394}
395
396static void rtc_mrst_do_remove(struct device *dev)
397{
398	struct mrst_rtc	*mrst = dev_get_drvdata(dev);
399	struct resource *iomem;
400
401	rtc_mrst_do_shutdown();
402
403	if (mrst->irq)
404		free_irq(mrst->irq, mrst->rtc);
405
406	rtc_device_unregister(mrst->rtc);
407	mrst->rtc = NULL;
408
409	iomem = mrst->iomem;
410	release_mem_region(iomem->start, resource_size(iomem));
411	mrst->iomem = NULL;
412
413	mrst->dev = NULL;
414}
415
416#ifdef	CONFIG_PM
417static int mrst_suspend(struct device *dev, pm_message_t mesg)
418{
419	struct mrst_rtc	*mrst = dev_get_drvdata(dev);
420	unsigned char	tmp;
421
422	/* Only the alarm might be a wakeup event source */
423	spin_lock_irq(&rtc_lock);
424	mrst->suspend_ctrl = tmp = vrtc_cmos_read(RTC_CONTROL);
425	if (tmp & (RTC_PIE | RTC_AIE)) {
426		unsigned char	mask;
427
428		if (device_may_wakeup(dev))
429			mask = RTC_IRQMASK & ~RTC_AIE;
430		else
431			mask = RTC_IRQMASK;
432		tmp &= ~mask;
433		vrtc_cmos_write(tmp, RTC_CONTROL);
434
435		mrst_checkintr(mrst, tmp);
436	}
437	spin_unlock_irq(&rtc_lock);
438
439	if (tmp & RTC_AIE) {
440		mrst->enabled_wake = 1;
441		enable_irq_wake(mrst->irq);
442	}
443
444	dev_dbg(&mrst_rtc.rtc->dev, "suspend%s, ctrl %02x\n",
445			(tmp & RTC_AIE) ? ", alarm may wake" : "",
446			tmp);
447
448	return 0;
449}
450
451/*
452 * We want RTC alarms to wake us from the deep power saving state
453 */
454static inline int mrst_poweroff(struct device *dev)
455{
456	return mrst_suspend(dev, PMSG_HIBERNATE);
457}
458
459static int mrst_resume(struct device *dev)
460{
461	struct mrst_rtc	*mrst = dev_get_drvdata(dev);
462	unsigned char tmp = mrst->suspend_ctrl;
463
464	/* Re-enable any irqs previously active */
465	if (tmp & RTC_IRQMASK) {
466		unsigned char	mask;
467
468		if (mrst->enabled_wake) {
469			disable_irq_wake(mrst->irq);
470			mrst->enabled_wake = 0;
471		}
472
473		spin_lock_irq(&rtc_lock);
474		do {
475			vrtc_cmos_write(tmp, RTC_CONTROL);
476
477			mask = vrtc_cmos_read(RTC_INTR_FLAGS);
478			mask &= (tmp & RTC_IRQMASK) | RTC_IRQF;
479			if (!is_intr(mask))
480				break;
481
482			rtc_update_irq(mrst->rtc, 1, mask);
483			tmp &= ~RTC_AIE;
484		} while (mask & RTC_AIE);
485		spin_unlock_irq(&rtc_lock);
486	}
487
488	dev_dbg(&mrst_rtc.rtc->dev, "resume, ctrl %02x\n", tmp);
489
490	return 0;
491}
492
493#else
494#define	mrst_suspend	NULL
495#define	mrst_resume	NULL
496
497static inline int mrst_poweroff(struct device *dev)
498{
499	return -ENOSYS;
500}
501
502#endif
503
504static int vrtc_mrst_platform_probe(struct platform_device *pdev)
505{
506	return vrtc_mrst_do_probe(&pdev->dev,
507			platform_get_resource(pdev, IORESOURCE_MEM, 0),
508			platform_get_irq(pdev, 0));
509}
510
511static int vrtc_mrst_platform_remove(struct platform_device *pdev)
512{
513	rtc_mrst_do_remove(&pdev->dev);
514	return 0;
515}
516
517static void vrtc_mrst_platform_shutdown(struct platform_device *pdev)
518{
519	if (system_state == SYSTEM_POWER_OFF && !mrst_poweroff(&pdev->dev))
520		return;
521
522	rtc_mrst_do_shutdown();
523}
524
525MODULE_ALIAS("platform:vrtc_mrst");
526
527static struct platform_driver vrtc_mrst_platform_driver = {
528	.probe		= vrtc_mrst_platform_probe,
529	.remove		= vrtc_mrst_platform_remove,
530	.shutdown	= vrtc_mrst_platform_shutdown,
531	.driver = {
532		.name		= (char *) driver_name,
533		.suspend	= mrst_suspend,
534		.resume		= mrst_resume,
535	}
536};
537
538module_platform_driver(vrtc_mrst_platform_driver);
539
540MODULE_AUTHOR("Jacob Pan; Feng Tang");
541MODULE_DESCRIPTION("Driver for Moorestown virtual RTC");
542MODULE_LICENSE("GPL");