drivers/rtc/rtc-sa1100.c - kernel/msm-4.9 - Gitiles

 /*
  * Real Time Clock interface for StrongARM SA1x00 and XScale PXA2xx
  *
  * Copyright (c) 2000 Nils Faerber
  *
  * Based on rtc.c by Paul Gortmaker
  *
  * Original Driver by Nils Faerber <nils@kernelconcepts.de>
  *
  * Modifications from:
  *   CIH <cih@coventive.com>
  *   Nicolas Pitre <nico@cam.org>
  *   Andrew Christian <andrew.christian@hp.com>
  *
  * Converted to the RTC subsystem and Driver Model
  *   by Richard Purdie <rpurdie@rpsys.net>
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version
  * 2 of the License, or (at your option) any later version.
  */

 #include <linux/platform_device.h>
 #include <linux/module.h>
 #include <linux/rtc.h>
 #include <linux/init.h>
 #include <linux/fs.h>
 #include <linux/interrupt.h>
 #include <linux/string.h>
 #include <linux/pm.h>
 #include <linux/bitops.h>

 #include <asm/hardware.h>
 #include <asm/irq.h>
 #include <asm/rtc.h>

 #ifdef CONFIG_ARCH_PXA
 #include <asm/arch/pxa-regs.h>
 #endif

 #define TIMER_FREQ		CLOCK_TICK_RATE
 #define RTC_DEF_DIVIDER		32768 - 1
 #define RTC_DEF_TRIM		0

 static unsigned long rtc_freq = 1024;
 static struct rtc_time rtc_alarm;
 static DEFINE_SPINLOCK(sa1100_rtc_lock);

 static int rtc_update_alarm(struct rtc_time *alrm)
 {
 	struct rtc_time alarm_tm, now_tm;
 	unsigned long now, time;
 	int ret;

 	do {
 		now = RCNR;
 		rtc_time_to_tm(now, &now_tm);
 		rtc_next_alarm_time(&alarm_tm, &now_tm, alrm);
 		ret = rtc_tm_to_time(&alarm_tm, &time);
 		if (ret != 0)
 			break;

 		RTSR = RTSR & (RTSR_HZE|RTSR_ALE|RTSR_AL);
 		RTAR = time;
 	} while (now != RCNR);

 	return ret;
 }

 static irqreturn_t sa1100_rtc_interrupt(int irq, void *dev_id)
 {
 	struct platform_device *pdev = to_platform_device(dev_id);
 	struct rtc_device *rtc = platform_get_drvdata(pdev);
 	unsigned int rtsr;
 	unsigned long events = 0;

 	spin_lock(&sa1100_rtc_lock);

 	rtsr = RTSR;
 	/* clear interrupt sources */
 	RTSR = 0;
 	RTSR = (RTSR_AL | RTSR_HZ) & (rtsr >> 2);

 	/* clear alarm interrupt if it has occurred */
 	if (rtsr & RTSR_AL)
 		rtsr &= ~RTSR_ALE;
 	RTSR = rtsr & (RTSR_ALE | RTSR_HZE);

 	/* update irq data & counter */
 	if (rtsr & RTSR_AL)
 		events |= RTC_AF | RTC_IRQF;
 	if (rtsr & RTSR_HZ)
 		events |= RTC_UF | RTC_IRQF;

 	rtc_update_irq(rtc, 1, events);

 	if (rtsr & RTSR_AL && rtc_periodic_alarm(&rtc_alarm))
 		rtc_update_alarm(&rtc_alarm);

 	spin_unlock(&sa1100_rtc_lock);

 	return IRQ_HANDLED;
 }

 static int rtc_timer1_count;

 static irqreturn_t timer1_interrupt(int irq, void *dev_id)
 {
 	struct platform_device *pdev = to_platform_device(dev_id);
 	struct rtc_device *rtc = platform_get_drvdata(pdev);

 	/*
 	 * If we match for the first time, rtc_timer1_count will be 1.
 	 * Otherwise, we wrapped around (very unlikely but
 	 * still possible) so compute the amount of missed periods.
 	 * The match reg is updated only when the data is actually retrieved
 	 * to avoid unnecessary interrupts.
 	 */
 	OSSR = OSSR_M1;	/* clear match on timer1 */

 	rtc_update_irq(rtc, rtc_timer1_count, RTC_PF | RTC_IRQF);

 	if (rtc_timer1_count == 1)
 		rtc_timer1_count = (rtc_freq * ((1<<30)/(TIMER_FREQ>>2)));

 	return IRQ_HANDLED;
 }

 static int sa1100_rtc_read_callback(struct device *dev, int data)
 {
 	if (data & RTC_PF) {
 		/* interpolate missed periods and set match for the next */
 		unsigned long period = TIMER_FREQ/rtc_freq;
 		unsigned long oscr = OSCR;
 		unsigned long osmr1 = OSMR1;
 		unsigned long missed = (oscr - osmr1)/period;
 		data += missed << 8;
 		OSSR = OSSR_M1;	/* clear match on timer 1 */
 		OSMR1 = osmr1 + (missed + 1)*period;
 		/* Ensure we didn't miss another match in the mean time.
 		 * Here we compare (match - OSCR) 8 instead of 0 --
 		 * see comment in pxa_timer_interrupt() for explanation.
 		 */
 		while( (signed long)((osmr1 = OSMR1) - OSCR) <= 8 ) {
 			data += 0x100;
 			OSSR = OSSR_M1;	/* clear match on timer 1 */
 			OSMR1 = osmr1 + period;
 		}
 	}
 	return data;
 }

 static int sa1100_rtc_open(struct device *dev)
 {
 	int ret;

 	ret = request_irq(IRQ_RTC1Hz, sa1100_rtc_interrupt, IRQF_DISABLED,
 				"rtc 1Hz", dev);
 	if (ret) {
 		dev_err(dev, "IRQ %d already in use.\n", IRQ_RTC1Hz);
 		goto fail_ui;
 	}
 	ret = request_irq(IRQ_RTCAlrm, sa1100_rtc_interrupt, IRQF_DISABLED,
 				"rtc Alrm", dev);
 	if (ret) {
 		dev_err(dev, "IRQ %d already in use.\n", IRQ_RTCAlrm);
 		goto fail_ai;
 	}
 	ret = request_irq(IRQ_OST1, timer1_interrupt, IRQF_DISABLED,
 				"rtc timer", dev);
 	if (ret) {
 		dev_err(dev, "IRQ %d already in use.\n", IRQ_OST1);
 		goto fail_pi;
 	}
 	return 0;

  fail_pi:
 	free_irq(IRQ_RTCAlrm, dev);
  fail_ai:
 	free_irq(IRQ_RTC1Hz, dev);
  fail_ui:
 	return ret;
 }

 static void sa1100_rtc_release(struct device *dev)
 {
 	spin_lock_irq(&sa1100_rtc_lock);
 	RTSR = 0;
 	OIER &= ~OIER_E1;
 	OSSR = OSSR_M1;
 	spin_unlock_irq(&sa1100_rtc_lock);

 	free_irq(IRQ_OST1, dev);
 	free_irq(IRQ_RTCAlrm, dev);
 	free_irq(IRQ_RTC1Hz, dev);
 }


 static int sa1100_rtc_ioctl(struct device *dev, unsigned int cmd,
 		unsigned long arg)
 {
 	switch(cmd) {
 	case RTC_AIE_OFF:
 		spin_lock_irq(&sa1100_rtc_lock);
 		RTSR &= ~RTSR_ALE;
 		spin_unlock_irq(&sa1100_rtc_lock);
 		return 0;
 	case RTC_AIE_ON:
 		spin_lock_irq(&sa1100_rtc_lock);
 		RTSR |= RTSR_ALE;
 		spin_unlock_irq(&sa1100_rtc_lock);
 		return 0;
 	case RTC_UIE_OFF:
 		spin_lock_irq(&sa1100_rtc_lock);
 		RTSR &= ~RTSR_HZE;
 		spin_unlock_irq(&sa1100_rtc_lock);
 		return 0;
 	case RTC_UIE_ON:
 		spin_lock_irq(&sa1100_rtc_lock);
 		RTSR |= RTSR_HZE;
 		spin_unlock_irq(&sa1100_rtc_lock);
 		return 0;
 	case RTC_PIE_OFF:
 		spin_lock_irq(&sa1100_rtc_lock);
 		OIER &= ~OIER_E1;
 		spin_unlock_irq(&sa1100_rtc_lock);
 		return 0;
 	case RTC_PIE_ON:
 		spin_lock_irq(&sa1100_rtc_lock);
 		OSMR1 = TIMER_FREQ/rtc_freq + OSCR;
 		OIER |= OIER_E1;
 		rtc_timer1_count = 1;
 		spin_unlock_irq(&sa1100_rtc_lock);
 		return 0;
 	case RTC_IRQP_READ:
 		return put_user(rtc_freq, (unsigned long *)arg);
 	case RTC_IRQP_SET:
 		if (arg < 1 || arg > TIMER_FREQ)
 			return -EINVAL;
 		rtc_freq = arg;
 		return 0;
 	}
 	return -ENOIOCTLCMD;
 }

 static int sa1100_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	rtc_time_to_tm(RCNR, tm);
 	return 0;
 }

 static int sa1100_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	unsigned long time;
 	int ret;

 	ret = rtc_tm_to_time(tm, &time);
 	if (ret == 0)
 		RCNR = time;
 	return ret;
 }

 static int sa1100_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
 	u32	rtsr;

 	memcpy(&alrm->time, &rtc_alarm, sizeof(struct rtc_time));
 	rtsr = RTSR;
 	alrm->enabled = (rtsr & RTSR_ALE) ? 1 : 0;
 	alrm->pending = (rtsr & RTSR_AL) ? 1 : 0;
 	return 0;
 }

 static int sa1100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
 	int ret;

 	spin_lock_irq(&sa1100_rtc_lock);
 	ret = rtc_update_alarm(&alrm->time);
 	if (ret == 0) {
 		if (alrm->enabled)
 			RTSR |= RTSR_ALE;
 		else
 			RTSR &= ~RTSR_ALE;
 	}
 	spin_unlock_irq(&sa1100_rtc_lock);

 	return ret;
 }

 static int sa1100_rtc_proc(struct device *dev, struct seq_file *seq)
 {
 	seq_printf(seq, "trim/divider\t: 0x%08x\n", (u32) RTTR);
 	seq_printf(seq, "update_IRQ\t: %s\n",
 			(RTSR & RTSR_HZE) ? "yes" : "no");
 	seq_printf(seq, "periodic_IRQ\t: %s\n",
 			(OIER & OIER_E1) ? "yes" : "no");
 	seq_printf(seq, "periodic_freq\t: %ld\n", rtc_freq);

 	return 0;
 }

 static const struct rtc_class_ops sa1100_rtc_ops = {
 	.open = sa1100_rtc_open,
 	.read_callback = sa1100_rtc_read_callback,
 	.release = sa1100_rtc_release,
 	.ioctl = sa1100_rtc_ioctl,
 	.read_time = sa1100_rtc_read_time,
 	.set_time = sa1100_rtc_set_time,
 	.read_alarm = sa1100_rtc_read_alarm,
 	.set_alarm = sa1100_rtc_set_alarm,
 	.proc = sa1100_rtc_proc,
 };

 static int sa1100_rtc_probe(struct platform_device *pdev)
 {
 	struct rtc_device *rtc;

 	/*
 	 * According to the manual we should be able to let RTTR be zero
 	 * and then a default diviser for a 32.768KHz clock is used.
 	 * Apparently this doesn't work, at least for my SA1110 rev 5.
 	 * If the clock divider is uninitialized then reset it to the
 	 * default value to get the 1Hz clock.
 	 */
 	if (RTTR == 0) {
 		RTTR = RTC_DEF_DIVIDER + (RTC_DEF_TRIM << 16);
 		dev_warn(&pdev->dev, "warning: initializing default clock divider/trim value\n");
 		/* The current RTC value probably doesn't make sense either */
 		RCNR = 0;
 	}

 	rtc = rtc_device_register(pdev->name, &pdev->dev, &sa1100_rtc_ops,
 				THIS_MODULE);

 	if (IS_ERR(rtc))
 		return PTR_ERR(rtc);

 	platform_set_drvdata(pdev, rtc);

 	return 0;
 }

 static int sa1100_rtc_remove(struct platform_device *pdev)
 {
 	struct rtc_device *rtc = platform_get_drvdata(pdev);

  	if (rtc)
 		rtc_device_unregister(rtc);

 	return 0;
 }

 static struct platform_driver sa1100_rtc_driver = {
 	.probe		= sa1100_rtc_probe,
 	.remove		= sa1100_rtc_remove,
 	.driver		= {
 		.name		= "sa1100-rtc",
 	},
 };

 static int __init sa1100_rtc_init(void)
 {
 	return platform_driver_register(&sa1100_rtc_driver);
 }

 static void __exit sa1100_rtc_exit(void)
 {
 	platform_driver_unregister(&sa1100_rtc_driver);
 }

 module_init(sa1100_rtc_init);
 module_exit(sa1100_rtc_exit);

 MODULE_AUTHOR("Richard Purdie <rpurdie@rpsys.net>");
 MODULE_DESCRIPTION("SA11x0/PXA2xx Realtime Clock Driver (RTC)");
 MODULE_LICENSE("GPL");
	/*
	* Real Time Clock interface for StrongARM SA1x00 and XScale PXA2xx
	*
	* Copyright (c) 2000 Nils Faerber
	*
	* Based on rtc.c by Paul Gortmaker
	*
	* Original Driver by Nils Faerber <nils@kernelconcepts.de>
	*
	* Modifications from:
	* CIH <cih@coventive.com>
	* Nicolas Pitre <nico@cam.org>
	* Andrew Christian <andrew.christian@hp.com>
	*
	* Converted to the RTC subsystem and Driver Model
	* by Richard Purdie <rpurdie@rpsys.net>
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License
	* as published by the Free Software Foundation; either version
	* 2 of the License, or (at your option) any later version.
	*/

	#include <linux/platform_device.h>
	#include <linux/module.h>
	#include <linux/rtc.h>
	#include <linux/init.h>
	#include <linux/fs.h>
	#include <linux/interrupt.h>
	#include <linux/string.h>
	#include <linux/pm.h>
	#include <linux/bitops.h>

	#include <asm/hardware.h>
	#include <asm/irq.h>
	#include <asm/rtc.h>

	#ifdef CONFIG_ARCH_PXA
	#include <asm/arch/pxa-regs.h>
	#endif

	#define TIMER_FREQ CLOCK_TICK_RATE
	#define RTC_DEF_DIVIDER 32768 - 1
	#define RTC_DEF_TRIM 0

	static unsigned long rtc_freq = 1024;
	static struct rtc_time rtc_alarm;
	static DEFINE_SPINLOCK(sa1100_rtc_lock);

	static int rtc_update_alarm(struct rtc_time *alrm)
	{
	struct rtc_time alarm_tm, now_tm;
	unsigned long now, time;
	int ret;

	do {
	now = RCNR;
	rtc_time_to_tm(now, &now_tm);
	rtc_next_alarm_time(&alarm_tm, &now_tm, alrm);
	ret = rtc_tm_to_time(&alarm_tm, &time);
	if (ret != 0)
	break;

	RTSR = RTSR & (RTSR_HZE\|RTSR_ALE\|RTSR_AL);
	RTAR = time;
	} while (now != RCNR);

	return ret;
	}

	static irqreturn_t sa1100_rtc_interrupt(int irq, void *dev_id)
	{
	struct platform_device *pdev = to_platform_device(dev_id);
	struct rtc_device *rtc = platform_get_drvdata(pdev);
	unsigned int rtsr;
	unsigned long events = 0;

	spin_lock(&sa1100_rtc_lock);

	rtsr = RTSR;
	/* clear interrupt sources */
	RTSR = 0;
	RTSR = (RTSR_AL \| RTSR_HZ) & (rtsr >> 2);

	/* clear alarm interrupt if it has occurred */
	if (rtsr & RTSR_AL)
	rtsr &= ~RTSR_ALE;
	RTSR = rtsr & (RTSR_ALE \| RTSR_HZE);

	/* update irq data & counter */
	if (rtsr & RTSR_AL)
	events \|= RTC_AF \| RTC_IRQF;
	if (rtsr & RTSR_HZ)
	events \|= RTC_UF \| RTC_IRQF;

	rtc_update_irq(rtc, 1, events);

	if (rtsr & RTSR_AL && rtc_periodic_alarm(&rtc_alarm))
	rtc_update_alarm(&rtc_alarm);

	spin_unlock(&sa1100_rtc_lock);

	return IRQ_HANDLED;
	}

	static int rtc_timer1_count;

	static irqreturn_t timer1_interrupt(int irq, void *dev_id)
	{
	struct platform_device *pdev = to_platform_device(dev_id);
	struct rtc_device *rtc = platform_get_drvdata(pdev);

	/*
	* If we match for the first time, rtc_timer1_count will be 1.
	* Otherwise, we wrapped around (very unlikely but
	* still possible) so compute the amount of missed periods.
	* The match reg is updated only when the data is actually retrieved
	* to avoid unnecessary interrupts.
	*/
	OSSR = OSSR_M1; /* clear match on timer1 */

	rtc_update_irq(rtc, rtc_timer1_count, RTC_PF \| RTC_IRQF);

	if (rtc_timer1_count == 1)
	rtc_timer1_count = (rtc_freq * ((1<<30)/(TIMER_FREQ>>2)));

	return IRQ_HANDLED;
	}

	static int sa1100_rtc_read_callback(struct device *dev, int data)
	{
	if (data & RTC_PF) {
	/* interpolate missed periods and set match for the next */
	unsigned long period = TIMER_FREQ/rtc_freq;
	unsigned long oscr = OSCR;
	unsigned long osmr1 = OSMR1;
	unsigned long missed = (oscr - osmr1)/period;
	data += missed << 8;
	OSSR = OSSR_M1; /* clear match on timer 1 */
	OSMR1 = osmr1 + (missed + 1)*period;
	/* Ensure we didn't miss another match in the mean time.
	* Here we compare (match - OSCR) 8 instead of 0 --
	* see comment in pxa_timer_interrupt() for explanation.
	*/
	while( (signed long)((osmr1 = OSMR1) - OSCR) <= 8 ) {
	data += 0x100;
	OSSR = OSSR_M1; /* clear match on timer 1 */
	OSMR1 = osmr1 + period;
	}
	}
	return data;
	}

	static int sa1100_rtc_open(struct device *dev)
	{
	int ret;

	ret = request_irq(IRQ_RTC1Hz, sa1100_rtc_interrupt, IRQF_DISABLED,
	"rtc 1Hz", dev);
	if (ret) {
	dev_err(dev, "IRQ %d already in use.\n", IRQ_RTC1Hz);
	goto fail_ui;
	}
	ret = request_irq(IRQ_RTCAlrm, sa1100_rtc_interrupt, IRQF_DISABLED,
	"rtc Alrm", dev);
	if (ret) {
	dev_err(dev, "IRQ %d already in use.\n", IRQ_RTCAlrm);
	goto fail_ai;
	}
	ret = request_irq(IRQ_OST1, timer1_interrupt, IRQF_DISABLED,
	"rtc timer", dev);
	if (ret) {
	dev_err(dev, "IRQ %d already in use.\n", IRQ_OST1);
	goto fail_pi;
	}
	return 0;

	fail_pi:
	free_irq(IRQ_RTCAlrm, dev);
	fail_ai:
	free_irq(IRQ_RTC1Hz, dev);
	fail_ui:
	return ret;
	}

	static void sa1100_rtc_release(struct device *dev)
	{
	spin_lock_irq(&sa1100_rtc_lock);
	RTSR = 0;
	OIER &= ~OIER_E1;
	OSSR = OSSR_M1;
	spin_unlock_irq(&sa1100_rtc_lock);

	free_irq(IRQ_OST1, dev);
	free_irq(IRQ_RTCAlrm, dev);
	free_irq(IRQ_RTC1Hz, dev);
	}


	static int sa1100_rtc_ioctl(struct device *dev, unsigned int cmd,
	unsigned long arg)
	{
	switch(cmd) {
	case RTC_AIE_OFF:
	spin_lock_irq(&sa1100_rtc_lock);
	RTSR &= ~RTSR_ALE;
	spin_unlock_irq(&sa1100_rtc_lock);
	return 0;
	case RTC_AIE_ON:
	spin_lock_irq(&sa1100_rtc_lock);
	RTSR \|= RTSR_ALE;
	spin_unlock_irq(&sa1100_rtc_lock);
	return 0;
	case RTC_UIE_OFF:
	spin_lock_irq(&sa1100_rtc_lock);
	RTSR &= ~RTSR_HZE;
	spin_unlock_irq(&sa1100_rtc_lock);
	return 0;
	case RTC_UIE_ON:
	spin_lock_irq(&sa1100_rtc_lock);
	RTSR \|= RTSR_HZE;
	spin_unlock_irq(&sa1100_rtc_lock);
	return 0;
	case RTC_PIE_OFF:
	spin_lock_irq(&sa1100_rtc_lock);
	OIER &= ~OIER_E1;
	spin_unlock_irq(&sa1100_rtc_lock);
	return 0;
	case RTC_PIE_ON:
	spin_lock_irq(&sa1100_rtc_lock);
	OSMR1 = TIMER_FREQ/rtc_freq + OSCR;
	OIER \|= OIER_E1;
	rtc_timer1_count = 1;
	spin_unlock_irq(&sa1100_rtc_lock);
	return 0;
	case RTC_IRQP_READ:
	return put_user(rtc_freq, (unsigned long *)arg);
	case RTC_IRQP_SET:
	if (arg < 1 \|\| arg > TIMER_FREQ)
	return -EINVAL;
	rtc_freq = arg;
	return 0;
	}
	return -ENOIOCTLCMD;
	}

	static int sa1100_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	rtc_time_to_tm(RCNR, tm);
	return 0;
	}

	static int sa1100_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	unsigned long time;
	int ret;

	ret = rtc_tm_to_time(tm, &time);
	if (ret == 0)
	RCNR = time;
	return ret;
	}

	static int sa1100_rtc_read_alarm(struct device dev, struct rtc_wkalrm alrm)
	{
	u32 rtsr;

	memcpy(&alrm->time, &rtc_alarm, sizeof(struct rtc_time));
	rtsr = RTSR;
	alrm->enabled = (rtsr & RTSR_ALE) ? 1 : 0;
	alrm->pending = (rtsr & RTSR_AL) ? 1 : 0;
	return 0;
	}

	static int sa1100_rtc_set_alarm(struct device dev, struct rtc_wkalrm alrm)
	{
	int ret;

	spin_lock_irq(&sa1100_rtc_lock);
	ret = rtc_update_alarm(&alrm->time);
	if (ret == 0) {
	if (alrm->enabled)
	RTSR \|= RTSR_ALE;
	else
	RTSR &= ~RTSR_ALE;
	}
	spin_unlock_irq(&sa1100_rtc_lock);

	return ret;
	}

	static int sa1100_rtc_proc(struct device dev, struct seq_file seq)
	{
	seq_printf(seq, "trim/divider\t: 0x%08x\n", (u32) RTTR);
	seq_printf(seq, "update_IRQ\t: %s\n",
	(RTSR & RTSR_HZE) ? "yes" : "no");
	seq_printf(seq, "periodic_IRQ\t: %s\n",
	(OIER & OIER_E1) ? "yes" : "no");
	seq_printf(seq, "periodic_freq\t: %ld\n", rtc_freq);

	return 0;
	}

	static const struct rtc_class_ops sa1100_rtc_ops = {
	.open = sa1100_rtc_open,
	.read_callback = sa1100_rtc_read_callback,
	.release = sa1100_rtc_release,
	.ioctl = sa1100_rtc_ioctl,
	.read_time = sa1100_rtc_read_time,
	.set_time = sa1100_rtc_set_time,
	.read_alarm = sa1100_rtc_read_alarm,
	.set_alarm = sa1100_rtc_set_alarm,
	.proc = sa1100_rtc_proc,
	};

	static int sa1100_rtc_probe(struct platform_device *pdev)
	{
	struct rtc_device *rtc;

	/*
	* According to the manual we should be able to let RTTR be zero
	* and then a default diviser for a 32.768KHz clock is used.
	* Apparently this doesn't work, at least for my SA1110 rev 5.
	* If the clock divider is uninitialized then reset it to the
	* default value to get the 1Hz clock.
	*/
	if (RTTR == 0) {
	RTTR = RTC_DEF_DIVIDER + (RTC_DEF_TRIM << 16);
	dev_warn(&pdev->dev, "warning: initializing default clock divider/trim value\n");
	/* The current RTC value probably doesn't make sense either */
	RCNR = 0;
	}

	rtc = rtc_device_register(pdev->name, &pdev->dev, &sa1100_rtc_ops,
	THIS_MODULE);

	if (IS_ERR(rtc))
	return PTR_ERR(rtc);

	platform_set_drvdata(pdev, rtc);

	return 0;
	}

	static int sa1100_rtc_remove(struct platform_device *pdev)
	{
	struct rtc_device *rtc = platform_get_drvdata(pdev);

	if (rtc)
	rtc_device_unregister(rtc);

	return 0;
	}

	static struct platform_driver sa1100_rtc_driver = {
	.probe = sa1100_rtc_probe,
	.remove = sa1100_rtc_remove,
	.driver = {
	.name = "sa1100-rtc",
	},
	};

	static int __init sa1100_rtc_init(void)
	{
	return platform_driver_register(&sa1100_rtc_driver);
	}

	static void __exit sa1100_rtc_exit(void)
	{
	platform_driver_unregister(&sa1100_rtc_driver);
	}

	module_init(sa1100_rtc_init);
	module_exit(sa1100_rtc_exit);

	MODULE_AUTHOR("Richard Purdie <rpurdie@rpsys.net>");
	MODULE_DESCRIPTION("SA11x0/PXA2xx Realtime Clock Driver (RTC)");
	MODULE_LICENSE("GPL");