[PATCH] RTC subsystem: SA1100/PXA2XX driver

Add an RTC subsystem driver for the ARM SA1100/PXA2XX processor RTC.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 388 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-sa1100.c b/drivers/rtc/rtc-sa1100.c
new file mode 100644
index 0000000..83b2bb4
--- /dev/null
+++ b/drivers/rtc/rtc-sa1100.c
@@ -0,0 +1,388 @@
+/*
+ * 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 <asm/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 spinlock_t sa1100_rtc_lock = SPIN_LOCK_UNLOCKED;
+
+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 pt_regs *regs)
+{
+	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->class_dev, 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 pt_regs *regs)
+{
+	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->class_dev, 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, SA_INTERRUPT,
+				"rtc 1Hz", dev);
+	if (ret) {
+		printk(KERN_ERR "rtc: IRQ%d already in use.\n", IRQ_RTC1Hz);
+		goto fail_ui;
+	}
+	ret = request_irq(IRQ_RTCAlrm, sa1100_rtc_interrupt, SA_INTERRUPT,
+				"rtc Alrm", dev);
+	if (ret) {
+		printk(KERN_ERR "rtc: IRQ%d already in use.\n", IRQ_RTCAlrm);
+		goto fail_ai;
+	}
+	ret = request_irq(IRQ_OST1, timer1_interrupt, SA_INTERRUPT,
+				"rtc timer", dev);
+	if (ret) {
+		printk(KERN_ERR "rtc: IRQ%d already in use.\n", IRQ_OST1);
+		goto fail_pi;
+	}
+	return 0;
+
+ fail_pi:
+	free_irq(IRQ_RTCAlrm, NULL);
+ fail_ai:
+	free_irq(IRQ_RTC1Hz, NULL);
+ 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:
+		if ((rtc_freq > 64) && !capable(CAP_SYS_RESOURCE))
+			return -EACCES;
+		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;
+		if ((arg > 64) && (!capable(CAP_SYS_RESOURCE)))
+			return -EACCES;
+		rtc_freq = arg;
+		return 0;
+	}
+	return -EINVAL;
+}
+
+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)
+{
+	memcpy(&alrm->time, &rtc_alarm, sizeof(struct rtc_time));
+	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) {
+		memcpy(&rtc_alarm, &alrm->time, sizeof(struct rtc_time));
+
+		if (alrm->enabled)
+			enable_irq_wake(IRQ_RTCAlrm);
+		else
+			disable_irq_wake(IRQ_RTCAlrm);
+	}
+	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", RTTR);
+	seq_printf(seq, "alarm_IRQ\t: %s\n",
+			(RTSR & RTSR_ALE) ? "yes" : "no" );
+	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 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);
+		printk(KERN_WARNING "rtc: 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)) {
+		dev_err(&pdev->dev, "Unable to register the RTC device\n");
+		return PTR_ERR(rtc);
+	}
+
+	platform_set_drvdata(pdev, rtc);
+
+	dev_info(&pdev->dev, "SA11xx/PXA2xx RTC Registered\n");
+
+	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");