[PATCH] AT91RM9200 RTC driver

Adds support for the RTC integrated in the Atmel AT91RM9200 SoC.

Driver was originally written for 2.4 by Rick Bronson.  Then converted to
2.6 ARM RTC API by Steven Scholz.  Now converted to the RTC class model.
Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/rtc/Kconfig

@@ -202,6 +202,12 @@ config RTC_DRV_PL031
 	  To compile this driver as a module, choose M here: the
 	  module will be called rtc-pl031.
 
+config RTC_DRV_AT91
+	tristate "AT91RM9200"
+	depends on RTC_CLASS && ARCH_AT91RM9200
+	help
+	  Driver for the Atmel AT91RM9200's internal RTC (Realtime Clock).
+
 config RTC_DRV_TEST
 	tristate "Test driver/device"
 	depends on RTC_CLASS

drivers/rtc/Makefile

@@ -25,3 +25,4 @@ obj-$(CONFIG_RTC_DRV_VR41XX)	+= rtc-vr41xx.o
 obj-$(CONFIG_RTC_DRV_PL031)	+= rtc-pl031.o
 obj-$(CONFIG_RTC_DRV_MAX6902)	+= rtc-max6902.o
 obj-$(CONFIG_RTC_DRV_V3020)	+= rtc-v3020.o
+obj-$(CONFIG_RTC_DRV_AT91)	+= rtc-at91.o

drivers/rtc/rtc-at91.c

+/*
+ *	Real Time Clock interface for Linux on Atmel AT91RM9200
+ *
+ *	Copyright (C) 2002 Rick Bronson
+ *
+ *	Converted to RTC class model by Andrew Victor
+ *
+ *	Ported to Linux 2.6 by Steven Scholz
+ *	Based on s3c2410-rtc.c Simtec Electronics
+ *
+ *	Based on sa1100-rtc.c by Nils Faerber
+ *	Based on rtc.c by Paul Gortmaker
+ *
+ *	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/module.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/time.h>
+#include <linux/rtc.h>
+#include <linux/bcd.h>
+#include <linux/interrupt.h>
+#include <linux/ioctl.h>
+#include <linux/completion.h>
+
+#include <asm/uaccess.h>
+#include <asm/rtc.h>
+
+#include <asm/mach/time.h>
+
+
+#define AT91_RTC_FREQ		1
+#define AT91_RTC_EPOCH		1900UL	/* just like arch/arm/common/rtctime.c */
+
+static DECLARE_COMPLETION(at91_rtc_updated);
+static unsigned int at91_alarm_year = AT91_RTC_EPOCH;
+
+
+/*
+ * Decode time/date into rtc_time structure
+ */
+static void at91_rtc_decodetime(unsigned int timereg, unsigned int calreg, struct rtc_time *tm)
+{
+	unsigned int time, date;
+
+	/* must read twice in case it changes */
+	do {
+		time = at91_sys_read(timereg);
+		date = at91_sys_read(calreg);
+	} while ((time != at91_sys_read(timereg)) || (date != at91_sys_read(calreg)));
+
+	tm->tm_sec  = BCD2BIN((time & AT91_RTC_SEC) >> 0);
+	tm->tm_min  = BCD2BIN((time & AT91_RTC_MIN) >> 8);
+	tm->tm_hour = BCD2BIN((time & AT91_RTC_HOUR) >> 16);
+
+	/*
+	 * The Calendar Alarm register does not have a field for
+	 * the year - so these will return an invalid value.  When an
+	 * alarm is set, at91_alarm_year wille store the current year.
+	 */
+	tm->tm_year  = BCD2BIN(date & AT91_RTC_CENT) * 100;		/* century */
+	tm->tm_year += BCD2BIN((date & AT91_RTC_YEAR) >> 8);		/* year */
+
+	tm->tm_wday = BCD2BIN((date & AT91_RTC_DAY) >> 21) - 1;	/* day of the week [0-6], Sunday=0 */
+	tm->tm_mon  = BCD2BIN((date & AT91_RTC_MONTH) >> 16) - 1;
+	tm->tm_mday = BCD2BIN((date & AT91_RTC_DATE) >> 24);
+}
+
+/*
+ * Read current time and date in RTC
+ */
+static int at91_rtc_readtime(struct device *dev, struct rtc_time *tm)
+{
+	at91_rtc_decodetime(AT91_RTC_TIMR, AT91_RTC_CALR, tm);
+	tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
+	tm->tm_year = tm->tm_year - 1900;
+
+	pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __FUNCTION__,
+		1900 + tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec);
+
+	return 0;
+}
+
+/*
+ * Set current time and date in RTC
+ */
+static int at91_rtc_settime(struct device *dev, struct rtc_time *tm)
+{
+	unsigned long cr;
+
+	pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __FUNCTION__,
+		1900 + tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec);
+
+	/* Stop Time/Calendar from counting */
+	cr = at91_sys_read(AT91_RTC_CR);
+	at91_sys_write(AT91_RTC_CR, cr | AT91_RTC_UPDCAL | AT91_RTC_UPDTIM);
+
+	at91_sys_write(AT91_RTC_IER, AT91_RTC_ACKUPD);
+	wait_for_completion(&at91_rtc_updated);		/* wait for ACKUPD interrupt */
+	at91_sys_write(AT91_RTC_IDR, AT91_RTC_ACKUPD);
+
+	at91_sys_write(AT91_RTC_TIMR,
+			  BIN2BCD(tm->tm_sec) << 0
+			| BIN2BCD(tm->tm_min) << 8
+			| BIN2BCD(tm->tm_hour) << 16);
+
+	at91_sys_write(AT91_RTC_CALR,
+			  BIN2BCD((tm->tm_year + 1900) / 100)		/* century */
+			| BIN2BCD(tm->tm_year % 100) << 8		/* year */
+			| BIN2BCD(tm->tm_mon + 1) << 16			/* tm_mon starts at zero */
+			| BIN2BCD(tm->tm_wday + 1) << 21		/* day of the week [0-6], Sunday=0 */
+			| BIN2BCD(tm->tm_mday) << 24);
+
+	/* Restart Time/Calendar */
+	cr = at91_sys_read(AT91_RTC_CR);
+	at91_sys_write(AT91_RTC_CR, cr & ~(AT91_RTC_UPDCAL | AT91_RTC_UPDTIM));
+
+	return 0;
+}
+
+/*
+ * Read alarm time and date in RTC
+ */
+static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct rtc_time *tm = &alrm->time;
+
+	at91_rtc_decodetime(AT91_RTC_TIMALR, AT91_RTC_CALALR, tm);
+	tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
+	tm->tm_year = at91_alarm_year - 1900;
+
+	pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __FUNCTION__,
+		1900 + tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec);
+
+	return 0;
+}
+
+/*
+ * Set alarm time and date in RTC
+ */
+static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct rtc_time tm;
+
+	at91_rtc_decodetime(AT91_RTC_TIMR, AT91_RTC_CALR, &tm);
+
+	at91_alarm_year = tm.tm_year;
+
+	tm.tm_hour = alrm->time.tm_hour;
+	tm.tm_min = alrm->time.tm_min;
+	tm.tm_sec = alrm->time.tm_sec;
+
+	at91_sys_write(AT91_RTC_TIMALR,
+		  BIN2BCD(tm.tm_sec) << 0
+		| BIN2BCD(tm.tm_min) << 8
+		| BIN2BCD(tm.tm_hour) << 16
+		| AT91_RTC_HOUREN | AT91_RTC_MINEN | AT91_RTC_SECEN);
+	at91_sys_write(AT91_RTC_CALALR,
+		  BIN2BCD(tm.tm_mon + 1) << 16		/* tm_mon starts at zero */
+		| BIN2BCD(tm.tm_mday) << 24
+		| AT91_RTC_DATEEN | AT91_RTC_MTHEN);
+
+	pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __FUNCTION__,
+		at91_alarm_year, tm.tm_mon, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec);
+
+	return 0;
+}
+
+/*
+ * Handle commands from user-space
+ */
+static int at91_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
+{
+	int ret = 0;
+
+	pr_debug("%s(): cmd=%08x, arg=%08lx.\n", __FUNCTION__, cmd, arg);
+
+	switch (cmd) {
+	case RTC_AIE_OFF:	/* alarm off */
+		at91_sys_write(AT91_RTC_IDR, AT91_RTC_ALARM);
+		break;
+	case RTC_AIE_ON:	/* alarm on */
+		at91_sys_write(AT91_RTC_IER, AT91_RTC_ALARM);
+		break;
+	case RTC_UIE_OFF:	/* update off */
+	case RTC_PIE_OFF:	/* periodic off */
+		at91_sys_write(AT91_RTC_IDR, AT91_RTC_SECEV);
+		break;
+	case RTC_UIE_ON:	/* update on */
+	case RTC_PIE_ON:	/* periodic on */
+		at91_sys_write(AT91_RTC_IER, AT91_RTC_SECEV);
+		break;
+	case RTC_IRQP_READ:	/* read periodic alarm frequency */
+		ret = put_user(AT91_RTC_FREQ, (unsigned long *) arg);
+		break;
+	case RTC_IRQP_SET:	/* set periodic alarm frequency */
+		if (arg != AT91_RTC_FREQ)
+			ret = -EINVAL;
+		break;
+	default:
+		ret = -ENOIOCTLCMD;
+		break;
+	}
+
+	return ret;
+}
+
+/*
+ * Provide additional RTC information in /proc/driver/rtc
+ */
+static int at91_rtc_proc(struct device *dev, struct seq_file *seq)
+{
+	unsigned long imr = at91_sys_read(AT91_RTC_IMR);
+
+	seq_printf(seq, "alarm_IRQ\t: %s\n", (imr & AT91_RTC_ALARM) ? "yes" : "no");
+	seq_printf(seq, "update_IRQ\t: %s\n", (imr & AT91_RTC_ACKUPD) ? "yes" : "no");
+	seq_printf(seq, "periodic_IRQ\t: %s\n", (imr & AT91_RTC_SECEV) ? "yes" : "no");
+	seq_printf(seq, "periodic_freq\t: %ld\n", (unsigned long) AT91_RTC_FREQ);
+
+	return 0;
+}
+
+/*
+ * IRQ handler for the RTC
+ */
+static irqreturn_t at91_rtc_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+	struct platform_device *pdev = (struct platform_device *)dev_id;
+	struct rtc_device *rtc = platform_get_drvdata(pdev);
+	unsigned int rtsr;
+	unsigned long events = 0;
+
+	rtsr = at91_sys_read(AT91_RTC_SR) & at91_sys_read(AT91_RTC_IMR);
+	if (rtsr) {		/* this interrupt is shared!  Is it ours? */
+		if (rtsr & AT91_RTC_ALARM)
+			events |= (RTC_AF | RTC_IRQF);
+		if (rtsr & AT91_RTC_SECEV)
+			events |= (RTC_UF | RTC_IRQF);
+		if (rtsr & AT91_RTC_ACKUPD)
+			complete(&at91_rtc_updated);
+
+		at91_sys_write(AT91_RTC_SCCR, rtsr);		/* clear status reg */
+
+		rtc_update_irq(&rtc->class_dev, 1, events);
+
+		pr_debug("%s(): num=%ld, events=0x%02lx\n", __FUNCTION__,
+			events >> 8, events & 0x000000FF);
+
+		return IRQ_HANDLED;
+	}
+	return IRQ_NONE;		/* not handled */
+}
+
+static struct rtc_class_ops at91_rtc_ops = {
+	.ioctl		= at91_rtc_ioctl,
+	.read_time	= at91_rtc_readtime,
+	.set_time	= at91_rtc_settime,
+	.read_alarm	= at91_rtc_readalarm,
+	.set_alarm	= at91_rtc_setalarm,
+	.proc		= at91_rtc_proc,
+};
+
+/*
+ * Initialize and install RTC driver
+ */
+static int __init at91_rtc_probe(struct platform_device *pdev)
+{
+	struct rtc_device *rtc;
+	int ret;
+
+	at91_sys_write(AT91_RTC_CR, 0);
+	at91_sys_write(AT91_RTC_MR, 0);		/* 24 hour mode */
+
+	/* Disable all interrupts */
+	at91_sys_write(AT91_RTC_IDR, AT91_RTC_ACKUPD | AT91_RTC_ALARM | AT91_RTC_SECEV | AT91_RTC_TIMEV | AT91_RTC_CALEV);
+
+	ret = request_irq(AT91_ID_SYS, at91_rtc_interrupt, SA_SHIRQ, "at91_rtc", pdev);
+	if (ret) {
+		printk(KERN_ERR "at91_rtc: IRQ %d already in use.\n", AT91_ID_SYS);
+		return ret;
+	}
+
+	rtc = rtc_device_register(pdev->name, &pdev->dev, &at91_rtc_ops, THIS_MODULE);
+	if (IS_ERR(rtc)) {
+		free_irq(AT91_ID_SYS, pdev);
+		return PTR_ERR(rtc);
+	}
+	platform_set_drvdata(pdev, rtc);
+
+	printk(KERN_INFO "AT91 Real Time Clock driver.\n");
+	return 0;
+}
+
+/*
+ * Disable and remove the RTC driver
+ */
+static int __devexit at91_rtc_remove(struct platform_device *pdev)
+{
+	struct rtc_device *rtc = platform_get_drvdata(pdev);
+
+	/* Disable all interrupts */
+	at91_sys_write(AT91_RTC_IDR, AT91_RTC_ACKUPD | AT91_RTC_ALARM | AT91_RTC_SECEV | AT91_RTC_TIMEV | AT91_RTC_CALEV);
+	free_irq(AT91_ID_SYS, pdev);
+
+	rtc_device_unregister(rtc);
+	platform_set_drvdata(pdev, NULL);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+
+/* AT91RM9200 RTC Power management control */
+
+static struct timespec at91_rtc_delta;
+
+static int at91_rtc_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	struct rtc_time tm;
+	struct timespec time;
+
+	time.tv_nsec = 0;
+
+	/* calculate time delta for suspend */
+	at91_rtc_readtime(&pdev->dev, &tm);
+	rtc_tm_to_time(&tm, &time.tv_sec);
+	save_time_delta(&at91_rtc_delta, &time);
+
+	pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __FUNCTION__,
+		1900 + tm.tm_year, tm.tm_mon, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec);
+
+	return 0;
+}
+
+static int at91_rtc_resume(struct platform_device *pdev)
+{
+	struct rtc_time tm;
+	struct timespec time;
+
+	time.tv_nsec = 0;
+
+	at91_rtc_readtime(&pdev->dev, &tm);
+	rtc_tm_to_time(&tm, &time.tv_sec);
+	restore_time_delta(&at91_rtc_delta, &time);
+
+	pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __FUNCTION__,
+		1900 + tm.tm_year, tm.tm_mon, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec);
+
+	return 0;
+}
+#else
+#define at91_rtc_suspend NULL
+#define at91_rtc_resume  NULL
+#endif
+
+static struct platform_driver at91_rtc_driver = {
+	.probe		= at91_rtc_probe,
+	.remove		= at91_rtc_remove,
+	.suspend	= at91_rtc_suspend,
+	.resume		= at91_rtc_resume,
+	.driver		= {
+		.name	= "at91_rtc",
+		.owner	= THIS_MODULE,
+	},
+};
+
+static int __init at91_rtc_init(void)
+{
+	return platform_driver_register(&at91_rtc_driver);
+}
+
+static void __exit at91_rtc_exit(void)
+{
+	platform_driver_unregister(&at91_rtc_driver);
+}
+
+
+module_init(at91_rtc_init);
+module_exit(at91_rtc_exit);
+
+MODULE_AUTHOR("Rick Bronson");
+MODULE_DESCRIPTION("RTC driver for Atmel AT91RM9200");
+MODULE_LICENSE("GPL");