[PATCH] Add M48T35 RTC driver

Add M48T35 RTC driver for the SGI IP27 aka Origin 200, Origin 2000 and
Onyx 2.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/char/Kconfig

@@ -764,6 +764,17 @@ config SGI_DS1286
 	  via the file /proc/rtc and its behaviour is set by various ioctls on
 	  /dev/rtc.
 
+config SGI_IP27_RTC
+	bool "SGI M48T35 RTC support"
+	depends on SGI_IP27
+	help
+	  If you say Y here and create a character special file /dev/rtc with
+	  major number 10 and minor number 135 using mknod ("man mknod"), you
+	  will get access to the real time clock built into your computer.
+	  Every SGI has such a clock built in. It reports status information
+	  via the file /proc/rtc and its behaviour is set by various ioctls on
+	  /dev/rtc.
+
 config GEN_RTC
 	tristate "Generic /dev/rtc emulation"
 	depends on RTC!=y && !IA64

drivers/char/Makefile

@@ -57,6 +57,7 @@ obj-$(CONFIG_HPET) += hpet.o
 obj-$(CONFIG_GEN_RTC) += genrtc.o
 obj-$(CONFIG_EFI_RTC) += efirtc.o
 obj-$(CONFIG_SGI_DS1286) += ds1286.o
+obj-$(CONFIG_SGI_IP27_RTC) += ip27-rtc.o
 ifeq ($(CONFIG_GENERIC_NVRAM),y)
   obj-$(CONFIG_NVRAM) += generic_nvram.o
 else

drivers/char/ip27-rtc.c

+/*
+ *	Driver for the SGS-Thomson M48T35 Timekeeper RAM chip
+ *
+ *	Real Time Clock interface for Linux
+ *
+ *	TODO: Implement periodic interrupts.
+ *
+ *	Copyright (C) 2000 Silicon Graphics, Inc.
+ *	Written by Ulf Carlsson (ulfc@engr.sgi.com)
+ *
+ *	Based on code written by Paul Gortmaker.
+ *
+ *	This driver allows use of the real time clock (built into
+ *	nearly all computers) from user space. It exports the /dev/rtc
+ *	interface supporting various ioctl() and also the /proc/rtc
+ *	pseudo-file for status information.
+ *
+ *	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.
+ *
+ */
+
+#define RTC_VERSION		"1.09b"
+
+#include <linux/bcd.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/miscdevice.h>
+#include <linux/ioport.h>
+#include <linux/fcntl.h>
+#include <linux/rtc.h>
+#include <linux/init.h>
+#include <linux/poll.h>
+#include <linux/proc_fs.h>
+#include <linux/smp_lock.h>
+
+#include <asm/m48t35.h>
+#include <asm/sn/ioc3.h>
+#include <asm/io.h>
+#include <asm/uaccess.h>
+#include <asm/system.h>
+#include <asm/sn/klconfig.h>
+#include <asm/sn/sn0/ip27.h>
+#include <asm/sn/sn0/hub.h>
+#include <asm/sn/sn_private.h>
+
+static int rtc_ioctl(struct inode *inode, struct file *file,
+		     unsigned int cmd, unsigned long arg);
+
+static int rtc_read_proc(char *page, char **start, off_t off,
+                         int count, int *eof, void *data);
+
+static void get_rtc_time(struct rtc_time *rtc_tm);
+
+/*
+ *	Bits in rtc_status. (6 bits of room for future expansion)
+ */
+
+#define RTC_IS_OPEN		0x01	/* means /dev/rtc is in use	*/
+#define RTC_TIMER_ON		0x02	/* missed irq timer active	*/
+
+static unsigned char rtc_status;	/* bitmapped status byte.	*/
+static unsigned long rtc_freq;	/* Current periodic IRQ rate	*/
+static struct m48t35_rtc *rtc;
+
+/*
+ *	If this driver ever becomes modularised, it will be really nice
+ *	to make the epoch retain its value across module reload...
+ */
+
+static unsigned long epoch = 1970;	/* year corresponding to 0x00	*/
+
+static const unsigned char days_in_mo[] =
+{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
+
+static int rtc_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
+		     unsigned long arg)
+{
+
+	struct rtc_time wtime;
+
+	switch (cmd) {
+	case RTC_RD_TIME:	/* Read the time/date from RTC	*/
+	{
+		get_rtc_time(&wtime);
+		break;
+	}
+	case RTC_SET_TIME:	/* Set the RTC */
+	{
+		struct rtc_time rtc_tm;
+		unsigned char mon, day, hrs, min, sec, leap_yr;
+		unsigned int yrs;
+
+		if (!capable(CAP_SYS_TIME))
+			return -EACCES;
+
+		if (copy_from_user(&rtc_tm, (struct rtc_time*)arg,
+				   sizeof(struct rtc_time)))
+			return -EFAULT;
+
+		yrs = rtc_tm.tm_year + 1900;
+		mon = rtc_tm.tm_mon + 1;   /* tm_mon starts at zero */
+		day = rtc_tm.tm_mday;
+		hrs = rtc_tm.tm_hour;
+		min = rtc_tm.tm_min;
+		sec = rtc_tm.tm_sec;
+
+		if (yrs < 1970)
+			return -EINVAL;
+
+		leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));
+
+		if ((mon > 12) || (day == 0))
+			return -EINVAL;
+
+		if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
+			return -EINVAL;
+
+		if ((hrs >= 24) || (min >= 60) || (sec >= 60))
+			return -EINVAL;
+
+		if ((yrs -= epoch) > 255)    /* They are unsigned */
+			return -EINVAL;
+
+		if (yrs > 169)
+			return -EINVAL;
+
+		if (yrs >= 100)
+			yrs -= 100;
+
+		sec = BIN2BCD(sec);
+		min = BIN2BCD(min);
+		hrs = BIN2BCD(hrs);
+		day = BIN2BCD(day);
+		mon = BIN2BCD(mon);
+		yrs = BIN2BCD(yrs);
+
+		spin_lock_irq(&rtc_lock);
+		rtc->control |= M48T35_RTC_SET;
+		rtc->year = yrs;
+		rtc->month = mon;
+		rtc->date = day;
+		rtc->hour = hrs;
+		rtc->min = min;
+		rtc->sec = sec;
+		rtc->control &= ~M48T35_RTC_SET;
+		spin_unlock_irq(&rtc_lock);
+
+		return 0;
+	}
+	default:
+		return -EINVAL;
+	}
+	return copy_to_user((void *)arg, &wtime, sizeof wtime) ? -EFAULT : 0;
+}
+
+/*
+ *	We enforce only one user at a time here with the open/close.
+ *	Also clear the previous interrupt data on an open, and clean
+ *	up things on a close.
+ */
+
+static int rtc_open(struct inode *inode, struct file *file)
+{
+	spin_lock_irq(&rtc_lock);
+
+	if (rtc_status & RTC_IS_OPEN) {
+		spin_unlock_irq(&rtc_lock);
+		return -EBUSY;
+	}
+
+	rtc_status |= RTC_IS_OPEN;
+	spin_unlock_irq(&rtc_lock);
+
+	return 0;
+}
+
+static int rtc_release(struct inode *inode, struct file *file)
+{
+	/*
+	 * Turn off all interrupts once the device is no longer
+	 * in use, and clear the data.
+	 */
+
+	spin_lock_irq(&rtc_lock);
+	rtc_status &= ~RTC_IS_OPEN;
+	spin_unlock_irq(&rtc_lock);
+
+	return 0;
+}
+
+/*
+ *	The various file operations we support.
+ */
+
+static struct file_operations rtc_fops = {
+	.owner		= THIS_MODULE,
+	.ioctl		= rtc_ioctl,
+	.open		= rtc_open,
+	.release	= rtc_release,
+};
+
+static struct miscdevice rtc_dev=
+{
+	RTC_MINOR,
+	"rtc",
+	&rtc_fops
+};
+
+static int __init rtc_init(void)
+{
+	rtc = (struct m48t35_rtc *)
+	(KL_CONFIG_CH_CONS_INFO(master_nasid)->memory_base + IOC3_BYTEBUS_DEV0);
+
+	printk(KERN_INFO "Real Time Clock Driver v%s\n", RTC_VERSION);
+	if (misc_register(&rtc_dev)) {
+		printk(KERN_ERR "rtc: cannot register misc device.\n");
+		return -ENODEV;
+	}
+	if (!create_proc_read_entry("driver/rtc", 0, NULL, rtc_read_proc, NULL)) {
+		printk(KERN_ERR "rtc: cannot create /proc/rtc.\n");
+		misc_deregister(&rtc_dev);
+		return -ENOENT;
+	}
+
+	rtc_freq = 1024;
+
+	return 0;
+}
+
+static void __exit rtc_exit (void)
+{
+	/* interrupts and timer disabled at this point by rtc_release */
+
+	remove_proc_entry ("rtc", NULL);
+	misc_deregister(&rtc_dev);
+}
+
+module_init(rtc_init);
+module_exit(rtc_exit);
+
+/*
+ *	Info exported via "/proc/rtc".
+ */
+
+static int rtc_get_status(char *buf)
+{
+	char *p;
+	struct rtc_time tm;
+
+	/*
+	 * Just emulate the standard /proc/rtc
+	 */
+
+	p = buf;
+
+	get_rtc_time(&tm);
+
+	/*
+	 * There is no way to tell if the luser has the RTC set for local
+	 * time or for Universal Standard Time (GMT). Probably local though.
+	 */
+	p += sprintf(p,
+		     "rtc_time\t: %02d:%02d:%02d\n"
+		     "rtc_date\t: %04d-%02d-%02d\n"
+	 	     "rtc_epoch\t: %04lu\n"
+		     "24hr\t\t: yes\n",
+		     tm.tm_hour, tm.tm_min, tm.tm_sec,
+		     tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, epoch);
+
+	return  p - buf;
+}
+
+static int rtc_read_proc(char *page, char **start, off_t off,
+                                 int count, int *eof, void *data)
+{
+        int len = rtc_get_status(page);
+        if (len <= off+count) *eof = 1;
+        *start = page + off;
+        len -= off;
+        if (len>count) len = count;
+        if (len<0) len = 0;
+        return len;
+}
+
+static void get_rtc_time(struct rtc_time *rtc_tm)
+{
+	/*
+	 * Do we need to wait for the last update to finish?
+	 */
+
+	/*
+	 * Only the values that we read from the RTC are set. We leave
+	 * tm_wday, tm_yday and tm_isdst untouched. Even though the
+	 * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
+	 * by the RTC when initially set to a non-zero value.
+	 */
+	spin_lock_irq(&rtc_lock);
+	rtc->control |= M48T35_RTC_READ;
+	rtc_tm->tm_sec = rtc->sec;
+	rtc_tm->tm_min = rtc->min;
+	rtc_tm->tm_hour = rtc->hour;
+	rtc_tm->tm_mday = rtc->date;
+	rtc_tm->tm_mon = rtc->month;
+	rtc_tm->tm_year = rtc->year;
+	rtc->control &= ~M48T35_RTC_READ;
+	spin_unlock_irq(&rtc_lock);
+
+	rtc_tm->tm_sec = BCD2BIN(rtc_tm->tm_sec);
+	rtc_tm->tm_min = BCD2BIN(rtc_tm->tm_min);
+	rtc_tm->tm_hour = BCD2BIN(rtc_tm->tm_hour);
+	rtc_tm->tm_mday = BCD2BIN(rtc_tm->tm_mday);
+	rtc_tm->tm_mon = BCD2BIN(rtc_tm->tm_mon);
+	rtc_tm->tm_year = BCD2BIN(rtc_tm->tm_year);
+
+	/*
+	 * Account for differences between how the RTC uses the values
+	 * and how they are defined in a struct rtc_time;
+	 */
+	if ((rtc_tm->tm_year += (epoch - 1900)) <= 69)
+		rtc_tm->tm_year += 100;
+
+	rtc_tm->tm_mon--;
+}