--- /dev/null
+/*
+ * 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--;
+}
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