drivers/sbus/char/rtc.c

   1 /* $Id: rtc.c,v 1.28 2001/10/08 22:19:51 davem Exp $
   2  *
   3  * Linux/SPARC Real Time Clock Driver
   4  * Copyright (C) 1996 Thomas K. Dyas (tdyas@eden.rutgers.edu)
   5  *
   6  * This is a little driver that lets a user-level program access
   7  * the SPARC Mostek real time clock chip. It is no use unless you
   8  * use the modified clock utility.
   9  *
  10  * Get the modified clock utility from:
  11  *   ftp://vger.kernel.org/pub/linux/Sparc/userland/clock.c
  12  */
  13
  14 #include <linux/module.h>
  15 #include <linux/types.h>
  16 #include <linux/errno.h>
  17 #include <linux/miscdevice.h>
  18 #include <linux/slab.h>
  19 #include <linux/fcntl.h>
  20 #include <linux/poll.h>
  21 #include <linux/init.h>
  22 #include <linux/smp_lock.h>
  23 #include <asm/io.h>
  24 #include <asm/mostek.h>
  25 #include <asm/system.h>
  26 #include <asm/uaccess.h>
  27 #include <asm/rtc.h>
  28
  29 static int rtc_busy = 0;
  30
  31 /* Retrieve the current date and time from the real time clock. */
  32 static void get_rtc_time(struct rtc_time *t)
  33 {
  34         void * __iomem regs = mstk48t02_regs;
  35         u8 tmp;
  36
  37         spin_lock_irq(&mostek_lock);
  38
  39         tmp = mostek_read(regs + MOSTEK_CREG);
  40         tmp |= MSTK_CREG_READ;
  41         mostek_write(regs + MOSTEK_CREG, tmp);
  42
  43         t->sec = MSTK_REG_SEC(regs);
  44         t->min = MSTK_REG_MIN(regs);
  45         t->hour = MSTK_REG_HOUR(regs);
  46         t->dow = MSTK_REG_DOW(regs);
  47         t->dom = MSTK_REG_DOM(regs);
  48         t->month = MSTK_REG_MONTH(regs);
  49         t->year = MSTK_CVT_YEAR( MSTK_REG_YEAR(regs) );
  50
  51         tmp = mostek_read(regs + MOSTEK_CREG);
  52         tmp &= ~MSTK_CREG_READ;
  53         mostek_write(regs + MOSTEK_CREG, tmp);
  54
  55         spin_unlock_irq(&mostek_lock);
  56 }
  57
  58 /* Set the current date and time inthe real time clock. */
  59 void set_rtc_time(struct rtc_time *t)
  60 {
  61         void * __iomem regs = mstk48t02_regs;
  62         u8 tmp;
  63
  64         spin_lock_irq(&mostek_lock);
  65
  66         tmp = mostek_read(regs + MOSTEK_CREG);
  67         tmp |= MSTK_CREG_WRITE;
  68         mostek_write(regs + MOSTEK_CREG, tmp);
  69
  70         MSTK_SET_REG_SEC(regs,t->sec);
  71         MSTK_SET_REG_MIN(regs,t->min);
  72         MSTK_SET_REG_HOUR(regs,t->hour);
  73         MSTK_SET_REG_DOW(regs,t->dow);
  74         MSTK_SET_REG_DOM(regs,t->dom);
  75         MSTK_SET_REG_MONTH(regs,t->month);
  76         MSTK_SET_REG_YEAR(regs,t->year - MSTK_YEAR_ZERO);
  77
  78         tmp = mostek_read(regs + MOSTEK_CREG);
  79         tmp &= ~MSTK_CREG_WRITE;
  80         mostek_write(regs + MOSTEK_CREG, tmp);
  81
  82         spin_unlock_irq(&mostek_lock);
  83 }
  84
  85 static int rtc_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
  86         unsigned long arg)
  87 {
  88         struct rtc_time rtc_tm;
  89         void __user *argp = (void __user *)arg;
  90
  91         switch (cmd)
  92         {
  93         case RTCGET:
  94                 memset(&rtc_tm, 0, sizeof(struct rtc_time));
  95                 get_rtc_time(&rtc_tm);
  96
  97                 if (copy_to_user(argp, &rtc_tm, sizeof(struct rtc_time)))
  98                         return -EFAULT;
  99
 100                 return 0;
 101
 102
 103         case RTCSET:
 104                 if (!capable(CAP_SYS_TIME))
 105                         return -EPERM;
 106
 107                 if (copy_from_user(&rtc_tm, argp, sizeof(struct rtc_time)))
 108                         return -EFAULT;
 109
 110                 set_rtc_time(&rtc_tm);
 111
 112                 return 0;
 113
 114         default:
 115                 return -EINVAL;
 116         }
 117 }
 118
 119 static int rtc_open(struct inode *inode, struct file *file)
 120 {
 121         int ret;
 122
 123         spin_lock_irq(&mostek_lock);
 124         if (rtc_busy) {
 125                 ret = -EBUSY;
 126         } else {
 127                 rtc_busy = 1;
 128                 ret = 0;
 129         }
 130         spin_unlock_irq(&mostek_lock);
 131
 132         return ret;
 133 }
 134
 135 static int rtc_release(struct inode *inode, struct file *file)
 136 {
 137         rtc_busy = 0;
 138
 139         return 0;
 140 }
 141
 142 static struct file_operations rtc_fops = {
 143         .owner =        THIS_MODULE,
 144         .llseek =       no_llseek,
 145         .ioctl =        rtc_ioctl,
 146         .open =         rtc_open,
 147         .release =      rtc_release,
 148 };
 149
 150 static struct miscdevice rtc_dev = { RTC_MINOR, "rtc", &rtc_fops };
 151
 152 static int __init rtc_sun_init(void)
 153 {
 154         int error;
 155
 156         /* It is possible we are being driven by some other RTC chip
 157          * and thus another RTC driver is handling things.
 158          */
 159         if (mstk48t02_regs == 0)
 160                 return -ENODEV;
 161
 162         error = misc_register(&rtc_dev);
 163         if (error) {
 164                 printk(KERN_ERR "rtc: unable to get misc minor for Mostek\n");
 165                 return error;
 166         }
 167
 168         return 0;
 169 }
 170
 171 static void __exit rtc_sun_cleanup(void)
 172 {
 173         misc_deregister(&rtc_dev);
 174 }
 175
 176 module_init(rtc_sun_init);
 177 module_exit(rtc_sun_cleanup);
 178 MODULE_LICENSE("GPL");