[PATCH] real time clock support for PC9800 systems

drivers/char/upd4990a.c

+/*
+ * NEC PC-9800 Real Time Clock interface for Linux	
+ *
+ * Copyright (C) 1997-2001  Linux/98 project,
+ *			    Kyoto University Microcomputer Club.
+ *
+ * Based on:
+ *	drivers/char/rtc.c by Paul Gortmaker
+ *
+ * Changes:
+ *  2001-02-09	Call check_region on rtc_init and do not request I/O 0033h.
+ *		Call del_timer and release_region on rtc_exit. -- tak
+ *  2001-07-14	Rewrite <linux/upd4990a.h> and split to <linux/upd4990a.h>
+ *		and <asm-i386/upd4990a.h>.
+ *		Introduce a lot of spin_lock/unlock (&rtc_lock).
+ */
+
+#define RTC98_VERSION	"1.2"
+
+#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/bcd.h>
+#include <linux/upd4990a.h>
+#include <linux/init.h>
+#include <linux/poll.h>
+#include <linux/proc_fs.h>
+#include <linux/spinlock.h>
+
+#include <asm/io.h>
+#include <asm/uaccess.h>
+#include <asm/system.h>
+
+/*
+ *	We sponge a minor off of the misc major. No need slurping
+ *	up another valuable major dev number for this. If you add
+ *	an ioctl, make sure you don't conflict with SPARC's RTC
+ *	ioctls.
+ */
+
+static struct fasync_struct *rtc_async_queue;
+
+static DECLARE_WAIT_QUEUE_HEAD(rtc_wait);
+
+static struct timer_list rtc_uie_timer;
+static u8 old_refclk;
+
+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);
+
+/*
+ *	Bits in rtc_status. (5 bits of room for future expansion)
+ */
+
+#define RTC_IS_OPEN		0x01	/* means /dev/rtc is in use	*/
+#define RTC_TIMER_ON            0x02    /* not used */
+#define RTC_UIE_TIMER_ON        0x04	/* UIE emulation timer is active */
+
+/*
+ * rtc_status is never changed by rtc_interrupt, and ioctl/open/close is
+ * protected by the big kernel lock. However, ioctl can still disable the timer
+ * in rtc_status and then with del_timer after the interrupt has read
+ * rtc_status but before mod_timer is called, which would then reenable the
+ * timer (but you would need to have an awful timing before you'd trip on it)
+ */
+static unsigned char rtc_status;	/* bitmapped status byte.	*/
+static unsigned long rtc_irq_data;	/* our output to the world	*/
+
+static const unsigned char days_in_mo[] = 
+{31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
+
+extern spinlock_t rtc_lock;	/* defined in arch/i386/kernel/time.c */
+
+static void rtc_uie_intr(unsigned long data)
+{
+	u8 refclk, tmp;
+
+	/* Kernel timer does del_timer internally before calling
+	   each timer entry, so this is unnecessary.
+	   del_timer(&rtc_uie_timer);  */
+	spin_lock(&rtc_lock);
+
+	/* Detect rising edge of 1Hz reference clock.  */
+	refclk = UPD4990A_READ_DATA();
+	tmp = old_refclk & refclk;
+	old_refclk = ~refclk;
+	if (!(tmp & 1))
+		rtc_irq_data += 0x100;
+
+	spin_unlock(&rtc_lock);
+
+	if (!(tmp & 1)) {
+		/* Now do the rest of the actions */
+		wake_up_interruptible(&rtc_wait);
+		kill_fasync(&rtc_async_queue, SIGIO, POLL_IN);
+	}
+
+	rtc_uie_timer.expires = jiffies + 1;
+	add_timer(&rtc_uie_timer);
+}
+
+/*
+ *	Now all the various file operations that we export.
+ */
+
+static ssize_t rtc_read(struct file *file, char *buf,
+			size_t count, loff_t *ppos)
+{
+	DECLARE_WAITQUEUE(wait, current);
+	unsigned long data;
+	ssize_t retval = 0;
+	
+	if (count < sizeof(unsigned long))
+		return -EINVAL;
+
+	add_wait_queue(&rtc_wait, &wait);
+
+	set_current_state(TASK_INTERRUPTIBLE);
+
+	do {
+		/* First make it right. Then make it fast. Putting this whole
+		 * block within the parentheses of a while would be too
+		 * confusing. And no, xchg() is not the answer. */
+		spin_lock_irq(&rtc_lock);
+		data = rtc_irq_data;
+		rtc_irq_data = 0;
+		spin_unlock_irq(&rtc_lock);
+
+		if (data != 0)
+			break;
+		if (file->f_flags & O_NONBLOCK) {
+			retval = -EAGAIN;
+			goto out;
+		}
+		if (signal_pending(current)) {
+			retval = -ERESTARTSYS;
+			goto out;
+		}
+		schedule();
+	} while (1);
+
+	retval = put_user(data, (unsigned long *)buf);
+	if (!retval)
+		retval = sizeof(unsigned long); 
+ out:
+	set_current_state(TASK_RUNNING);
+	remove_wait_queue(&rtc_wait, &wait);
+
+	return retval;
+}
+
+static int rtc_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
+		     unsigned long arg)
+{
+	struct rtc_time wtime; 
+	struct upd4990a_raw_data raw;
+
+	switch (cmd) {
+	case RTC_UIE_OFF:	/* Mask ints from RTC updates.	*/
+		spin_lock_irq(&rtc_lock);
+		if (rtc_status & RTC_UIE_TIMER_ON) {
+			rtc_status &= ~RTC_UIE_TIMER_ON;
+			del_timer(&rtc_uie_timer);
+		}
+		spin_unlock_irq(&rtc_lock);
+		return 0;
+
+	case RTC_UIE_ON:	/* Allow ints for RTC updates.	*/
+		spin_lock_irq(&rtc_lock);
+		rtc_irq_data = 0;
+		if (!(rtc_status & RTC_UIE_TIMER_ON)) {
+			rtc_status |= RTC_UIE_TIMER_ON;
+			rtc_uie_timer.expires = jiffies + 1;
+			add_timer(&rtc_uie_timer);
+		}
+		/* Just in case... */
+		upd4990a_serial_command(UPD4990A_REGISTER_HOLD);
+		old_refclk = ~UPD4990A_READ_DATA();
+		spin_unlock_irq(&rtc_lock);
+		return 0;
+
+	case RTC_RD_TIME:	/* Read the time/date from RTC	*/
+		spin_lock_irq(&rtc_lock);
+		upd4990a_get_time(&raw, 0);
+		spin_unlock_irq(&rtc_lock);
+
+		wtime.tm_sec	= BCD2BIN(raw.sec);
+		wtime.tm_min	= BCD2BIN(raw.min);
+		wtime.tm_hour	= BCD2BIN(raw.hour);
+		wtime.tm_mday	= BCD2BIN(raw.mday);
+		wtime.tm_mon	= raw.mon - 1; /* convert to 0-base */
+		wtime.tm_wday	= raw.wday;
+
+		/*
+		 * Account for differences between how the RTC uses the values
+		 * and how they are defined in a struct rtc_time;
+		 */
+		if ((wtime.tm_year = BCD2BIN(raw.year)) < 95)
+			wtime.tm_year += 100;
+
+		wtime.tm_isdst = 0;
+		break;
+
+	case RTC_SET_TIME:	/* Set the RTC */
+	{
+		int leap_yr;
+
+		if (!capable(CAP_SYS_TIME))
+			return -EACCES;
+
+		if (copy_from_user(&wtime, (struct rtc_time *) arg,
+				    sizeof (struct rtc_time)))
+			return -EFAULT;
+
+		/* Valid year is 1995 - 2094, inclusive.  */
+		if (wtime.tm_year < 95 || wtime.tm_year > 194)
+			return -EINVAL;
+
+		if (wtime.tm_mon > 11 || wtime.tm_mday == 0)
+			return -EINVAL;
+
+		/* For acceptable year domain (1995 - 2094),
+		   this IS sufficient.  */
+		leap_yr = !(wtime.tm_year % 4);
+
+		if (wtime.tm_mday > (days_in_mo[wtime.tm_mon]
+				     + (wtime.tm_mon == 2 && leap_yr)))
+			return -EINVAL;
+			
+		if (wtime.tm_hour >= 24
+		    || wtime.tm_min >= 60 || wtime.tm_sec >= 60)
+			return -EINVAL;
+
+		if (wtime.tm_wday > 6)
+			return -EINVAL;
+
+		raw.sec  = BIN2BCD(wtime.tm_sec);
+		raw.min  = BIN2BCD(wtime.tm_min);
+		raw.hour = BIN2BCD(wtime.tm_hour);
+		raw.mday = BIN2BCD(wtime.tm_mday);
+		raw.mon  = wtime.tm_mon + 1;
+		raw.wday = wtime.tm_wday;
+		raw.year = BIN2BCD(wtime.tm_year % 100);
+
+		spin_lock_irq(&rtc_lock);
+		upd4990a_set_time(&raw, 0);
+		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)
+		goto out_busy;
+
+	rtc_status |= RTC_IS_OPEN;
+
+	rtc_irq_data = 0;
+	spin_unlock_irq(&rtc_lock);
+	return 0;
+
+ out_busy:
+	spin_unlock_irq(&rtc_lock);
+	return -EBUSY;
+}
+
+static int rtc_fasync(int fd, struct file *filp, int on)
+{
+	return fasync_helper(fd, filp, on, &rtc_async_queue);
+}
+
+static int rtc_release(struct inode *inode, struct file *file)
+{
+	del_timer(&rtc_uie_timer);
+
+	if (file->f_flags & FASYNC)
+		rtc_fasync(-1, file, 0);
+
+	rtc_irq_data = 0;
+
+	/* No need for locking -- nobody else can do anything until this rmw is
+	 * committed, and no timer is running. */
+	rtc_status &= ~(RTC_IS_OPEN | RTC_UIE_TIMER_ON);
+	return 0;
+}
+
+static unsigned int rtc_poll(struct file *file, poll_table *wait)
+{
+	unsigned long l;
+
+	poll_wait(file, &rtc_wait, wait);
+
+	spin_lock_irq(&rtc_lock);
+	l = rtc_irq_data;
+	spin_unlock_irq(&rtc_lock);
+
+	if (l != 0)
+		return POLLIN | POLLRDNORM;
+	return 0;
+}
+
+/*
+ *	The various file operations we support.
+ */
+
+static struct file_operations rtc_fops = {
+	.owner		= THIS_MODULE,
+	.read		= rtc_read,
+	.poll		= rtc_poll,
+	.ioctl		= rtc_ioctl,
+	.open		= rtc_open,
+	.release	= rtc_release,
+	.fasync		= rtc_fasync,
+};
+
+static struct miscdevice rtc_dev=
+{
+	.minor	= RTC_MINOR,
+	.name	= "rtc",
+	.fops	= &rtc_fops,
+};
+
+static int __init rtc_init(void)
+{
+	if (!request_region(UPD4990A_IO, 1, "rtc")) {
+		printk(KERN_ERR "upd4990a: could not acquire I/O port %#x\n",
+			UPD4990A_IO);
+		return -EBUSY;
+	}
+
+#if 0
+	printk(KERN_INFO "\xB6\xDA\xDD\xC0\xDE \xC4\xDE\xB9\xB2 Driver\n");  /* Calender Clock Driver */
+#else
+	printk(KERN_INFO
+	       "Real Time Clock driver for NEC PC-9800 v" RTC98_VERSION "\n");
+#endif
+	misc_register(&rtc_dev);
+	create_proc_read_entry("driver/rtc", 0, NULL, rtc_read_proc, NULL);
+
+	init_timer(&rtc_uie_timer);
+	rtc_uie_timer.function = rtc_uie_intr;
+
+	return 0;
+}
+
+module_init (rtc_init);
+
+static void __exit rtc_exit(void)
+{
+	del_timer(&rtc_uie_timer);
+	release_region(UPD4990A_IO, 1);
+	remove_proc_entry("driver/rtc", NULL);
+	misc_deregister(&rtc_dev);
+}
+
+module_exit (rtc_exit);
+
+/*
+ *	Info exported via "/proc/driver/rtc".
+ */
+
+static inline int rtc_get_status(char *buf)
+{
+	char *p;
+	unsigned int year;
+	struct upd4990a_raw_data data;
+
+	p = buf;
+
+	upd4990a_get_time(&data, 0);
+
+	/*
+	 * 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.
+	 */
+	if ((year = BCD2BIN(data.year) + 1900) < 1995)
+		year += 100;
+	p += sprintf(p,
+		     "rtc_time\t: %02d:%02d:%02d\n"
+		     "rtc_date\t: %04d-%02d-%02d\n",
+		     BCD2BIN(data.hour), BCD2BIN(data.min),
+		     BCD2BIN(data.sec),
+		     year, data.mon, BCD2BIN(data.mday));
+
+	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;
+}