Subject: [RFC and PATCH] Move the m68k genrtc driver into 2.5 and use on PPC

From: Tom Rini <[email-masked]>
Date: Thu, 13 Jun 2002 12:06:46 -0700

Hello all.  A few months back yet another RTC thread was started.  I've
finally gotten around to trying to do something about the generic RTC
issue.  The following patch takes the m68k generic RTC driver
(drivers/char/genrtc.c) and drops it into 2.5.21, along with
include/asm-ppc/rtc.h with the needed inlines to get basic functionality
going.

My first question is to the MIPS people.  What did you end up doing in
the end about a 'generic' RTC driver?  Did you do something
quick-and-dirty ala drivers/macintosh/rtc.c or did you go and take the
m68k one?  If you did something other than take the m68k driver, did you
find any problems with genrtc.c that stopped you from using it?  Or was
it the generic code changes (include/linux/rtc.h)

Secondly to the m68k people, does anyone have an objection (or would
like to do it themselves?) with me trying to get Linus to take the
changes to include/linux/rtc.h?  radeonfb.c currently conflicts with the
'pll_info' struct, but Ani Joshi is renaming it.  Also, CONFIG_GEN_RTC
used to be define_bool'ed to y on CONFIG_SUN3, but I'm not sure if that
looks nice in a common file.  Any idea on how to solve this nicely?
(create arch/m68k/configs/*defconfig ala ppc or arch/m68k/defconfig-xxx
ala mips or arch/m68k/def-configs/ ala arm?)

And to everyone, while this patch is vs 2.5.21'ish, it should mostly
apply to 2.4.x, so please test this on your favorite arch (or for MIPS,
create <asm/rtc.h> and test :)) and get back to me.  What I'd like to
try and do in the end is perhaps replace drivers/char/rtc.c, but at a
miniumum, I'd like to kill off drivers/macintosh/rtc.c.

--
Tom Rini (TR1265)
http://gate.crashing.org/~trini/

diff -Nru a/drivers/char/Config.help b/drivers/char/Config.help
--- a/drivers/char/Config.help	Thu Jun 13 12:03:49 2002
+++ b/drivers/char/Config.help	Thu Jun 13 12:03:49 2002
@@ -1058,6 +1058,34 @@
   The module is called rtc.o. If you want to compile it as a module,
   say M here and read <file:Documentation/modules.txt>.

+Generic Real Time Clock Support
+CONFIG_GEN_RTC
+  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 (or hardware clock) built
+  into your computer.
+
+  In 2.4 and later kernels this is the only way to set and get rtc
+  time on m68k systems so it is highly recommended.
+
+  It reports status information via the file /proc/driver/rtc and its
+  behaviour is set by various ioctls on /dev/rtc. If you enable the
+  "extended RTC operation" below it will also provide an emulation
+  for RTC_UIE which is required by some programs and may improve
+  precision in some cases.
+
+  This driver is also available as a module ( = code which can be
+  inserted in and removed from the running kernel whenever you want).
+  The module is called rtc.o. If you want to compile it as a module,
+  say M here and read <file:Documentation/modules.txt>. To load the
+  module automaticaly add 'alias char-major-10-135 genrtc' to your
+  /etc/modules.conf
+
+Extended RTC operation
+CONFIG_GEN_RTC_X
+  Provides an emulation for RTC_UIE which is required by some programs
+  and may improve precision of the generic RTC support in some cases.
+
 CONFIG_H8
   The Hitachi H8/337 is a microcontroller used to deal with the power
   and thermal environment. If you say Y here, you will be able to
diff -Nru a/drivers/char/Config.in b/drivers/char/Config.in
--- a/drivers/char/Config.in	Thu Jun 13 12:03:49 2002
+++ b/drivers/char/Config.in	Thu Jun 13 12:03:49 2002
@@ -188,6 +188,14 @@
 dep_tristate 'Intel i8x0 Random Number Generator support' CONFIG_INTEL_RNG $CONFIG_PCI
 tristate '/dev/nvram support' CONFIG_NVRAM
 tristate 'Enhanced Real Time Clock Support' CONFIG_RTC
+# XXX: RTC drivers conflict.  Only allow one.
+if [ "$CONFIG_RTC" = "n" ]; then
+   # XXX: CONFIG_SUN3 used to define_bool this to y
+   tristate 'Generic /dev/rtc emulation' CONFIG_GEN_RTC
+   if [ "$CONFIG_GEN_RTC" != "n" ]; then
+      bool '   Extended RTC operation' CONFIG_GEN_RTC_X
+   fi
+fi
 if [ "$CONFIG_IA64" = "y" ]; then
    bool 'EFI Real Time Clock Services' CONFIG_EFI_RTC
 fi
diff -Nru a/drivers/char/Makefile b/drivers/char/Makefile
--- a/drivers/char/Makefile	Thu Jun 13 12:03:49 2002
+++ b/drivers/char/Makefile	Thu Jun 13 12:03:49 2002
@@ -173,6 +173,7 @@
 obj-$(CONFIG_ADBMOUSE) += adbmouse.o
 obj-$(CONFIG_PC110_PAD) += pc110pad.o
 obj-$(CONFIG_RTC) += rtc.o
+obj-$(CONFIG_GEN_RTC) += genrtc.o
 obj-$(CONFIG_EFI_RTC) += efirtc.o
 ifeq ($(CONFIG_PPC),)
   obj-$(CONFIG_NVRAM) += nvram.o
diff -Nru a/drivers/char/genrtc.c b/drivers/char/genrtc.c
--- /dev/null	Wed Dec 31 16:00:00 1969
+++ b/drivers/char/genrtc.c	Thu Jun 13 12:03:49 2002
@@ -0,0 +1,517 @@
+/*
+ *	Real Time Clock interface for q40 and other m68k machines
+ *      emulate some RTC irq capabilities in software
+ *
+ *      Copyright (C) 1999 Richard Zidlicky
+ *
+ *	based on Paul Gortmaker's rtc.c device and
+ *           Sam Creasey Generic rtc driver
+ *
+ *	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/dev/rtc
+ *	pseudo-file for status information.
+ *
+ *	The ioctls can be used to set the interrupt behaviour where
+ *  supported.
+ *
+ *	The /dev/rtc interface will block on reads until an interrupt
+ *	has been received. If a RTC interrupt has already happened,
+ *	it will output an unsigned long and then block. The output value
+ *	contains the interrupt status in the low byte and the number of
+ *	interrupts since the last read in the remaining high bytes. The
+ *	/dev/rtc interface can also be used with the select(2) call.
+ *
+ *	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.
+ *
+
+ *      1.01 fix for 2.3.X                    [email-masked]
+ *      1.02 merged with code from genrtc.c   [email-masked]
+ *      1.03 make it more portable            [email-masked]
+ *      1.04 removed useless timer code       [email-masked]
+ *      1.05 portable RTC_UIE emulation       [email-masked]
+ */
+
+#define RTC_VERSION	"1.05"
+
+#include <linux/module.h>
+#include <linux/config.h>
+#include <linux/errno.h>
+#include <linux/miscdevice.h>
+#include <linux/fcntl.h>
+
+#include <linux/rtc.h>
+#include <linux/init.h>
+#include <linux/poll.h>
+#include <linux/proc_fs.h>
+
+#include <asm/uaccess.h>
+#include <asm/system.h>
+#include <asm/rtc.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 DECLARE_WAIT_QUEUE_HEAD(gen_rtc_wait);
+
+static int gen_rtc_ioctl(struct inode *inode, struct file *file,
+		     unsigned int cmd, unsigned long arg);
+
+/*
+ *	Bits in gen_rtc_status.
+ */
+
+#define RTC_IS_OPEN		0x01	/* means /dev/rtc is in use	*/
+
+unsigned char gen_rtc_status;		/* bitmapped status byte.	*/
+unsigned long gen_rtc_irq_data;		/* our output to the world	*/
+
+/* months start at 0 now */
+unsigned char days_in_mo[] =
+{31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
+
+static int irq_active;
+
+#ifdef CONFIG_GEN_RTC_X
+struct tq_struct genrtc_task;
+static struct timer_list timer_task;
+
+static unsigned int oldsecs;
+static int lostint;
+static int tt_exp;
+
+void gen_rtc_timer(unsigned long data);
+
+static volatile int stask_active;              /* schedule_task */
+static volatile int ttask_active;              /* timer_task */
+static int stop_rtc_timers;                    /* don't requeue tasks */
+static spinlock_t gen_rtc_lock = SPIN_LOCK_UNLOCKED;
+
+/*
+ * Routine to poll RTC seconds field for change as often as posible,
+ * after first RTC_UIE use timer to reduce polling
+ */
+void genrtc_troutine(void *data)
+{
+	unsigned int tmp = get_rtc_ss();
+
+	if (stop_rtc_timers) {
+		stask_active = 0;
+		return;
+	}
+
+	if (oldsecs != tmp){
+		oldsecs = tmp;
+
+		timer_task.function = gen_rtc_timer;
+		timer_task.expires = jiffies + HZ - (HZ/10);
+		tt_exp=timer_task.expires;
+		ttask_active=1;
+		stask_active=0;
+		add_timer(&timer_task);
+
+		gen_rtc_interrupt(0);
+	} else if (schedule_task(&genrtc_task) == 0)
+		stask_active = 0;
+}
+
+void gen_rtc_timer(unsigned long data)
+{
+	lostint = get_rtc_ss() - oldsecs ;
+	if (lostint<0)
+		lostint = 60 - lostint;
+	if (jiffies-tt_exp>1)
+		printk("genrtc: timer task delayed by %ld jiffies\n",
+		       jiffies-tt_exp);
+	ttask_active=0;
+	stask_active=1;
+	if ((schedule_task(&genrtc_task) == 0))
+		stask_active = 0;
+}
+
+/*
+ * call gen_rtc_interrupt function to signal an RTC_UIE,
+ * arg is unused.
+ * Could be invoked either from a real interrupt handler or
+ * from some routine that periodically (eg 100HZ) monitors
+ * whether RTC_SECS changed
+ */
+void gen_rtc_interrupt(unsigned long arg)
+{
+	/*  We store the status in the low byte and the number of
+	 *	interrupts received since the last read in the remainder
+	 *	of rtc_irq_data.  */
+
+	gen_rtc_irq_data += 0x100;
+	gen_rtc_irq_data &= ~0xff;
+	gen_rtc_irq_data |= RTC_UIE;
+
+	if (lostint){
+		printk("genrtc: system delaying clock ticks?\n");
+		/* increment count so that userspace knows something is wrong */
+		gen_rtc_irq_data += ((lostint-1)<<8);
+		lostint = 0;
+	}
+
+	wake_up_interruptible(&gen_rtc_wait);
+}
+
+/*
+ *	Now all the various file operations that we export.
+ */
+static ssize_t gen_rtc_read(struct file *file, char *buf,
+			size_t count, loff_t *ppos)
+{
+	DECLARE_WAITQUEUE(wait, current);
+	unsigned long data;
+	ssize_t retval;
+
+	if (count < sizeof(unsigned long))
+		return -EINVAL;
+
+	if (file->f_flags & O_NONBLOCK && !gen_rtc_irq_data)
+		return -EAGAIN;
+
+	add_wait_queue(&gen_rtc_wait, &wait);
+	retval = -ERESTARTSYS;
+
+	while (1) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		data = xchg(&gen_rtc_irq_data, 0);
+		if (data)
+			break;
+		if (signal_pending(current))
+			goto out;
+		schedule();
+	}
+
+	retval = put_user(data, (unsigned long *)buf);
+	if (!retval)
+		retval = sizeof(unsigned long);
+ out:
+	current->state = TASK_RUNNING;
+	remove_wait_queue(&gen_rtc_wait, &wait);
+
+	return retval;
+}
+
+static unsigned int gen_rtc_poll(struct file *file,
+				 struct poll_table_struct *wait)
+{
+	poll_wait(file, &gen_rtc_wait, wait);
+	if (gen_rtc_irq_data != 0)
+		return POLLIN | POLLRDNORM;
+	return 0;
+}
+
+#endif
+
+/*
+ * Used to disable/enable interrupts, only RTC_UIE supported
+ * We also clear out any old irq data after an ioctl() that
+ * meddles with the interrupt enable/disable bits.
+ */
+
+static inline void gen_clear_rtc_irq_bit(unsigned char bit)
+{
+#ifdef CONFIG_GEN_RTC_X
+	stop_rtc_timers = 1;
+	if (ttask_active){
+		del_timer_sync(&timer_task);
+		ttask_active = 0;
+	}
+	while (stask_active)
+		schedule();
+
+	spin_lock(&gen_rtc_lock);
+	irq_active = 0;
+	spin_unlock(&gen_rtc_lock);
+#endif
+}
+
+static inline int gen_set_rtc_irq_bit(unsigned char bit)
+{
+#ifdef CONFIG_GEN_RTC_X
+	spin_lock(&gen_rtc_lock);
+	if ( !irq_active ) {
+		irq_active = 1;
+		stop_rtc_timers = 0;
+		lostint = 0;
+		genrtc_task.routine = genrtc_troutine;
+		oldsecs = get_rtc_ss();
+		init_timer(&timer_task);
+
+		stask_active = 1;
+		if (schedule_task(&genrtc_task) == 0){
+			stask_active = 0;
+		}
+	}
+	spin_unlock(&gen_rtc_lock);
+	gen_rtc_irq_data = 0;
+	return 0;
+#else
+	return -EINVAL;
+#endif
+}
+
+static int gen_rtc_ioctl(struct inode *inode, struct file *file,
+			 unsigned int cmd, unsigned long arg)
+{
+	struct rtc_time wtime;
+	struct pll_info pll;
+
+	switch (cmd) {
+
+	case RTC_PLL_GET:
+	    if (get_rtc_pll(&pll))
+	 	    return -EINVAL;
+	    else
+		    return copy_to_user((void *)arg, &pll, sizeof pll) ? -EFAULT : 0;
+
+	case RTC_PLL_SET:
+		if (!capable(CAP_SYS_TIME))
+			return -EACCES;
+		if (copy_from_user(&pll, (struct pll_info*)arg,
+				   sizeof(pll)))
+			return -EFAULT;
+	    return set_rtc_pll(&pll);
+
+	case RTC_UIE_OFF:	/* disable ints from RTC updates.	*/
+		gen_clear_rtc_irq_bit(RTC_UIE);
+		return 0;
+
+	case RTC_UIE_ON:	/* enable ints for RTC updates.	*/
+	        return gen_set_rtc_irq_bit(RTC_UIE);
+
+	case RTC_RD_TIME:	/* Read the time/date from RTC	*/
+		/* this doesn't get week-day, who cares */
+		memset(&wtime, 0, sizeof(wtime));
+		get_rtc_time(&wtime);
+
+		return copy_to_user((void *)arg, &wtime, sizeof(wtime)) ? -EFAULT : 0;
+
+	case RTC_SET_TIME:	/* Set the RTC */
+	    {
+		int year;
+		unsigned char leap_yr;
+
+		if (!capable(CAP_SYS_TIME))
+			return -EACCES;
+
+		if (copy_from_user(&wtime, (struct rtc_time *)arg,
+				   sizeof(wtime)))
+			return -EFAULT;
+
+		year = wtime.tm_year + 1900;
+		leap_yr = ((!(year % 4) && (year % 100)) ||
+			   !(year % 400));
+
+		if ((wtime.tm_mon < 0 || wtime.tm_mon > 11) || (wtime.tm_mday < 1))
+			return -EINVAL;
+
+		if (wtime.tm_mday < 0 || wtime.tm_mday >
+		    (days_in_mo[wtime.tm_mon] + ((wtime.tm_mon == 1) && leap_yr)))
+			return -EINVAL;
+
+		if (wtime.tm_hour < 0 || wtime.tm_hour >= 24 ||
+		    wtime.tm_min < 0 || wtime.tm_min >= 60 ||
+		    wtime.tm_sec < 0 || wtime.tm_sec >= 60)
+			return -EINVAL;
+
+		set_rtc_time(&wtime);
+		return 0;
+	    }
+	}
+
+	return -EINVAL;
+}
+
+/*
+ *	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 gen_rtc_open(struct inode *inode, struct file *file)
+{
+	if (gen_rtc_status & RTC_IS_OPEN)
+		return -EBUSY;
+
+	MOD_INC_USE_COUNT;
+
+	gen_rtc_status |= RTC_IS_OPEN;
+	gen_rtc_irq_data = 0;
+	irq_active = 0;
+
+	return 0;
+}
+
+static int gen_rtc_release(struct inode *inode, struct file *file)
+{
+	/*
+	 * Turn off all interrupts once the device is no longer
+	 * in use and clear the data.
+	 */
+
+	gen_clear_rtc_irq_bit(RTC_PIE|RTC_AIE|RTC_UIE);
+
+	gen_rtc_status &= ~RTC_IS_OPEN;
+	MOD_DEC_USE_COUNT;
+
+	return 0;
+}
+
+static int gen_rtc_read_proc(char *page, char **start, off_t off,
+			     int count, int *eof, void *data);
+
+
+/*
+ *	The various file operations we support.
+ */
+
+static struct file_operations gen_rtc_fops = {
+	owner:		THIS_MODULE,
+#ifdef CONFIG_GEN_RTC_X
+	read:		gen_rtc_read,
+	poll:		gen_rtc_poll,
+#endif
+	ioctl:		gen_rtc_ioctl,
+	open:		gen_rtc_open,
+	release:	gen_rtc_release
+};
+
+static struct miscdevice rtc_gen_dev =
+{
+	RTC_MINOR,
+	"rtc",
+	&gen_rtc_fops
+};
+
+int __init rtc_generic_init(void)
+{
+
+		printk(KERN_INFO "Generic RTC Driver v%s\n", RTC_VERSION);
+
+	misc_register(&rtc_gen_dev);
+	create_proc_read_entry ("driver/rtc", 0, 0, gen_rtc_read_proc, NULL);
+
+	return 0;
+}
+
+static void __exit rtc_generic_exit(void)
+{
+	remove_proc_entry ("driver/rtc", NULL);
+	misc_deregister(&rtc_gen_dev);
+}
+
+module_init(rtc_generic_init);
+module_exit(rtc_generic_exit);
+EXPORT_NO_SYMBOLS;
+
+
+/*
+ *	Info exported via "/proc/rtc".
+ */
+
+int gen_rtc_proc_output(char *buf)
+{
+	char *p;
+	struct rtc_time tm;
+	unsigned tmp;
+	struct pll_info pll;
+
+	p = buf;
+
+	get_rtc_time(&tm);
+
+	p += sprintf(p,
+		     "rtc_time\t: %02d:%02d:%02d\n"
+		     "rtc_date\t: %04d-%02d-%02d\n"
+		     "rtc_epoch\t: %04u\n",
+		     tm.tm_hour, tm.tm_min, tm.tm_sec,
+		     tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, 1900);
+
+	tm.tm_hour=0;tm.tm_min=0;tm.tm_sec=0;
+
+	p += sprintf(p, "alarm\t\t: ");
+	if (tm.tm_hour <= 24)
+		p += sprintf(p, "%02d:", tm.tm_hour);
+	else
+		p += sprintf(p, "**:");
+
+	if (tm.tm_min <= 59)
+		p += sprintf(p, "%02d:", tm.tm_min);
+	else
+		p += sprintf(p, "**:");
+
+	if (tm.tm_sec <= 59)
+		p += sprintf(p, "%02d\n", tm.tm_sec);
+	else
+		p += sprintf(p, "**\n");
+
+	tmp= RTC_24H ;
+	p += sprintf(p,
+		     "DST_enable\t: %s\n"
+		     "BCD\t\t: %s\n"
+		     "24hr\t\t: %s\n"
+		     "square_wave\t: %s\n"
+		     "alarm_IRQ\t: %s\n"
+		     "update_IRQ\t: %s\n"
+		     "periodic_IRQ\t: %s\n"
+		     "periodic_freq\t: %ld\n"
+		     "batt_status\t: %s\n",
+		     (tmp & RTC_DST_EN) ? "yes" : "no",
+		     (tmp & RTC_DM_BINARY) ? "no" : "yes",
+		     (tmp & RTC_24H) ? "yes" : "no",
+		     (tmp & RTC_SQWE) ? "yes" : "no",
+		     (tmp & RTC_AIE) ? "yes" : "no",
+		     irq_active ? "yes" : "no",
+		     (tmp & RTC_PIE) ? "yes" : "no",
+		     0L /* freq */,
+		     "okay" );
+	if (!get_rtc_pll(&pll))
+	    p += sprintf(p,
+			 "PLL adjustment\t: %d\n"
+			 "PLL max +ve adjustment\t: %d\n"
+			 "PLL max -ve adjustment\t: %d\n"
+			 "PLL +ve adjustment factor\t: %d\n"
+			 "PLL -ve adjustment factor\t: %d\n"
+			 "PLL frequency\t: %ld\n",
+			 pll.pll_value,
+			 pll.pll_max,
+			 pll.pll_min,
+			 pll.pll_posmult,
+			 pll.pll_negmult,
+			 pll.pll_clock);
+	return  p - buf;
+}
+
+static int gen_rtc_read_proc(char *page, char **start, off_t off,
+			     int count, int *eof, void *data)
+{
+	int len = gen_rtc_proc_output (page);
+        if (len <= off+count) *eof = 1;
+	*start = page + off;
+	len -= off;
+        if (len>count) len = count;
+        if (len<0) len = 0;
+	return len;
+}
+
+
+MODULE_AUTHOR("Richard Zidlicky");
+MODULE_LICENSE("GPL");
+
+/*
+ * Local variables:
+ * compile-command: "m68k-linux-gcc -D__KERNEL__ -I../../include -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer -pipe -fno-strength-reduce -ffixed-a2 -c -o genrtc.o genrtc.c"
+ * End:
+ */
+
diff -Nru a/drivers/video/radeonfb.c b/drivers/video/radeonfb.c
--- a/drivers/video/radeonfb.c	Thu Jun 13 12:03:49 2002
+++ b/drivers/video/radeonfb.c	Thu Jun 13 12:03:49 2002
@@ -190,7 +190,7 @@
 } __attribute__ ((packed)) PLL_BLOCK;

-struct pll_info {
+struct radeon_pll_info {
 	int ppll_max;
 	int ppll_min;
 	int xclk;
@@ -304,7 +304,7 @@

 	u32 dp_gui_master_cntl;

-	struct pll_info pll;
+	struct radeon_pll_info pll;
 	int pll_output_freq, post_div, fb_div;

 	struct ram_info ram;
diff -Nru a/include/asm-ppc/rtc.h b/include/asm-ppc/rtc.h
--- /dev/null	Wed Dec 31 16:00:00 1969
+++ b/include/asm-ppc/rtc.h	Thu Jun 13 12:03:49 2002
@@ -0,0 +1,94 @@
+/*
+ * inclue/asm-ppc/rtc.h
+ *
+ * Copyright 2002 MontaVista Software Inc.
+ * Author: Tom Rini <[email-masked]>
+ *
+ * Based on:
+ * include/asm-m68k/rtc.h
+ *
+ * Copyright Richard Zidlicky
+ * implementation details for genrtc/q40rtc driver
+ *
+ * And the old drivers/macintosh/rtc.c which was heavily based on:
+ * Linux/SPARC Real Time Clock Driver
+ * Copyright (C) 1996 Thomas K. Dyas ([email-masked])
+ *
+ * With additional work by Paul Mackerras and Franz Sirl.
+ */
+/* permission is hereby granted to copy, modify and redistribute this code
+ * in terms of the GNU Library General Public License, Version 2 or later,
+ * at your option.
+ */
+
+#ifndef __ASM_RTC_H__
+#define __ASM_RTC_H__
+
+#ifdef __KERNEL__
+
+#include <linux/rtc.h>
+
+#include <asm/machdep.h>
+#include <asm/time.h>
+
+#define RTC_PIE 0x40		/* periodic interrupt enable */
+#define RTC_AIE 0x20		/* alarm interrupt enable */
+#define RTC_UIE 0x10		/* update-finished interrupt enable */
+
+extern void gen_rtc_interrupt(unsigned long);
+
+/* some dummy definitions */
+#define RTC_SQWE 0x08		/* enable square-wave output */
+#define RTC_DM_BINARY 0x04	/* all time/date values are BCD if clear */
+#define RTC_24H 0x02		/* 24 hour mode - else hours bit 7 means pm */
+#define RTC_DST_EN 0x01	        /* auto switch DST - works f. USA only */
+
+static inline void get_rtc_time(struct rtc_time *time)
+{
+	if (ppc_md.get_rtc_time) {
+		unsigned long nowtime;
+
+		nowtime = (ppc_md.get_rtc_time)();
+
+		to_tm(nowtime, time);
+
+		time->tm_year -= 1900;
+		time->tm_mon -= 1; /* Make sure userland has a 0-based month */
+	} else
+		return -EINVAL;
+}
+
+/* Set the current date and time in the real time clock. */
+static inline void set_rtc_time(struct rtc_time *time)
+{
+	if (ppc_md.get_rtc_time) {
+		unsigned long nowtime;
+
+		nowtime = mktime(time->tm_year+1900, time->tm_mon+1,
+				time->tm_mday, time->tm_hour, time->tm_min,
+				time->tm_sec);
+
+		(ppc_md.set_rtc_time)(nowtime);
+	} else
+		return -EINVAL;
+}
+
+static inline unsigned int get_rtc_ss(void)
+{
+	struct rtc_time h;
+
+	get_rtc_time(&h);
+	return h.tm_sec;
+}
+
+static inline int get_rtc_pll(struct pll_info *pll)
+{
+	return -EINVAL;
+}
+static inline int set_rtc_pll(struct pll_info *pll)
+{
+	return -EINVAL;
+}
+
+#endif /* __KERNEL__ */
+#endif /* __ASM_RTC_H__ */
diff -Nru a/include/linux/rtc.h b/include/linux/rtc.h
--- a/include/linux/rtc.h	Thu Jun 13 12:03:49 2002
+++ b/include/linux/rtc.h	Thu Jun 13 12:03:49 2002
@@ -39,10 +39,32 @@
 	struct rtc_time time;	/* time the alarm is set to */
 };

+/*
+ * Data structure to control PLL correction some better RTC feature
+ * pll_value is used to get or set current value of correction,
+ * the rest of the struct is used to query HW capabilities.
+ * This is modeled after the RTC used in Q40/Q60 computers but
+ * should be sufficiently flexible for other devices
+ *
+ * +ve pll_value means clock will run faster by
+ *   pll_value*pll_posmult/pll_clock
+ * -ve pll_value means clock will run slower by
+ *   pll_value*pll_negmult/pll_clock
+ */
+
+struct pll_info {
+	int pll_ctrl;       /* placeholder for fancier control */
+	int pll_value;      /* get/set correction value */
+	int pll_max;        /* max +ve (faster) adjustment value */
+	int pll_min;        /* max -ve (slower) adjustment value */
+	int pll_posmult;    /* factor for +ve corection */
+	int pll_negmult;    /* factor for -ve corection */
+	long pll_clock;     /* base PLL frequency */
+};

 /*
  * ioctl calls that are permitted to the /dev/rtc interface, if
- * CONFIG_RTC/CONFIG_EFI_RTC was enabled.
+ * any of the RTC drivers are enabled.
  */

 #define RTC_AIE_ON	_IO('p', 0x01)	/* Alarm int. enable on		*/
@@ -65,6 +87,9 @@

 #define RTC_WKALM_SET	_IOW('p', 0x0f, struct rtc_wkalrm)/* Set wakeup alarm*/
 #define RTC_WKALM_RD	_IOR('p', 0x10, struct rtc_wkalrm)/* Get wakeup alarm*/
+#define RTC_PLL_GET	_IOR('p', 0x11, struct pll_info)  /* Get PLL correction */
+#define RTC_PLL_SET	_IOW('p', 0x12, struct pll_info)  /* Set PLL correction */
+#

 #ifdef __KERNEL__

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