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    Subject[PATCH][RESEND] A generic RTC driver [3/3]
    This is part 3 of 3 of the genrtc patches.  This is my own slight bit
    of work, as well as some work by Randolph Chung. This changes
    set_rtc_time(struct *rtc_time) to return an int instead of void.
    This was done so that the arch-specific code here could do additional
    checks on the time and return an error if needed. This then introduces
    include/asm-generic/rtc.h, include/asm-i386/rtc.h and
    include/asm-alpha/rtc.h. include/asm-generic/rtc.h contains the
    get_rtc_time and set_rtc_time logic that is in drivers/char/rtc.c and
    has been tested on SMP i386. This also modifies include/asm-ppc/rtc.h
    to return -ENODEV if no rtc hardware is present.

    Additionally, Dave Jones pointed out to me a place where we might not be
    safe when jiffies wraps, so this switches that to time_after().

    From Randolph Chung, is supprt for a 64bit kernel and a 32bit userland.

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

    --- linux-2.5/include/asm-ppc/rtc.h 2002-07-24 13:25:15.000000000 -0700
    +++ linux-2.5/include/asm-ppc/rtc.h 2002-07-24 13:25:36.000000000 -0700
    @@ -68,7 +68,10 @@
    time->tm_sec);

    (ppc_md.set_rtc_time)(nowtime);
    - }
    +
    + return 0;
    + } else
    + return -EINVAL;
    }

    static inline unsigned int get_rtc_ss(void)
    --- /dev/null 1969-12-31 17:00:00.000000000 -0700
    +++ linux-2.5/include/asm-generic/rtc.h 2002-07-24 11:06:48.000000000 -0700
    @@ -0,0 +1,211 @@
    +/*
    + * inclue/asm-generic/rtc.h
    + *
    + * Author: Tom Rini <trini@mvista.com>
    + *
    + * Based on:
    + * drivers/char/rtc.c
    + *
    + * Please read the COPYING file for all license details.
    + */
    +
    +#ifndef __ASM_RTC_H__
    +#define __ASM_RTC_H__
    +
    +#ifdef __KERNEL__
    +
    +#include <linux/mc146818rtc.h>
    +#include <linux/rtc.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 */
    +
    +/*
    + * Returns true if a clock update is in progress
    + */
    +static inline unsigned char rtc_is_updating(void)
    +{
    + unsigned char uip;
    +
    + spin_lock_irq(&rtc_lock);
    + uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
    + spin_unlock_irq(&rtc_lock);
    + return uip;
    +}
    +
    +static inline void get_rtc_time(struct rtc_time *time)
    +{
    + unsigned long uip_watchdog = jiffies;
    + unsigned char ctrl;
    +#ifdef CONFIG_DECSTATION
    + unsigned int real_year;
    +#endif
    +
    + /*
    + * read RTC once any update in progress is done. The update
    + * can take just over 2ms. We wait 10 to 20ms. There is no need to
    + * to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
    + * If you need to know *exactly* when a second has started, enable
    + * periodic update complete interrupts, (via ioctl) and then
    + * immediately read /dev/rtc which will block until you get the IRQ.
    + * Once the read clears, read the RTC time (again via ioctl). Easy.
    + */
    +
    + if (rtc_is_updating() != 0)
    + while (jiffies - uip_watchdog < 2*HZ/100) {
    + barrier();
    + cpu_relax();
    + }
    +
    + /*
    + * 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);
    + time->tm_sec = CMOS_READ(RTC_SECONDS);
    + time->tm_min = CMOS_READ(RTC_MINUTES);
    + time->tm_hour = CMOS_READ(RTC_HOURS);
    + time->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
    + time->tm_mon = CMOS_READ(RTC_MONTH);
    + time->tm_year = CMOS_READ(RTC_YEAR);
    +#ifdef CONFIG_DECSTATION
    + real_year = CMOS_READ(RTC_DEC_YEAR);
    +#endif
    + ctrl = CMOS_READ(RTC_CONTROL);
    + spin_unlock_irq(&rtc_lock);
    +
    + if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
    + {
    + BCD_TO_BIN(time->tm_sec);
    + BCD_TO_BIN(time->tm_min);
    + BCD_TO_BIN(time->tm_hour);
    + BCD_TO_BIN(time->tm_mday);
    + BCD_TO_BIN(time->tm_mon);
    + BCD_TO_BIN(time->tm_year);
    + }
    +
    +#ifdef CONFIG_DECSTATION
    + time->tm_year += real_year - 72;
    +#endif
    +
    + /*
    + * Account for differences between how the RTC uses the values
    + * and how they are defined in a struct rtc_time;
    + */
    + if (time->tm_year <= 69)
    + time->tm_year += 100;
    +
    + time->tm_mon--;
    +}
    +
    +/* Set the current date and time in the real time clock. */
    +static inline int set_rtc_time(struct rtc_time *time)
    +{
    + unsigned char mon, day, hrs, min, sec;
    + unsigned char save_control, save_freq_select;
    + unsigned int yrs;
    +#ifdef CONFIG_DECSTATION
    + unsigned int real_yrs, leap_yr;
    +#endif
    +
    + yrs = time->tm_year;
    + mon = time->tm_mon + 1; /* tm_mon starts at zero */
    + day = time->tm_mday;
    + hrs = time->tm_hour;
    + min = time->tm_min;
    + sec = time->tm_sec;
    +
    + if (yrs > 255) /* They are unsigned */
    + return -EINVAL;
    +
    + spin_lock_irq(&rtc_lock);
    +#ifdef CONFIG_DECSTATION
    + real_yrs = yrs;
    + leap_yr = ((!((yrs + 1900) % 4) && ((yrs + 1900) % 100)) ||
    + !((yrs + 1900) % 400));
    + yrs = 72;
    +
    + /*
    + * We want to keep the year set to 73 until March
    + * for non-leap years, so that Feb, 29th is handled
    + * correctly.
    + */
    + if (!leap_yr && mon < 3) {
    + real_yrs--;
    + yrs = 73;
    + }
    +#endif
    + /* These limits and adjustments are independant of
    + * whether the chip is in binary mode or not.
    + */
    + if (yrs > 169) {
    + spin_unlock_irq(&rtc_lock);
    + return -EINVAL;
    + }
    +
    + if (yrs >= 100)
    + yrs -= 100;
    +
    + if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)
    + || RTC_ALWAYS_BCD) {
    + BIN_TO_BCD(sec);
    + BIN_TO_BCD(min);
    + BIN_TO_BCD(hrs);
    + BIN_TO_BCD(day);
    + BIN_TO_BCD(mon);
    + BIN_TO_BCD(yrs);
    + }
    +
    + save_control = CMOS_READ(RTC_CONTROL);
    + CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
    + save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
    + CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
    +
    +#ifdef CONFIG_DECSTATION
    + CMOS_WRITE(real_yrs, RTC_DEC_YEAR);
    +#endif
    + CMOS_WRITE(yrs, RTC_YEAR);
    + CMOS_WRITE(mon, RTC_MONTH);
    + CMOS_WRITE(day, RTC_DAY_OF_MONTH);
    + CMOS_WRITE(hrs, RTC_HOURS);
    + CMOS_WRITE(min, RTC_MINUTES);
    + CMOS_WRITE(sec, RTC_SECONDS);
    +
    + CMOS_WRITE(save_control, RTC_CONTROL);
    + CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
    +
    + spin_unlock_irq(&rtc_lock);
    +
    + return 0;
    +}
    +
    +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 rtc_pll_info *pll)
    +{
    + return -EINVAL;
    +}
    +static inline int set_rtc_pll(struct rtc_pll_info *pll)
    +{
    + return -EINVAL;
    +}
    +
    +#endif /* __KERNEL__ */
    +#endif /* __ASM_RTC_H__ */
    --- /dev/null 1969-12-31 17:00:00.000000000 -0700
    +++ linux-2.5/include/asm-i386/rtc.h 2002-07-23 10:38:32.000000000 -0700
    @@ -0,0 +1,10 @@
    +#ifndef _I386_RTC_H
    +#define _I386_RTC_H
    +
    +/*
    + * x86 uses the default access methods for the RTC.
    + */
    +
    +#include <asm-generic/rtc.h>
    +
    +#endif
    --- /dev/null 1969-12-31 17:00:00.000000000 -0700
    +++ linux-2.5/include/asm-alpha/rtc.h 2002-07-23 10:38:32.000000000 -0700
    @@ -0,0 +1,10 @@
    +#ifndef _ALPHA_RTC_H
    +#define _ALPHA_RTC_H
    +
    +/*
    + * Alpha uses the default access methods for the RTC.
    + */
    +
    +#include <asm-generic/rtc.h>
    +
    +#endif
    --- /dev/null 1969-12-31 17:00:00.000000000 -0700
    +++ linux-2.5/include/asm-parisc/rtc.h 2002-08-02 08:22:16.000000000 -0700
    @@ -0,0 +1,131 @@
    +/*
    + * inclue/asm-parisc/rtc.h
    + *
    + * Copyright 2002 Randolph CHung <tausq@debian.org>
    + *
    + * Based on: include/asm-ppc/rtc.h and the genrtc driver in the
    + * 2.4 parisc linux tree
    + */
    +
    +#ifndef __ASM_RTC_H__
    +#define __ASM_RTC_H__
    +
    +#ifdef __KERNEL__
    +
    +#include <linux/rtc.h>
    +
    +#include <asm/pdc.h>
    +
    +#define SECS_PER_HOUR (60 * 60)
    +#define SECS_PER_DAY (SECS_PER_HOUR * 24)
    +
    +
    +#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 */
    +
    +# define __isleap(year) \
    + ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
    +
    +/* How many days come before each month (0-12). */
    +static const unsigned short int __mon_yday[2][13] =
    +{
    + /* Normal years. */
    + { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
    + /* Leap years. */
    + { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
    +};
    +
    +static int get_rtc_time(struct rtc_time *wtime)
    +{
    + struct pdc_tod tod_data;
    + long int days, rem, y;
    + const unsigned short int *ip;
    +
    + if(pdc_tod_read(&tod_data) < 0)
    + return -1;
    +
    +
    + // most of the remainder of this function is:
    +// Copyright (C) 1991, 1993, 1997, 1998 Free Software Foundation, Inc.
    +// This was originally a part of the GNU C Library.
    +// It is distributed under the GPL, and was swiped from offtime.c
    +
    +
    + days = tod_data.tod_sec / SECS_PER_DAY;
    + rem = tod_data.tod_sec % SECS_PER_DAY;
    +
    + wtime->tm_hour = rem / SECS_PER_HOUR;
    + rem %= SECS_PER_HOUR;
    + wtime->tm_min = rem / 60;
    + wtime->tm_sec = rem % 60;
    +
    + y = 1970;
    +
    +#define DIV(a, b) ((a) / (b) - ((a) % (b) < 0))
    +#define LEAPS_THRU_END_OF(y) (DIV (y, 4) - DIV (y, 100) + DIV (y, 400))
    +
    + while (days < 0 || days >= (__isleap (y) ? 366 : 365))
    + {
    + /* Guess a corrected year, assuming 365 days per year. */
    + long int yg = y + days / 365 - (days % 365 < 0);
    +
    + /* Adjust DAYS and Y to match the guessed year. */
    + days -= ((yg - y) * 365
    + + LEAPS_THRU_END_OF (yg - 1)
    + - LEAPS_THRU_END_OF (y - 1));
    + y = yg;
    + }
    + wtime->tm_year = y - 1900;
    +
    + ip = __mon_yday[__isleap(y)];
    + for (y = 11; days < (long int) ip[y]; --y)
    + continue;
    + days -= ip[y];
    + wtime->tm_mon = y;
    + wtime->tm_mday = days + 1;
    +
    + return 0;
    +}
    +
    +static int set_rtc_time(struct rtc_time *wtime)
    +{
    + u_int32_t secs;
    +
    + secs = mktime(wtime->tm_year + 1900, wtime->tm_mon + 1, wtime->tm_mday,
    + wtime->tm_hour, wtime->tm_min, wtime->tm_sec);
    +
    + if(pdc_tod_set(secs, 0) < 0)
    + return -1;
    + else
    + return 0;
    +
    +}
    +
    +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 rtc_pll_info *pll)
    +{
    + return -EINVAL;
    +}
    +static inline int set_rtc_pll(struct rtc_pll_info *pll)
    +{
    + return -EINVAL;
    +}
    +
    +#endif /* __KERNEL__ */
    +#endif /* __ASM_RTC_H__ */
    --- linux-2.5/drivers/char/genrtc.c 2002-08-02 08:24:32.000000000 -0700
    +++ linux-2.5/drivers/char/genrtc.c 2002-08-02 09:01:59.000000000 -0700
    @@ -33,9 +33,10 @@
    * 1.03 make it more portable zippel@linux-m68k.org
    * 1.04 removed useless timer code rz@linux-m68k.org
    * 1.05 portable RTC_UIE emulation rz@linux-m68k.org
    + * 1.06 set_rtc_time can return an error trini@kernel.crashing.org
    */

    -#define RTC_VERSION "1.05"
    +#define RTC_VERSION "1.06"

    #include <linux/module.h>
    #include <linux/config.h>
    @@ -128,8 +129,8 @@
    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",
    + if (time_after(jiffies, tt_exp))
    + printk(KERN_INFO "genrtc: timer task delayed by %ld jiffies\n",
    jiffies-tt_exp);
    ttask_active=0;
    stask_active=1;
    @@ -174,7 +175,7 @@
    unsigned long data;
    ssize_t retval;

    - if (count < sizeof(unsigned long))
    + if (count != sizeof (unsigned int) && count != sizeof (unsigned long))
    return -EINVAL;

    if (file->f_flags & O_NONBLOCK && !gen_rtc_irq_data)
    @@ -193,7 +194,14 @@
    schedule();
    }

    - retval = put_user(data, (unsigned long *)buf);
    + /* first test allows optimizer to nuke this case for 32-bit machines */
    + if (sizeof (int) != sizeof (long) && count == sizeof (unsigned int)) {
    + unsigned int uidata = data;
    + retval = put_user(uidata, (unsigned long *)buf);
    + }
    + else {
    + retval = put_user(data, (unsigned long *)buf);
    + }
    if (!retval)
    retval = sizeof(unsigned long);
    out:
    @@ -326,8 +334,7 @@
    wtime.tm_sec < 0 || wtime.tm_sec >= 60)
    return -EINVAL;

    - set_rtc_time(&wtime);
    - return 0;
    + return set_rtc_time(&wtime);
    }
    }

    -
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