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Re: a patch for generic MIPS RTC

To: macro@linux-mips.org
Subject: Re: a patch for generic MIPS RTC
From: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Date: Tue, 20 Sep 2005 01:48:36 +0900 (JST)
Cc: spodstavin@ru.mvista.com, linux-mips@linux-mips.org, ralf@linux-mips.org
In-reply-to: <20050907.005517.25909840.anemo@mba.ocn.ne.jp>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20050905.224534.25910293.anemo@mba.ocn.ne.jp> <Pine.LNX.4.61L.0509051620020.29615@blysk.ds.pg.gda.pl> <20050907.005517.25909840.anemo@mba.ocn.ne.jp>
Sender: linux-mips-bounce@linux-mips.org
>>>>> On Wed, 07 Sep 2005 00:55:17 +0900 (JST), Atsushi Nemoto 
>>>>> <anemo@mba.ocn.ne.jp> said:

anemo> OK, and I also found some rtc routines might take a few
anemo> SECONDS, therefore protecting whole these rtc routines entirely
anemo> with spinlock is really bad idea.

anemo> How about this (untested) one?

Now one fix for asm-mips/rtc.h is done.
Here is a revised patch.  Comments are welcome.  Thank you.

* Get rid of mips_rtc_lock.
* Use rtc_lock (and disable irq) to protect HW access in each rtc routines.

diff -ur linux-mips/arch/mips/ddb5xxx/common/rtc_ds1386.c 
linux/arch/mips/ddb5xxx/common/rtc_ds1386.c
--- linux-mips/arch/mips/ddb5xxx/common/rtc_ds1386.c    2005-09-07 
00:26:47.000000000 +0900
+++ linux/arch/mips/ddb5xxx/common/rtc_ds1386.c 2005-09-20 01:39:27.315888352 
+0900
@@ -41,7 +41,9 @@
        u8 byte;
        u8 temp;
        unsigned int year, month, day, hour, minute, second;
+       unsigned long flags;
 
+       spin_lock_irqsave(&rtc_lock, flags);
        /* let us freeze external registers */
        byte = READ_RTC(0xB);
        byte &= 0x3f;
@@ -70,6 +72,7 @@
                /* 24 hour format */
                hour = BCD2BIN(temp & 0x3f);
        }
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        return mktime(year, month, day, hour, minute, second);
 }
@@ -81,7 +84,9 @@
        u8 byte;
        u8 temp;
        u8 year, month, day, hour, minute, second;
+       unsigned long flags;
 
+       spin_lock_irqsave(&rtc_lock, flags);
        /* let us freeze external registers */
        byte = READ_RTC(0xB);
        byte &= 0x3f;
@@ -133,6 +138,7 @@
        if (second != READ_RTC(0x1)) {
                WRITE_RTC(0x1, second);
        }
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        return 0;
 }
diff -ur linux-mips/arch/mips/dec/time.c linux/arch/mips/dec/time.c
--- linux-mips/arch/mips/dec/time.c     2005-09-07 00:26:47.000000000 +0900
+++ linux/arch/mips/dec/time.c  2005-09-20 01:39:27.316888200 +0900
@@ -37,10 +37,25 @@
 #include <asm/dec/machtype.h>
 
 
+/*
+ * Returns true if a clock update is in progress
+ */
+static inline unsigned char dec_rtc_is_updating(void)
+{
+       unsigned char uip;
+       unsigned long flags;
+
+       spin_lock_irqsave(&rtc_lock, flags);
+       uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
+       spin_unlock_irqrestore(&rtc_lock, flags);
+       return uip;
+}
+
 static unsigned long dec_rtc_get_time(void)
 {
        unsigned int year, mon, day, hour, min, sec, real_year;
        int i;
+       unsigned long flags;
 
        /* The Linux interpretation of the DS1287 clock register contents:
         * When the Update-In-Progress (UIP) flag goes from 1 to 0, the
@@ -49,11 +64,12 @@
         */
        /* read RTC exactly on falling edge of update flag */
        for (i = 0; i < 1000000; i++)   /* may take up to 1 second... */
-               if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP)
+               if (dec_rtc_is_updating())
                        break;
        for (i = 0; i < 1000000; i++)   /* must try at least 2.228 ms */
-               if (!(CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
+               if (!dec_rtc_is_updating())
                        break;
+       spin_lock_irqsave(&rtc_lock, flags);
        /* Isn't this overkill?  UIP above should guarantee consistency */
        do {
                sec = CMOS_READ(RTC_SECONDS);
@@ -78,6 +94,7 @@
         */
        real_year = CMOS_READ(RTC_DEC_YEAR);
        year += real_year - 72 + 2000;
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        return mktime(year, mon, day, hour, min, sec);
 }
@@ -95,6 +112,8 @@
        int real_seconds, real_minutes, cmos_minutes;
        unsigned char save_control, save_freq_select;
 
+       /* irq are locally disabled here */
+       spin_lock(&rtc_lock);
        /* tell the clock it's being set */
        save_control = CMOS_READ(RTC_CONTROL);
        CMOS_WRITE((save_control | RTC_SET), RTC_CONTROL);
@@ -141,6 +160,7 @@
         */
        CMOS_WRITE(save_control, RTC_CONTROL);
        CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
+       spin_unlock(&rtc_lock);
 
        return retval;
 }
diff -ur linux-mips/arch/mips/ite-boards/generic/time.c 
linux/arch/mips/ite-boards/generic/time.c
--- linux-mips/arch/mips/ite-boards/generic/time.c      2005-09-07 
00:26:47.000000000 +0900
+++ linux/arch/mips/ite-boards/generic/time.c   2005-09-20 01:39:27.316888200 
+0900
@@ -149,15 +149,15 @@
 it8172_rtc_get_time(void)
 {
        unsigned int year, mon, day, hour, min, sec;
-       unsigned int flags;
+       unsigned long flags;
 
        /* avoid update-in-progress. */
        for (;;) {
-               local_irq_save(flags);
+               spin_lock_irqsave(&rtc_lock, flags);
                if (! (CMOS_READ(RTC_REG_A) & RTC_UIP))
                        break;
                /* don't hold intr closed all the time */
-               local_irq_restore(flags);
+               spin_unlock_irqrestore(&rtc_lock, flags);
        }
 
        /* Read regs. */
@@ -170,7 +170,7 @@
                hw_to_bin(*rtc_century_reg) * 100;
 
        /* restore interrupts */
-       local_irq_restore(flags);
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        return mktime(year, mon, day, hour, min, sec);
 }
@@ -179,18 +179,18 @@
 it8172_rtc_set_time(unsigned long t)
 {
        struct rtc_time tm;
-       unsigned int flags;
+       unsigned long flags;
 
        /* convert */
        to_tm(t, &tm);
 
        /* avoid update-in-progress. */
        for (;;) {
-               local_irq_save(flags);
+               spin_lock_irqsave(&rtc_lock, flags);
                if (! (CMOS_READ(RTC_REG_A) & RTC_UIP))
                        break;
                /* don't hold intr closed all the time */
-               local_irq_restore(flags);
+               spin_unlock_irqrestore(&rtc_lock, flags);
        }
 
        *rtc_century_reg = bin_to_hw(tm.tm_year/100);
@@ -202,7 +202,7 @@
        CMOS_WRITE(bin_to_hw(tm.tm_year%100), RTC_YEAR);
 
        /* restore interrupts */
-       local_irq_restore(flags);
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        return 0;
 }
diff -ur linux-mips/arch/mips/jmr3927/common/rtc_ds1742.c 
linux/arch/mips/jmr3927/common/rtc_ds1742.c
--- linux-mips/arch/mips/jmr3927/common/rtc_ds1742.c    2005-09-07 
00:26:47.000000000 +0900
+++ linux/arch/mips/jmr3927/common/rtc_ds1742.c 2005-09-20 01:39:27.316888200 
+0900
@@ -57,7 +57,9 @@
 {
        unsigned int year, month, day, hour, minute, second;
        unsigned int century;
+       unsigned long flags;
 
+       spin_lock_irqsave(&rtc_lock, flags);
        CMOS_WRITE(RTC_READ, RTC_CONTROL);
        second = BCD2BIN(CMOS_READ(RTC_SECONDS) & RTC_SECONDS_MASK);
        minute = BCD2BIN(CMOS_READ(RTC_MINUTES));
@@ -67,6 +69,7 @@
        year = BCD2BIN(CMOS_READ(RTC_YEAR));
        century = BCD2BIN(CMOS_READ(RTC_CENTURY) & RTC_CENTURY_MASK);
        CMOS_WRITE(0, RTC_CONTROL);
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        year += century * 100;
 
@@ -81,7 +84,9 @@
        u8 year, month, day, hour, minute, second;
        u8 cmos_year, cmos_month, cmos_day, cmos_hour, cmos_minute, cmos_second;
        int cmos_century;
+       unsigned long flags;
 
+       spin_lock_irqsave(&rtc_lock, flags);
        CMOS_WRITE(RTC_READ, RTC_CONTROL);
        cmos_second = (u8)(CMOS_READ(RTC_SECONDS) & RTC_SECONDS_MASK);
        cmos_minute = (u8)CMOS_READ(RTC_MINUTES);
@@ -139,6 +144,7 @@
 
        /* RTC_CENTURY and RTC_CONTROL share same address... */
        CMOS_WRITE(cmos_century, RTC_CONTROL);
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        return 0;
 }
diff -ur linux-mips/arch/mips/lasat/ds1603.c linux/arch/mips/lasat/ds1603.c
--- linux-mips/arch/mips/lasat/ds1603.c 2005-09-07 00:26:47.000000000 +0900
+++ linux/arch/mips/lasat/ds1603.c      2005-09-20 01:39:27.317888048 +0900
@@ -8,6 +8,7 @@
 #include <asm/lasat/lasat.h>
 #include <linux/delay.h>
 #include <asm/lasat/ds1603.h>
+#include <asm/time.h>
 
 #include "ds1603.h"
 
@@ -138,19 +139,27 @@
 unsigned long ds1603_read(void)
 {
        unsigned long word;
+       unsigned long flags;
+
+       spin_lock_irqsave(&rtc_lock, flags);
        rtc_init_op();
        rtc_write_byte(READ_TIME_CMD);
        word = rtc_read_word();
        rtc_end_op();
+       spin_unlock_irqrestore(&rtc_lock, flags);
        return word;
 }
 
 int ds1603_set(unsigned long time)
 {
+       unsigned long flags;
+
+       spin_lock_irqsave(&rtc_lock, flags);
        rtc_init_op();
        rtc_write_byte(SET_TIME_CMD);
        rtc_write_word(time);
        rtc_end_op();
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        return 0;
 }
diff -ur linux-mips/arch/mips/momentum/jaguar_atx/setup.c 
linux/arch/mips/momentum/jaguar_atx/setup.c
--- linux-mips/arch/mips/momentum/jaguar_atx/setup.c    2005-09-07 
00:26:47.000000000 +0900
+++ linux/arch/mips/momentum/jaguar_atx/setup.c 2005-09-20 01:39:27.317888048 
+0900
@@ -149,7 +149,9 @@
 unsigned long m48t37y_get_time(void)
 {
        unsigned int year, month, day, hour, min, sec;
+       unsigned long flags;
 
+       spin_lock_irqsave(&rtc_lock, flags);
        /* stop the update */
        rtc_base[0x7ff8] = 0x40;
 
@@ -166,6 +168,7 @@
 
        /* start the update */
        rtc_base[0x7ff8] = 0x00;
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        return mktime(year, month, day, hour, min, sec);
 }
@@ -173,11 +176,13 @@
 int m48t37y_set_time(unsigned long sec)
 {
        struct rtc_time tm;
+       unsigned long flags;
 
        /* convert to a more useful format -- note months count from 0 */
        to_tm(sec, &tm);
        tm.tm_mon += 1;
 
+       spin_lock_irqsave(&rtc_lock, flags);
        /* enable writing */
        rtc_base[0x7ff8] = 0x80;
 
@@ -201,6 +206,7 @@
 
        /* disable writing */
        rtc_base[0x7ff8] = 0x00;
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        return 0;
 }
diff -ur linux-mips/arch/mips/momentum/ocelot_3/setup.c 
linux/arch/mips/momentum/ocelot_3/setup.c
--- linux-mips/arch/mips/momentum/ocelot_3/setup.c      2005-09-07 
00:26:47.000000000 +0900
+++ linux/arch/mips/momentum/ocelot_3/setup.c   2005-09-20 01:39:27.317888048 
+0900
@@ -135,7 +135,9 @@
 unsigned long m48t37y_get_time(void)
 {
        unsigned int year, month, day, hour, min, sec;
+       unsigned long flags;
 
+       spin_lock_irqsave(&rtc_lock, flags);
        /* stop the update */
        rtc_base[0x7ff8] = 0x40;
 
@@ -152,6 +154,7 @@
 
        /* start the update */
        rtc_base[0x7ff8] = 0x00;
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        return mktime(year, month, day, hour, min, sec);
 }
@@ -159,11 +162,13 @@
 int m48t37y_set_time(unsigned long sec)
 {
        struct rtc_time tm;
+       unsigned long flags;
 
        /* convert to a more useful format -- note months count from 0 */
        to_tm(sec, &tm);
        tm.tm_mon += 1;
 
+       spin_lock_irqsave(&rtc_lock, flags);
        /* enable writing */
        rtc_base[0x7ff8] = 0x80;
 
@@ -187,6 +192,7 @@
 
        /* disable writing */
        rtc_base[0x7ff8] = 0x00;
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        return 0;
 }
diff -ur linux-mips/arch/mips/momentum/ocelot_c/setup.c 
linux/arch/mips/momentum/ocelot_c/setup.c
--- linux-mips/arch/mips/momentum/ocelot_c/setup.c      2005-09-07 
00:26:47.000000000 +0900
+++ linux/arch/mips/momentum/ocelot_c/setup.c   2005-09-20 01:39:27.318887896 
+0900
@@ -140,7 +140,9 @@
        unsigned char* rtc_base = (unsigned char*)0xfc800000;
 #endif
        unsigned int year, month, day, hour, min, sec;
+       unsigned long flags;
 
+       spin_lock_irqsave(&rtc_lock, flags);
        /* stop the update */
        rtc_base[0x7ff8] = 0x40;
 
@@ -157,6 +159,7 @@
 
        /* start the update */
        rtc_base[0x7ff8] = 0x00;
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        return mktime(year, month, day, hour, min, sec);
 }
@@ -169,11 +172,13 @@
        unsigned char* rtc_base = (unsigned char*)0xfc800000;
 #endif
        struct rtc_time tm;
+       unsigned long flags;
 
        /* convert to a more useful format -- note months count from 0 */
        to_tm(sec, &tm);
        tm.tm_mon += 1;
 
+       spin_lock_irqsave(&rtc_lock, flags);
        /* enable writing */
        rtc_base[0x7ff8] = 0x80;
 
@@ -197,6 +202,7 @@
 
        /* disable writing */
        rtc_base[0x7ff8] = 0x00;
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        return 0;
 }
diff -ur linux-mips/arch/mips/pmc-sierra/yosemite/setup.c 
linux/arch/mips/pmc-sierra/yosemite/setup.c
--- linux-mips/arch/mips/pmc-sierra/yosemite/setup.c    2005-09-07 
00:26:47.000000000 +0900
+++ linux/arch/mips/pmc-sierra/yosemite/setup.c 2005-09-20 01:39:27.318887896 
+0900
@@ -73,7 +73,9 @@
 unsigned long m48t37y_get_time(void)
 {
        unsigned int year, month, day, hour, min, sec;
+       unsigned long flags;
 
+       spin_lock_irqsave(&rtc_lock, flags);
        /* Stop the update to the time */
        m48t37_base->control = 0x40;
 
@@ -88,6 +90,7 @@
 
        /* Start the update to the time again */
        m48t37_base->control = 0x00;
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        return mktime(year, month, day, hour, min, sec);
 }
@@ -95,11 +98,13 @@
 int m48t37y_set_time(unsigned long sec)
 {
        struct rtc_time tm;
+       unsigned long flags;
 
        /* convert to a more useful format -- note months count from 0 */
        to_tm(sec, &tm);
        tm.tm_mon += 1;
 
+       spin_lock_irqsave(&rtc_lock, flags);
        /* enable writing */
        m48t37_base->control = 0x80;
 
@@ -123,6 +128,7 @@
 
        /* disable writing */
        m48t37_base->control = 0x00;
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        return 0;
 }
diff -ur linux-mips/arch/mips/sgi-ip22/ip22-time.c 
linux/arch/mips/sgi-ip22/ip22-time.c
--- linux-mips/arch/mips/sgi-ip22/ip22-time.c   2005-09-07 00:26:47.000000000 
+0900
+++ linux/arch/mips/sgi-ip22/ip22-time.c        2005-09-20 01:39:27.359881664 
+0900
@@ -35,7 +35,9 @@
 {
        unsigned int yrs, mon, day, hrs, min, sec;
        unsigned int save_control;
+       unsigned long flags;
 
+       spin_lock_irqsave(&rtc_lock, flags);
        save_control = hpc3c0->rtcregs[RTC_CMD] & 0xff;
        hpc3c0->rtcregs[RTC_CMD] = save_control | RTC_TE;
 
@@ -47,6 +49,7 @@
        yrs = BCD2BIN(hpc3c0->rtcregs[RTC_YEAR] & 0xff);
 
        hpc3c0->rtcregs[RTC_CMD] = save_control;
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        if (yrs < 45)
                yrs += 30;
@@ -60,6 +63,7 @@
 {
        struct rtc_time tm;
        unsigned int save_control;
+       unsigned long flags;
 
        to_tm(tim, &tm);
 
@@ -68,6 +72,7 @@
        if (tm.tm_year >= 100)
                tm.tm_year -= 100;
 
+       spin_lock_irqsave(&rtc_lock, flags);
        save_control = hpc3c0->rtcregs[RTC_CMD] & 0xff;
        hpc3c0->rtcregs[RTC_CMD] = save_control | RTC_TE;
 
@@ -80,6 +85,7 @@
        hpc3c0->rtcregs[RTC_HUNDREDTH_SECOND] = 0;
 
        hpc3c0->rtcregs[RTC_CMD] = save_control;
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        return 0;
 }
diff -ur linux-mips/arch/mips/sibyte/swarm/rtc_m41t81.c 
linux/arch/mips/sibyte/swarm/rtc_m41t81.c
--- linux-mips/arch/mips/sibyte/swarm/rtc_m41t81.c      2005-09-07 
00:26:47.000000000 +0900
+++ linux/arch/mips/sibyte/swarm/rtc_m41t81.c   2005-09-20 01:39:27.360881512 
+0900
@@ -144,6 +144,7 @@
 int m41t81_set_time(unsigned long t)
 {
        struct rtc_time tm;
+       unsigned long flags;
 
        to_tm(t, &tm);
 
@@ -153,6 +154,7 @@
         * believe we should finish writing min within a second.
         */
 
+       spin_lock_irqsave(&rtc_lock, flags);
        tm.tm_sec = BIN2BCD(tm.tm_sec);
        m41t81_write(M41T81REG_SC, tm.tm_sec);
 
@@ -180,6 +182,7 @@
        tm.tm_year %= 100;
        tm.tm_year = BIN2BCD(tm.tm_year);
        m41t81_write(M41T81REG_YR, tm.tm_year);
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        return 0;
 }
@@ -187,14 +190,17 @@
 unsigned long m41t81_get_time(void)
 {
        unsigned int year, mon, day, hour, min, sec;
+       unsigned long flags;
 
        /*
         * min is valid if two reads of sec are the same.
         */
        for (;;) {
+               spin_lock_irqsave(&rtc_lock, flags);
                sec = m41t81_read(M41T81REG_SC);
                min = m41t81_read(M41T81REG_MN);
                if (sec == m41t81_read(M41T81REG_SC)) break;
+               spin_unlock_irqrestore(&rtc_lock, flags);
        }
        hour = m41t81_read(M41T81REG_HR) & 0x3f;
        day = m41t81_read(M41T81REG_DT);
@@ -207,6 +213,7 @@
        day = BCD2BIN(day);
        mon = BCD2BIN(mon);
        year = BCD2BIN(year);
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        year += 2000;
 
diff -ur linux-mips/arch/mips/sibyte/swarm/rtc_xicor1241.c 
linux/arch/mips/sibyte/swarm/rtc_xicor1241.c
--- linux-mips/arch/mips/sibyte/swarm/rtc_xicor1241.c   2005-09-07 
00:26:47.000000000 +0900
+++ linux/arch/mips/sibyte/swarm/rtc_xicor1241.c        2005-09-20 
01:39:27.361881360 +0900
@@ -113,9 +113,11 @@
 {
        struct rtc_time tm;
        int tmp;
+       unsigned long flags;
 
        to_tm(t, &tm);
 
+       spin_lock_irqsave(&rtc_lock, flags);
        /* unlock writes to the CCR */
        xicor_write(X1241REG_SR, X1241REG_SR_WEL);
        xicor_write(X1241REG_SR, X1241REG_SR_WEL | X1241REG_SR_RWEL);
@@ -160,6 +162,7 @@
        xicor_write(X1241REG_HR, tmp);
 
        xicor_write(X1241REG_SR, 0);
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        return 0;
 }
@@ -167,7 +170,9 @@
 unsigned long xicor_get_time(void)
 {
        unsigned int year, mon, day, hour, min, sec, y2k;
+       unsigned long flags;
 
+       spin_lock_irqsave(&rtc_lock, flags);
        sec = xicor_read(X1241REG_SC);
        min = xicor_read(X1241REG_MN);
        hour = xicor_read(X1241REG_HR);
@@ -183,6 +188,7 @@
        mon = xicor_read(X1241REG_MO);
        year = xicor_read(X1241REG_YR);
        y2k = xicor_read(X1241REG_Y2K);
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        sec = BCD2BIN(sec);
        min = BCD2BIN(min);
diff -ur linux-mips/arch/mips/tx4938/common/rtc_rx5c348.c 
linux/arch/mips/tx4938/common/rtc_rx5c348.c
--- linux-mips/arch/mips/tx4938/common/rtc_rx5c348.c    2005-09-07 
00:26:47.000000000 +0900
+++ linux/arch/mips/tx4938/common/rtc_rx5c348.c 2005-09-20 01:39:27.362881208 
+0900
@@ -67,14 +67,20 @@
 {
        unsigned char *inbufs[1], *outbufs[1];
        unsigned int incounts[2], outcounts[2];
+       int ret;
+       unsigned long flags;
+
        inbufs[0] = inbuf;
        incounts[0] = count;
        incounts[1] = 0;
        outbufs[0] = outbuf;
        outcounts[0] = count;
        outcounts[1] = 0;
-       return txx9_spi_io(srtc_chipid, &srtc_dev_desc,
-                          inbufs, incounts, outbufs, outcounts, 0);
+       spin_lock_irqsave(&rtc_lock, flags);
+       ret = txx9_spi_io(srtc_chipid, &srtc_dev_desc,
+                         inbufs, incounts, outbufs, outcounts, 0);
+       spin_unlock_irqrestore(&rtc_lock, flags);
+       return ret;
 }
 
 /*
diff -ur linux-mips/include/asm-mips/mc146818-time.h 
linux/include/asm-mips/mc146818-time.h
--- linux-mips/include/asm-mips/mc146818-time.h 2005-09-07 00:26:47.000000000 
+0900
+++ linux/include/asm-mips/mc146818-time.h      2005-09-20 01:39:27.363881056 
+0900
@@ -33,7 +33,9 @@
        int real_seconds, real_minutes, cmos_minutes;
        unsigned char save_control, save_freq_select;
        int retval = 0;
+       unsigned long flags;
 
+       spin_lock_irqsave(&rtc_lock, flags);
        save_control = CMOS_READ(RTC_CONTROL); /* tell the clock it's being set 
*/
        CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
 
@@ -79,14 +81,30 @@
         */
        CMOS_WRITE(save_control, RTC_CONTROL);
        CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        return retval;
 }
 
+/*
+ * Returns true if a clock update is in progress
+ */
+static inline unsigned char rtc_is_updating(void)
+{
+       unsigned char uip;
+       unsigned long flags;
+
+       spin_lock_irqsave(&rtc_lock, flags);
+       uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
+       spin_unlock_irqrestore(&rtc_lock, flags);
+       return uip;
+}
+
 static inline unsigned long mc146818_get_cmos_time(void)
 {
        unsigned int year, mon, day, hour, min, sec;
        int i;
+       unsigned long flags;
 
        /*
         * The Linux interpretation of the CMOS clock register contents:
@@ -97,12 +115,13 @@
 
        /* read RTC exactly on falling edge of update flag */
        for (i = 0 ; i < 1000000 ; i++) /* may take up to 1 second... */
-               if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP)
+               if (rtc_is_updating())
                        break;
        for (i = 0 ; i < 1000000 ; i++) /* must try at least 2.228 ms */
-               if (!(CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
+               if (!rtc_is_updating())
                        break;
 
+       spin_lock_irqsave(&rtc_lock, flags);
        do { /* Isn't this overkill ? UIP above should guarantee consistency */
                sec = CMOS_READ(RTC_SECONDS);
                min = CMOS_READ(RTC_MINUTES);
@@ -121,6 +140,7 @@
                BCD_TO_BIN(year);
        }
        year = mc146818_decode_year(year);
+       spin_unlock_irqrestore(&rtc_lock, flags);
 
        return mktime(year, mon, day, hour, min, sec);
 }
diff -ur linux-mips/include/asm-mips/rtc.h linux/include/asm-mips/rtc.h
--- linux-mips/include/asm-mips/rtc.h   2005-09-20 01:32:52.109968784 +0900
+++ linux/include/asm-mips/rtc.h        2005-09-20 01:39:27.366880600 +0900
@@ -14,7 +14,6 @@
 
 #ifdef __KERNEL__
 
-#include <linux/spinlock.h>
 #include <linux/rtc.h>
 #include <asm/time.h>
 
@@ -29,17 +28,13 @@
 #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 DEFINE_SPINLOCK(mips_rtc_lock);
-
 static inline unsigned int get_rtc_time(struct rtc_time *time)
 {
        unsigned long nowtime;
 
-       spin_lock(&mips_rtc_lock);
        nowtime = rtc_get_time();
        to_tm(nowtime, time);
        time->tm_year -= 1900;
-       spin_unlock(&mips_rtc_lock);
 
        return RTC_24H;
 }
@@ -49,12 +44,10 @@
        unsigned long nowtime;
        int ret;
 
-       spin_lock(&mips_rtc_lock);
        nowtime = mktime(time->tm_year+1900, time->tm_mon+1,
                        time->tm_mday, time->tm_hour, time->tm_min,
                        time->tm_sec);
        ret = rtc_set_time(nowtime);
-       spin_unlock(&mips_rtc_lock);
 
        return ret;
 }
diff -ur linux-mips/include/asm-mips/time.h linux/include/asm-mips/time.h
--- linux-mips/include/asm-mips/time.h  2005-09-07 00:26:47.000000000 +0900
+++ linux/include/asm-mips/time.h       2005-09-20 01:39:27.367880448 +0900
@@ -20,6 +20,9 @@
 #include <linux/linkage.h>
 #include <linux/ptrace.h>
 #include <linux/rtc.h>
+#include <linux/spinlock.h>
+
+extern spinlock_t rtc_lock;
 
 /*
  * RTC ops.  By default, they point to no-RTC functions.

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