diff options
Diffstat (limited to 'arch/mips/galileo-boards/ev96100/time.c')
| -rw-r--r-- | arch/mips/galileo-boards/ev96100/time.c | 278 |
1 files changed, 278 insertions, 0 deletions
diff --git a/arch/mips/galileo-boards/ev96100/time.c b/arch/mips/galileo-boards/ev96100/time.c new file mode 100644 index 000000000..d5e66fe7b --- /dev/null +++ b/arch/mips/galileo-boards/ev96100/time.c @@ -0,0 +1,278 @@ +/* + * + * BRIEF MODULE DESCRIPTION + * Galileo EV96100 rtc routines. + * + * Copyright 2000 MontaVista Software Inc. + * Author: MontaVista Software, Inc. + * ppopov@mvista.com or support@mvista.com + * + * This file was derived from Carsten Langgaard's + * arch/mips/mips-boards/atlas/atlas_rtc.c. + * + * Carsten Langgaard, carstenl@mips.com + * Copyright (C) 1999,2000 MIPS Technologies, Inc. All rights reserved. + * + * 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. + * + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN + * NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF + * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON + * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <linux/config.h> +#include <linux/init.h> +#include <linux/kernel_stat.h> +#include <linux/sched.h> +#include <linux/spinlock.h> + +#include <asm/mipsregs.h> +#include <asm/ptrace.h> + +#include <linux/timex.h> + + +#define ALLINTS (IE_IRQ0 | IE_IRQ1 | IE_IRQ2 | IE_IRQ3 | IE_IRQ4 | IE_IRQ5) + +extern volatile unsigned long wall_jiffies; +static long last_rtc_update = 0; +unsigned long missed_heart_beats = 0; + +static unsigned long r4k_offset; /* Amount to increment compare reg each time */ +static unsigned long r4k_cur; /* What counter should be at next timer irq */ +extern rwlock_t xtime_lock; + + +static unsigned int timer_tick_count=0; + +static inline void ack_r4ktimer(unsigned long newval) +{ + write_32bit_cp0_register(CP0_COMPARE, newval); +} + +static int set_rtc_mmss(unsigned long nowtime) +{ + /* EV96100 does not have a real time clock */ + int retval = 0; + + return retval; +} + +/* + * There are a lot of conceptually broken versions of the MIPS timer interrupt + * handler floating around. This one is rather different, but the algorithm + * is probably more robust. + */ +static unsigned long alive; +void mips_timer_interrupt(struct pt_regs *regs) +{ + unsigned long status; + unsigned long ret_addr; + int irq = 7; /* FIX ME */ + + if (r4k_offset == 0) { + goto null; + } + + do { + kstat.irqs[0][irq]++; + do_timer(regs); + r4k_cur += r4k_offset; + ack_r4ktimer(r4k_cur); + + } while (((unsigned long)read_32bit_cp0_register(CP0_COUNT) + - r4k_cur) < 0x7fffffff); + return; + +null: + ack_r4ktimer(0); +} + +/* + * Figure out the r4k offset, the amount to increment the compare + * register for each time tick. + * Use the RTC to calculate offset. + */ +static unsigned long __init cal_r4koff(void) +{ + unsigned long count; + count = 300000000/2; + return (count / HZ); +} + +static unsigned long __init get_mips_time(void) +{ + unsigned int year, mon, day, hour, min, sec; + unsigned char save_control; + + year = 2000; + mon = 10; + day = 31; + hour = 0; + min = 0; + sec = 0; + return mktime(year, mon, day, hour, min, sec); +} + + +/* + * called from start_kernel() + */ +void __init time_init(void) +{ + + unsigned int est_freq, flags; + + r4k_offset = cal_r4koff(); + + est_freq = 2*r4k_offset*HZ; + est_freq += 5000; /* round */ + est_freq -= est_freq%10000; + printk("CPU frequency %d.%02d MHz\n", est_freq/1000000, + (est_freq%1000000)*100/1000000); + r4k_cur = (read_32bit_cp0_register(CP0_COUNT) + r4k_offset); + + write_32bit_cp0_register(CP0_COMPARE, r4k_cur); + + /* FIX ME */ + set_cp0_status(ST0_IM, IE_IRQ5); +} + +/* This is for machines which generate the exact clock. */ +#define USECS_PER_JIFFY (1000000/HZ) + +/* Cycle counter value at the previous timer interrupt.. */ + +static unsigned int timerhi = 0, timerlo = 0; + +/* + * FIXME: Does playing with the RP bit in c0_status interfere with this code? + */ +static unsigned long do_fast_gettimeoffset(void) +{ + u32 count; + unsigned long res, tmp; + + /* Last jiffy when do_fast_gettimeoffset() was called. */ + static unsigned long last_jiffies=0; + unsigned long quotient; + + /* + * Cached "1/(clocks per usec)*2^32" value. + * It has to be recalculated once each jiffy. + */ + static unsigned long cached_quotient=0; + + tmp = jiffies; + + quotient = cached_quotient; + + if (tmp && last_jiffies != tmp) { + last_jiffies = tmp; + __asm__(".set\tnoreorder\n\t" + ".set\tnoat\n\t" + ".set\tmips3\n\t" + "lwu\t%0,%2\n\t" + "dsll32\t$1,%1,0\n\t" + "or\t$1,$1,%0\n\t" + "ddivu\t$0,$1,%3\n\t" + "mflo\t$1\n\t" + "dsll32\t%0,%4,0\n\t" + "nop\n\t" + "ddivu\t$0,%0,$1\n\t" + "mflo\t%0\n\t" + ".set\tmips0\n\t" + ".set\tat\n\t" + ".set\treorder" + :"=&r" (quotient) + :"r" (timerhi), + "m" (timerlo), + "r" (tmp), + "r" (USECS_PER_JIFFY) + :"$1"); + cached_quotient = quotient; + } + + /* Get last timer tick in absolute kernel time */ + count = read_32bit_cp0_register(CP0_COUNT); + + /* .. relative to previous jiffy (32 bits is enough) */ + count -= timerlo; + + __asm__("multu\t%1,%2\n\t" + "mfhi\t%0" + :"=r" (res) + :"r" (count), + "r" (quotient)); + + /* + * Due to possible jiffies inconsistencies, we need to check + * the result so that we'll get a timer that is monotonic. + */ + if (res >= USECS_PER_JIFFY) + res = USECS_PER_JIFFY-1; + + return res; +} + +void do_gettimeofday(struct timeval *tv) +{ + unsigned int flags; + + read_lock_irqsave (&xtime_lock, flags); + *tv = xtime; + tv->tv_usec += do_fast_gettimeoffset(); + + /* + * xtime is atomically updated in timer_bh. jiffies - wall_jiffies + * is nonzero if the timer bottom half hasnt executed yet. + */ + if (jiffies - wall_jiffies) + tv->tv_usec += USECS_PER_JIFFY; + + read_unlock_irqrestore (&xtime_lock, flags); + + if (tv->tv_usec >= 1000000) { + tv->tv_usec -= 1000000; + tv->tv_sec++; + } +} + +void do_settimeofday(struct timeval *tv) +{ + write_lock_irq (&xtime_lock); + + /* This is revolting. We need to set the xtime.tv_usec correctly. + * However, the value in this location is is value at the last tick. + * Discover what correction gettimeofday would have done, and then + * undo it! + */ + tv->tv_usec -= do_fast_gettimeoffset(); + + if (tv->tv_usec < 0) { + tv->tv_usec += 1000000; + tv->tv_sec--; + } + + xtime = *tv; + time_adjust = 0; /* stop active adjtime() */ + time_status |= STA_UNSYNC; + time_maxerror = NTP_PHASE_LIMIT; + time_esterror = NTP_PHASE_LIMIT; + + write_unlock_irq (&xtime_lock); +} |