arch/mips/sibyte/sb1250/time.c

   1 /*
   2  * Copyright (C) 2000, 2001 Broadcom Corporation
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  17  */
  18
  19 /*
  20  * These are routines to set up and handle interrupts from the
  21  * sb1250 general purpose timer 0.  We're using the timer as a
  22  * system clock, so we set it up to run at 100 Hz.  On every
  23  * interrupt, we update our idea of what the time of day is,
  24  * then call do_timer() in the architecture-independent kernel
  25  * code to do general bookkeeping (e.g. update jiffies, run
  26  * bottom halves, etc.)
  27  */
  28 #include <linux/config.h>
  29 #include <linux/interrupt.h>
  30 #include <linux/sched.h>
  31 #include <linux/spinlock.h>
  32 #include <linux/kernel_stat.h>
  33
  34 #include <asm/irq.h>
  35 #include <asm/ptrace.h>
  36 #include <asm/addrspace.h>
  37 #include <asm/time.h>
  38 #include <asm/io.h>
  39
  40 #include <asm/sibyte/sb1250.h>
  41 #include <asm/sibyte/sb1250_regs.h>
  42 #include <asm/sibyte/sb1250_int.h>
  43 #include <asm/sibyte/sb1250_scd.h>
  44
  45
  46 #define IMR_IP2_VAL     K_INT_MAP_I0
  47 #define IMR_IP3_VAL     K_INT_MAP_I1
  48 #define IMR_IP4_VAL     K_INT_MAP_I2
  49
  50 extern int sb1250_steal_irq(int irq);
  51
  52 void sb1250_time_init(void)
  53 {
  54         int cpu = smp_processor_id();
  55         int irq = K_INT_TIMER_0+cpu;
  56
  57         /* Only have 4 general purpose timers */
  58         if (cpu > 3) {
  59                 BUG();
  60         }
  61
  62         if (!cpu) {
  63                 /* Use our own gettimeoffset() routine */
  64                 do_gettimeoffset = sb1250_gettimeoffset;
  65         }
  66
  67         sb1250_mask_irq(cpu, irq);
  68
  69         /* Map the timer interrupt to ip[4] of this cpu */
  70         bus_writeq(IMR_IP4_VAL,
  71                    IOADDR(A_IMR_REGISTER(cpu, R_IMR_INTERRUPT_MAP_BASE) +
  72                           (irq << 3)));
  73
  74         /* the general purpose timer ticks at 1 Mhz independent if the rest of the system */
  75         /* Disable the timer and set up the count */
  76         bus_writeq(0, IOADDR(A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_CFG)));
  77 #ifdef CONFIG_SIMULATION
  78         bus_writeq(50000 / HZ,
  79                    IOADDR(A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_INIT)));
  80 #else
  81         bus_writeq(1000000/HZ,
  82                    IOADDR(A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_INIT)));
  83 #endif
  84
  85         /* Set the timer running */
  86         bus_writeq(M_SCD_TIMER_ENABLE | M_SCD_TIMER_MODE_CONTINUOUS,
  87                    IOADDR(A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_CFG)));
  88
  89         sb1250_unmask_irq(cpu, irq);
  90         sb1250_steal_irq(irq);
  91         /*
  92          * This interrupt is "special" in that it doesn't use the request_irq
  93          * way to hook the irq line.  The timer interrupt is initialized early
  94          * enough to make this a major pain, and it's also firing enough to
  95          * warrant a bit of special case code.  sb1250_timer_interrupt is
  96          * called directly from irq_handler.S when IP[4] is set during an
  97          * interrupt
  98          */
  99 }
 100
 101 void sb1250_timer_interrupt(struct pt_regs *regs)
 102 {
 103         extern asmlinkage void ll_local_timer_interrupt(int irq, struct pt_regs *regs);
 104         int cpu = smp_processor_id();
 105         int irq = K_INT_TIMER_0 + cpu;
 106
 107         /* Reset the timer */
 108         __bus_writeq(M_SCD_TIMER_ENABLE | M_SCD_TIMER_MODE_CONTINUOUS,
 109                      IOADDR(A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_CFG)));
 110
 111         /*
 112          * CPU 0 handles the global timer interrupt job
 113          */
 114         if (cpu == 0) {
 115                 ll_timer_interrupt(irq, regs);
 116         }
 117
 118         /*
 119          * every CPU should do profiling and process accouting
 120          */
 121         ll_local_timer_interrupt(irq, regs);
 122 }
 123
 124 /*
 125  * We use our own do_gettimeoffset() instead of the generic one,
 126  * because the generic one does not work for SMP case.
 127  * In addition, since we use general timer 0 for system time,
 128  * we can get accurate intra-jiffy offset without calibration.
 129  */
 130 unsigned long sb1250_gettimeoffset(void)
 131 {
 132         unsigned long count =
 133                 bus_readq(IOADDR(A_SCD_TIMER_REGISTER(0, R_SCD_TIMER_CNT)));
 134
 135         return 1000000/HZ - count;
 136  }