arch/mips/sibyte/bcm1480/time.c

   1 /*
   2  * Copyright (C) 2000,2001,2004 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  * bcm1480 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/interrupt.h>
  29 #include <linux/sched.h>
  30 #include <linux/spinlock.h>
  31 #include <linux/kernel_stat.h>
  32
  33 #include <asm/irq.h>
  34 #include <asm/addrspace.h>
  35 #include <asm/time.h>
  36 #include <asm/io.h>
  37
  38 #include <asm/sibyte/bcm1480_regs.h>
  39 #include <asm/sibyte/sb1250_regs.h>
  40 #include <asm/sibyte/bcm1480_int.h>
  41 #include <asm/sibyte/bcm1480_scd.h>
  42
  43 #include <asm/sibyte/sb1250.h>
  44
  45
  46 #define IMR_IP2_VAL     K_BCM1480_INT_MAP_I0
  47 #define IMR_IP3_VAL     K_BCM1480_INT_MAP_I1
  48 #define IMR_IP4_VAL     K_BCM1480_INT_MAP_I2
  49
  50 #ifdef CONFIG_SIMULATION
  51 #define BCM1480_HPT_VALUE       50000
  52 #else
  53 #define BCM1480_HPT_VALUE       1000000
  54 #endif
  55
  56 extern int bcm1480_steal_irq(int irq);
  57
  58 void bcm1480_time_init(void)
  59 {
  60         int cpu = smp_processor_id();
  61         int irq = K_BCM1480_INT_TIMER_0+cpu;
  62
  63         /* Only have 4 general purpose timers */
  64         if (cpu > 3) {
  65                 BUG();
  66         }
  67
  68         bcm1480_mask_irq(cpu, irq);
  69
  70         /* Map the timer interrupt to ip[4] of this cpu */
  71         __raw_writeq(IMR_IP4_VAL, IOADDR(A_BCM1480_IMR_REGISTER(cpu, R_BCM1480_IMR_INTERRUPT_MAP_BASE_H)
  72               + (irq<<3)));
  73
  74         /* the general purpose timer ticks at 1 Mhz independent of the rest of the system */
  75         /* Disable the timer and set up the count */
  76         __raw_writeq(0, IOADDR(A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_CFG)));
  77         __raw_writeq(
  78                 BCM1480_HPT_VALUE/HZ
  79                 , IOADDR(A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_INIT)));
  80
  81         /* Set the timer running */
  82         __raw_writeq(M_SCD_TIMER_ENABLE|M_SCD_TIMER_MODE_CONTINUOUS,
  83               IOADDR(A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_CFG)));
  84
  85         bcm1480_unmask_irq(cpu, irq);
  86         bcm1480_steal_irq(irq);
  87         /*
  88          * This interrupt is "special" in that it doesn't use the request_irq
  89          * way to hook the irq line.  The timer interrupt is initialized early
  90          * enough to make this a major pain, and it's also firing enough to
  91          * warrant a bit of special case code.  bcm1480_timer_interrupt is
  92          * called directly from irq_handler.S when IP[4] is set during an
  93          * interrupt
  94          */
  95 }
  96
  97 void bcm1480_timer_interrupt(void)
  98 {
  99         int cpu = smp_processor_id();
 100         int irq = K_BCM1480_INT_TIMER_0 + cpu;
 101
 102         /* Reset the timer */
 103         __raw_writeq(M_SCD_TIMER_ENABLE|M_SCD_TIMER_MODE_CONTINUOUS,
 104               IOADDR(A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_CFG)));
 105
 106         if (cpu == 0) {
 107                 /*
 108                  * CPU 0 handles the global timer interrupt job
 109                  */
 110                 ll_timer_interrupt(irq);
 111         }
 112         else {
 113                 /*
 114                  * other CPUs should just do profiling and process accounting
 115                  */
 116                 ll_local_timer_interrupt(irq);
 117         }
 118 }
 119
 120 static cycle_t bcm1480_hpt_read(void)
 121 {
 122         /* We assume this function is called xtime_lock held. */
 123         unsigned long count =
 124                 __raw_readq(IOADDR(A_SCD_TIMER_REGISTER(0, R_SCD_TIMER_CNT)));
 125         return (jiffies + 1) * (BCM1480_HPT_VALUE / HZ) - count;
 126 }
 127
 128 void __init bcm1480_hpt_setup(void)
 129 {
 130         clocksource_mips.read = bcm1480_hpt_read;
 131         mips_hpt_frequency = BCM1480_HPT_VALUE;
 132 }