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/clockchips.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/addrspace.h>
  36 #include <asm/time.h>
  37 #include <asm/io.h>
  38
  39 #include <asm/sibyte/bcm1480_regs.h>
  40 #include <asm/sibyte/sb1250_regs.h>
  41 #include <asm/sibyte/bcm1480_int.h>
  42 #include <asm/sibyte/bcm1480_scd.h>
  43
  44 #include <asm/sibyte/sb1250.h>
  45
  46
  47 #define IMR_IP2_VAL     K_BCM1480_INT_MAP_I0
  48 #define IMR_IP3_VAL     K_BCM1480_INT_MAP_I1
  49 #define IMR_IP4_VAL     K_BCM1480_INT_MAP_I2
  50
  51 #ifdef CONFIG_SIMULATION
  52 #define BCM1480_HPT_VALUE       50000
  53 #else
  54 #define BCM1480_HPT_VALUE       1000000
  55 #endif
  56
  57 extern int bcm1480_steal_irq(int irq);
  58
  59 void __init plat_time_init(void)
  60 {
  61         unsigned int cpu = smp_processor_id();
  62         unsigned int irq = K_BCM1480_INT_TIMER_0 + cpu;
  63
  64         BUG_ON(cpu > 3);        /* Only have 4 general purpose timers */
  65
  66         bcm1480_mask_irq(cpu, irq);
  67
  68         /* Map the timer interrupt to ip[4] of this cpu */
  69         __raw_writeq(IMR_IP4_VAL, IOADDR(A_BCM1480_IMR_REGISTER(cpu, R_BCM1480_IMR_INTERRUPT_MAP_BASE_H)
  70               + (irq<<3)));
  71
  72         bcm1480_unmask_irq(cpu, irq);
  73         bcm1480_steal_irq(irq);
  74 }
  75
  76 /*
  77  * The general purpose timer ticks at 1 Mhz independent if
  78  * the rest of the system
  79  */
  80 static void sibyte_set_mode(enum clock_event_mode mode,
  81                            struct clock_event_device *evt)
  82 {
  83         unsigned int cpu = smp_processor_id();
  84         void __iomem *timer_cfg, *timer_init;
  85
  86         timer_cfg = IOADDR(A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_CFG));
  87         timer_init = IOADDR(A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_INIT));
  88
  89         switch (mode) {
  90         case CLOCK_EVT_MODE_PERIODIC:
  91                 __raw_writeq(0, timer_cfg);
  92                 __raw_writeq(BCM1480_HPT_VALUE / HZ - 1, timer_init);
  93                 __raw_writeq(M_SCD_TIMER_ENABLE | M_SCD_TIMER_MODE_CONTINUOUS,
  94                              timer_cfg);
  95                 break;
  96
  97         case CLOCK_EVT_MODE_ONESHOT:
  98                 /* Stop the timer until we actually program a shot */
  99         case CLOCK_EVT_MODE_SHUTDOWN:
 100                 __raw_writeq(0, timer_cfg);
 101                 break;
 102
 103         case CLOCK_EVT_MODE_UNUSED:     /* shuddup gcc */
 104                 ;
 105         }
 106 }
 107
 108 struct clock_event_device sibyte_hpt_clockevent = {
 109         .name           = "bcm1480-counter",
 110         .features       = CLOCK_EVT_FEAT_PERIODIC,
 111         .set_mode       = sibyte_set_mode,
 112         .shift          = 32,
 113         .irq            = 0,
 114 };
 115
 116 static irqreturn_t sibyte_counter_handler(int irq, void *dev_id)
 117 {
 118         struct clock_event_device *cd = &sibyte_hpt_clockevent;
 119         unsigned int cpu = smp_processor_id();
 120
 121         /* Reset the timer */
 122         __raw_writeq(M_SCD_TIMER_ENABLE|M_SCD_TIMER_MODE_CONTINUOUS,
 123                      IOADDR(A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_CFG)));
 124         cd->event_handler(cd);
 125
 126         return IRQ_HANDLED;
 127 }
 128
 129 static struct irqaction sibyte_counter_irqaction = {
 130         .handler        = sibyte_counter_handler,
 131         .flags          = IRQF_DISABLED | IRQF_PERCPU,
 132         .name           = "timer",
 133 };
 134
 135 /*
 136  * This interrupt is "special" in that it doesn't use the request_irq
 137  * way to hook the irq line.  The timer interrupt is initialized early
 138  * enough to make this a major pain, and it's also firing enough to
 139  * warrant a bit of special case code.  bcm1480_timer_interrupt is
 140  * called directly from irq_handler.S when IP[4] is set during an
 141  * interrupt
 142  */
 143 static void __init sb1480_clockevent_init(void)
 144 {
 145         unsigned int cpu = smp_processor_id();
 146         unsigned int irq = K_BCM1480_INT_TIMER_0 + cpu;
 147
 148         setup_irq(irq, &sibyte_counter_irqaction);
 149 }
 150
 151 void bcm1480_timer_interrupt(void)
 152 {
 153         int cpu = smp_processor_id();
 154         int irq = K_BCM1480_INT_TIMER_0 + cpu;
 155
 156         /* Reset the timer */
 157         __raw_writeq(M_SCD_TIMER_ENABLE|M_SCD_TIMER_MODE_CONTINUOUS,
 158               IOADDR(A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_CFG)));
 159
 160         ll_timer_interrupt(irq);
 161 }
 162
 163 static cycle_t bcm1480_hpt_read(void)
 164 {
 165         /* We assume this function is called xtime_lock held. */
 166         unsigned long count =
 167                 __raw_readq(IOADDR(A_SCD_TIMER_REGISTER(0, R_SCD_TIMER_CNT)));
 168         return (jiffies + 1) * (BCM1480_HPT_VALUE / HZ) - count;
 169 }
 170
 171 void __init bcm1480_hpt_setup(void)
 172 {
 173         clocksource_mips.read = bcm1480_hpt_read;
 174         mips_hpt_frequency = BCM1480_HPT_VALUE;
 175         sb1480_clockevent_init();
 176 }