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 } 133