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 } 177