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
39#include <asm/sibyte/sb1250.h>
40#include <asm/sibyte/sb1250_regs.h>
41#include <asm/sibyte/sb1250_int.h>
42#include <asm/sibyte/sb1250_scd.h>
43#include <asm/sibyte/64bit.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
50extern int sb1250_steal_irq(int irq);
51
52void 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	out64(IMR_IP4_VAL, KSEG1 + A_IMR_REGISTER(cpu, R_IMR_INTERRUPT_MAP_BASE)
71	      + (irq<<3));
72
73	/* the general purpose timer ticks at 1 Mhz independent if the rest of the system */
74	/* Disable the timer and set up the count */
75	out64(0, KSEG1 + A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_CFG));
76	out64(
77#ifndef CONFIG_SIMULATION
78		1000000/HZ
79#else
80		50000/HZ
81#endif
82		, KSEG1 + A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_INIT));
83
84	/* Set the timer running */
85	out64(M_SCD_TIMER_ENABLE|M_SCD_TIMER_MODE_CONTINUOUS,
86	      KSEG1 + A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_CFG));
87
88	sb1250_unmask_irq(cpu, irq);
89	sb1250_steal_irq(irq);
90	/*
91	 * This interrupt is "special" in that it doesn't use the request_irq
92	 * way to hook the irq line.  The timer interrupt is initialized early
93	 * enough to make this a major pain, and it's also firing enough to
94	 * warrant a bit of special case code.  sb1250_timer_interrupt is
95	 * called directly from irq_handler.S when IP[4] is set during an
96	 * interrupt
97	 */
98}
99
100void sb1250_timer_interrupt(struct pt_regs *regs)
101{
102	int cpu = smp_processor_id();
103	int irq = K_INT_TIMER_0+cpu;
104
105	kstat.irqs[cpu][irq]++;
106	/* Reset the timer */
107	out64(M_SCD_TIMER_ENABLE|M_SCD_TIMER_MODE_CONTINUOUS,
108	      KSEG1 + A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_CFG));
109
110	/*
111	 * CPU 0 handles the global timer interrupt job
112	 */
113	if (cpu == 0) {
114		ll_timer_interrupt(irq, regs);
115	}
116
117	/*
118	 * every CPU should do profiling and process accouting
119	 */
120	ll_local_timer_interrupt(irq, regs);
121}
122
123/*
124 * We use our own do_gettimeoffset() instead of the generic one,
125 * because the generic one does not work for SMP case.
126 * In addition, since we use general timer 0 for system time,
127 * we can get accurate intra-jiffy offset without calibration.
128 */
129unsigned long sb1250_gettimeoffset(void)
130{
131	unsigned long count =
132		in64(KSEG1 + A_SCD_TIMER_REGISTER(0, R_SCD_TIMER_CNT));
133
134	return 1000000/HZ - count;
135 }
136