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
50 extern int sb1250_steal_irq(int irq);
51
sb1250_time_init(void)52 void 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
sb1250_timer_interrupt(struct pt_regs * regs)100 void sb1250_timer_interrupt(struct pt_regs *regs)
101 {
102 int cpu = smp_processor_id();
103 int irq = K_INT_TIMER_0+cpu;
104
105 /* Reset the timer */
106 out64(M_SCD_TIMER_ENABLE|M_SCD_TIMER_MODE_CONTINUOUS,
107 KSEG1 + A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_CFG));
108
109 /*
110 * CPU 0 handles the global timer interrupt job
111 */
112 if (cpu == 0) {
113 ll_timer_interrupt(irq, regs);
114 }
115
116 /*
117 * every CPU should do profiling and process accouting
118 */
119 ll_local_timer_interrupt(irq, regs);
120 }
121
122 /*
123 * We use our own do_gettimeoffset() instead of the generic one,
124 * because the generic one does not work for SMP case.
125 * In addition, since we use general timer 0 for system time,
126 * we can get accurate intra-jiffy offset without calibration.
127 */
sb1250_gettimeoffset(void)128 unsigned long sb1250_gettimeoffset(void)
129 {
130 unsigned long count =
131 in64(KSEG1 + A_SCD_TIMER_REGISTER(0, R_SCD_TIMER_CNT));
132
133 return 1000000/HZ - count;
134 }
135