1 /*
2 * SMP support for BPA machines.
3 *
4 * Dave Engebretsen, Peter Bergner, and
5 * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
6 *
7 * Plus various changes from other IBM teams...
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * as published by the Free Software Foundation; either version
12 * 2 of the License, or (at your option) any later version.
13 */
14
15 #undef DEBUG
16
17 #include <linux/kernel.h>
18 #include <linux/sched.h>
19 #include <linux/smp.h>
20 #include <linux/interrupt.h>
21 #include <linux/delay.h>
22 #include <linux/init.h>
23 #include <linux/spinlock.h>
24 #include <linux/cache.h>
25 #include <linux/err.h>
26 #include <linux/device.h>
27 #include <linux/cpu.h>
28
29 #include <asm/ptrace.h>
30 #include <linux/atomic.h>
31 #include <asm/irq.h>
32 #include <asm/page.h>
33 #include <asm/pgtable.h>
34 #include <asm/io.h>
35 #include <asm/prom.h>
36 #include <asm/smp.h>
37 #include <asm/paca.h>
38 #include <asm/machdep.h>
39 #include <asm/cputable.h>
40 #include <asm/firmware.h>
41 #include <asm/rtas.h>
42 #include <asm/cputhreads.h>
43 #include <asm/code-patching.h>
44
45 #include "interrupt.h"
46 #include <asm/udbg.h>
47
48 #ifdef DEBUG
49 #define DBG(fmt...) udbg_printf(fmt)
50 #else
51 #define DBG(fmt...)
52 #endif
53
54 /*
55 * The Primary thread of each non-boot processor was started from the OF client
56 * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
57 */
58 static cpumask_t of_spin_map;
59
60 /**
61 * smp_startup_cpu() - start the given cpu
62 *
63 * At boot time, there is nothing to do for primary threads which were
64 * started from Open Firmware. For anything else, call RTAS with the
65 * appropriate start location.
66 *
67 * Returns:
68 * 0 - failure
69 * 1 - success
70 */
smp_startup_cpu(unsigned int lcpu)71 static inline int smp_startup_cpu(unsigned int lcpu)
72 {
73 int status;
74 unsigned long start_here =
75 __pa(ppc_function_entry(generic_secondary_smp_init));
76 unsigned int pcpu;
77 int start_cpu;
78
79 if (cpumask_test_cpu(lcpu, &of_spin_map))
80 /* Already started by OF and sitting in spin loop */
81 return 1;
82
83 pcpu = get_hard_smp_processor_id(lcpu);
84
85 /* Fixup atomic count: it exited inside IRQ handler. */
86 task_thread_info(paca_ptrs[lcpu]->__current)->preempt_count = 0;
87
88 /*
89 * If the RTAS start-cpu token does not exist then presume the
90 * cpu is already spinning.
91 */
92 start_cpu = rtas_token("start-cpu");
93 if (start_cpu == RTAS_UNKNOWN_SERVICE)
94 return 1;
95
96 status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, lcpu);
97 if (status != 0) {
98 printk(KERN_ERR "start-cpu failed: %i\n", status);
99 return 0;
100 }
101
102 return 1;
103 }
104
smp_cell_setup_cpu(int cpu)105 static void smp_cell_setup_cpu(int cpu)
106 {
107 if (cpu != boot_cpuid)
108 iic_setup_cpu();
109
110 /*
111 * change default DABRX to allow user watchpoints
112 */
113 mtspr(SPRN_DABRX, DABRX_KERNEL | DABRX_USER);
114 }
115
smp_cell_kick_cpu(int nr)116 static int smp_cell_kick_cpu(int nr)
117 {
118 if (nr < 0 || nr >= nr_cpu_ids)
119 return -EINVAL;
120
121 if (!smp_startup_cpu(nr))
122 return -ENOENT;
123
124 /*
125 * The processor is currently spinning, waiting for the
126 * cpu_start field to become non-zero After we set cpu_start,
127 * the processor will continue on to secondary_start
128 */
129 paca_ptrs[nr]->cpu_start = 1;
130
131 return 0;
132 }
133
134 static struct smp_ops_t bpa_iic_smp_ops = {
135 .message_pass = iic_message_pass,
136 .probe = iic_request_IPIs,
137 .kick_cpu = smp_cell_kick_cpu,
138 .setup_cpu = smp_cell_setup_cpu,
139 .cpu_bootable = smp_generic_cpu_bootable,
140 };
141
142 /* This is called very early */
smp_init_cell(void)143 void __init smp_init_cell(void)
144 {
145 int i;
146
147 DBG(" -> smp_init_cell()\n");
148
149 smp_ops = &bpa_iic_smp_ops;
150
151 /* Mark threads which are still spinning in hold loops. */
152 if (cpu_has_feature(CPU_FTR_SMT)) {
153 for_each_present_cpu(i) {
154 if (cpu_thread_in_core(i) == 0)
155 cpumask_set_cpu(i, &of_spin_map);
156 }
157 } else
158 cpumask_copy(&of_spin_map, cpu_present_mask);
159
160 cpumask_clear_cpu(boot_cpuid, &of_spin_map);
161
162 /* Non-lpar has additional take/give timebase */
163 if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
164 smp_ops->give_timebase = rtas_give_timebase;
165 smp_ops->take_timebase = rtas_take_timebase;
166 }
167
168 DBG(" <- smp_init_cell()\n");
169 }
170
