1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * SMP support for BPA machines.
4 *
5 * Dave Engebretsen, Peter Bergner, and
6 * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
7 *
8 * Plus various changes from other IBM teams...
9 */
10
11 #undef DEBUG
12
13 #include <linux/kernel.h>
14 #include <linux/sched.h>
15 #include <linux/smp.h>
16 #include <linux/interrupt.h>
17 #include <linux/delay.h>
18 #include <linux/init.h>
19 #include <linux/spinlock.h>
20 #include <linux/cache.h>
21 #include <linux/err.h>
22 #include <linux/device.h>
23 #include <linux/cpu.h>
24 #include <linux/pgtable.h>
25
26 #include <asm/ptrace.h>
27 #include <linux/atomic.h>
28 #include <asm/irq.h>
29 #include <asm/page.h>
30 #include <asm/io.h>
31 #include <asm/smp.h>
32 #include <asm/paca.h>
33 #include <asm/machdep.h>
34 #include <asm/cputable.h>
35 #include <asm/firmware.h>
36 #include <asm/rtas.h>
37 #include <asm/cputhreads.h>
38 #include <asm/code-patching.h>
39
40 #include "interrupt.h"
41 #include <asm/udbg.h>
42
43 #ifdef DEBUG
44 #define DBG(fmt...) udbg_printf(fmt)
45 #else
46 #define DBG(fmt...)
47 #endif
48
49 /*
50 * The Primary thread of each non-boot processor was started from the OF client
51 * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
52 */
53 static cpumask_t of_spin_map;
54
55 /**
56 * smp_startup_cpu() - start the given cpu
57 *
58 * At boot time, there is nothing to do for primary threads which were
59 * started from Open Firmware. For anything else, call RTAS with the
60 * appropriate start location.
61 *
62 * Returns:
63 * 0 - failure
64 * 1 - success
65 */
smp_startup_cpu(unsigned int lcpu)66 static inline int smp_startup_cpu(unsigned int lcpu)
67 {
68 int status;
69 unsigned long start_here =
70 __pa(ppc_function_entry(generic_secondary_smp_init));
71 unsigned int pcpu;
72 int start_cpu;
73
74 if (cpumask_test_cpu(lcpu, &of_spin_map))
75 /* Already started by OF and sitting in spin loop */
76 return 1;
77
78 pcpu = get_hard_smp_processor_id(lcpu);
79
80 /*
81 * If the RTAS start-cpu token does not exist then presume the
82 * cpu is already spinning.
83 */
84 start_cpu = rtas_function_token(RTAS_FN_START_CPU);
85 if (start_cpu == RTAS_UNKNOWN_SERVICE)
86 return 1;
87
88 status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, lcpu);
89 if (status != 0) {
90 printk(KERN_ERR "start-cpu failed: %i\n", status);
91 return 0;
92 }
93
94 return 1;
95 }
96
smp_cell_setup_cpu(int cpu)97 static void smp_cell_setup_cpu(int cpu)
98 {
99 if (cpu != boot_cpuid)
100 iic_setup_cpu();
101
102 /*
103 * change default DABRX to allow user watchpoints
104 */
105 mtspr(SPRN_DABRX, DABRX_KERNEL | DABRX_USER);
106 }
107
smp_cell_kick_cpu(int nr)108 static int smp_cell_kick_cpu(int nr)
109 {
110 if (nr < 0 || nr >= nr_cpu_ids)
111 return -EINVAL;
112
113 if (!smp_startup_cpu(nr))
114 return -ENOENT;
115
116 /*
117 * The processor is currently spinning, waiting for the
118 * cpu_start field to become non-zero After we set cpu_start,
119 * the processor will continue on to secondary_start
120 */
121 paca_ptrs[nr]->cpu_start = 1;
122
123 return 0;
124 }
125
126 static struct smp_ops_t bpa_iic_smp_ops = {
127 .message_pass = iic_message_pass,
128 .probe = iic_request_IPIs,
129 .kick_cpu = smp_cell_kick_cpu,
130 .setup_cpu = smp_cell_setup_cpu,
131 .cpu_bootable = smp_generic_cpu_bootable,
132 };
133
134 /* This is called very early */
smp_init_cell(void)135 void __init smp_init_cell(void)
136 {
137 int i;
138
139 DBG(" -> smp_init_cell()\n");
140
141 smp_ops = &bpa_iic_smp_ops;
142
143 /* Mark threads which are still spinning in hold loops. */
144 if (cpu_has_feature(CPU_FTR_SMT)) {
145 for_each_present_cpu(i) {
146 if (cpu_thread_in_core(i) == 0)
147 cpumask_set_cpu(i, &of_spin_map);
148 }
149 } else
150 cpumask_copy(&of_spin_map, cpu_present_mask);
151
152 cpumask_clear_cpu(boot_cpuid, &of_spin_map);
153
154 /* Non-lpar has additional take/give timebase */
155 if (rtas_function_token(RTAS_FN_FREEZE_TIME_BASE) != RTAS_UNKNOWN_SERVICE) {
156 smp_ops->give_timebase = rtas_give_timebase;
157 smp_ops->take_timebase = rtas_take_timebase;
158 }
159
160 DBG(" <- smp_init_cell()\n");
161 }
162