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/prom.h>
32#include <asm/smp.h>
33#include <asm/paca.h>
34#include <asm/machdep.h>
35#include <asm/cputable.h>
36#include <asm/firmware.h>
37#include <asm/rtas.h>
38#include <asm/cputhreads.h>
39#include <asm/code-patching.h>
40
41#include "interrupt.h"
42#include <asm/udbg.h>
43
44#ifdef DEBUG
45#define DBG(fmt...) udbg_printf(fmt)
46#else
47#define DBG(fmt...)
48#endif
49
50/*
51 * The Primary thread of each non-boot processor was started from the OF client
52 * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
53 */
54static cpumask_t of_spin_map;
55
56/**
57 * smp_startup_cpu() - start the given cpu
58 *
59 * At boot time, there is nothing to do for primary threads which were
60 * started from Open Firmware.  For anything else, call RTAS with the
61 * appropriate start location.
62 *
63 * Returns:
64 *	0	- failure
65 *	1	- success
66 */
67static inline int smp_startup_cpu(unsigned int lcpu)
68{
69	int status;
70	unsigned long start_here =
71			__pa(ppc_function_entry(generic_secondary_smp_init));
72	unsigned int pcpu;
73	int start_cpu;
74
75	if (cpumask_test_cpu(lcpu, &of_spin_map))
76		/* Already started by OF and sitting in spin loop */
77		return 1;
78
79	pcpu = get_hard_smp_processor_id(lcpu);
80
81	/*
82	 * If the RTAS start-cpu token does not exist then presume the
83	 * cpu is already spinning.
84	 */
85	start_cpu = rtas_token("start-cpu");
86	if (start_cpu == RTAS_UNKNOWN_SERVICE)
87		return 1;
88
89	status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, lcpu);
90	if (status != 0) {
91		printk(KERN_ERR "start-cpu failed: %i\n", status);
92		return 0;
93	}
94
95	return 1;
96}
97
98static void smp_cell_setup_cpu(int cpu)
99{
100	if (cpu != boot_cpuid)
101		iic_setup_cpu();
102
103	/*
104	 * change default DABRX to allow user watchpoints
105	 */
106	mtspr(SPRN_DABRX, DABRX_KERNEL | DABRX_USER);
107}
108
109static int smp_cell_kick_cpu(int nr)
110{
111	if (nr < 0 || nr >= nr_cpu_ids)
112		return -EINVAL;
113
114	if (!smp_startup_cpu(nr))
115		return -ENOENT;
116
117	/*
118	 * The processor is currently spinning, waiting for the
119	 * cpu_start field to become non-zero After we set cpu_start,
120	 * the processor will continue on to secondary_start
121	 */
122	paca_ptrs[nr]->cpu_start = 1;
123
124	return 0;
125}
126
127static struct smp_ops_t bpa_iic_smp_ops = {
128	.message_pass	= iic_message_pass,
129	.probe		= iic_request_IPIs,
130	.kick_cpu	= smp_cell_kick_cpu,
131	.setup_cpu	= smp_cell_setup_cpu,
132	.cpu_bootable	= smp_generic_cpu_bootable,
133};
134
135/* This is called very early */
136void __init smp_init_cell(void)
137{
138	int i;
139
140	DBG(" -> smp_init_cell()\n");
141
142	smp_ops = &bpa_iic_smp_ops;
143
144	/* Mark threads which are still spinning in hold loops. */
145	if (cpu_has_feature(CPU_FTR_SMT)) {
146		for_each_present_cpu(i) {
147			if (cpu_thread_in_core(i) == 0)
148				cpumask_set_cpu(i, &of_spin_map);
149		}
150	} else
151		cpumask_copy(&of_spin_map, cpu_present_mask);
152
153	cpumask_clear_cpu(boot_cpuid, &of_spin_map);
154
155	/* Non-lpar has additional take/give timebase */
156	if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
157		smp_ops->give_timebase = rtas_give_timebase;
158		smp_ops->take_timebase = rtas_take_timebase;
159	}
160
161	DBG(" <- smp_init_cell()\n");
162}
163