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 */
53static 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 */
66static 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
97static 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
108static 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
126static 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 */
135void __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