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 */
58static 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 */
71static 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[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
105static 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
116static int smp_cell_kick_cpu(int nr)
117{
118	BUG_ON(nr < 0 || nr >= NR_CPUS);
119
120	if (!smp_startup_cpu(nr))
121		return -ENOENT;
122
123	/*
124	 * The processor is currently spinning, waiting for the
125	 * cpu_start field to become non-zero After we set cpu_start,
126	 * the processor will continue on to secondary_start
127	 */
128	paca[nr].cpu_start = 1;
129
130	return 0;
131}
132
133static struct smp_ops_t bpa_iic_smp_ops = {
134	.message_pass	= iic_message_pass,
135	.probe		= iic_request_IPIs,
136	.kick_cpu	= smp_cell_kick_cpu,
137	.setup_cpu	= smp_cell_setup_cpu,
138	.cpu_bootable	= smp_generic_cpu_bootable,
139};
140
141/* This is called very early */
142void __init smp_init_cell(void)
143{
144	int i;
145
146	DBG(" -> smp_init_cell()\n");
147
148	smp_ops = &bpa_iic_smp_ops;
149
150	/* Mark threads which are still spinning in hold loops. */
151	if (cpu_has_feature(CPU_FTR_SMT)) {
152		for_each_present_cpu(i) {
153			if (cpu_thread_in_core(i) == 0)
154				cpumask_set_cpu(i, &of_spin_map);
155		}
156	} else
157		cpumask_copy(&of_spin_map, cpu_present_mask);
158
159	cpumask_clear_cpu(boot_cpuid, &of_spin_map);
160
161	/* Non-lpar has additional take/give timebase */
162	if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
163		smp_ops->give_timebase = rtas_give_timebase;
164		smp_ops->take_timebase = rtas_take_timebase;
165	}
166
167	DBG(" <- smp_init_cell()\n");
168}
169