/arch/powerpc/platforms/cell/smp.c

  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/module.h>
 19#include <linux/sched.h>
 20#include <linux/smp.h>
 21#include <linux/interrupt.h>
 22#include <linux/delay.h>
 23#include <linux/init.h>
 24#include <linux/spinlock.h>
 25#include <linux/cache.h>
 26#include <linux/err.h>
 27#include <linux/sysdev.h>
 28#include <linux/cpu.h>
 29
 30#include <asm/ptrace.h>
 31#include <asm/atomic.h>
 32#include <asm/irq.h>
 33#include <asm/page.h>
 34#include <asm/pgtable.h>
 35#include <asm/io.h>
 36#include <asm/prom.h>
 37#include <asm/smp.h>
 38#include <asm/paca.h>
 39#include <asm/machdep.h>
 40#include <asm/cputable.h>
 41#include <asm/firmware.h>
 42#include <asm/system.h>
 43#include <asm/rtas.h>
 44#include <asm/cputhreads.h>
 45
 46#include "interrupt.h"
 47#include <asm/udbg.h>
 48
 49#ifdef DEBUG
 50#define DBG(fmt...) udbg_printf(fmt)
 51#else
 52#define DBG(fmt...)
 53#endif
 54
 55/*
 56 * The Primary thread of each non-boot processor was started from the OF client
 57 * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
 58 */
 59static cpumask_t of_spin_map;
 60
 61/**
 62 * smp_startup_cpu() - start the given cpu
 63 *
 64 * At boot time, there is nothing to do for primary threads which were
 65 * started from Open Firmware.  For anything else, call RTAS with the
 66 * appropriate start location.
 67 *
 68 * Returns:
 69 *	0	- failure
 70 *	1	- success
 71 */
 72static inline int __devinit smp_startup_cpu(unsigned int lcpu)
 73{
 74	int status;
 75	unsigned long start_here = __pa((u32)*((unsigned long *)
 76					       generic_secondary_smp_init));
 77	unsigned int pcpu;
 78	int start_cpu;
 79
 80	if (cpu_isset(lcpu, of_spin_map))
 81		/* Already started by OF and sitting in spin loop */
 82		return 1;
 83
 84	pcpu = get_hard_smp_processor_id(lcpu);
 85
 86	/* Fixup atomic count: it exited inside IRQ handler. */
 87	task_thread_info(paca[lcpu].__current)->preempt_count	= 0;
 88
 89	/*
 90	 * If the RTAS start-cpu token does not exist then presume the
 91	 * cpu is already spinning.
 92	 */
 93	start_cpu = rtas_token("start-cpu");
 94	if (start_cpu == RTAS_UNKNOWN_SERVICE)
 95		return 1;
 96
 97	status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, lcpu);
 98	if (status != 0) {
 99		printk(KERN_ERR "start-cpu failed: %i\n", status);
100		return 0;
101	}
102
103	return 1;
104}
105
106static void smp_iic_message_pass(int target, int msg)
107{
108	unsigned int i;
109
110	if (target < NR_CPUS) {
111		iic_cause_IPI(target, msg);
112	} else {
113		for_each_online_cpu(i) {
114			if (target == MSG_ALL_BUT_SELF
115			    && i == smp_processor_id())
116				continue;
117			iic_cause_IPI(i, msg);
118		}
119	}
120}
121
122static int __init smp_iic_probe(void)
123{
124	iic_request_IPIs();
125
126	return cpus_weight(cpu_possible_map);
127}
128
129static void __devinit smp_cell_setup_cpu(int cpu)
130{
131	if (cpu != boot_cpuid)
132		iic_setup_cpu();
133
134	/*
135	 * change default DABRX to allow user watchpoints
136	 */
137	mtspr(SPRN_DABRX, DABRX_KERNEL | DABRX_USER);
138}
139
140static void __devinit smp_cell_kick_cpu(int nr)
141{
142	BUG_ON(nr < 0 || nr >= NR_CPUS);
143
144	if (!smp_startup_cpu(nr))
145		return;
146
147	/*
148	 * The processor is currently spinning, waiting for the
149	 * cpu_start field to become non-zero After we set cpu_start,
150	 * the processor will continue on to secondary_start
151	 */
152	paca[nr].cpu_start = 1;
153}
154
155static int smp_cell_cpu_bootable(unsigned int nr)
156{
157	/* Special case - we inhibit secondary thread startup
158	 * during boot if the user requests it.  Odd-numbered
159	 * cpus are assumed to be secondary threads.
160	 */
161	if (system_state < SYSTEM_RUNNING &&
162	    cpu_has_feature(CPU_FTR_SMT) &&
163	    !smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)
164		return 0;
165
166	return 1;
167}
168static struct smp_ops_t bpa_iic_smp_ops = {
169	.message_pass	= smp_iic_message_pass,
170	.probe		= smp_iic_probe,
171	.kick_cpu	= smp_cell_kick_cpu,
172	.setup_cpu	= smp_cell_setup_cpu,
173	.cpu_bootable	= smp_cell_cpu_bootable,
174};
175
176/* This is called very early */
177void __init smp_init_cell(void)
178{
179	int i;
180
181	DBG(" -> smp_init_cell()\n");
182
183	smp_ops = &bpa_iic_smp_ops;
184
185	/* Mark threads which are still spinning in hold loops. */
186	if (cpu_has_feature(CPU_FTR_SMT)) {
187		for_each_present_cpu(i) {
188			if (cpu_thread_in_core(i) == 0)
189				cpu_set(i, of_spin_map);
190		}
191	} else {
192		of_spin_map = cpu_present_map;
193	}
194
195	cpu_clear(boot_cpuid, of_spin_map);
196
197	/* Non-lpar has additional take/give timebase */
198	if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
199		smp_ops->give_timebase = rtas_give_timebase;
200		smp_ops->take_timebase = rtas_take_timebase;
201	}
202
203	DBG(" <- smp_init_cell()\n");
204}