aboutsummaryrefslogtreecommitdiffstats
path: root/arch/arm
diff options
context:
space:
mode:
authorRussell King <rmk@dyn-67.arm.linux.org.uk>2005-11-02 17:24:33 -0500
committerRussell King <rmk+kernel@arm.linux.org.uk>2005-11-02 17:24:33 -0500
commita054a811597a17ffbe92bc4db04a4dc2f1b1ea55 (patch)
treeb600081d964d6fe7cc1cfe2669a739da0e1743f4 /arch/arm
parent273c2cdb2b6d6743d85ddbde82e71f8adbf5bf10 (diff)
[ARM SMP] Add hotplug CPU infrastructure
This patch adds the infrastructure to support hotplug CPU on ARM platforms. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm')
-rw-r--r--arch/arm/Kconfig7
-rw-r--r--arch/arm/kernel/irq.c31
-rw-r--r--arch/arm/kernel/process.c9
-rw-r--r--arch/arm/kernel/smp.c85
4 files changed, 132 insertions, 0 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index dc6d8342e5e6..6b12d71978de 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -349,6 +349,13 @@ config NR_CPUS
349 depends on SMP 349 depends on SMP
350 default "4" 350 default "4"
351 351
352config HOTPLUG_CPU
353 bool "Support for hot-pluggable CPUs (EXPERIMENTAL)"
354 depends on SMP && HOTPLUG && EXPERIMENTAL
355 help
356 Say Y here to experiment with turning CPUs off and on. CPUs
357 can be controlled through /sys/devices/system/cpu.
358
352config PREEMPT 359config PREEMPT
353 bool "Preemptible Kernel (EXPERIMENTAL)" 360 bool "Preemptible Kernel (EXPERIMENTAL)"
354 depends on EXPERIMENTAL 361 depends on EXPERIMENTAL
diff --git a/arch/arm/kernel/irq.c b/arch/arm/kernel/irq.c
index 3284118f356b..9def4404e1f2 100644
--- a/arch/arm/kernel/irq.c
+++ b/arch/arm/kernel/irq.c
@@ -1050,3 +1050,34 @@ static int __init noirqdebug_setup(char *str)
1050} 1050}
1051 1051
1052__setup("noirqdebug", noirqdebug_setup); 1052__setup("noirqdebug", noirqdebug_setup);
1053
1054#ifdef CONFIG_HOTPLUG_CPU
1055/*
1056 * The CPU has been marked offline. Migrate IRQs off this CPU. If
1057 * the affinity settings do not allow other CPUs, force them onto any
1058 * available CPU.
1059 */
1060void migrate_irqs(void)
1061{
1062 unsigned int i, cpu = smp_processor_id();
1063
1064 for (i = 0; i < NR_IRQS; i++) {
1065 struct irqdesc *desc = irq_desc + i;
1066
1067 if (desc->cpu == cpu) {
1068 unsigned int newcpu = any_online_cpu(desc->affinity);
1069
1070 if (newcpu == NR_CPUS) {
1071 if (printk_ratelimit())
1072 printk(KERN_INFO "IRQ%u no longer affine to CPU%u\n",
1073 i, cpu);
1074
1075 cpus_setall(desc->affinity);
1076 newcpu = any_online_cpu(desc->affinity);
1077 }
1078
1079 route_irq(desc, i, newcpu);
1080 }
1081 }
1082}
1083#endif /* CONFIG_HOTPLUG_CPU */
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 409db6d5ec99..ba298277becd 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -26,6 +26,7 @@
26#include <linux/interrupt.h> 26#include <linux/interrupt.h>
27#include <linux/kallsyms.h> 27#include <linux/kallsyms.h>
28#include <linux/init.h> 28#include <linux/init.h>
29#include <linux/cpu.h>
29 30
30#include <asm/system.h> 31#include <asm/system.h>
31#include <asm/io.h> 32#include <asm/io.h>
@@ -105,6 +106,14 @@ void cpu_idle(void)
105 /* endless idle loop with no priority at all */ 106 /* endless idle loop with no priority at all */
106 while (1) { 107 while (1) {
107 void (*idle)(void) = pm_idle; 108 void (*idle)(void) = pm_idle;
109
110#ifdef CONFIG_HOTPLUG_CPU
111 if (cpu_is_offline(smp_processor_id())) {
112 leds_event(led_idle_start);
113 cpu_die();
114 }
115#endif
116
108 if (!idle) 117 if (!idle)
109 idle = default_idle; 118 idle = default_idle;
110 preempt_disable(); 119 preempt_disable();
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index b40915dcd533..edb5a406922f 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -159,6 +159,91 @@ int __cpuinit __cpu_up(unsigned int cpu)
159 return ret; 159 return ret;
160} 160}
161 161
162#ifdef CONFIG_HOTPLUG_CPU
163/*
164 * __cpu_disable runs on the processor to be shutdown.
165 */
166int __cpuexit __cpu_disable(void)
167{
168 unsigned int cpu = smp_processor_id();
169 struct task_struct *p;
170 int ret;
171
172 ret = mach_cpu_disable(cpu);
173 if (ret)
174 return ret;
175
176 /*
177 * Take this CPU offline. Once we clear this, we can't return,
178 * and we must not schedule until we're ready to give up the cpu.
179 */
180 cpu_clear(cpu, cpu_online_map);
181
182 /*
183 * OK - migrate IRQs away from this CPU
184 */
185 migrate_irqs();
186
187 /*
188 * Flush user cache and TLB mappings, and then remove this CPU
189 * from the vm mask set of all processes.
190 */
191 flush_cache_all();
192 local_flush_tlb_all();
193
194 read_lock(&tasklist_lock);
195 for_each_process(p) {
196 if (p->mm)
197 cpu_clear(cpu, p->mm->cpu_vm_mask);
198 }
199 read_unlock(&tasklist_lock);
200
201 return 0;
202}
203
204/*
205 * called on the thread which is asking for a CPU to be shutdown -
206 * waits until shutdown has completed, or it is timed out.
207 */
208void __cpuexit __cpu_die(unsigned int cpu)
209{
210 if (!platform_cpu_kill(cpu))
211 printk("CPU%u: unable to kill\n", cpu);
212}
213
214/*
215 * Called from the idle thread for the CPU which has been shutdown.
216 *
217 * Note that we disable IRQs here, but do not re-enable them
218 * before returning to the caller. This is also the behaviour
219 * of the other hotplug-cpu capable cores, so presumably coming
220 * out of idle fixes this.
221 */
222void __cpuexit cpu_die(void)
223{
224 unsigned int cpu = smp_processor_id();
225
226 local_irq_disable();
227 idle_task_exit();
228
229 /*
230 * actual CPU shutdown procedure is at least platform (if not
231 * CPU) specific
232 */
233 platform_cpu_die(cpu);
234
235 /*
236 * Do not return to the idle loop - jump back to the secondary
237 * cpu initialisation. There's some initialisation which needs
238 * to be repeated to undo the effects of taking the CPU offline.
239 */
240 __asm__("mov sp, %0\n"
241 " b secondary_start_kernel"
242 :
243 : "r" ((void *)current->thread_info + THREAD_SIZE - 8));
244}
245#endif /* CONFIG_HOTPLUG_CPU */
246
162/* 247/*
163 * This is the secondary CPU boot entry. We're using this CPUs 248 * This is the secondary CPU boot entry. We're using this CPUs
164 * idle thread stack, but a set of temporary page tables. 249 * idle thread stack, but a set of temporary page tables.