From: Paul Mackerras <paulus@samba.org>
Date: Sat, 10 Sep 2005 11:13:13 +0000 (+1000)
Subject: [PATCH] ppc32: support hotplug cpu on powermacs
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=31139971b3dc9fbb2e8a8572fb81e6e8470f363a;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git
[PATCH] ppc32: support hotplug cpu on powermacs
This allows cpus to be off-lined on 32-bit SMP powermacs. When a cpu
is off-lined, it is put into sleep mode with interrupts disabled. It
can be on-lined again by asserting its soft-reset pin, which is
connected to a GPIO pin.
With this I can off-line the second cpu in my dual G4 powermac, which
means that I can then suspend the machine (the suspend/resume code
refuses to suspend if more than one cpu is online, and making it cope
with multiple cpus is surprisingly messy).
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
diff --git a/arch/ppc/Kconfig b/arch/ppc/Kconfig
index e3f1ce33e642..347ea284140b 100644
--- a/arch/ppc/Kconfig
+++ b/arch/ppc/Kconfig
@@ -265,6 +265,15 @@ config PPC601_SYNC_FIX
If in doubt, say Y here.
+config HOTPLUG_CPU
+ bool "Support for enabling/disabling CPUs"
+ depends on SMP && HOTPLUG && EXPERIMENTAL && PPC_PMAC
+ ---help---
+ Say Y here to be able to disable and re-enable individual
+ CPUs at runtime on SMP machines.
+
+ Say N if you are unsure.
+
source arch/ppc/platforms/4xx/Kconfig
source arch/ppc/platforms/85xx/Kconfig
diff --git a/arch/ppc/kernel/head.S b/arch/ppc/kernel/head.S
index 55daf1210f32..1960fb8c259c 100644
--- a/arch/ppc/kernel/head.S
+++ b/arch/ppc/kernel/head.S
@@ -1023,23 +1023,21 @@ __secondary_start_gemini:
andc r4,r4,r3
mtspr SPRN_HID0,r4
sync
- bl gemini_prom_init
b __secondary_start
#endif /* CONFIG_GEMINI */
- .globl __secondary_start_psurge
-__secondary_start_psurge:
- li r24,1 /* cpu # */
- b __secondary_start_psurge99
- .globl __secondary_start_psurge2
-__secondary_start_psurge2:
- li r24,2 /* cpu # */
- b __secondary_start_psurge99
- .globl __secondary_start_psurge3
-__secondary_start_psurge3:
- li r24,3 /* cpu # */
- b __secondary_start_psurge99
-__secondary_start_psurge99:
- /* we come in here with IR=0 and DR=1, and DBAT 0
+
+ .globl __secondary_start_pmac_0
+__secondary_start_pmac_0:
+ /* NB the entries for cpus 0, 1, 2 must each occupy 8 bytes. */
+ li r24,0
+ b 1f
+ li r24,1
+ b 1f
+ li r24,2
+ b 1f
+ li r24,3
+1:
+ /* on powersurge, we come in here with IR=0 and DR=1, and DBAT 0
set to map the 0xf0000000 - 0xffffffff region */
mfmsr r0
rlwinm r0,r0,0,28,26 /* clear DR (0x10) */
diff --git a/arch/ppc/kernel/idle.c b/arch/ppc/kernel/idle.c
index 53547b6de45b..fba29c876b62 100644
--- a/arch/ppc/kernel/idle.c
+++ b/arch/ppc/kernel/idle.c
@@ -22,6 +22,7 @@
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/sysctl.h>
+#include <linux/cpu.h>
#include <asm/pgtable.h>
#include <asm/uaccess.h>
@@ -35,6 +36,7 @@
void default_idle(void)
{
void (*powersave)(void);
+ int cpu = smp_processor_id();
powersave = ppc_md.power_save;
@@ -44,7 +46,7 @@ void default_idle(void)
#ifdef CONFIG_SMP
else {
set_thread_flag(TIF_POLLING_NRFLAG);
- while (!need_resched())
+ while (!need_resched() && !cpu_is_offline(cpu))
barrier();
clear_thread_flag(TIF_POLLING_NRFLAG);
}
@@ -52,6 +54,8 @@ void default_idle(void)
}
if (need_resched())
schedule();
+ if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
+ cpu_die();
}
/*
diff --git a/arch/ppc/kernel/smp.c b/arch/ppc/kernel/smp.c
index e70b587b9e51..726fe7ce1747 100644
--- a/arch/ppc/kernel/smp.c
+++ b/arch/ppc/kernel/smp.c
@@ -45,6 +45,7 @@ cpumask_t cpu_online_map;
cpumask_t cpu_possible_map;
int smp_hw_index[NR_CPUS];
struct thread_info *secondary_ti;
+static struct task_struct *idle_tasks[NR_CPUS];
EXPORT_SYMBOL(cpu_online_map);
EXPORT_SYMBOL(cpu_possible_map);
@@ -286,7 +287,8 @@ static void __devinit smp_store_cpu_info(int id)
void __init smp_prepare_cpus(unsigned int max_cpus)
{
- int num_cpus, i;
+ int num_cpus, i, cpu;
+ struct task_struct *p;
/* Fixup boot cpu */
smp_store_cpu_info(smp_processor_id());
@@ -308,6 +310,17 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
if (smp_ops->space_timers)
smp_ops->space_timers(num_cpus);
+
+ for_each_cpu(cpu) {
+ if (cpu == smp_processor_id())
+ continue;
+ /* create a process for the processor */
+ p = fork_idle(cpu);
+ if (IS_ERR(p))
+ panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p));
+ p->thread_info->cpu = cpu;
+ idle_tasks[cpu] = p;
+ }
}
void __devinit smp_prepare_boot_cpu(void)
@@ -334,12 +347,17 @@ int __devinit start_secondary(void *unused)
set_dec(tb_ticks_per_jiffy);
cpu_callin_map[cpu] = 1;
- printk("CPU %i done callin...\n", cpu);
+ printk("CPU %d done callin...\n", cpu);
smp_ops->setup_cpu(cpu);
- printk("CPU %i done setup...\n", cpu);
- local_irq_enable();
+ printk("CPU %d done setup...\n", cpu);
smp_ops->take_timebase();
- printk("CPU %i done timebase take...\n", cpu);
+ printk("CPU %d done timebase take...\n", cpu);
+
+ spin_lock(&call_lock);
+ cpu_set(cpu, cpu_online_map);
+ spin_unlock(&call_lock);
+
+ local_irq_enable();
cpu_idle();
return 0;
@@ -347,17 +365,11 @@ int __devinit start_secondary(void *unused)
int __cpu_up(unsigned int cpu)
{
- struct task_struct *p;
char buf[32];
int c;
- /* create a process for the processor */
- /* only regs.msr is actually used, and 0 is OK for it */
- p = fork_idle(cpu);
- if (IS_ERR(p))
- panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p));
- secondary_ti = p->thread_info;
- p->thread_info->cpu = cpu;
+ secondary_ti = idle_tasks[cpu]->thread_info;
+ mb();
/*
* There was a cache flush loop here to flush the cache
@@ -389,7 +401,11 @@ int __cpu_up(unsigned int cpu)
printk("Processor %d found.\n", cpu);
smp_ops->give_timebase();
- cpu_set(cpu, cpu_online_map);
+
+ /* Wait until cpu puts itself in the online map */
+ while (!cpu_online(cpu))
+ cpu_relax();
+
return 0;
}
diff --git a/arch/ppc/platforms/pmac_sleep.S b/arch/ppc/platforms/pmac_sleep.S
index 8d67adc76925..88419c77ac43 100644
--- a/arch/ppc/platforms/pmac_sleep.S
+++ b/arch/ppc/platforms/pmac_sleep.S
@@ -161,6 +161,8 @@ _GLOBAL(low_sleep_handler)
addi r3,r3,sleep_storage@l
stw r5,0(r3)
+ .globl low_cpu_die
+low_cpu_die:
/* Flush & disable all caches */
bl flush_disable_caches
diff --git a/arch/ppc/platforms/pmac_smp.c b/arch/ppc/platforms/pmac_smp.c
index 8e049dab4e63..794a23994b82 100644
--- a/arch/ppc/platforms/pmac_smp.c
+++ b/arch/ppc/platforms/pmac_smp.c
@@ -33,6 +33,7 @@
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/hardirq.h>
+#include <linux/cpu.h>
#include <asm/ptrace.h>
#include <asm/atomic.h>
@@ -55,9 +56,7 @@
* Powersurge (old powermac SMP) support.
*/
-extern void __secondary_start_psurge(void);
-extern void __secondary_start_psurge2(void); /* Temporary horrible hack */
-extern void __secondary_start_psurge3(void); /* Temporary horrible hack */
+extern void __secondary_start_pmac_0(void);
/* Addresses for powersurge registers */
#define HAMMERHEAD_BASE 0xf8000000
@@ -119,7 +118,7 @@ static volatile int sec_tb_reset = 0;
static unsigned int pri_tb_hi, pri_tb_lo;
static unsigned int pri_tb_stamp;
-static void __init core99_init_caches(int cpu)
+static void __devinit core99_init_caches(int cpu)
{
if (!cpu_has_feature(CPU_FTR_L2CR))
return;
@@ -346,7 +345,7 @@ static int __init smp_psurge_probe(void)
static void __init smp_psurge_kick_cpu(int nr)
{
- void (*start)(void) = __secondary_start_psurge;
+ unsigned long start = __pa(__secondary_start_pmac_0) + nr * 8;
unsigned long a;
/* may need to flush here if secondary bats aren't setup */
@@ -356,17 +355,7 @@ static void __init smp_psurge_kick_cpu(int nr)
if (ppc_md.progress) ppc_md.progress("smp_psurge_kick_cpu", 0x353);
- /* setup entry point of secondary processor */
- switch (nr) {
- case 2:
- start = __secondary_start_psurge2;
- break;
- case 3:
- start = __secondary_start_psurge3;
- break;
- }
-
- out_be32(psurge_start, __pa(start));
+ out_be32(psurge_start, start);
mb();
psurge_set_ipi(nr);
@@ -500,14 +489,14 @@ static int __init smp_core99_probe(void)
return ncpus;
}
-static void __init smp_core99_kick_cpu(int nr)
+static void __devinit smp_core99_kick_cpu(int nr)
{
unsigned long save_vector, new_vector;
unsigned long flags;
volatile unsigned long *vector
= ((volatile unsigned long *)(KERNELBASE+0x100));
- if (nr < 1 || nr > 3)
+ if (nr < 0 || nr > 3)
return;
if (ppc_md.progress) ppc_md.progress("smp_core99_kick_cpu", 0x346);
@@ -518,19 +507,9 @@ static void __init smp_core99_kick_cpu(int nr)
save_vector = *vector;
/* Setup fake reset vector that does
- * b __secondary_start_psurge - KERNELBASE
+ * b __secondary_start_pmac_0 + nr*8 - KERNELBASE
*/
- switch(nr) {
- case 1:
- new_vector = (unsigned long)__secondary_start_psurge;
- break;
- case 2:
- new_vector = (unsigned long)__secondary_start_psurge2;
- break;
- case 3:
- new_vector = (unsigned long)__secondary_start_psurge3;
- break;
- }
+ new_vector = (unsigned long) __secondary_start_pmac_0 + nr * 8;
*vector = 0x48000002 + new_vector - KERNELBASE;
/* flush data cache and inval instruction cache */
@@ -554,7 +533,7 @@ static void __init smp_core99_kick_cpu(int nr)
if (ppc_md.progress) ppc_md.progress("smp_core99_kick_cpu done", 0x347);
}
-static void __init smp_core99_setup_cpu(int cpu_nr)
+static void __devinit smp_core99_setup_cpu(int cpu_nr)
{
/* Setup L2/L3 */
if (cpu_nr != 0)
@@ -668,3 +647,47 @@ struct smp_ops_t core99_smp_ops __pmacdata = {
.give_timebase = smp_core99_give_timebase,
.take_timebase = smp_core99_take_timebase,
};
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+int __cpu_disable(void)
+{
+ cpu_clear(smp_processor_id(), cpu_online_map);
+
+ /* XXX reset cpu affinity here */
+ openpic_set_priority(0xf);
+ asm volatile("mtdec %0" : : "r" (0x7fffffff));
+ mb();
+ udelay(20);
+ asm volatile("mtdec %0" : : "r" (0x7fffffff));
+ return 0;
+}
+
+extern void low_cpu_die(void) __attribute__((noreturn)); /* in pmac_sleep.S */
+static int cpu_dead[NR_CPUS];
+
+void cpu_die(void)
+{
+ local_irq_disable();
+ cpu_dead[smp_processor_id()] = 1;
+ mb();
+ low_cpu_die();
+}
+
+void __cpu_die(unsigned int cpu)
+{
+ int timeout;
+
+ timeout = 1000;
+ while (!cpu_dead[cpu]) {
+ if (--timeout == 0) {
+ printk("CPU %u refused to die!\n", cpu);
+ break;
+ }
+ msleep(1);
+ }
+ cpu_callin_map[cpu] = 0;
+ cpu_dead[cpu] = 0;
+}
+
+#endif
diff --git a/include/asm-ppc/smp.h b/include/asm-ppc/smp.h
index 17530c232c76..829481c0a9dc 100644
--- a/include/asm-ppc/smp.h
+++ b/include/asm-ppc/smp.h
@@ -41,6 +41,10 @@ extern void smp_send_xmon_break(int cpu);
struct pt_regs;
extern void smp_message_recv(int, struct pt_regs *);
+extern int __cpu_disable(void);
+extern void __cpu_die(unsigned int cpu);
+extern void cpu_die(void) __attribute__((noreturn));
+
#define NO_PROC_ID 0xFF /* No processor magic marker */
#define PROC_CHANGE_PENALTY 20
@@ -64,6 +68,8 @@ extern struct klock_info_struct klock_info;
#else /* !(CONFIG_SMP) */
+static inline void cpu_die(void) { }
+
#endif /* !(CONFIG_SMP) */
#endif /* !(_PPC_SMP_H) */