[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 e3f1ce33e64251a62502bfead0eab6102f6ee4fd..347ea284140b28be32262dbb0427af539845940b 100644 (file)
--- 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 55daf1210f3228050c5841f968f1b1fabfe44d4c..1960fb8c259c6e268c270ac716c3498302279784 100644 (file)
--- 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 53547b6de45bd491e96c0444907b74b36915592c..fba29c876b62ab843d06e308ef2590c9f3999f85 100644 (file)
--- 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 e70b587b9e514ae39b80ca70a2601ea7776fdb62..726fe7ce1747ae004570f9c6e05766907a89d4bb 100644 (file)
--- 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 8d67adc7692580d8207597a2245d13025e057ea2..88419c77ac439cd72b341c59dab10201efee9240 100644 (file)
--- 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 8e049dab4e6321f28354e0e821fe0569f36bac35..794a23994b82a09185b82ad3b797859ae96cda83 100644 (file)
--- 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 17530c232c7690c6a47a0b87a0e50ea4e23b8788..829481c0a9dc2fd6321a71a629045d3a5d94f4b1 100644 (file)
--- 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) */