From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sipsolutions.net (crystal.sipsolutions.net [195.210.38.204]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id 35F98DDE22 for ; Wed, 21 Mar 2007 23:12:41 +1100 (EST) Message-Id: <20070321104210.090659000@sipsolutions.net> References: <20070321104037.696668000@sipsolutions.net> Date: Wed, 21 Mar 2007 11:40:38 +0100 From: Johannes Berg To: linuxppc-dev@ozlabs.org Subject: [RFC 1/6] powermac: support G5 CPU hotplug Mime-Version: 1.0 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , This patch allows "hotplugging" of CPUs on G5 machines. CPUs that are disabled are put into an idle loop with the decrementer frequency set to minimum. To wake them up again we kick them just like when bringing them up. To stop those CPUs from messing with any global state we stop them from entering the timer interrupt. Signed-off-by: Johannes Berg Cc: Benjamin Herrenschmidt --- arch/powerpc/kernel/idle_power4.S | 14 +++++++++--- arch/powerpc/platforms/powermac/setup.c | 35 +++++++++++++++++++++++++++++++- arch/powerpc/platforms/powermac/smp.c | 12 +++++++++- include/asm-powerpc/machdep.h | 2 + 4 files changed, 56 insertions(+), 7 deletions(-) --- linux-2.6.orig/arch/powerpc/platforms/powermac/smp.c 2007-03-21 11:18:47.542243895 +0100 +++ linux-2.6/arch/powerpc/platforms/powermac/smp.c 2007-03-21 11:23:27.332243895 +0100 @@ -897,7 +897,7 @@ void smp_core99_cpu_die(unsigned int cpu cpu_dead[cpu] = 0; } -#endif +#endif /* CONFIG_HOTPLUG_CPU && CONFIG_PP32 */ /* Core99 Macs (dual G4s and G5s) */ struct smp_ops_t core99_smp_ops = { @@ -907,8 +907,16 @@ struct smp_ops_t core99_smp_ops = { .setup_cpu = smp_core99_setup_cpu, .give_timebase = smp_core99_give_timebase, .take_timebase = smp_core99_take_timebase, -#if defined(CONFIG_HOTPLUG_CPU) && defined(CONFIG_PPC32) +#if defined(CONFIG_HOTPLUG_CPU) +# if defined(CONFIG_PPC32) .cpu_disable = smp_core99_cpu_disable, .cpu_die = smp_core99_cpu_die, +# endif +# if defined(CONFIG_PPC64) + .cpu_disable = generic_cpu_disable, + .cpu_die = generic_cpu_die, + /* intentionally do *NOT* assign cpu_enable, + * the generic code will use kick_cpu then! */ +# endif #endif }; --- linux-2.6.orig/arch/powerpc/platforms/powermac/setup.c 2007-03-21 11:18:47.612243895 +0100 +++ linux-2.6/arch/powerpc/platforms/powermac/setup.c 2007-03-21 11:28:28.542243895 +0100 @@ -425,6 +425,9 @@ static int initializing = 1; static int pmac_late_init(void) { initializing = 0; + /* this is udbg (which is __init) and we can later use it during + * cpu hotplug (in smp_core99_kick_cpu) */ + ppc_md.progress = NULL; return 0; } @@ -651,6 +654,36 @@ static int pmac_pci_probe_mode(struct pc return PCI_PROBE_NORMAL; return PCI_PROBE_DEVTREE; } + +#ifdef CONFIG_HOTPLUG_CPU +/* access per cpu vars from generic smp.c */ +DECLARE_PER_CPU(int, cpu_state); + +static void pmac_cpu_die(void) +{ + /* turn off as much as possible, we'll be + * kicked out as this will only be invoked + * on core99 platforms for now ... */ + + printk(KERN_INFO "CPU#%d offline\n", smp_processor_id()); + __get_cpu_var(cpu_state) = CPU_DEAD; + smp_wmb(); + + /* during the path that leads here preemption is disabled, + * reenable it now so that when coming up preempt count is + * zero correctly */ + preempt_enable(); + + while (1) { + /* let's not take timer interrupts too often ... */ + set_dec(0x7fffffff); + printk("CPU %d dead\n", smp_processor_id()); + + power4_idle_irqs_softdisabled(); + } +} +#endif + #endif define_machine(powermac) { @@ -689,6 +722,6 @@ define_machine(powermac) { .phys_mem_access_prot = pci_phys_mem_access_prot, #endif #if defined(CONFIG_HOTPLUG_CPU) && defined(CONFIG_PPC64) - .cpu_die = generic_mach_cpu_die, + .cpu_die = pmac_cpu_die, #endif }; --- linux-2.6.orig/arch/powerpc/kernel/idle_power4.S 2007-03-21 11:18:47.662243895 +0100 +++ linux-2.6/arch/powerpc/kernel/idle_power4.S 2007-03-21 11:23:27.342243895 +0100 @@ -19,7 +19,12 @@ .text +_GLOBAL(power4_idle_irqs_softdisabled) + li r6,0 + b 0f _GLOBAL(power4_idle) + li r6,1 +0: BEGIN_FTR_SECTION blr END_FTR_SECTION_IFCLR(CPU_FTR_CAN_NAP) @@ -35,8 +40,8 @@ END_FTR_SECTION_IFCLR(CPU_FTR_CAN_NAP) rotldi r0,r0,16 mtmsrd r0,1 /* hard-disable interrupts */ li r0,1 - stb r0,PACASOFTIRQEN(r13) /* we'll hard-enable shortly */ - stb r0,PACAHARDIRQEN(r13) + stb r0,PACAHARDIRQEN(r13) /* we'll hard-enable shortly */ + stb r6,PACASOFTIRQEN(r13) /* set softirqs enabled bit */ BEGIN_FTR_SECTION DSSALL sync @@ -51,5 +56,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC) isync mtmsrd r7 isync - b 1b - + cmpdi 0,r6,0 + bne+ 1b /* return for softirq-disabled case */ + blr --- linux-2.6.orig/include/asm-powerpc/machdep.h 2007-03-21 11:18:47.682243895 +0100 +++ linux-2.6/include/asm-powerpc/machdep.h 2007-03-21 11:27:55.412243895 +0100 @@ -252,6 +252,8 @@ struct machdep_calls { extern void power4_idle(void); extern void ppc6xx_idle(void); +/* this one is for CPU hotplug (e.g. powermac) */ +extern void power4_idle_irqs_softdisabled(void); /* * ppc_md contains a copy of the machine description structure for the --