diff options
author | James Hogan <james.hogan@imgtec.com> | 2012-10-05 15:56:56 (GMT) |
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committer | James Hogan <james.hogan@imgtec.com> | 2013-03-02 20:09:51 (GMT) |
commit | 42682c6c42a5765b2c7cccfca170368fef6191ef (patch) | |
tree | adcfa5e96cd98527ee75fc541efc279357bbe6a2 /arch/metag/kernel/smp.c | |
parent | fdabf525b4b7aab3945c19eac39d3a65b68d0c4f (diff) | |
download | linux-42682c6c42a5765b2c7cccfca170368fef6191ef.tar.xz |
metag: SMP support
Add SMP support for metag. This allows Linux to take control of multiple
hardware threads on a single Meta core, treating them as separate Linux
CPUs.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Diffstat (limited to 'arch/metag/kernel/smp.c')
-rw-r--r-- | arch/metag/kernel/smp.c | 575 |
1 files changed, 575 insertions, 0 deletions
diff --git a/arch/metag/kernel/smp.c b/arch/metag/kernel/smp.c new file mode 100644 index 0000000..d116312 --- /dev/null +++ b/arch/metag/kernel/smp.c @@ -0,0 +1,575 @@ +/* + * Copyright (C) 2009,2010,2011 Imagination Technologies Ltd. + * + * Copyright (C) 2002 ARM Limited, All Rights Reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ +#include <linux/atomic.h> +#include <linux/delay.h> +#include <linux/init.h> +#include <linux/spinlock.h> +#include <linux/sched.h> +#include <linux/interrupt.h> +#include <linux/cache.h> +#include <linux/profile.h> +#include <linux/errno.h> +#include <linux/mm.h> +#include <linux/err.h> +#include <linux/cpu.h> +#include <linux/smp.h> +#include <linux/seq_file.h> +#include <linux/irq.h> +#include <linux/bootmem.h> + +#include <asm/cacheflush.h> +#include <asm/cachepart.h> +#include <asm/core_reg.h> +#include <asm/cpu.h> +#include <asm/mmu_context.h> +#include <asm/pgtable.h> +#include <asm/pgalloc.h> +#include <asm/processor.h> +#include <asm/setup.h> +#include <asm/tlbflush.h> +#include <asm/hwthread.h> +#include <asm/traps.h> + +DECLARE_PER_CPU(PTBI, pTBI); + +void *secondary_data_stack; + +/* + * structures for inter-processor calls + * - A collection of single bit ipi messages. + */ +struct ipi_data { + spinlock_t lock; + unsigned long ipi_count; + unsigned long bits; +}; + +static DEFINE_PER_CPU(struct ipi_data, ipi_data) = { + .lock = __SPIN_LOCK_UNLOCKED(ipi_data.lock), +}; + +static DEFINE_SPINLOCK(boot_lock); + +/* + * "thread" is assumed to be a valid Meta hardware thread ID. + */ +int __cpuinit boot_secondary(unsigned int thread, struct task_struct *idle) +{ + u32 val; + + /* + * set synchronisation state between this boot processor + * and the secondary one + */ + spin_lock(&boot_lock); + + core_reg_write(TXUPC_ID, 0, thread, (unsigned int)secondary_startup); + core_reg_write(TXUPC_ID, 1, thread, 0); + + /* + * Give the thread privilege (PSTAT) and clear potentially problematic + * bits in the process (namely ISTAT, CBMarker, CBMarkerI, LSM_STEP). + */ + core_reg_write(TXUCT_ID, TXSTATUS_REGNUM, thread, TXSTATUS_PSTAT_BIT); + + /* Clear the minim enable bit. */ + val = core_reg_read(TXUCT_ID, TXPRIVEXT_REGNUM, thread); + core_reg_write(TXUCT_ID, TXPRIVEXT_REGNUM, thread, val & ~0x80); + + /* + * set the ThreadEnable bit (0x1) in the TXENABLE register + * for the specified thread - off it goes! + */ + val = core_reg_read(TXUCT_ID, TXENABLE_REGNUM, thread); + core_reg_write(TXUCT_ID, TXENABLE_REGNUM, thread, val | 0x1); + + /* + * now the secondary core is starting up let it run its + * calibrations, then wait for it to finish + */ + spin_unlock(&boot_lock); + + return 0; +} + +int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *idle) +{ + unsigned int thread = cpu_2_hwthread_id[cpu]; + int ret; + + load_pgd(swapper_pg_dir, thread); + + flush_tlb_all(); + + /* + * Tell the secondary CPU where to find its idle thread's stack. + */ + secondary_data_stack = task_stack_page(idle); + + wmb(); + + /* + * Now bring the CPU into our world. + */ + ret = boot_secondary(thread, idle); + if (ret == 0) { + unsigned long timeout; + + /* + * CPU was successfully started, wait for it + * to come online or time out. + */ + timeout = jiffies + HZ; + while (time_before(jiffies, timeout)) { + if (cpu_online(cpu)) + break; + + udelay(10); + barrier(); + } + + if (!cpu_online(cpu)) + ret = -EIO; + } + + secondary_data_stack = NULL; + + if (ret) { + pr_crit("CPU%u: processor failed to boot\n", cpu); + + /* + * FIXME: We need to clean up the new idle thread. --rmk + */ + } + + return ret; +} + +#ifdef CONFIG_HOTPLUG_CPU +static DECLARE_COMPLETION(cpu_killed); + +/* + * __cpu_disable runs on the processor to be shutdown. + */ +int __cpuexit __cpu_disable(void) +{ + unsigned int cpu = smp_processor_id(); + struct task_struct *p; + + /* + * Take this CPU offline. Once we clear this, we can't return, + * and we must not schedule until we're ready to give up the cpu. + */ + set_cpu_online(cpu, false); + + /* + * OK - migrate IRQs away from this CPU + */ + migrate_irqs(); + + /* + * Flush user cache and TLB mappings, and then remove this CPU + * from the vm mask set of all processes. + */ + flush_cache_all(); + local_flush_tlb_all(); + + read_lock(&tasklist_lock); + for_each_process(p) { + if (p->mm) + cpumask_clear_cpu(cpu, mm_cpumask(p->mm)); + } + read_unlock(&tasklist_lock); + + return 0; +} + +/* + * called on the thread which is asking for a CPU to be shutdown - + * waits until shutdown has completed, or it is timed out. + */ +void __cpuexit __cpu_die(unsigned int cpu) +{ + if (!wait_for_completion_timeout(&cpu_killed, msecs_to_jiffies(1))) + pr_err("CPU%u: unable to kill\n", cpu); +} + +/* + * Called from the idle thread for the CPU which has been shutdown. + * + * Note that we do not return from this function. If this cpu is + * brought online again it will need to run secondary_startup(). + */ +void __cpuexit cpu_die(void) +{ + local_irq_disable(); + idle_task_exit(); + + complete(&cpu_killed); + + asm ("XOR TXENABLE, D0Re0,D0Re0\n"); +} +#endif /* CONFIG_HOTPLUG_CPU */ + +/* + * Called by both boot and secondaries to move global data into + * per-processor storage. + */ +void __cpuinit smp_store_cpu_info(unsigned int cpuid) +{ + struct cpuinfo_metag *cpu_info = &per_cpu(cpu_data, cpuid); + + cpu_info->loops_per_jiffy = loops_per_jiffy; +} + +/* + * This is the secondary CPU boot entry. We're using this CPUs + * idle thread stack and the global page tables. + */ +asmlinkage void secondary_start_kernel(void) +{ + struct mm_struct *mm = &init_mm; + unsigned int cpu = smp_processor_id(); + + /* + * All kernel threads share the same mm context; grab a + * reference and switch to it. + */ + atomic_inc(&mm->mm_users); + atomic_inc(&mm->mm_count); + current->active_mm = mm; + cpumask_set_cpu(cpu, mm_cpumask(mm)); + enter_lazy_tlb(mm, current); + local_flush_tlb_all(); + + /* + * TODO: Some day it might be useful for each Linux CPU to + * have its own TBI structure. That would allow each Linux CPU + * to run different interrupt handlers for the same IRQ + * number. + * + * For now, simply copying the pointer to the boot CPU's TBI + * structure is sufficient because we always want to run the + * same interrupt handler whatever CPU takes the interrupt. + */ + per_cpu(pTBI, cpu) = __TBI(TBID_ISTAT_BIT); + + if (!per_cpu(pTBI, cpu)) + panic("No TBI found!"); + + per_cpu_trap_init(cpu); + + preempt_disable(); + + setup_txprivext(); + + /* + * Enable local interrupts. + */ + tbi_startup_interrupt(TBID_SIGNUM_TRT); + notify_cpu_starting(cpu); + local_irq_enable(); + + pr_info("CPU%u (thread %u): Booted secondary processor\n", + cpu, cpu_2_hwthread_id[cpu]); + + calibrate_delay(); + smp_store_cpu_info(cpu); + + /* + * OK, now it's safe to let the boot CPU continue + */ + set_cpu_online(cpu, true); + + /* + * Check for cache aliasing. + * Preemption is disabled + */ + check_for_cache_aliasing(cpu); + + /* + * OK, it's off to the idle thread for us + */ + cpu_idle(); +} + +void __init smp_cpus_done(unsigned int max_cpus) +{ + int cpu; + unsigned long bogosum = 0; + + for_each_online_cpu(cpu) + bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy; + + pr_info("SMP: Total of %d processors activated (%lu.%02lu BogoMIPS).\n", + num_online_cpus(), + bogosum / (500000/HZ), + (bogosum / (5000/HZ)) % 100); +} + +void __init smp_prepare_cpus(unsigned int max_cpus) +{ + unsigned int cpu = smp_processor_id(); + + init_new_context(current, &init_mm); + current_thread_info()->cpu = cpu; + + smp_store_cpu_info(cpu); + init_cpu_present(cpu_possible_mask); +} + +void __init smp_prepare_boot_cpu(void) +{ + unsigned int cpu = smp_processor_id(); + + per_cpu(pTBI, cpu) = __TBI(TBID_ISTAT_BIT); + + if (!per_cpu(pTBI, cpu)) + panic("No TBI found!"); +} + +static void smp_cross_call(cpumask_t callmap, enum ipi_msg_type msg); + +static void send_ipi_message(const struct cpumask *mask, enum ipi_msg_type msg) +{ + unsigned long flags; + unsigned int cpu; + cpumask_t map; + + cpumask_clear(&map); + local_irq_save(flags); + + for_each_cpu(cpu, mask) { + struct ipi_data *ipi = &per_cpu(ipi_data, cpu); + + spin_lock(&ipi->lock); + + /* + * KICK interrupts are queued in hardware so we'll get + * multiple interrupts if we call smp_cross_call() + * multiple times for one msg. The problem is that we + * only have one bit for each message - we can't queue + * them in software. + * + * The first time through ipi_handler() we'll clear + * the msg bit, having done all the work. But when we + * return we'll get _another_ interrupt (and another, + * and another until we've handled all the queued + * KICKs). Running ipi_handler() when there's no work + * to do is bad because that's how kick handler + * chaining detects who the KICK was intended for. + * See arch/metag/kernel/kick.c for more details. + * + * So only add 'cpu' to 'map' if we haven't already + * queued a KICK interrupt for 'msg'. + */ + if (!(ipi->bits & (1 << msg))) { + ipi->bits |= 1 << msg; + cpumask_set_cpu(cpu, &map); + } + + spin_unlock(&ipi->lock); + } + + /* + * Call the platform specific cross-CPU call function. + */ + smp_cross_call(map, msg); + + local_irq_restore(flags); +} + +void arch_send_call_function_ipi_mask(const struct cpumask *mask) +{ + send_ipi_message(mask, IPI_CALL_FUNC); +} + +void arch_send_call_function_single_ipi(int cpu) +{ + send_ipi_message(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE); +} + +void show_ipi_list(struct seq_file *p) +{ + unsigned int cpu; + + seq_puts(p, "IPI:"); + + for_each_present_cpu(cpu) + seq_printf(p, " %10lu", per_cpu(ipi_data, cpu).ipi_count); + + seq_putc(p, '\n'); +} + +static DEFINE_SPINLOCK(stop_lock); + +/* + * Main handler for inter-processor interrupts + * + * For Meta, the ipimask now only identifies a single + * category of IPI (Bit 1 IPIs have been replaced by a + * different mechanism): + * + * Bit 0 - Inter-processor function call + */ +static int do_IPI(struct pt_regs *regs) +{ + unsigned int cpu = smp_processor_id(); + struct ipi_data *ipi = &per_cpu(ipi_data, cpu); + struct pt_regs *old_regs = set_irq_regs(regs); + unsigned long msgs, nextmsg; + int handled = 0; + + ipi->ipi_count++; + + spin_lock(&ipi->lock); + msgs = ipi->bits; + nextmsg = msgs & -msgs; + ipi->bits &= ~nextmsg; + spin_unlock(&ipi->lock); + + if (nextmsg) { + handled = 1; + + nextmsg = ffz(~nextmsg); + switch (nextmsg) { + case IPI_RESCHEDULE: + scheduler_ipi(); + break; + + case IPI_CALL_FUNC: + generic_smp_call_function_interrupt(); + break; + + case IPI_CALL_FUNC_SINGLE: + generic_smp_call_function_single_interrupt(); + break; + + default: + pr_crit("CPU%u: Unknown IPI message 0x%lx\n", + cpu, nextmsg); + break; + } + } + + set_irq_regs(old_regs); + + return handled; +} + +void smp_send_reschedule(int cpu) +{ + send_ipi_message(cpumask_of(cpu), IPI_RESCHEDULE); +} + +static void stop_this_cpu(void *data) +{ + unsigned int cpu = smp_processor_id(); + + if (system_state == SYSTEM_BOOTING || + system_state == SYSTEM_RUNNING) { + spin_lock(&stop_lock); + pr_crit("CPU%u: stopping\n", cpu); + dump_stack(); + spin_unlock(&stop_lock); + } + + set_cpu_online(cpu, false); + + local_irq_disable(); + + hard_processor_halt(HALT_OK); +} + +void smp_send_stop(void) +{ + smp_call_function(stop_this_cpu, NULL, 0); +} + +/* + * not supported here + */ +int setup_profiling_timer(unsigned int multiplier) +{ + return -EINVAL; +} + +/* + * We use KICKs for inter-processor interrupts. + * + * For every CPU in "callmap" the IPI data must already have been + * stored in that CPU's "ipi_data" member prior to calling this + * function. + */ +static void kick_raise_softirq(cpumask_t callmap, unsigned int irq) +{ + int cpu; + + for_each_cpu(cpu, &callmap) { + unsigned int thread; + + thread = cpu_2_hwthread_id[cpu]; + + BUG_ON(thread == BAD_HWTHREAD_ID); + + metag_out32(1, T0KICKI + (thread * TnXKICK_STRIDE)); + } +} + +static TBIRES ipi_handler(TBIRES State, int SigNum, int Triggers, + int Inst, PTBI pTBI, int *handled) +{ + *handled = do_IPI((struct pt_regs *)State.Sig.pCtx); + + return State; +} + +static struct kick_irq_handler ipi_irq = { + .func = ipi_handler, +}; + +static void smp_cross_call(cpumask_t callmap, enum ipi_msg_type msg) +{ + kick_raise_softirq(callmap, 1); +} + +static inline unsigned int get_core_count(void) +{ + int i; + unsigned int ret = 0; + + for (i = 0; i < CONFIG_NR_CPUS; i++) { + if (core_reg_read(TXUCT_ID, TXENABLE_REGNUM, i)) + ret++; + } + + return ret; +} + +/* + * Initialise the CPU possible map early - this describes the CPUs + * which may be present or become present in the system. + */ +void __init smp_init_cpus(void) +{ + unsigned int i, ncores = get_core_count(); + + /* If no hwthread_map early param was set use default mapping */ + for (i = 0; i < NR_CPUS; i++) + if (cpu_2_hwthread_id[i] == BAD_HWTHREAD_ID) { + cpu_2_hwthread_id[i] = i; + hwthread_id_2_cpu[i] = i; + } + + for (i = 0; i < ncores; i++) + set_cpu_possible(i, true); + + kick_register_func(&ipi_irq); +} |