From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- arch/arc/kernel/smp.c | 342 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 342 insertions(+) create mode 100644 arch/arc/kernel/smp.c (limited to 'arch/arc/kernel/smp.c') diff --git a/arch/arc/kernel/smp.c b/arch/arc/kernel/smp.c new file mode 100644 index 000000000..6a400b1b0 --- /dev/null +++ b/arch/arc/kernel/smp.c @@ -0,0 +1,342 @@ +/* + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + * + * 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. + * + * RajeshwarR: Dec 11, 2007 + * -- Added support for Inter Processor Interrupts + * + * Vineetg: Nov 1st, 2007 + * -- Initial Write (Borrowed heavily from ARM) + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#ifndef CONFIG_ARC_HAS_LLSC +arch_spinlock_t smp_atomic_ops_lock = __ARCH_SPIN_LOCK_UNLOCKED; +arch_spinlock_t smp_bitops_lock = __ARCH_SPIN_LOCK_UNLOCKED; +#endif + +struct plat_smp_ops plat_smp_ops; + +/* XXX: per cpu ? Only needed once in early seconday boot */ +struct task_struct *secondary_idle_tsk; + +/* Called from start_kernel */ +void __init smp_prepare_boot_cpu(void) +{ +} + +/* + * 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; + + for (i = 0; i < NR_CPUS; i++) + set_cpu_possible(i, true); +} + +/* called from init ( ) => process 1 */ +void __init smp_prepare_cpus(unsigned int max_cpus) +{ + int i; + + /* + * Initialise the present map, which describes the set of CPUs + * actually populated at the present time. + */ + for (i = 0; i < max_cpus; i++) + set_cpu_present(i, true); +} + +void __init smp_cpus_done(unsigned int max_cpus) +{ + +} + +/* + * After power-up, a non Master CPU needs to wait for Master to kick start it + * + * The default implementation halts + * + * This relies on platform specific support allowing Master to directly set + * this CPU's PC (to be @first_lines_of_secondary() and kick start it. + * + * In lack of such h/w assist, platforms can override this function + * - make this function busy-spin on a token, eventually set by Master + * (from arc_platform_smp_wakeup_cpu()) + * - Once token is available, jump to @first_lines_of_secondary + * (using inline asm). + * + * Alert: can NOT use stack here as it has not been determined/setup for CPU. + * If it turns out to be elaborate, it's better to code it in assembly + * + */ +void __weak arc_platform_smp_wait_to_boot(int cpu) +{ + /* + * As a hack for debugging - since debugger will single-step over the + * FLAG insn - wrap the halt itself it in a self loop + */ + __asm__ __volatile__( + "1: \n" + " flag 1 \n" + " b 1b \n"); +} + +const char *arc_platform_smp_cpuinfo(void) +{ + return plat_smp_ops.info ? : ""; +} + +/* + * The very first "C" code executed by secondary + * Called from asm stub in head.S + * "current"/R25 already setup by low level boot code + */ +void start_kernel_secondary(void) +{ + struct mm_struct *mm = &init_mm; + unsigned int cpu = smp_processor_id(); + + /* MMU, Caches, Vector Table, Interrupts etc */ + setup_processor(); + + atomic_inc(&mm->mm_users); + atomic_inc(&mm->mm_count); + current->active_mm = mm; + cpumask_set_cpu(cpu, mm_cpumask(mm)); + + notify_cpu_starting(cpu); + set_cpu_online(cpu, true); + + pr_info("## CPU%u LIVE ##: Executing Code...\n", cpu); + + if (machine_desc->init_smp) + machine_desc->init_smp(cpu); + + arc_local_timer_setup(); + + local_irq_enable(); + preempt_disable(); + cpu_startup_entry(CPUHP_ONLINE); +} + +/* + * Called from kernel_init( ) -> smp_init( ) - for each CPU + * + * At this point, Secondary Processor is "HALT"ed: + * -It booted, but was halted in head.S + * -It was configured to halt-on-reset + * So need to wake it up. + * + * Essential requirements being where to run from (PC) and stack (SP) +*/ +int __cpu_up(unsigned int cpu, struct task_struct *idle) +{ + unsigned long wait_till; + + secondary_idle_tsk = idle; + + pr_info("Idle Task [%d] %p", cpu, idle); + pr_info("Trying to bring up CPU%u ...\n", cpu); + + if (plat_smp_ops.cpu_kick) + plat_smp_ops.cpu_kick(cpu, + (unsigned long)first_lines_of_secondary); + + /* wait for 1 sec after kicking the secondary */ + wait_till = jiffies + HZ; + while (time_before(jiffies, wait_till)) { + if (cpu_online(cpu)) + break; + } + + if (!cpu_online(cpu)) { + pr_info("Timeout: CPU%u FAILED to comeup !!!\n", cpu); + return -1; + } + + secondary_idle_tsk = NULL; + + return 0; +} + +/* + * not supported here + */ +int __init setup_profiling_timer(unsigned int multiplier) +{ + return -EINVAL; +} + +/*****************************************************************************/ +/* Inter Processor Interrupt Handling */ +/*****************************************************************************/ + +enum ipi_msg_type { + IPI_EMPTY = 0, + IPI_RESCHEDULE = 1, + IPI_CALL_FUNC, + IPI_CPU_STOP, +}; + +/* + * In arches with IRQ for each msg type (above), receiver can use IRQ-id to + * figure out what msg was sent. For those which don't (ARC has dedicated IPI + * IRQ), the msg-type needs to be conveyed via per-cpu data + */ + +static DEFINE_PER_CPU(unsigned long, ipi_data); + +static void ipi_send_msg_one(int cpu, enum ipi_msg_type msg) +{ + unsigned long __percpu *ipi_data_ptr = per_cpu_ptr(&ipi_data, cpu); + unsigned long old, new; + unsigned long flags; + + pr_debug("%d Sending msg [%d] to %d\n", smp_processor_id(), msg, cpu); + + local_irq_save(flags); + + /* + * Atomically write new msg bit (in case others are writing too), + * and read back old value + */ + do { + new = old = ACCESS_ONCE(*ipi_data_ptr); + new |= 1U << msg; + } while (cmpxchg(ipi_data_ptr, old, new) != old); + + /* + * Call the platform specific IPI kick function, but avoid if possible: + * Only do so if there's no pending msg from other concurrent sender(s). + * Otherwise, recevier will see this msg as well when it takes the + * IPI corresponding to that msg. This is true, even if it is already in + * IPI handler, because !@old means it has not yet dequeued the msg(s) + * so @new msg can be a free-loader + */ + if (plat_smp_ops.ipi_send && !old) + plat_smp_ops.ipi_send(cpu); + + local_irq_restore(flags); +} + +static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg) +{ + unsigned int cpu; + + for_each_cpu(cpu, callmap) + ipi_send_msg_one(cpu, msg); +} + +void smp_send_reschedule(int cpu) +{ + ipi_send_msg_one(cpu, IPI_RESCHEDULE); +} + +void smp_send_stop(void) +{ + struct cpumask targets; + cpumask_copy(&targets, cpu_online_mask); + cpumask_clear_cpu(smp_processor_id(), &targets); + ipi_send_msg(&targets, IPI_CPU_STOP); +} + +void arch_send_call_function_single_ipi(int cpu) +{ + ipi_send_msg_one(cpu, IPI_CALL_FUNC); +} + +void arch_send_call_function_ipi_mask(const struct cpumask *mask) +{ + ipi_send_msg(mask, IPI_CALL_FUNC); +} + +/* + * ipi_cpu_stop - handle IPI from smp_send_stop() + */ +static void ipi_cpu_stop(void) +{ + machine_halt(); +} + +static inline void __do_IPI(unsigned long msg) +{ + switch (msg) { + case IPI_RESCHEDULE: + scheduler_ipi(); + break; + + case IPI_CALL_FUNC: + generic_smp_call_function_interrupt(); + break; + + case IPI_CPU_STOP: + ipi_cpu_stop(); + break; + + default: + pr_warn("IPI with unexpected msg %ld\n", msg); + } +} + +/* + * arch-common ISR to handle for inter-processor interrupts + * Has hooks for platform specific IPI + */ +irqreturn_t do_IPI(int irq, void *dev_id) +{ + unsigned long pending; + + pr_debug("IPI [%ld] received on cpu %d\n", + *this_cpu_ptr(&ipi_data), smp_processor_id()); + + if (plat_smp_ops.ipi_clear) + plat_smp_ops.ipi_clear(irq); + + /* + * "dequeue" the msg corresponding to this IPI (and possibly other + * piggybacked msg from elided IPIs: see ipi_send_msg_one() above) + */ + pending = xchg(this_cpu_ptr(&ipi_data), 0); + + do { + unsigned long msg = __ffs(pending); + __do_IPI(msg); + pending &= ~(1U << msg); + } while (pending); + + return IRQ_HANDLED; +} + +/* + * API called by platform code to hookup arch-common ISR to their IPI IRQ + */ +static DEFINE_PER_CPU(int, ipi_dev); + +int smp_ipi_irq_setup(int cpu, int irq) +{ + int *dev = per_cpu_ptr(&ipi_dev, cpu); + + arc_request_percpu_irq(irq, cpu, do_IPI, "IPI Interrupt", dev); + + return 0; +} -- cgit v1.2.3-54-g00ecf