arch/arc/kernel/smp.c - linux - Git at Google

 /*
  * 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 <linux/module.h>
 #include <linux/init.h>
 #include <linux/spinlock.h>
 #include <linux/sched.h>
 #include <linux/interrupt.h>
 #include <linux/profile.h>
 #include <linux/errno.h>
 #include <linux/err.h>
 #include <linux/mm.h>
 #include <linux/cpu.h>
 #include <linux/smp.h>
 #include <linux/irq.h>
 #include <linux/delay.h>
 #include <linux/atomic.h>
 #include <linux/percpu.h>
 #include <linux/cpumask.h>
 #include <linux/spinlock_types.h>
 #include <linux/reboot.h>
 #include <asm/processor.h>
 #include <asm/setup.h>
 #include <asm/mach_desc.h>

 arch_spinlock_t smp_atomic_ops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
 arch_spinlock_t smp_bitops_lock = __ARCH_SPIN_LOCK_UNLOCKED;

 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 __attribute__((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;

 	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(smp_processor_id());

 	arc_local_timer_setup(cpu);

 	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                           */
 /*****************************************************************************/

 /*
  * structures for inter-processor calls
  * A Collection of single bit ipi messages
  *
  */

 /*
  * TODO_rajesh investigate tlb message types.
  * IPI Timer not needed because each ARC has an individual Interrupting Timer
  */
 enum ipi_msg_type {
 	IPI_NOP = 0,
 	IPI_RESCHEDULE = 1,
 	IPI_CALL_FUNC,
 	IPI_CALL_FUNC_SINGLE,
 	IPI_CPU_STOP
 };

 struct ipi_data {
 	unsigned long bits;
 };

 static DEFINE_PER_CPU(struct ipi_data, ipi_data);

 static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
 {
 	unsigned long flags;
 	unsigned int cpu;

 	local_irq_save(flags);

 	for_each_cpu(cpu, callmap) {
 		struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
 		set_bit(msg, &ipi->bits);
 	}

 	/* Call the platform specific cross-CPU call function  */
 	if (plat_smp_ops.ipi_send)
 		plat_smp_ops.ipi_send((void *)callmap);

 	local_irq_restore(flags);
 }

 void smp_send_reschedule(int cpu)
 {
 	ipi_send_msg(cpumask_of(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(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
 }

 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(unsigned int cpu)
 {
 	machine_halt();
 }

 static inline void __do_IPI(unsigned long *ops, struct ipi_data *ipi, int cpu)
 {
 	unsigned long msg = 0;

 	do {
 		msg = find_next_bit(ops, BITS_PER_LONG, msg+1);

 		switch (msg) {
 		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;

 		case IPI_CPU_STOP:
 			ipi_cpu_stop(cpu);
 			break;
 		}
 	} while (msg < BITS_PER_LONG);

 }

 /*
  * arch-common ISR to handle for inter-processor interrupts
  * Has hooks for platform specific IPI
  */
 irqreturn_t do_IPI(int irq, void *dev_id)
 {
 	int cpu = smp_processor_id();
 	struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
 	unsigned long ops;

 	if (plat_smp_ops.ipi_clear)
 		plat_smp_ops.ipi_clear(cpu, irq);

 	/*
 	 * XXX: is this loop really needed
 	 * And do we need to move ipi_clean inside
 	 */
 	while ((ops = xchg(&ipi->bits, 0)) != 0)
 		__do_IPI(&ops, ipi, cpu);

 	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_id = &per_cpu(ipi_dev, smp_processor_id());
 	return request_percpu_irq(irq, do_IPI, "IPI Interrupt", dev_id);
 }
	/*
	* 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 <linux/module.h>
	#include <linux/init.h>
	#include <linux/spinlock.h>
	#include <linux/sched.h>
	#include <linux/interrupt.h>
	#include <linux/profile.h>
	#include <linux/errno.h>
	#include <linux/err.h>
	#include <linux/mm.h>
	#include <linux/cpu.h>
	#include <linux/smp.h>
	#include <linux/irq.h>
	#include <linux/delay.h>
	#include <linux/atomic.h>
	#include <linux/percpu.h>
	#include <linux/cpumask.h>
	#include <linux/spinlock_types.h>
	#include <linux/reboot.h>
	#include <asm/processor.h>
	#include <asm/setup.h>
	#include <asm/mach_desc.h>

	arch_spinlock_t smp_atomic_ops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
	arch_spinlock_t smp_bitops_lock = __ARCH_SPIN_LOCK_UNLOCKED;

	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 __attribute__((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;

	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(smp_processor_id());

	arc_local_timer_setup(cpu);

	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 */
	/*****************************************************************************/

	/*
	* structures for inter-processor calls
	* A Collection of single bit ipi messages
	*
	*/

	/*
	* TODO_rajesh investigate tlb message types.
	* IPI Timer not needed because each ARC has an individual Interrupting Timer
	*/
	enum ipi_msg_type {
	IPI_NOP = 0,
	IPI_RESCHEDULE = 1,
	IPI_CALL_FUNC,
	IPI_CALL_FUNC_SINGLE,
	IPI_CPU_STOP
	};

	struct ipi_data {
	unsigned long bits;
	};

	static DEFINE_PER_CPU(struct ipi_data, ipi_data);

	static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
	{
	unsigned long flags;
	unsigned int cpu;

	local_irq_save(flags);

	for_each_cpu(cpu, callmap) {
	struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
	set_bit(msg, &ipi->bits);
	}

	/* Call the platform specific cross-CPU call function */
	if (plat_smp_ops.ipi_send)
	plat_smp_ops.ipi_send((void *)callmap);

	local_irq_restore(flags);
	}

	void smp_send_reschedule(int cpu)
	{
	ipi_send_msg(cpumask_of(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(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
	}

	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(unsigned int cpu)
	{
	machine_halt();
	}

	static inline void __do_IPI(unsigned long ops, struct ipi_data ipi, int cpu)
	{
	unsigned long msg = 0;

	do {
	msg = find_next_bit(ops, BITS_PER_LONG, msg+1);

	switch (msg) {
	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;

	case IPI_CPU_STOP:
	ipi_cpu_stop(cpu);
	break;
	}
	} while (msg < BITS_PER_LONG);

	}

	/*
	* arch-common ISR to handle for inter-processor interrupts
	* Has hooks for platform specific IPI
	*/
	irqreturn_t do_IPI(int irq, void *dev_id)
	{
	int cpu = smp_processor_id();
	struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
	unsigned long ops;

	if (plat_smp_ops.ipi_clear)
	plat_smp_ops.ipi_clear(cpu, irq);

	/*
	* XXX: is this loop really needed
	* And do we need to move ipi_clean inside
	*/
	while ((ops = xchg(&ipi->bits, 0)) != 0)
	__do_IPI(&ops, ipi, cpu);

	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_id = &per_cpu(ipi_dev, smp_processor_id());
	return request_percpu_irq(irq, do_IPI, "IPI Interrupt", dev_id);
	}