/*
* 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/spinlock.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/profile.h>
#include <linux/mm.h>
#include <linux/cpu.h>
#include <linux/irq.h>
#include <linux/atomic.h>
#include <linux/cpumask.h>
#include <linux/reboot.h>
#include <asm/processor.h>
#include <asm/setup.h>
#include <asm/mach_desc.h>
#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 __weak 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 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 int __do_IPI(unsigned long msg)
{
int rc = 0;
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:
rc = 1;
}
return rc;
}
/*
* 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;
unsigned long __maybe_unused copy;
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)
*/
copy = pending = xchg(this_cpu_ptr(&ipi_data), 0);
do {
unsigned long msg = __ffs(pending);
int rc;
rc = __do_IPI(msg);
#ifdef CONFIG_ARC_IPI_DBG
/* IPI received but no valid @msg */
if (rc)
pr_info("IPI with bogus msg %ld in %ld\n", msg, copy);
#endif
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;
}
