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/*
* SMP initialisation and IPI support
* Based on arch/arm64/kernel/smp.c
*
* Copyright (C) 2012 ARM Ltd.
* Copyright (C) 2015 Regents of the University of California
* Copyright (C) 2017 SiFive
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/interrupt.h>
#include <linux/smp.h>
#include <linux/sched.h>
#include <asm/sbi.h>
#include <asm/tlbflush.h>
#include <asm/cacheflush.h>
/* A collection of single bit ipi messages. */
static struct {
unsigned long bits ____cacheline_aligned;
} ipi_data[NR_CPUS] __cacheline_aligned;
enum ipi_message_type {
IPI_RESCHEDULE,
IPI_CALL_FUNC,
IPI_MAX
};
irqreturn_t handle_ipi(void)
{
unsigned long *pending_ipis = &ipi_data[smp_processor_id()].bits;
/* Clear pending IPI */
csr_clear(sip, SIE_SSIE);
while (true) {
unsigned long ops;
/* Order bit clearing and data access. */
mb();
ops = xchg(pending_ipis, 0);
if (ops == 0)
return IRQ_HANDLED;
if (ops & (1 << IPI_RESCHEDULE))
scheduler_ipi();
if (ops & (1 << IPI_CALL_FUNC))
generic_smp_call_function_interrupt();
BUG_ON((ops >> IPI_MAX) != 0);
/* Order data access and bit testing. */
mb();
}
return IRQ_HANDLED;
}
static void
send_ipi_message(const struct cpumask *to_whom, enum ipi_message_type operation)
{
int i;
mb();
for_each_cpu(i, to_whom)
set_bit(operation, &ipi_data[i].bits);
mb();
sbi_send_ipi(cpumask_bits(to_whom));
}
void arch_send_call_function_ipi_mask(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);
}
static void ipi_stop(void *unused)
{
while (1)
wait_for_interrupt();
}
void smp_send_stop(void)
{
on_each_cpu(ipi_stop, NULL, 1);
}
void smp_send_reschedule(int cpu)
{
send_ipi_message(cpumask_of(cpu), IPI_RESCHEDULE);
}
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