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/*
* Copyright 2010 Tilera Corporation. 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
* as published by the Free Software Foundation, version 2.
*
* 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, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*
* TILE SMP support routines.
*/
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <asm/cacheflush.h>
HV_Topology smp_topology __write_once;
EXPORT_SYMBOL(smp_topology);
#if CHIP_HAS_IPI()
static unsigned long __iomem *ipi_mappings[NR_CPUS];
#endif
/*
* Top-level send_IPI*() functions to send messages to other cpus.
*/
/* Set by smp_send_stop() to avoid recursive panics. */
static int stopping_cpus;
static void __send_IPI_many(HV_Recipient *recip, int nrecip, int tag)
{
int sent = 0;
while (sent < nrecip) {
int rc = hv_send_message(recip, nrecip,
(HV_VirtAddr)&tag, sizeof(tag));
if (rc < 0) {
if (!stopping_cpus) /* avoid recursive panic */
panic("hv_send_message returned %d", rc);
break;
}
WARN_ONCE(rc == 0, "hv_send_message() returned zero\n");
sent += rc;
}
}
void send_IPI_single(int cpu, int tag)
{
HV_Recipient recip = {
.y = cpu / smp_width,
.x = cpu % smp_width,
.state = HV_TO_BE_SENT
};
__send_IPI_many(&recip, 1, tag);
}
void send_IPI_many(const struct cpumask *mask, int tag)
{
HV_Recipient recip[NR_CPUS];
int cpu;
int nrecip = 0;
int my_cpu = smp_processor_id();
for_each_cpu(cpu, mask) {
HV_Recipient *r;
BUG_ON(cpu == my_cpu);
r = &recip[nrecip++];
r->y = cpu / smp_width;
r->x = cpu % smp_width;
r->state = HV_TO_BE_SENT;
}
__send_IPI_many(recip, nrecip, tag);
}
void send_IPI_allbutself(int tag)
{
struct cpumask mask;
cpumask_copy(&mask, cpu_online_mask);
cpumask_clear_cpu(smp_processor_id(), &mask);
send_IPI_many(&mask, tag);
}
/*
* Functions related to starting/stopping cpus.
*/
/* Handler to start the current cpu. */
static void smp_start_cpu_interrupt(void)
{
get_irq_regs()->pc = start_cpu_function_addr;
}
/* Handler to stop the current cpu. */
static void smp_stop_cpu_interrupt(void)
{
arch_local_irq_disable_all();
set_cpu_online(smp_processor_id(), 0);
for (;;)
asm("nap; nop");
}
/* This function calls the 'stop' function on all other CPUs in the system. */
void smp_send_stop(void)
{
stopping_cpus = 1;
send_IPI_allbutself(MSG_TAG_STOP_CPU);
}
/* On panic, just wait; we may get an smp_send_stop() later on. */
void panic_smp_self_stop(void)
{
while (1)
asm("nap; nop");
}
/*
* Dispatch code called from hv_message_intr() for HV_MSG_TILE hv messages.
*/
void evaluate_message(int tag)
{
switch (tag) {
case MSG_TAG_START_CPU: /* Start up a cpu */
smp_start_cpu_interrupt();
break;
case MSG_TAG_STOP_CPU: /* Sent to shut down slave CPU's */
smp_stop_cpu_interrupt();
break;
case MSG_TAG_CALL_FUNCTION_MANY: /* Call function on cpumask */
generic_smp_call_function_interrupt();
break;
case MSG_TAG_CALL_FUNCTION_SINGLE: /* Call function on one other CPU */
generic_smp_call_function_single_interrupt();
break;
default:
panic("Unknown IPI message tag %d", tag);
break;
}
}
/*
* flush_icache_range() code uses smp_call_function().
*/
struct ipi_flush {
unsigned long start;
unsigned long end;
};
static void ipi_flush_icache_range(void *info)
{
struct ipi_flush *flush = (struct ipi_flush *) info;
__flush_icache_range(flush->start, flush->end);
}
void flush_icache_range(unsigned long start, unsigned long end)
{
struct ipi_flush flush = { start, end };
preempt_disable();
on_each_cpu(ipi_flush_icache_range, &flush, 1);
preempt_enable();
}
/* Called when smp_send_reschedule() triggers IRQ_RESCHEDULE. */
static irqreturn_t handle_reschedule_ipi(int irq, void *token)
{
__get_cpu_var(irq_stat).irq_resched_count++;
scheduler_ipi();
return IRQ_HANDLED;
}
static struct irqaction resched_action = {
.handler = handle_reschedule_ipi,
.name = "resched",
.dev_id = handle_reschedule_ipi /* unique token */,
};
void __init ipi_init(void)
{
#if CHIP_HAS_IPI()
int cpu;
/* Map IPI trigger MMIO addresses. */
for_each_possible_cpu(cpu) {
HV_Coord tile;
HV_PTE pte;
unsigned long offset;
tile.x = cpu_x(cpu);
tile.y = cpu_y(cpu);
if (hv_get_ipi_pte(tile, KERNEL_PL, &pte) != 0)
panic("Failed to initialize IPI for cpu %d\n", cpu);
offset = PFN_PHYS(pte_pfn(pte));
ipi_mappings[cpu] = ioremap_prot(offset, PAGE_SIZE, pte);
}
#endif
/* Bind handle_reschedule_ipi() to IRQ_RESCHEDULE. */
tile_irq_activate(IRQ_RESCHEDULE, TILE_IRQ_PERCPU);
BUG_ON(setup_irq(IRQ_RESCHEDULE, &resched_action));
}
#if CHIP_HAS_IPI()
void smp_send_reschedule(int cpu)
{
WARN_ON(cpu_is_offline(cpu));
/*
* We just want to do an MMIO store. The traditional writeq()
* functions aren't really correct here, since they're always
* directed at the PCI shim. For now, just do a raw store,
* casting away the __iomem attribute.
*/
((unsigned long __force *)ipi_mappings[cpu])[IRQ_RESCHEDULE] = 0;
}
#else
void smp_send_reschedule(int cpu)
{
HV_Coord coord;
WARN_ON(cpu_is_offline(cpu));
coord.y = cpu_y(cpu);
coord.x = cpu_x(cpu);
hv_trigger_ipi(coord, IRQ_RESCHEDULE);
}
#endif /* CHIP_HAS_IPI() */
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