/*
* SMP support for BPA machines.
*
* Dave Engebretsen, Peter Bergner, and
* Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
*
* Plus various changes from other IBM teams...
*
* 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; either version
* 2 of the License, or (at your option) any later version.
*/
#undef DEBUG
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/cache.h>
#include <linux/err.h>
#include <linux/sysdev.h>
#include <linux/cpu.h>
#include <asm/ptrace.h>
#include <asm/atomic.h>
#include <asm/irq.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/smp.h>
#include <asm/paca.h>
#include <asm/time.h>
#include <asm/machdep.h>
#include <asm/cputable.h>
#include <asm/firmware.h>
#include <asm/system.h>
#include <asm/rtas.h>
#include "interrupt.h"
#ifdef DEBUG
#define DBG(fmt...) udbg_printf(fmt)
#else
#define DBG(fmt...)
#endif
/*
* The primary thread of each non-boot processor is recorded here before
* smp init.
*/
static cpumask_t of_spin_map;
extern void generic_secondary_smp_init(unsigned long);
/**
* smp_startup_cpu() - start the given cpu
*
* At boot time, there is nothing to do for primary threads which were
* started from Open Firmware. For anything else, call RTAS with the
* appropriate start location.
*
* Returns:
* 0 - failure
* 1 - success
*/
static inline int __devinit smp_startup_cpu(unsigned int lcpu)
{
int status;
unsigned long start_here = __pa((u32)*((unsigned long *)
generic_secondary_smp_init));
unsigned int pcpu;
int start_cpu;
if (cpu_isset(lcpu, of_spin_map))
/* Already started by OF and sitting in spin loop */
return 1;
pcpu = get_hard_smp_processor_id(lcpu);
/* Fixup atomic count: it exited inside IRQ handler. */
task_thread_info(paca[lcpu].__current)->preempt_count = 0;
/*
* If the RTAS start-cpu token does not exist then presume the
* cpu is already spinning.
*/
start_cpu = rtas_token("start-cpu");
if (start_cpu == RTAS_UNKNOWN_SERVICE)
return 1;
status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, lcpu);
if (status != 0) {
printk(KERN_ERR "start-cpu failed: %i\n", status);
return 0;
}
return 1;
}
static void smp_iic_message_pass(int target, int msg)
{
unsigned int i;
if (target < NR_CPUS) {
iic_cause_IPI(target, msg);
} else {
for_each_online_cpu(i) {
if (target == MSG_ALL_BUT_SELF
&& i == smp_processor_id())
continue;
iic_cause_IPI(i, msg);
}
}
}
static int __init smp_iic_probe(void)
{
iic_request_IPIs();
return cpus_weight(cpu_possible_map);
}
static void __devinit smp_iic_setup_cpu(int cpu)
{
if (cpu != boot_cpuid)
iic_setup_cpu();
}
static DEFINE_SPINLOCK(timebase_lock);
static unsigned long timebase = 0;
static void __devinit cell_give_timebase(void)
{
spin_lock(&timebase_lock);
rtas_call(rtas_token("freeze-time-base"), 0, 1, NULL);
timebase = get_tb();
spin_unlock(&timebase_lock);
while (timebase)
barrier();
rtas_call(rtas_token("thaw-time-base"), 0, 1, NULL);
}
static void __devinit cell_take_timebase(void)
{
while (!timebase)
barrier();
spin_lock(&timebase_lock);
set_tb(timebase >> 32, timebase & 0xffffffff);
timebase = 0;
spin_unlock(&timebase_lock);
}
static void __devinit smp_cell_kick_cpu(int nr)
{
BUG_ON(nr < 0 || nr >= NR_CPUS);
if (!smp_startup_cpu(nr))
return;
/*
* The processor is currently spinning, waiting for the
* cpu_start field to become non-zero After we set cpu_start,
* the processor will continue on to secondary_start
*/
paca[nr].cpu_start = 1;
}
static int smp_cell_cpu_bootable(unsigned int nr)
{
/* Special case - we inhibit secondary thread startup
* during boot if the user requests it. Odd-numbered
* cpus are assumed to be secondary threads.
*/
if (system_state < SYSTEM_RUNNING &&
cpu_has_feature(CPU_FTR_SMT) &&
!smt_enabled_at_boot && nr % 2 != 0)
return 0;
return 1;
}
static struct smp_ops_t bpa_iic_smp_ops = {
.message_pass = smp_iic_message_pass,
.probe = smp_iic_probe,
.kick_cpu = smp_cell_kick_cpu,
.setup_cpu = smp_iic_setup_cpu,
.cpu_bootable = smp_cell_cpu_bootable,
};
/* This is called very early */
void __init smp_init_cell(void)
{
int i;
DBG(" -> smp_init_cell()\n");
smp_ops = &bpa_iic_smp_ops;
/* Mark threads which are still spinning in hold loops. */
if (cpu_has_feature(CPU_FTR_SMT)) {
for_each_present_cpu(i) {
if (i % 2 == 0)
/*
* Even-numbered logical cpus correspond to
* primary threads.
*/
cpu_set(i, of_spin_map);
}
} else {
of_spin_map = cpu_present_map;
}
cpu_clear(boot_cpuid, of_spin_map);
/* Non-lpar has additional take/give timebase */
if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
smp_ops->give_timebase = cell_give_timebase;
smp_ops->take_timebase = cell_take_timebase;
}
DBG(" <- smp_init_cell()\n");
}
