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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* 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...
*/
#undef DEBUG
#include <linux/kernel.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/device.h>
#include <linux/cpu.h>
#include <asm/ptrace.h>
#include <linux/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/machdep.h>
#include <asm/cputable.h>
#include <asm/firmware.h>
#include <asm/rtas.h>
#include <asm/cputhreads.h>
#include <asm/code-patching.h>
#include "interrupt.h"
#include <asm/udbg.h>
#ifdef DEBUG
#define DBG(fmt...) udbg_printf(fmt)
#else
#define DBG(fmt...)
#endif
/*
* The Primary thread of each non-boot processor was started from the OF client
* interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
*/
static cpumask_t of_spin_map;
/**
* 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 smp_startup_cpu(unsigned int lcpu)
{
int status;
unsigned long start_here =
__pa(ppc_function_entry(generic_secondary_smp_init));
unsigned int pcpu;
int start_cpu;
if (cpumask_test_cpu(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_ptrs[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_cell_setup_cpu(int cpu)
{
if (cpu != boot_cpuid)
iic_setup_cpu();
/*
* change default DABRX to allow user watchpoints
*/
mtspr(SPRN_DABRX, DABRX_KERNEL | DABRX_USER);
}
static int smp_cell_kick_cpu(int nr)
{
if (nr < 0 || nr >= nr_cpu_ids)
return -EINVAL;
if (!smp_startup_cpu(nr))
return -ENOENT;
/*
* 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_ptrs[nr]->cpu_start = 1;
return 0;
}
static struct smp_ops_t bpa_iic_smp_ops = {
.message_pass = iic_message_pass,
.probe = iic_request_IPIs,
.kick_cpu = smp_cell_kick_cpu,
.setup_cpu = smp_cell_setup_cpu,
.cpu_bootable = smp_generic_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 (cpu_thread_in_core(i) == 0)
cpumask_set_cpu(i, &of_spin_map);
}
} else
cpumask_copy(&of_spin_map, cpu_present_mask);
cpumask_clear_cpu(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 = rtas_give_timebase;
smp_ops->take_timebase = rtas_take_timebase;
}
DBG(" <- smp_init_cell()\n");
}
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