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smp.cc
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smp.cc
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/* Copyright (C) 2015 Goswin von Brederlow <[email protected]>
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 3 of the License, or
(at your option) any later version.
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, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/*
* SMP support for the Raspberry Pi
*/
#include <stdint.h>
#include "smp.h"
#include "stdio.h"
#include "mmu.h"
#include "fpu.h"
namespace SMP {
// Setup SMP (Boot Offset = $4000008C + ($10 * Core), Core = 1..3)
enum {
CORE_BASE = 0x4000008C,
Core0Boot = 0x00, // Core 0 Boot Offset
Core1Boot = 0x10, // Core 1 Boot Offset
Core2Boot = 0x20, // Core 2 Boot Offset
Core3Boot = 0x30, // Core 3 Boot Offset
};
typedef void (*fn)(void);
constexpr volatile fn * mailbox(int core) {
return (volatile fn *)(CORE_BASE + core * 0x10);
}
// Multiprocessor Affinity Register (MPIDR)
uint32_t get_mpidr(void) {
uint32_t mpidr;
asm volatile ("mrc p15,0,%0,c0,c0,5" : "=r" (mpidr));
return mpidr;
}
extern "C" {
void core_wakeup(void);
void core_main(void);
}
static start_fn_t start_fn;
void *start_arg;
volatile bool started;
void core_main(void) {
puts("core is up: MPIDR = ");
put_uint32(get_mpidr());
putc('\n');
MMU::init();
puts("core is virtual\n");
FPU::init();
puts("core is floating\n");
start_fn_t temp_fn = start_fn;
void *temp_arg = start_arg;
started = true;
temp_fn(temp_arg);
// FIXME: make restartable?
while(true) { }
}
void start_core(int core, start_fn_t start, void *arg) {
start_fn = start;
start_arg = arg;
puts("starting core ");
putc("0123"[core]);
putc('\n');
started = false;
*mailbox(core) = core_wakeup;
while(!started) { }
puts("started core ");
putc("0123"[core]);
putc('\n');
}
}