blob: 7f0c7aaaec15084d30586d423e932a3ea0858a92 [file] [log] [blame]
// CPU count detection
//
// Copyright (C) 2008 Kevin O'Connor <kevin@koconnor.net>
// Copyright (C) 2006 Fabrice Bellard
//
// This file may be distributed under the terms of the GNU GPLv3 license.
#include "util.h" // dprintf
#include "config.h" // CONFIG_*
#define CPUID_APIC (1 << 9)
#define APIC_ICR_LOW ((u8*)BUILD_APIC_ADDR + 0x300)
#define APIC_SVR ((u8*)BUILD_APIC_ADDR + 0x0F0)
#define APIC_ENABLED 0x0100
static inline void writel(void *addr, u32 val)
{
*(volatile u32 *)addr = val;
}
static inline void writew(void *addr, u16 val)
{
*(volatile u16 *)addr = val;
}
static inline void writeb(void *addr, u8 val)
{
*(volatile u8 *)addr = val;
}
static inline u32 readl(const void *addr)
{
return *(volatile const u32 *)addr;
}
static inline u16 readw(const void *addr)
{
return *(volatile const u16 *)addr;
}
static inline u8 readb(const void *addr)
{
return *(volatile const u8 *)addr;
}
extern void smp_ap_boot_code();
extern u32 smp_cpus;
#if MODE16
u32 smp_cpus VISIBLE16;
asm(
" .global smp_ap_boot_code\n"
"smp_ap_boot_code:\n"
// Increment the cpu counter
" movw $" __stringify(SEG_BIOS) ", %ax\n"
" movw %ax, %ds\n"
" lock incl smp_cpus\n"
// Halt the processor.
" jmp permanent_halt\n"
);
#endif
/* find the number of CPUs by launching a SIPI to them */
int
smp_probe(void)
{
if (smp_cpus)
return smp_cpus;
u32 eax, ebx, ecx, cpuid_features;
cpuid(1, &eax, &ebx, &ecx, &cpuid_features);
if (! (cpuid_features & CPUID_APIC)) {
// No apic - only the main cpu is present.
smp_cpus = 1;
return 1;
}
// Init the counter.
writel(&smp_cpus, 1);
// Setup jump trampoline to counter code.
u64 old = *(u64*)BUILD_AP_BOOT_ADDR;
// ljmpw $SEG_BIOS, $(smp_ap_boot_code - BUILD_BIOS_ADDR)
u64 new = (0xea | ((u64)SEG_BIOS<<24)
| (((u32)smp_ap_boot_code - BUILD_BIOS_ADDR) << 8));
*(u64*)BUILD_AP_BOOT_ADDR = new;
// enable local APIC
u32 val = readl(APIC_SVR);
writel(APIC_SVR, val | APIC_ENABLED);
// broadcast SIPI
writel(APIC_ICR_LOW, 0x000C4500);
u32 sipi_vector = BUILD_AP_BOOT_ADDR >> 12;
writel(APIC_ICR_LOW, 0x000C4600 | sipi_vector);
// Wait for other CPUs to process the SIPI.
mdelay(10);
// Restore memory.
writel(APIC_SVR, val);
*(u64*)BUILD_AP_BOOT_ADDR = old;
u32 count = readl(&smp_cpus);
dprintf(1, "Found %d cpu(s)\n", count);
return count;
}
// Reset smp_cpus to zero (forces a recheck on reboots).
void
smp_probe_setup(void)
{
smp_cpus = 0;
}