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// Support for enabling/disabling BIOS ram shadowing.
//
// 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" // memcpy
#include "pci.h" // pci_config_writeb
#define BIOS_TMP_STORAGE 0x30000 /* 64 KB used to copy the BIOS to shadow RAM */
// Test if 'addr' is in the range from 'start'..'start+size'
#define IN_RANGE(addr, start, size) ({ \
u32 __addr = (addr); \
u32 __start = (start); \
u32 __size = (size); \
(__addr - __start < __size); \
})
// Enable shadowing and copy bios.
static void
copy_bios(PCIDevice d)
{
int v = pci_config_readb(d, 0x59);
v |= 0x30;
pci_config_writeb(d, 0x59, v);
memcpy((void *)0x000f0000, (void *)BIOS_TMP_STORAGE, 0x10000);
}
// Make the BIOS code segment area (0xf0000) writable.
void
make_bios_writable()
{
if (CONFIG_COREBOOT)
return;
dprintf(3, "enabling shadow ram\n");
// Locate chip controlling ram shadowing.
PCIDevice d;
int ret = pci_find_device(0x8086, 0x1237, 0, &d);
if (ret) {
dprintf(1, "Unable to unlock ram - bridge not found\n");
return;
}
// Copy the bios to a temporary area.
memcpy((void *)BIOS_TMP_STORAGE, (void *)0x000f0000, 0x10000);
// Enable shadowing and copy bios.
if (IN_RANGE((u32)copy_bios, 0xf0000, 0x10000)) {
// Jump to shadow enable function - use the copy in the
// temporary storage area so that memory does not change under
// the executing code.
u32 pos = (u32)copy_bios - 0xf0000 + BIOS_TMP_STORAGE;
void (*func)(PCIDevice) = (void*)pos;
func(d);
} else {
copy_bios(d);
}
// Clear the temporary area.
memset((void *)BIOS_TMP_STORAGE, 0, 0x10000);
}
// Make the BIOS code segment area (0xf0000) read-only.
void
make_bios_readonly()
{
if (CONFIG_COREBOOT)
return;
dprintf(3, "locking shadow ram\n");
PCIDevice d;
int ret = pci_find_device(0x8086, 0x1237, 0, &d);
if (ret) {
dprintf(1, "Unable to lock ram - bridge not found\n");
return;
}
wbinvd();
int v = pci_config_readb(d, 0x59);
v = (v & 0x0f) | (0x10);
pci_config_writeb(d, 0x59, v);
}
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