| /* |
| * This file is part of the coreboot project. |
| * |
| * 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; version 2 of the License. |
| * |
| * 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. |
| */ |
| |
| #define __SIMPLE_DEVICE__ |
| |
| #include <stdint.h> |
| #include <arch/io.h> |
| #include <cpu/x86/msr.h> |
| #include <cpu/amd/mtrr.h> |
| #include <cbmem.h> |
| |
| #define CBMEM_TOP_SCRATCHPAD 0x78 |
| |
| void backup_top_of_low_cacheable(uintptr_t ramtop) |
| { |
| uint16_t top_cache = ramtop >> 16; |
| pci_write_config16(PCI_DEV(0,0,0), CBMEM_TOP_SCRATCHPAD, top_cache); |
| } |
| |
| uintptr_t restore_top_of_low_cacheable(void) |
| { |
| uint16_t top_cache; |
| top_cache = pci_read_config16(PCI_DEV(0,0,0), CBMEM_TOP_SCRATCHPAD); |
| return (top_cache << 16); |
| } |
| |
| void *cbmem_top(void) |
| { |
| msr_t tom = rdmsr(TOP_MEM); |
| |
| if (!tom.lo) |
| return 0; |
| else |
| return (void *)restore_top_of_low_cacheable(); |
| } |