| /* SPDX-License-Identifier: GPL-2.0-or-later */ |
| |
| #include <console/console.h> |
| #include <cpu/x86/mtrr.h> |
| #include <ip_checksum.h> |
| #include <intelbasecode/ramtop.h> |
| #include <pc80/mc146818rtc.h> |
| #include <stdint.h> |
| |
| /* We need a region in CMOS to store the RAMTOP address */ |
| |
| #define RAMTOP_SIGNATURE 0x52544F50 /* 'RTOP' */ |
| |
| /* |
| * Address of the ramtop byte in CMOS. Should be reserved |
| * in mainboards' cmos.layout and not covered by checksum. |
| */ |
| |
| #if CONFIG(USE_OPTION_TABLE) |
| #include "option_table.h" |
| |
| #ifndef CMOS_VSTART_ramtop |
| #error "The `ramtop` CMOS entry is missing, please add it to your cmos.layout." |
| #endif |
| |
| #if CMOS_VSTART_ramtop % 8 != 0 |
| #error "The `ramtop` CMOS entry needs to be byte aligned, check your cmos.layout." |
| #endif // CMOS_VSTART_ramtop % 8 != 0 |
| |
| #if CMOS_VLEN_ramtop != (10 * 8) |
| #error "The `ramtop` CMOS entry needs to be 10 bytes long, check your cmos.layout." |
| #endif // CMOS_VLEN_ramtop != (10 * 8) |
| |
| #else |
| #define CMOS_VSTART_ramtop 800 |
| #endif // CONFIG(USE_OPTION_TABLE) |
| |
| struct ramtop_table { |
| uint32_t signature; |
| uint32_t addr; |
| uint16_t checksum; |
| } __packed; |
| |
| /* Read and validate ramtop_table structure from CMOS */ |
| static int ramtop_cmos_read(struct ramtop_table *ramtop) |
| { |
| u8 i, *p; |
| u16 csum; |
| |
| for (p = (u8 *)ramtop, i = 0; i < sizeof(*ramtop); i++, p++) |
| *p = cmos_read((CMOS_VSTART_ramtop / 8) + i); |
| |
| /* Verify signature */ |
| if (ramtop->signature != RAMTOP_SIGNATURE) { |
| printk(BIOS_DEBUG, "ramtop_table invalid signature\n"); |
| return -1; |
| } |
| |
| /* Verify checksum over signature and counter only */ |
| csum = compute_ip_checksum(ramtop, offsetof(struct ramtop_table, checksum)); |
| |
| if (csum != ramtop->checksum) { |
| printk(BIOS_DEBUG, "ramtop_table checksum mismatch\n"); |
| return -1; |
| } |
| |
| return 0; |
| } |
| |
| /* Write ramtop_table structure to CMOS */ |
| static void ramtop_cmos_write(struct ramtop_table *ramtop) |
| { |
| u8 i, *p; |
| |
| /* Checksum over signature and counter only */ |
| ramtop->checksum = compute_ip_checksum( |
| ramtop, offsetof(struct ramtop_table, checksum)); |
| |
| for (p = (u8 *)ramtop, i = 0; i < sizeof(*ramtop); i++, p++) |
| cmos_write(*p, (CMOS_VSTART_ramtop / 8) + i); |
| } |
| |
| /* Update the RAMTOP if required based on the input top_of_ram address */ |
| void update_ramtop(uint32_t addr) |
| { |
| struct ramtop_table ramtop; |
| |
| /* Read and update ramtop (if required) */ |
| if (ramtop_cmos_read(&ramtop) < 0) { |
| /* Structure invalid, re-initialize */ |
| ramtop.signature = RAMTOP_SIGNATURE; |
| ramtop.addr = 0; |
| } |
| |
| /* Update ramtop if required */ |
| if (ramtop.addr == addr) |
| return; |
| |
| ramtop.addr = addr; |
| |
| /* Write the new top_of_ram address to CMOS */ |
| ramtop_cmos_write(&ramtop); |
| |
| printk(BIOS_DEBUG, "Updated the RAMTOP address into CMOS 0x%x\n", ramtop.addr); |
| } |
| |
| static uint32_t get_ramtop_addr(void) |
| { |
| struct ramtop_table ramtop; |
| |
| if (ramtop_cmos_read(&ramtop) < 0) |
| return 0; |
| |
| return ramtop.addr; |
| } |
| |
| /* Early caching of top_of_ram region */ |
| void early_ramtop_enable_cache_range(void) |
| { |
| uint32_t ramtop = get_ramtop_addr(); |
| if (!ramtop) |
| return; |
| |
| int mtrr = get_free_var_mtrr(); |
| if (mtrr == -1) { |
| printk(BIOS_WARNING, "ramtop_table update failure due to no free MTRR available!\n"); |
| return; |
| } |
| /* |
| * We need to make sure late romstage (including FSP-M post mem) will be run |
| * cached. Caching 16MB below ramtop is a safe to cover late romstage. |
| */ |
| set_var_mtrr(mtrr, ramtop - 16 * MiB, 16 * MiB, MTRR_TYPE_WRBACK); |
| } |