| /* SPDX-License-Identifier: GPL-2.0-only */ |
| |
| #include <stdint.h> |
| #include <console/console.h> |
| #include <pc80/mc146818rtc.h> |
| #include <fallback.h> |
| |
| #if CONFIG_MAX_REBOOT_CNT > 15 |
| #error "CONFIG_MAX_REBOOT_CNT too high" |
| #endif |
| |
| static int boot_count(uint8_t rtc_byte) |
| { |
| return rtc_byte >> 4; |
| } |
| |
| static uint8_t increment_boot_count(uint8_t rtc_byte) |
| { |
| return rtc_byte + (1 << 4); |
| } |
| |
| static uint8_t boot_set_fallback(uint8_t rtc_byte) |
| { |
| return rtc_byte & ~RTC_BOOT_NORMAL; |
| } |
| |
| static int boot_use_normal(uint8_t rtc_byte) |
| { |
| return rtc_byte & RTC_BOOT_NORMAL; |
| } |
| |
| int do_normal_boot(void) |
| { |
| unsigned char byte; |
| |
| if (cmos_error() || (CONFIG(USE_OPTION_TABLE) && !cmos_lb_cks_valid())) { |
| printk(BIOS_WARNING, |
| "Invalid CMOS checksum detected! Force fallback boot...\n"); |
| byte = cmos_read(RTC_BOOT_BYTE); |
| byte &= boot_set_fallback(byte) & 0x0f; |
| byte |= 0xf << 4; |
| cmos_write(byte, RTC_BOOT_BYTE); |
| } |
| |
| /* The RTC_BOOT_BYTE is now o.k. see where to go. */ |
| byte = cmos_read(RTC_BOOT_BYTE); |
| |
| /* Are we attempting to boot normally? */ |
| if (boot_use_normal(byte)) { |
| /* Are we already at the max count? */ |
| if (boot_count(byte) < CONFIG_MAX_REBOOT_CNT) |
| byte = increment_boot_count(byte); |
| else |
| byte = boot_set_fallback(byte); |
| } |
| |
| /* Save the boot byte */ |
| cmos_write(byte, RTC_BOOT_BYTE); |
| |
| /* Return selected code path for this boot attempt */ |
| return boot_use_normal(byte); |
| } |