/* SPDX-License-Identifier: GPL-2.0-only */ #include <console/console.h> #include <fallback.h> #include <pc80/mc146818rtc.h> #include <stdint.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); }