1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 3 #include <console/console.h> 4 #include <fallback.h> 5 #include <pc80/mc146818rtc.h> 6 #include <stdint.h> 7 8 #if CONFIG_MAX_REBOOT_CNT > 15 9 #error "CONFIG_MAX_REBOOT_CNT too high" 10 #endif 11 boot_count(uint8_t rtc_byte)12static int boot_count(uint8_t rtc_byte) 13 { 14 return rtc_byte >> 4; 15 } 16 increment_boot_count(uint8_t rtc_byte)17static uint8_t increment_boot_count(uint8_t rtc_byte) 18 { 19 return rtc_byte + (1 << 4); 20 } 21 boot_set_fallback(uint8_t rtc_byte)22static uint8_t boot_set_fallback(uint8_t rtc_byte) 23 { 24 return rtc_byte & ~RTC_BOOT_NORMAL; 25 } 26 boot_use_normal(uint8_t rtc_byte)27static int boot_use_normal(uint8_t rtc_byte) 28 { 29 return rtc_byte & RTC_BOOT_NORMAL; 30 } 31 do_normal_boot(void)32int do_normal_boot(void) 33 { 34 unsigned char byte; 35 36 if (cmos_error() || (CONFIG(USE_OPTION_TABLE) && !cmos_lb_cks_valid())) { 37 printk(BIOS_WARNING, 38 "Invalid CMOS checksum detected! Force fallback boot...\n"); 39 byte = cmos_read(RTC_BOOT_BYTE); 40 byte &= boot_set_fallback(byte) & 0x0f; 41 byte |= 0xf << 4; 42 cmos_write(byte, RTC_BOOT_BYTE); 43 } 44 45 /* The RTC_BOOT_BYTE is now o.k. see where to go. */ 46 byte = cmos_read(RTC_BOOT_BYTE); 47 48 /* Are we attempting to boot normally? */ 49 if (boot_use_normal(byte)) { 50 /* Are we already at the max count? */ 51 if (boot_count(byte) < CONFIG_MAX_REBOOT_CNT) 52 byte = increment_boot_count(byte); 53 else 54 byte = boot_set_fallback(byte); 55 } 56 57 /* Save the boot byte */ 58 cmos_write(byte, RTC_BOOT_BYTE); 59 60 /* Return selected code path for this boot attempt */ 61 return boot_use_normal(byte); 62 } 63