| #include <stdint.h> |
| #include <pc80/mc146818rtc.h> |
| #include <fallback.h> |
| #if CONFIG_USE_OPTION_TABLE |
| #include "option_table.h" |
| #endif |
| |
| #if CONFIG_MAX_REBOOT_CNT > 15 |
| #error "CONFIG_MAX_REBOOT_CNT too high" |
| #endif |
| |
| static int cmos_error(void) |
| { |
| unsigned char reg_d; |
| /* See if the cmos error condition has been flagged */ |
| reg_d = cmos_read(RTC_REG_D); |
| return (reg_d & RTC_VRT) == 0; |
| } |
| |
| static int cmos_chksum_valid(void) |
| { |
| #if CONFIG_USE_OPTION_TABLE |
| unsigned char addr; |
| u16 sum, old_sum; |
| sum = 0; |
| /* Compute the cmos checksum */ |
| for(addr = LB_CKS_RANGE_START; addr <= LB_CKS_RANGE_END; addr++) { |
| sum += cmos_read(addr); |
| } |
| |
| /* Read the stored checksum */ |
| old_sum = cmos_read(LB_CKS_LOC) << 8; |
| old_sum |= cmos_read(LB_CKS_LOC+1); |
| |
| return sum == old_sum; |
| #else |
| return 0; |
| #endif |
| } |
| |
| static inline __attribute__((unused)) int boot_count(uint8_t rtc_byte) |
| { |
| return rtc_byte >> 4; |
| } |
| |
| static inline __attribute__((unused)) uint8_t increment_boot_count(uint8_t rtc_byte) |
| { |
| return rtc_byte + (1 << 4); |
| } |
| |
| static inline __attribute__((unused)) uint8_t boot_set_fallback(uint8_t rtc_byte) |
| { |
| return rtc_byte & ~RTC_BOOT_NORMAL; |
| } |
| |
| static inline __attribute__((unused)) int boot_use_normal(uint8_t rtc_byte) |
| { |
| return rtc_byte & RTC_BOOT_NORMAL; |
| } |
| |
| static inline __attribute__((unused)) int do_normal_boot(void) |
| { |
| unsigned char byte; |
| |
| if (cmos_error() || !cmos_chksum_valid()) { |
| /* Invalid CMOS checksum detected! |
| * Force fallback boot... |
| */ |
| 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); |
| } |
| |
| unsigned read_option_lowlevel(unsigned start, unsigned size, unsigned def) |
| { |
| #if CONFIG_USE_OPTION_TABLE |
| unsigned byte; |
| byte = cmos_read(start/8); |
| return (byte >> (start & 7U)) & ((1U << size) - 1U); |
| #else |
| return def; |
| #endif |
| } |