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/* 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);
}
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