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#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
}
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