diff options
Diffstat (limited to 'src/drivers/pc80/rtc/mc146818rtc_romcc.c')
-rw-r--r-- | src/drivers/pc80/rtc/mc146818rtc_romcc.c | 104 |
1 files changed, 104 insertions, 0 deletions
diff --git a/src/drivers/pc80/rtc/mc146818rtc_romcc.c b/src/drivers/pc80/rtc/mc146818rtc_romcc.c new file mode 100644 index 0000000000..8bebc4229d --- /dev/null +++ b/src/drivers/pc80/rtc/mc146818rtc_romcc.c @@ -0,0 +1,104 @@ +#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 +} |