M41T94_REG_SECONDS
res = spi_w8r8(spi, M41T94_REG_SECONDS);
buf[0] = 0x80 | M41T94_REG_SECONDS; /* write time + date */
buf[M41T94_REG_SECONDS] = bin2bcd(tm->tm_sec);
ret = spi_w8r8(spi, M41T94_REG_SECONDS);
buf[0] = 0x80 | M41T94_REG_SECONDS;
tm->tm_sec = bcd2bin(spi_w8r8(spi, M41T94_REG_SECONDS));