csum8
is_valid = csum8(&data[2], sizeof(__be32), 0) == data[1];
.checksum = csum8((const void *)&cmd_data, sizeof(cmd_data),
.checksum = csum8((const void *)&cmd_data, sizeof(cmd_data),
.checksum = csum8(data, rem, COMMAND_SEND_DATA),
u8 *buf8 = (u8 *) buf, csum8 = 0;
csum8 += buf8[i];
csum8 += buf8[i];
csum8 += buf8[i];
if (csum8 == 0) {