Simple USB data transfer

#define CMD_ID_START_MEASUREMENTS 0x18
#define CMD_ID_INIT               0x1A

struct output_packet {
        u8 cmd;
        u8 params[7];
} __attribute__((packed));

static int send_cmd(struct gotemp *gdev, u8 cmd)
{
        struct output_packet *pkt;
        int retval;

        pkt = kmalloc(sizeof(*pkt), GFP_KERNEL);
        if (!pkt)
                return -ENOMEM;
        memset(pkt, 0x00, sizeof(*pkt));
        pkt->cmd = cmd;