DC_SCRATCH
[DC_SCRATCH] = REG_FIELD(ISP176x_DC_SCRATCH, 0, 15),
[DC_SCRATCH] = REG_FIELD(ISP1763_DC_SCRATCH, 0, 15),
isp1760_udc_write(udc, DC_SCRATCH, 0xbabe);
scratch = isp1760_udc_read(udc, DC_SCRATCH);