SDW_REGADDR
size = min_t(size_t, count, (SDW_REGADDR + 1) - (addr & SDW_REGADDR));
bytes = SDW_REG_NO_PAGE - (reg & SDW_REGADDR); /* to end of page */
bytes = SDW_REG_NO_PAGE - (reg & SDW_REGADDR); /* to end of page */