bcmmdio_read_4
uint32_t mgt = bcmmdio_read_4(sc, MIIMGT);
while (bcmmdio_read_4(sc, MIIMGT) & MIIMGT_BSY) {
int val = __SHIFTOUT(bcmmdio_read_4(sc, MIICMD), MIICMD_DATA);
uint32_t miimgt = bcmmdio_read_4(sc, MIIMGT);