SM0CTL1_TRI
iowrite32(SM0CTL1_START | SM0CTL1_TRI, i2c->base + REG_SM0CTL1_REG);
iowrite32(SM0CTL1_STOP | SM0CTL1_TRI, i2c->base + REG_SM0CTL1_REG);
iowrite32(cmd | SM0CTL1_TRI | SM0CTL1_PGLEN(page_len),
val, !(val & SM0CTL1_TRI),