The interrupt routine is similar to the asynchronous version, with the addition of the call to start() and the removal of the call to cv_signal(9F).
static u_int xxintr(caddr_t arg) { struct xxstate *xsp = (struct xxstate *)arg; struct buf *bp; uint8_t status; mutex_enter(&xsp->mu); status = ddi_get8(xsp->data_access_handle, &xsp->regp->csr); if (!(status & INTERRUPTING)) { mutex_exit(&xsp->mu); return (DDI_INTR_UNCLAIMED); } /* Get the buf responsible for this interrupt */ bp = xsp->bp; xsp->bp = NULL; /* * This example is for a simple device which either * succeeds or fails the data transfer, indicated in the * command/status register. */ if (status & DEVICE_ERROR) { /* failure */ bp->b_resid = bp->b_bcount; bioerror(bp, EIO); } else { /* success */ bp->b_resid = 0; } ddi_put8(xsp->data_access_handle, &xsp->regp->csr, CLEAR_INTERRUPT); /* The transfer has finished, successfully or not */ biodone(bp); /* * If the device has power manageable components that were * marked busy in strategy(9F), mark them idle now with * pm_idle_component(9F) * Release any resources used in the transfer, such as DMA * resources (ddi_dma_unbind_handle(9F) and * ddi_dma_free_handle(9F)). * * Let the next I/O thread have access to the device. */ xsp->busy = 0; mutex_exit(&xsp->mu); (void) xxstart((caddr_t)xsp); return (DDI_INTR_CLAIMED); }