From 86a4b08dc76531d75cca5b7043dccb3f00e03068 Mon Sep 17 00:00:00 2001 From: Luoqi Chen Date: Thu, 21 Oct 1999 15:49:25 +0000 Subject: Non-functional changes. Add some comments before I start to forget how everything works myself. --- sys/dev/aic/aic.c | 114 ++++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 111 insertions(+), 3 deletions(-) (limited to 'sys/dev/aic') diff --git a/sys/dev/aic/aic.c b/sys/dev/aic/aic.c index f99e21680d3c..db8c2b7f109a 100644 --- a/sys/dev/aic/aic.c +++ b/sys/dev/aic/aic.c @@ -330,6 +330,9 @@ aic_execute_scb(void *arg, bus_dma_segment_t *dm_segs, int nseg, int error) splx(s); } +/* + * Start another command if the controller is not busy. + */ static void aic_start(struct aic_softc *aic) { @@ -354,6 +357,9 @@ aic_start(struct aic_softc *aic) aic_outb(aic, SCSISEQ, ENRESELI); } +/* + * Start a selection. + */ static void aic_select(struct aic_softc *aic) { @@ -374,6 +380,10 @@ aic_select(struct aic_softc *aic) aic_outb(aic, SCSISEQ, ENRESELI|ENSELO|ENAUTOATNO); } +/* + * We have successfully selected a target, prepare for the information + * transfer phases. + */ static void aic_selected(struct aic_softc *aic) { @@ -398,6 +408,8 @@ aic_selected(struct aic_softc *aic) if ((ti->flags & TINFO_SDTR_NEGO) != 0) aic->msg_outq |= AIC_MSG_SDTR; } + + /* mark target/lun busy only for untagged operations */ if ((aic->msg_outq & AIC_MSG_TAG_Q) == 0) ti->lubusy |= 1 << scb->lun; @@ -409,6 +421,10 @@ aic_selected(struct aic_softc *aic) aic_outb(aic, SCSIRATE, ti->scsirate); } +/* + * We are re-selected by a target, save the target id and wait for the + * target to further identify itself. + */ static void aic_reselected(struct aic_softc *aic) { @@ -417,6 +433,10 @@ aic_reselected(struct aic_softc *aic) CAM_DEBUG_PRINT(CAM_DEBUG_TRACE, ("aic_reselected\n")); + /* + * If we have started a selection, it must have lost out in + * the arbitration, put the command back to the pending queue. + */ if (aic->nexus) { TAILQ_INSERT_HEAD(&aic->pending_ccbs, &aic->nexus->ccb->ccb_h, sim_links.tqe); @@ -425,7 +445,9 @@ aic_reselected(struct aic_softc *aic) selid = aic_inb(aic, SELID) & SCSI_ID_MASK; if (selid & (selid - 1)) { - ; + /* this should never have happened */ + aic_reset(aic, /*initiate_reset*/TRUE); + return; } aic->state = AIC_RESELECTED; @@ -441,6 +463,9 @@ aic_reselected(struct aic_softc *aic) aic_outb(aic, SCSIRATE, ti->scsirate); } +/* + * Wait for SPIORDY (SCSI PIO ready) flag, or a phase change. + */ static __inline int aic_spiordy(struct aic_softc *aic) { @@ -453,6 +478,9 @@ aic_spiordy(struct aic_softc *aic) return (spiordy); } +/* + * Read messages. + */ static void aic_msgin(struct aic_softc *aic) { @@ -466,6 +494,11 @@ aic_msgin(struct aic_softc *aic) aic->flags &= ~AIC_DROP_MSGIN; aic->msg_len = 0; do { + /* + * If a parity error is detected, drop the remaining + * bytes and inform the target so it could resend + * the messages. + */ if (aic_inb(aic, SSTAT1) & SCSIPERR) { aic_outb(aic, CLRSINT1, CLRSCSIPERR); aic->flags |= AIC_DROP_MSGIN; @@ -475,6 +508,7 @@ aic_msgin(struct aic_softc *aic) aic_inb(aic, SCSIDAT); continue; } + /* read the message byte without ACKing on it */ aic->msg_buf[aic->msg_len++] = aic_inb(aic, SCSIBUS); if (aic->msg_buf[0] == MSG_EXTENDED) { if (aic->msg_len < 2) { @@ -501,10 +535,15 @@ aic_msgin(struct aic_softc *aic) msglen = 2; else msglen = 1; + /* + * If we have a complete message, handle it before the final + * ACK (in case we decide to reject the message). + */ if (aic->msg_len == msglen) { aic_handle_msgin(aic); aic->msg_len = 0; } + /* ACK on the message byte */ (void) aic_inb(aic, SCSIDAT); } while (aic_spiordy(aic)); @@ -512,6 +551,9 @@ aic_msgin(struct aic_softc *aic) aic_outb(aic, SIMODE1, ENSCSIRST|ENBUSFREE|ENREQINIT); } +/* + * Handle a message. + */ static void aic_handle_msgin(struct aic_softc *aic) { @@ -524,7 +566,10 @@ aic_handle_msgin(struct aic_softc *aic) int tag; ti = &aic->tinfo[aic->target]; - + /* + * We expect to see an IDENTIFY message, possibly followed + * by a tagged queue message. + */ if (MSG_ISIDENTIFY(aic->msg_buf[0])) { aic->lun = aic->msg_buf[0] & MSG_IDENTIFY_LUNMASK; if (ti->flags & TINFO_TAG_ENB) @@ -539,6 +584,7 @@ aic_handle_msgin(struct aic_softc *aic) return; } + /* Find the nexus */ TAILQ_FOREACH(ccb_h, &aic->nexus_ccbs, sim_links.tqe) { scb = (struct aic_scb *)ccb_h->ccb_scb_ptr; if (ccb_h->target_id == aic->target && @@ -547,11 +593,13 @@ aic_handle_msgin(struct aic_softc *aic) break; } + /* ABORT if nothing is found */ if (!ccb_h) { aic_sched_msgout(aic, MSG_ABORT); /* MSG_ABORT_TAG?*/ return; } + /* Reestablish the nexus */ TAILQ_REMOVE(&aic->nexus_ccbs, ccb_h, sim_links.tqe); aic->nexus = scb; scb->flags &= ~SCB_DISCONNECTED; @@ -567,12 +615,13 @@ aic_handle_msgin(struct aic_softc *aic) csio = &scb->ccb->csio; ccb_h->status &= ~CAM_STATUS_MASK; if ((scb->flags & SCB_SENSE) != 0) { + /* auto REQUEST SENSE command */ scb->flags &= ~SCB_SENSE; csio->sense_resid = scb->data_len; if (scb->status == SCSI_STATUS_OK) { ccb_h->status |= CAM_SCSI_STATUS_ERROR|CAM_AUTOSNS_VALID; - scsi_sense_print(csio); + /*scsi_sense_print(csio);*/ } else { ccb_h->status |= CAM_AUTOSENSE_FAIL; printf("ccb %p sense failed %x\n", @@ -582,10 +631,12 @@ aic_handle_msgin(struct aic_softc *aic) csio->scsi_status = scb->status; csio->resid = scb->data_len; if (scb->status == SCSI_STATUS_OK) { + /* everything goes well */ ccb_h->status |= CAM_REQ_CMP; } else if ((ccb_h->flags & CAM_DIS_AUTOSENSE) == 0 && (csio->scsi_status == SCSI_STATUS_CHECK_COND || csio->scsi_status == SCSI_STATUS_CMD_TERMINATED)) { + /* try to retrieve sense information */ scb->flags |= SCB_SENSE; aic->flags |= AIC_BUSFREE_OK; return; @@ -609,6 +660,10 @@ aic_handle_msgin(struct aic_softc *aic) max(ti->goal.period, aic->msg_buf[3]); ti->current.offset = aic->msg_buf[4] = min(ti->goal.offset, aic->msg_buf[4]); + /* + * The target initiated the negotiation, + * send back a response. + */ aic_sched_msgout(aic, 0); } ti->flags &= ~(TINFO_SDTR_SENT|TINFO_SDTR_NEGO); @@ -643,6 +698,7 @@ aic_handle_msgin(struct aic_softc *aic) scb = aic->nexus; ti = &aic->tinfo[scb->target]; ti->flags &= ~TINFO_TAG_ENB; + ti->lubusy |= 1 << scb->lun; break; case AIC_MSG_SDTR: scb = aic->nexus; @@ -676,6 +732,9 @@ aic_handle_msgin(struct aic_softc *aic) } } +/* + * Raise ATNO to signal the target that we have a message for it. + */ static void aic_sched_msgout(struct aic_softc *aic, u_int8_t msg) { @@ -687,6 +746,9 @@ aic_sched_msgout(struct aic_softc *aic, u_int8_t msg) aic_outb(aic, SCSISIGO, aic_inb(aic, SCSISIGI) | ATNO); } +/* + * Send messages. + */ static void aic_msgout(struct aic_softc *aic) { @@ -700,12 +762,19 @@ aic_msgout(struct aic_softc *aic) aic_outb(aic, SIMODE1, ENSCSIRST|ENPHASEMIS|ENBUSFREE); aic_outb(aic, SXFRCTL0, CHEN|SPIOEN); + /* + * If the previous phase is also the message out phase, + * we need to retransmit all the messages, probably + * because the target has detected a parity error during + * the past transmission. + */ if (aic->prev_phase == PH_MSGOUT) aic->msg_outq = aic->msg_sent; do { int q = aic->msg_outq; if (msgidx > 0 && msgidx == aic->msg_len) { + /* complete message sent, start the next one */ q &= -q; aic->msg_sent |= q; aic->msg_outq ^= q; @@ -713,6 +782,7 @@ aic_msgout(struct aic_softc *aic) msgidx = 0; } if (msgidx == 0) { + /* setup the message */ switch (q & -q) { case AIC_MSG_IDENTIFY: scb = aic->nexus; @@ -742,6 +812,7 @@ aic_msgout(struct aic_softc *aic) ti->flags |= TINFO_SDTR_SENT; break; case AIC_MSG_MSGBUF: + /* a single message already in the buffer */ if (aic->msg_buf[0] == MSG_BUS_DEV_RESET || aic->msg_buf[0] == MSG_ABORT || aic->msg_buf[0] == MSG_ABORT_TAG) @@ -749,8 +820,13 @@ aic_msgout(struct aic_softc *aic) break; } } + /* + * If this is the last message byte of all messages, + * clear ATNO to signal transmission complete. + */ if ((q & (q - 1)) == 0 && msgidx == aic->msg_len - 1) aic_outb(aic, CLRSINT1, CLRATNO); + /* transmit the message byte */ aic_outb(aic, SCSIDAT, aic->msg_buf[msgidx++]); } while (aic_spiordy(aic)); @@ -758,6 +834,9 @@ aic_msgout(struct aic_softc *aic) aic_outb(aic, SIMODE1, ENSCSIRST|ENBUSFREE|ENREQINIT); } +/* + * Read data bytes. + */ static void aic_datain(struct aic_softc *aic) { @@ -772,6 +851,7 @@ aic_datain(struct aic_softc *aic) while (scb->data_len > 0) { for (;;) { + /* wait for the fifo the fill up or a phase change */ dmastat = aic_inb(aic, DMASTAT); if (dmastat & (INTSTAT|DFIFOFULL)) break; @@ -779,6 +859,10 @@ aic_datain(struct aic_softc *aic) if (dmastat & DFIFOFULL) { n = FIFOSIZE; } else { + /* + * No more data, wait for the remaining bytes in + * the scsi fifo to be transfer to the host fifo. + */ while (!(aic_inb(aic, SSTAT2) & SEMPTY)) ; n = aic_inb(aic, FIFOSTAT); @@ -813,6 +897,9 @@ aic_datain(struct aic_softc *aic) aic_outb(aic, SIMODE1, ENSCSIRST|ENBUSFREE|ENREQINIT); } +/* + * Send data bytes. + */ static void aic_dataout(struct aic_softc *aic) { @@ -827,6 +914,7 @@ aic_dataout(struct aic_softc *aic) while (scb->data_len > 0) { for (;;) { + /* wait for the fifo to clear up or a phase change */ dmastat = aic_inb(aic, DMASTAT); if (dmastat & (INTSTAT|DFIFOEMP)) break; @@ -857,6 +945,7 @@ aic_dataout(struct aic_softc *aic) } for (;;) { + /* wait until all bytes in the fifos are transmitted */ dmastat = aic_inb(aic, DMASTAT); if (dmastat & INTSTAT) break; @@ -868,6 +957,9 @@ aic_dataout(struct aic_softc *aic) aic_outb(aic, SIMODE1, ENSCSIRST|ENBUSFREE|ENREQINIT); } +/* + * Send the scsi command. + */ static void aic_cmd(struct aic_softc *aic) { @@ -875,6 +967,7 @@ aic_cmd(struct aic_softc *aic) struct scsi_request_sense sense_cmd; if (scb->flags & SCB_SENSE) { + /* autosense request */ sense_cmd.opcode = REQUEST_SENSE; sense_cmd.byte2 = scb->lun << 2; sense_cmd.length = scb->ccb->csio.sense_len; @@ -897,6 +990,10 @@ aic_cmd(struct aic_softc *aic) aic_outb(aic, SXFRCTL0, CHEN); } +/* + * Finish off a command. The caller is responsible to remove the ccb + * from any queue. + */ static void aic_done(struct aic_softc *aic, struct aic_scb *scb) { @@ -1052,6 +1149,7 @@ aic_intr(void *arg) sstat1 = aic_inb(aic, SSTAT1); if ((sstat1 & SCSIRSTI) != 0) { + /* a device-initiated bus reset */ aic_outb(aic, CLRSINT1, CLRSCSIRSTI); aic_reset(aic, /*initiate_reset*/FALSE); return; @@ -1142,6 +1240,7 @@ aic_intr(void *arg) ccb->ccb_h.status = CAM_UNEXP_BUSFREE; aic_done(aic, scb); } else if (scb->flags & SCB_SENSE) { + /* autosense request */ aic->flags &= ~AIC_BUSFREE_OK; aic_select(aic); aic_outb(aic, DMACNTRL0, INTEN); @@ -1160,6 +1259,9 @@ aic_intr(void *arg) aic_outb(aic, DMACNTRL0, INTEN); } +/* + * Reset ourselves. + */ static void aic_chip_reset(struct aic_softc *aic) { @@ -1200,6 +1302,9 @@ aic_chip_reset(struct aic_softc *aic) aic_outb(aic, BRSTCNTRL, EISA_BRST_TIM); } +/* + * Reset the SCSI bus + */ static void aic_scsi_reset(struct aic_softc *aic) { @@ -1209,6 +1314,9 @@ aic_scsi_reset(struct aic_softc *aic) DELAY(50); } +/* + * Reset. Abort all pending commands. + */ static void aic_reset(struct aic_softc *aic, int initiate_reset) { -- cgit v1.2.3