[PATCH] libata: interrupt driven pio for libata-core

- add PIO_ST_FIRST for the state before sending ATAPI CDB or sending
"ATA PIO data out" first data block.
- add ATA_TFLAG_POLLING and ATA_DFLAG_CDB_INTR flags
- remove the ATA_FLAG_NOINTR flag since the interrupt handler is now
aware of the states
- modify ata_pio_sector() and atapi_pio_bytes() to work in the interrupt
context
- modify the ata_host_intr() to handle PIO interrupts
- modify ata_qc_issue_prot() to initialize states
- atapi_packet_task() changed to handle "ATA PIO data out" first data block
- support the pre-ATA4 ATAPI device which raise interrupt when ready to
receive CDB

Signed-off-by: Albert Lee <albertcc@tw.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

3 files changed, 271 insertions, 69 deletions

diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index c4fcdc30f18c..cc2d1308826e 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -1292,6 +1292,9 @@ retry:
                 ap->cdb_len = (unsigned int) rc;
                 ap->host->max_cmd_len = (unsigned char) ap->cdb_len;
 
+                if (ata_id_cdb_intr(dev->id))
+                        dev->flags |= ATA_DFLAG_CDB_INTR;
+
                 /* print device info to dmesg */
                 printk(KERN_INFO "ata%u: dev %u ATAPI, max %s\n",
                        ap->id, device,
@@ -2405,7 +2408,6 @@ void ata_poll_qc_complete(struct ata_queued_cmd *qc, u8 drv_stat)
         unsigned long flags;
 
         spin_lock_irqsave(&ap->host_set->lock, flags);
-        ap->flags &= ~ATA_FLAG_NOINTR;
         ata_irq_on(ap);
         ata_qc_complete(qc, drv_stat);
         spin_unlock_irqrestore(&ap->host_set->lock, flags);
@@ -2660,6 +2662,7 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)
         struct page *page;
         unsigned int offset;
         unsigned char *buf;
+        unsigned long flags;
 
         if (qc->cursect == (qc->nsect - 1))
                 ap->hsm_task_state = HSM_ST_LAST;
@@ -2671,7 +2674,8 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)
         page = nth_page(page, (offset >> PAGE_SHIFT));
         offset %= PAGE_SIZE;
 
-        buf = kmap(page) + offset;
+        local_irq_save(flags);
+        buf = kmap_atomic(page, KM_IRQ0) + offset;
 
         qc->cursect++;
         qc->cursg_ofs++;
@@ -2687,7 +2691,8 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)
         do_write = (qc->tf.flags & ATA_TFLAG_WRITE);
         ata_data_xfer(ap, buf, ATA_SECT_SIZE, do_write);
 
-        kunmap(page);
+        kunmap_atomic(buf - offset, KM_IRQ0);
+        local_irq_restore(flags);
 }
 
 /**
@@ -2710,6 +2715,7 @@ static void __atapi_pio_bytes(struct ata_queued_cmd *qc, unsigned int bytes)
         struct page *page;
         unsigned char *buf;
         unsigned int offset, count;
+        unsigned long flags;
 
         if (qc->curbytes + bytes >= qc->nbytes)
                 ap->hsm_task_state = HSM_ST_LAST;
@@ -2753,7 +2759,8 @@ next_sg:
         /* don't cross page boundaries */
         count = min(count, (unsigned int)PAGE_SIZE - offset);
 
-        buf = kmap(page) + offset;
+        local_irq_save(flags);
+        buf = kmap_atomic(page, KM_IRQ0) + offset;
 
         bytes -= count;
         qc->curbytes += count;
@@ -2769,7 +2776,8 @@ next_sg:
         /* do the actual data transfer */
         ata_data_xfer(ap, buf, count, do_write);
 
-        kunmap(page);
+        kunmap_atomic(buf - offset, KM_IRQ0);
+        local_irq_restore(flags);
 
         if (bytes)
                 goto next_sg;
@@ -2808,6 +2816,8 @@ static void atapi_pio_bytes(struct ata_queued_cmd *qc)
         if (do_write != i_write)
                 goto err_out;
 
+        VPRINTK("ata%u: xfering %d bytes\n", ap->id, bytes);
+
         __atapi_pio_bytes(qc, bytes);
 
         return;
@@ -3054,6 +3064,8 @@ static void ata_qc_timeout(struct ata_queued_cmd *qc)
                 printk(KERN_ERR "ata%u: command 0x%x timeout, stat 0x%x host_stat 0x%x\n",
                        ap->id, qc->tf.command, drv_stat, host_stat);
 
+                ap->hsm_task_state = HSM_ST_IDLE;
+
                 /* complete taskfile transaction */
                 ata_qc_complete(qc, drv_stat);
                 break;
@@ -3344,43 +3356,96 @@ int ata_qc_issue_prot(struct ata_queued_cmd *qc)
 {
         struct ata_port *ap = qc->ap;
 
+        /* select the device */
         ata_dev_select(ap, qc->dev->devno, 1, 0);
 
+        /* start the command */
         switch (qc->tf.protocol) {
         case ATA_PROT_NODATA:
+                if (qc->tf.flags & ATA_TFLAG_POLLING)
+                        ata_qc_set_polling(qc);
+
                 ata_tf_to_host_nolock(ap, &qc->tf);
+                ap->hsm_task_state = HSM_ST_LAST;
+
+                if (qc->tf.flags & ATA_TFLAG_POLLING)
+                        queue_work(ata_wq, &ap->pio_task);
+
                 break;
 
         case ATA_PROT_DMA:
+                assert(!(qc->tf.flags & ATA_TFLAG_POLLING));
+
                 ap->ops->tf_load(ap, &qc->tf);   /* load tf registers */
                 ap->ops->bmdma_setup(qc);           /* set up bmdma */
                 ap->ops->bmdma_start(qc);           /* initiate bmdma */
+                ap->hsm_task_state = HSM_ST_LAST;
                 break;
 
-        case ATA_PROT_PIO: /* load tf registers, initiate polling pio */
-                ata_qc_set_polling(qc);
+        case ATA_PROT_PIO:
+                if (qc->tf.flags & ATA_TFLAG_POLLING)
+                        ata_qc_set_polling(qc);
+
                 ata_tf_to_host_nolock(ap, &qc->tf);
-                ap->hsm_task_state = HSM_ST;
-                queue_work(ata_wq, &ap->pio_task);
+
+                if (qc->tf.flags & ATA_TFLAG_POLLING) {
+                        /* polling PIO */
+                        ap->hsm_task_state = HSM_ST;
+                        queue_work(ata_wq, &ap->pio_task);
+                } else {
+                        /* interrupt driven PIO */
+                        if (qc->tf.flags & ATA_TFLAG_WRITE) {
+                                /* PIO data out protocol */
+                                ap->hsm_task_state = HSM_ST_FIRST;
+                                queue_work(ata_wq, &ap->packet_task);
+
+                                /* send first data block by polling */
+                        } else {
+                                /* PIO data in protocol */
+                                ap->hsm_task_state = HSM_ST;
+
+                                /* interrupt handler takes over from here */
+                        }
+                }
+
                 break;
 
         case ATA_PROT_ATAPI:
-                ata_qc_set_polling(qc);
+                if (qc->tf.flags & ATA_TFLAG_POLLING)
+                        ata_qc_set_polling(qc);
+
                 ata_tf_to_host_nolock(ap, &qc->tf);
-                queue_work(ata_wq, &ap->packet_task);
+                ap->hsm_task_state = HSM_ST_FIRST;
+
+                /* send cdb by polling if no cdb interrupt */
+                if ((!(qc->dev->flags & ATA_DFLAG_CDB_INTR)) ||
+                    (qc->tf.flags & ATA_TFLAG_POLLING))
+                        queue_work(ata_wq, &ap->packet_task);
                 break;
 
         case ATA_PROT_ATAPI_NODATA:
-                ap->flags |= ATA_FLAG_NOINTR;
+                if (qc->tf.flags & ATA_TFLAG_POLLING)
+                        ata_qc_set_polling(qc);
+
                 ata_tf_to_host_nolock(ap, &qc->tf);
-                queue_work(ata_wq, &ap->packet_task);
+                ap->hsm_task_state = HSM_ST_FIRST;
+
+                /* send cdb by polling if no cdb interrupt */
+                if ((!(qc->dev->flags & ATA_DFLAG_CDB_INTR)) ||
+                    (qc->tf.flags & ATA_TFLAG_POLLING))
+                        queue_work(ata_wq, &ap->packet_task);
                 break;
 
         case ATA_PROT_ATAPI_DMA:
-                ap->flags |= ATA_FLAG_NOINTR;
+                assert(!(qc->tf.flags & ATA_TFLAG_POLLING));
+
                 ap->ops->tf_load(ap, &qc->tf);   /* load tf registers */
                 ap->ops->bmdma_setup(qc);           /* set up bmdma */
-                queue_work(ata_wq, &ap->packet_task);
+                ap->hsm_task_state = HSM_ST_FIRST;
+
+                /* send cdb by polling if no cdb interrupt */
+                if (!(qc->dev->flags & ATA_DFLAG_CDB_INTR))
+                        queue_work(ata_wq, &ap->packet_task);
                 break;
 
         default:
@@ -3623,6 +3688,42 @@ void ata_bmdma_stop(struct ata_queued_cmd *qc)
 }
 
 /**
+ *      atapi_send_cdb - Write CDB bytes to hardware
+ *      @ap: Port to which ATAPI device is attached.
+ *      @qc: Taskfile currently active
+ *
+ *      When device has indicated its readiness to accept
+ *      a CDB, this function is called.  Send the CDB.
+ *
+ *      LOCKING:
+ *      caller.
+ */
+
+static void atapi_send_cdb(struct ata_port *ap, struct ata_queued_cmd *qc)
+{
+        /* send SCSI cdb */
+        DPRINTK("send cdb\n");
+        assert(ap->cdb_len >= 12);
+
+        ata_data_xfer(ap, qc->cdb, ap->cdb_len, 1);
+        ata_altstatus(ap); /* flush */
+
+        switch (qc->tf.protocol) {
+        case ATA_PROT_ATAPI:
+                ap->hsm_task_state = HSM_ST;
+                break;
+        case ATA_PROT_ATAPI_NODATA:
+                ap->hsm_task_state = HSM_ST_LAST;
+                break;
+        case ATA_PROT_ATAPI_DMA:
+                ap->hsm_task_state = HSM_ST_LAST;
+                /* initiate bmdma */
+                ap->ops->bmdma_start(qc);
+                break;
+        }
+}
+
+/**
  *      ata_host_intr - Handle host interrupt for given (port, task)
  *      @ap: Port on which interrupt arrived (possibly...)
  *      @qc: Taskfile currently active in engine
@@ -3641,47 +3742,142 @@ void ata_bmdma_stop(struct ata_queued_cmd *qc)
 inline unsigned int ata_host_intr (struct ata_port *ap,
                                    struct ata_queued_cmd *qc)
 {
-        u8 status, host_stat;
-
-        switch (qc->tf.protocol) {
+        u8 status, host_stat = 0;
 
-        case ATA_PROT_DMA:
-        case ATA_PROT_ATAPI_DMA:
-        case ATA_PROT_ATAPI:
-                /* check status of DMA engine */
-                host_stat = ap->ops->bmdma_status(ap);
-                VPRINTK("ata%u: host_stat 0x%X\n", ap->id, host_stat);
+        VPRINTK("ata%u: protocol %d task_state %d\n",
+                ap->id, qc->tf.protocol, ap->hsm_task_state);
 
-                /* if it's not our irq... */
-                if (!(host_stat & ATA_DMA_INTR))
+        /* Check whether we are expecting interrupt in this state */
+        switch (ap->hsm_task_state) {
+        case HSM_ST_FIRST:
+                /* Check the ATA_DFLAG_CDB_INTR flag is enough here.
+                 * The flag was turned on only for atapi devices.
+                 * No need to check is_atapi_taskfile(&qc->tf) again.
+                 */
+                if (!(qc->dev->flags & ATA_DFLAG_CDB_INTR))
                         goto idle_irq;
+                break;
+        case HSM_ST_LAST:
+                if (qc->tf.protocol == ATA_PROT_DMA ||
+                    qc->tf.protocol == ATA_PROT_ATAPI_DMA) {
+                        /* check status of DMA engine */
+                        host_stat = ap->ops->bmdma_status(ap);
+                        VPRINTK("ata%u: host_stat 0x%X\n", ap->id, host_stat);
+
+                        /* if it's not our irq... */
+                        if (!(host_stat & ATA_DMA_INTR))
+                                goto idle_irq;
+
+                        /* before we do anything else, clear DMA-Start bit */
+                        ap->ops->bmdma_stop(qc);
+                }
+                break;
+        case HSM_ST:
+                break;
+        default:
+                goto idle_irq;
+        }
 
-                /* before we do anything else, clear DMA-Start bit */
-                ap->ops->bmdma_stop(qc);
+        /* check altstatus */
+        status = ata_altstatus(ap);
+        if (status & ATA_BUSY)
+                goto idle_irq;
 
-                /* fall through */
+        /* check main status, clearing INTRQ */
+        status = ata_chk_status(ap);
+        if (unlikely(status & ATA_BUSY))
+                goto idle_irq;
 
-        case ATA_PROT_ATAPI_NODATA:
-        case ATA_PROT_NODATA:
-                /* check altstatus */
-                status = ata_altstatus(ap);
-                if (status & ATA_BUSY)
-                        goto idle_irq;
+        DPRINTK("ata%u: protocol %d task_state %d (dev_stat 0x%X)\n",
+                ap->id, qc->tf.protocol, ap->hsm_task_state, status);
 
-                /* check main status, clearing INTRQ */
-                status = ata_chk_status(ap);
-                if (unlikely(status & ATA_BUSY))
-                        goto idle_irq;
-                DPRINTK("ata%u: protocol %d (dev_stat 0x%X)\n",
-                        ap->id, qc->tf.protocol, status);
+        /* ack bmdma irq events */
+        ap->ops->irq_clear(ap);
 
-                /* ack bmdma irq events */
-                ap->ops->irq_clear(ap);
+        /* check error */
+        if (unlikely((status & ATA_ERR) || (host_stat & ATA_DMA_ERR)))
+                ap->hsm_task_state = HSM_ST_ERR;
+
+fsm_start:
+        switch (ap->hsm_task_state) {
+        case HSM_ST_FIRST:
+                /* Some pre-ATAPI-4 devices assert INTRQ 
+                 * at this state when ready to receive CDB.
+                 */
+
+                /* check device status */
+                if (unlikely((status & (ATA_BUSY | ATA_DRQ)) != ATA_DRQ)) {
+                        /* Wrong status. Let EH handle this */
+                        ap->hsm_task_state = HSM_ST_ERR;
+                        goto fsm_start;
+                }
+
+                atapi_send_cdb(ap, qc);
+
+                break;
+
+        case HSM_ST:
+                /* complete command or read/write the data register */
+                if (qc->tf.protocol == ATA_PROT_ATAPI) {
+                        /* ATAPI PIO protocol */
+                        if ((status & ATA_DRQ) == 0) {
+                                /* no more data to transfer */
+                                ap->hsm_task_state = HSM_ST_LAST;
+                                goto fsm_start;
+                        }
+                        
+                        atapi_pio_bytes(qc);
+
+                        if (unlikely(ap->hsm_task_state == HSM_ST_ERR))
+                                /* bad ireason reported by device */
+                                goto fsm_start;
+
+                } else {
+                        /* ATA PIO protocol */
+                        if (unlikely((status & ATA_DRQ) == 0)) {
+                                /* handle BSY=0, DRQ=0 as error */
+                                ap->hsm_task_state = HSM_ST_ERR;
+                                goto fsm_start;
+                        }
+
+                        ata_pio_sector(qc);
+
+                        if (ap->hsm_task_state == HSM_ST_LAST &&
+                            (!(qc->tf.flags & ATA_TFLAG_WRITE))) {
+                                /* all data read */
+                                ata_altstatus(ap);
+                                status = ata_chk_status(ap);
+                                goto fsm_start;
+                        }
+                }
+
+                ata_altstatus(ap); /* flush */
+                break;
+
+        case HSM_ST_LAST:
+                if (unlikely(status & ATA_DRQ)) {
+                        /* handle DRQ=1 as error */
+                        ap->hsm_task_state = HSM_ST_ERR;
+                        goto fsm_start;
+                }
+
+                /* no more data to transfer */
+                DPRINTK("ata%u: command complete, drv_stat 0x%x\n",
+                        ap->id, status);
+
+                ap->hsm_task_state = HSM_ST_IDLE;
 
                 /* complete taskfile transaction */
                 ata_qc_complete(qc, status);
                 break;
 
+        case HSM_ST_ERR:
+                printk(KERN_ERR "ata%u: command error, drv_stat 0x%x host_stat 0x%x\n",
+                       ap->id, status, host_stat);
+
+                ap->hsm_task_state = HSM_ST_IDLE;
+                ata_qc_complete(qc, status | ATA_ERR);
+                break;
         default:
                 goto idle_irq;
         }
@@ -3733,11 +3929,11 @@ irqreturn_t ata_interrupt (int irq, void *dev_instance, struct pt_regs *regs)
 
                 ap = host_set->ports[i];
                 if (ap &&
-                    !(ap->flags & (ATA_FLAG_PORT_DISABLED | ATA_FLAG_NOINTR))) {
+                    !(ap->flags & ATA_FLAG_PORT_DISABLED)) {
                         struct ata_queued_cmd *qc;
 
                         qc = ata_qc_from_tag(ap, ap->active_tag);
-                        if (qc && (!(qc->tf.ctl & ATA_NIEN)) &&
+                        if (qc && (!(qc->tf.flags & ATA_TFLAG_POLLING)) &&
                             (qc->flags & ATA_QCFLAG_ACTIVE))
                                 handled |= ata_host_intr(ap, qc);
                 }
@@ -3767,6 +3963,7 @@ static void atapi_packet_task(void *_data)
         struct ata_port *ap = _data;
         struct ata_queued_cmd *qc;
         u8 status;
+        unsigned long flags;
 
         qc = ata_qc_from_tag(ap, ap->active_tag);
         assert(qc != NULL);
@@ -3782,38 +3979,40 @@ static void atapi_packet_task(void *_data)
         if ((status & (ATA_BUSY | ATA_DRQ)) != ATA_DRQ)
                 goto err_out;
 
-        /* send SCSI cdb */
-        DPRINTK("send cdb\n");
-        assert(ap->cdb_len >= 12);
+        /* Send the CDB (atapi) or the first data block (ata pio out).
+         * During the state transition, interrupt handler shouldn't
+         * be invoked before the data transfer is complete and
+         * hsm_task_state is changed. Hence, the following locking.
+         */
+        spin_lock_irqsave(&ap->host_set->lock, flags);
 
-        if (qc->tf.protocol == ATA_PROT_ATAPI_DMA ||
-            qc->tf.protocol == ATA_PROT_ATAPI_NODATA) {
-                unsigned long flags;
+        if (is_atapi_taskfile(&qc->tf)) {
+                /* send CDB */
+                atapi_send_cdb(ap, qc);
 
-                /* Once we're done issuing command and kicking bmdma,
-                 * irq handler takes over.  To not lose irq, we need
-                 * to clear NOINTR flag before sending cdb, but
-                 * interrupt handler shouldn't be invoked before we're
-                 * finished.  Hence, the following locking.
-                 */
-                spin_lock_irqsave(&ap->host_set->lock, flags);
-                ap->flags &= ~ATA_FLAG_NOINTR;
-                ata_data_xfer(ap, qc->cdb, ap->cdb_len, 1);
-                if (qc->tf.protocol == ATA_PROT_ATAPI_DMA)
-                        ap->ops->bmdma_start(qc);       /* initiate bmdma */
-                spin_unlock_irqrestore(&ap->host_set->lock, flags);
+                if (qc->tf.flags & ATA_TFLAG_POLLING)
+                        queue_work(ata_wq, &ap->pio_task);
         } else {
-                ata_data_xfer(ap, qc->cdb, ap->cdb_len, 1);
+                /* PIO data out protocol.
+                 * send first data block.
+                 */
 
-                /* PIO commands are handled by polling */
+                /* ata_pio_sector() might change the state to HSM_ST_LAST.
+                 * so, the state is changed here before ata_pio_sector().
+                 */
                 ap->hsm_task_state = HSM_ST;
-                queue_work(ata_wq, &ap->pio_task);
+                ata_pio_sector(qc);
+                ata_altstatus(ap); /* flush */
+
+                /* interrupt handler takes over from here */
         }
 
+        spin_unlock_irqrestore(&ap->host_set->lock, flags);
+
         return;
 
 err_out:
-        ata_poll_qc_complete(qc, ATA_ERR);
+        ata_pio_error(ap);
 }
 
 
diff --git a/include/linux/ata.h b/include/linux/ata.h
index a5b74efab067..6fec2f6f2d59 100644
--- a/include/linux/ata.h
+++ b/include/linux/ata.h
@@ -181,6 +181,7 @@ enum {
         ATA_TFLAG_ISADDR        = (1 << 1), /* enable r/w to nsect/lba regs */
         ATA_TFLAG_DEVICE        = (1 << 2), /* enable r/w to device reg */
         ATA_TFLAG_WRITE         = (1 << 3), /* data dir: host->dev==1 (write) */
+        ATA_TFLAG_POLLING       = (1 << 4), /* set nIEN to 1 and use polling */
 };
 
 enum ata_tf_protocols {
@@ -250,6 +251,8 @@ struct ata_taskfile {
           ((u64) (id)[(n) + 1] << 16) | \
           ((u64) (id)[(n) + 0]) )
 
+#define ata_id_cdb_intr(id)     (((id)[0] & 0x60) == 0x20)
+
 static inline int atapi_cdb_len(u16 *dev_id)
 {
         u16 tmp = dev_id[0] & 0x3;
diff --git a/include/linux/libata.h b/include/linux/libata.h
index bb2d916bce44..9ac2b69df3c1 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -97,6 +97,7 @@ enum {
         ATA_DFLAG_LBA48         = (1 << 0), /* device supports LBA48 */
         ATA_DFLAG_PIO           = (1 << 1), /* device currently in PIO mode */
         ATA_DFLAG_LOCK_SECTORS  = (1 << 2), /* don't adjust max_sectors */
+        ATA_DFLAG_CDB_INTR      = (1 << 3), /* device asserts INTRQ when ready for CDB */
 
         ATA_DEV_UNKNOWN         = 0,    /* unknown device */
         ATA_DEV_ATA             = 1,    /* ATA device */
@@ -115,8 +116,6 @@ enum {
         ATA_FLAG_MMIO           = (1 << 6), /* use MMIO, not PIO */
         ATA_FLAG_SATA_RESET     = (1 << 7), /* use COMRESET */
         ATA_FLAG_PIO_DMA        = (1 << 8), /* PIO cmds via DMA */
-        ATA_FLAG_NOINTR         = (1 << 9), /* FIXME: Remove this once
-                                             * proper HSM is in place. */
 
         ATA_QCFLAG_ACTIVE       = (1 << 1), /* cmd not yet ack'd to scsi lyer */
         ATA_QCFLAG_SG           = (1 << 3), /* have s/g table? */
@@ -165,6 +164,7 @@ enum hsm_task_states {
         HSM_ST_LAST,
         HSM_ST_LAST_POLL,
         HSM_ST_ERR,
+        HSM_ST_FIRST,
 };
 
 /* forward declarations */