+static int adma_enabled = 1;
+
+static int nv_adma_slave_config(struct scsi_device *sdev)
+{
+ struct ata_port *ap = ata_shost_to_port(sdev->host);
+ u64 bounce_limit;
+ unsigned long segment_boundary;
+ unsigned short sg_tablesize;
+ int rc;
+
+ rc = ata_scsi_slave_config(sdev);
+
+ if (sdev->id >= ATA_MAX_DEVICES || sdev->channel || sdev->lun)
+ /* Not a proper libata device, ignore */
+ return rc;
+
+ if (ap->device[sdev->id].class == ATA_DEV_ATAPI) {
+ /*
+ * NVIDIA reports that ADMA mode does not support ATAPI commands.
+ * Therefore ATAPI commands are sent through the legacy interface.
+ * However, the legacy interface only supports 32-bit DMA.
+ * Restrict DMA parameters as required by the legacy interface
+ * when an ATAPI device is connected.
+ */
+ bounce_limit = ATA_DMA_MASK;
+ segment_boundary = ATA_DMA_BOUNDARY;
+ /* Subtract 1 since an extra entry may be needed for padding, see
+ libata-scsi.c */
+ sg_tablesize = LIBATA_MAX_PRD - 1;
+ }
+ else {
+ bounce_limit = *ap->dev->dma_mask;
+ segment_boundary = NV_ADMA_DMA_BOUNDARY;
+ sg_tablesize = NV_ADMA_SGTBL_TOTAL_LEN;
+ }
+
+ blk_queue_bounce_limit(sdev->request_queue, bounce_limit);
+ blk_queue_segment_boundary(sdev->request_queue, segment_boundary);
+ blk_queue_max_hw_segments(sdev->request_queue, sg_tablesize);
+ ata_port_printk(ap, KERN_INFO,
+ "bounce limit 0x%llX, segment boundary 0x%lX, hw segs %hu\n",
+ (unsigned long long)bounce_limit, segment_boundary, sg_tablesize);
+ return rc;
+}
+
+static unsigned int nv_adma_tf_to_cpb(struct ata_taskfile *tf, u16 *cpb)
+{
+ unsigned int idx = 0;
+
+ cpb[idx++] = cpu_to_le16((ATA_REG_DEVICE << 8) | tf->device | WNB);
+
+ if ((tf->flags & ATA_TFLAG_LBA48) == 0) {
+ cpb[idx++] = cpu_to_le16(IGN);
+ cpb[idx++] = cpu_to_le16(IGN);
+ cpb[idx++] = cpu_to_le16(IGN);
+ cpb[idx++] = cpu_to_le16(IGN);
+ cpb[idx++] = cpu_to_le16(IGN);
+ }
+ else {
+ cpb[idx++] = cpu_to_le16((ATA_REG_ERR << 8) | tf->hob_feature);
+ cpb[idx++] = cpu_to_le16((ATA_REG_NSECT << 8) | tf->hob_nsect);
+ cpb[idx++] = cpu_to_le16((ATA_REG_LBAL << 8) | tf->hob_lbal);
+ cpb[idx++] = cpu_to_le16((ATA_REG_LBAM << 8) | tf->hob_lbam);
+ cpb[idx++] = cpu_to_le16((ATA_REG_LBAH << 8) | tf->hob_lbah);
+ }
+ cpb[idx++] = cpu_to_le16((ATA_REG_ERR << 8) | tf->feature);
+ cpb[idx++] = cpu_to_le16((ATA_REG_NSECT << 8) | tf->nsect);
+ cpb[idx++] = cpu_to_le16((ATA_REG_LBAL << 8) | tf->lbal);
+ cpb[idx++] = cpu_to_le16((ATA_REG_LBAM << 8) | tf->lbam);
+ cpb[idx++] = cpu_to_le16((ATA_REG_LBAH << 8) | tf->lbah);
+
+ cpb[idx++] = cpu_to_le16((ATA_REG_CMD << 8) | tf->command | CMDEND);
+
+ return idx;
+}
+
+static inline void __iomem *__nv_adma_ctl_block(void __iomem *mmio,
+ unsigned int port_no)
+{
+ mmio += NV_ADMA_PORT + port_no * NV_ADMA_PORT_SIZE;
+ return mmio;
+}
+
+static inline void __iomem *nv_adma_ctl_block(struct ata_port *ap)
+{
+ return __nv_adma_ctl_block(ap->host->mmio_base, ap->port_no);
+}
+
+static inline void __iomem *nv_adma_gen_block(struct ata_port *ap)
+{
+ return (ap->host->mmio_base + NV_ADMA_GEN);
+}
+
+static inline void __iomem *nv_adma_notifier_clear_block(struct ata_port *ap)
+{
+ return (nv_adma_gen_block(ap) + NV_ADMA_NOTIFIER_CLEAR + (4 * ap->port_no));
+}
+
+static void nv_adma_check_cpb(struct ata_port *ap, int cpb_num, int force_err)
+{
+ struct nv_adma_port_priv *pp = ap->private_data;
+ int complete = 0, have_err = 0;
+ u16 flags = pp->cpb[cpb_num].resp_flags;
+
+ VPRINTK("CPB %d, flags=0x%x\n", cpb_num, flags);
+
+ if (flags & NV_CPB_RESP_DONE) {
+ VPRINTK("CPB flags done, flags=0x%x\n", flags);
+ complete = 1;
+ }
+ if (flags & NV_CPB_RESP_ATA_ERR) {
+ ata_port_printk(ap, KERN_ERR, "CPB flags ATA err, flags=0x%x\n", flags);
+ have_err = 1;
+ complete = 1;
+ }
+ if (flags & NV_CPB_RESP_CMD_ERR) {
+ ata_port_printk(ap, KERN_ERR, "CPB flags CMD err, flags=0x%x\n", flags);
+ have_err = 1;
+ complete = 1;
+ }
+ if (flags & NV_CPB_RESP_CPB_ERR) {
+ ata_port_printk(ap, KERN_ERR, "CPB flags CPB err, flags=0x%x\n", flags);
+ have_err = 1;
+ complete = 1;
+ }
+ if(complete || force_err)
+ {
+ struct ata_queued_cmd *qc = ata_qc_from_tag(ap, cpb_num);
+ if(likely(qc)) {
+ u8 ata_status = 0;
+ /* Only use the ATA port status for non-NCQ commands.
+ For NCQ commands the current status may have nothing to do with
+ the command just completed. */
+ if(qc->tf.protocol != ATA_PROT_NCQ)
+ ata_status = readb(nv_adma_ctl_block(ap) + (ATA_REG_STATUS * 4));
+
+ if(have_err || force_err)
+ ata_status |= ATA_ERR;
+
+ qc->err_mask |= ac_err_mask(ata_status);
+ DPRINTK("Completing qc from tag %d with err_mask %u\n",cpb_num,
+ qc->err_mask);
+ ata_qc_complete(qc);
+ }
+ }
+}
+
+static irqreturn_t nv_adma_interrupt(int irq, void *dev_instance)
+{
+ struct ata_host *host = dev_instance;
+ int i, handled = 0;
+
+ spin_lock(&host->lock);
+
+ for (i = 0; i < host->n_ports; i++) {
+ struct ata_port *ap = host->ports[i];
+
+ if (ap && !(ap->flags & ATA_FLAG_DISABLED)) {
+ struct nv_adma_port_priv *pp = ap->private_data;
+ void __iomem *mmio = nv_adma_ctl_block(ap);
+ u16 status;
+ u32 gen_ctl;
+ int have_global_err = 0;
+ u32 notifier, notifier_error;
+
+ /* if in ATA register mode, use standard ata interrupt handler */
+ if (pp->flags & NV_ADMA_PORT_REGISTER_MODE) {
+ struct ata_queued_cmd *qc;
+ VPRINTK("in ATA register mode\n");
+ qc = ata_qc_from_tag(ap, ap->active_tag);
+ if (qc && (!(qc->tf.flags & ATA_TFLAG_POLLING)))
+ handled += ata_host_intr(ap, qc);
+ else {
+ /* No request pending? Clear interrupt status
+ anyway, in case there's one pending. */
+ ap->ops->check_status(ap);
+ handled++;
+ }
+ continue;
+ }
+
+ notifier = readl(mmio + NV_ADMA_NOTIFIER);
+ notifier_error = readl(mmio + NV_ADMA_NOTIFIER_ERROR);
+
+ gen_ctl = readl(nv_adma_gen_block(ap) + NV_ADMA_GEN_CTL);
+
+ /* Seems necessary to clear notifiers even when they were 0.
+ Otherwise we seem to stop receiving further interrupts.
+ Unsure why. */
+ writel(notifier | notifier_error, nv_adma_notifier_clear_block(ap));
+
+ if( !NV_ADMA_CHECK_INTR(gen_ctl, ap->port_no) && !notifier &&
+ !notifier_error)
+ /* Nothing to do */
+ continue;
+
+ status = readw(mmio + NV_ADMA_STAT);
+
+ /* Clear status. Ensure the controller sees the clearing before we start
+ looking at any of the CPB statuses, so that any CPB completions after
+ this point in the handler will raise another interrupt. */
+ writew(status, mmio + NV_ADMA_STAT);
+ readw(mmio + NV_ADMA_STAT); /* flush posted write */
+ rmb();
+
+ /* freeze if hotplugged */
+ if (unlikely(status & (NV_ADMA_STAT_HOTPLUG | NV_ADMA_STAT_HOTUNPLUG))) {
+ ata_port_printk(ap, KERN_NOTICE, "Hotplug event, freezing\n");
+ ata_port_freeze(ap);
+ handled++;
+ continue;
+ }
+
+ if (status & NV_ADMA_STAT_TIMEOUT) {
+ ata_port_printk(ap, KERN_ERR, "timeout, stat=0x%x\n", status);
+ have_global_err = 1;
+ }
+ if (status & NV_ADMA_STAT_CPBERR) {
+ ata_port_printk(ap, KERN_ERR, "CPB error, stat=0x%x\n", status);
+ have_global_err = 1;
+ }
+ if ((status & NV_ADMA_STAT_DONE) || have_global_err) {
+ /** Check CPBs for completed commands */
+
+ if(ata_tag_valid(ap->active_tag))
+ /* Non-NCQ command */
+ nv_adma_check_cpb(ap, ap->active_tag, have_global_err ||
+ (notifier_error & (1 << ap->active_tag)));
+ else {
+ int pos;
+ u32 active = ap->sactive;
+ while( (pos = ffs(active)) ) {
+ pos--;
+ nv_adma_check_cpb(ap, pos, have_global_err ||
+ (notifier_error & (1 << pos)) );
+ active &= ~(1 << pos );
+ }
+ }
+ }
+
+ handled++; /* irq handled if we got here */
+ }
+ }
+
+ spin_unlock(&host->lock);
+
+ return IRQ_RETVAL(handled);
+}
+
+static void nv_adma_irq_clear(struct ata_port *ap)
+{
+ void __iomem *mmio = nv_adma_ctl_block(ap);
+ u16 status = readw(mmio + NV_ADMA_STAT);
+ u32 notifier = readl(mmio + NV_ADMA_NOTIFIER);
+ u32 notifier_error = readl(mmio + NV_ADMA_NOTIFIER_ERROR);
+
+ /* clear ADMA status */
+ writew(status, mmio + NV_ADMA_STAT);
+ writel(notifier | notifier_error,
+ nv_adma_notifier_clear_block(ap));
+
+ /** clear legacy status */
+ ap->flags &= ~ATA_FLAG_MMIO;
+ ata_bmdma_irq_clear(ap);
+ ap->flags |= ATA_FLAG_MMIO;
+}
+
+static void nv_adma_bmdma_setup(struct ata_queued_cmd *qc)
+{
+ struct nv_adma_port_priv *pp = qc->ap->private_data;
+
+ if(pp->flags & NV_ADMA_PORT_REGISTER_MODE) {
+ WARN_ON(1);
+ return;
+ }
+
+ qc->ap->flags &= ~ATA_FLAG_MMIO;
+ ata_bmdma_setup(qc);
+ qc->ap->flags |= ATA_FLAG_MMIO;
+}
+
+static void nv_adma_bmdma_start(struct ata_queued_cmd *qc)
+{
+ struct nv_adma_port_priv *pp = qc->ap->private_data;
+
+ if(pp->flags & NV_ADMA_PORT_REGISTER_MODE) {
+ WARN_ON(1);
+ return;
+ }
+
+ qc->ap->flags &= ~ATA_FLAG_MMIO;
+ ata_bmdma_start(qc);
+ qc->ap->flags |= ATA_FLAG_MMIO;
+}
+
+static void nv_adma_bmdma_stop(struct ata_queued_cmd *qc)
+{
+ struct nv_adma_port_priv *pp = qc->ap->private_data;
+
+ if(pp->flags & NV_ADMA_PORT_REGISTER_MODE)
+ return;
+
+ qc->ap->flags &= ~ATA_FLAG_MMIO;
+ ata_bmdma_stop(qc);
+ qc->ap->flags |= ATA_FLAG_MMIO;
+}
+
+static u8 nv_adma_bmdma_status(struct ata_port *ap)
+{
+ u8 status;
+ struct nv_adma_port_priv *pp = ap->private_data;
+
+ WARN_ON(pp->flags & NV_ADMA_PORT_REGISTER_MODE);
+
+ ap->flags &= ~ATA_FLAG_MMIO;
+ status = ata_bmdma_status(ap);
+ ap->flags |= ATA_FLAG_MMIO;
+ return status;
+}
+
+static void nv_adma_register_mode(struct ata_port *ap)
+{
+ void __iomem *mmio = nv_adma_ctl_block(ap);
+ struct nv_adma_port_priv *pp = ap->private_data;
+ u16 tmp;
+
+ if (pp->flags & NV_ADMA_PORT_REGISTER_MODE)
+ return;
+
+ tmp = readw(mmio + NV_ADMA_CTL);
+ writew(tmp & ~NV_ADMA_CTL_GO, mmio + NV_ADMA_CTL);
+
+ pp->flags |= NV_ADMA_PORT_REGISTER_MODE;
+}
+
+static void nv_adma_mode(struct ata_port *ap)
+{
+ void __iomem *mmio = nv_adma_ctl_block(ap);
+ struct nv_adma_port_priv *pp = ap->private_data;
+ u16 tmp;
+
+ if (!(pp->flags & NV_ADMA_PORT_REGISTER_MODE))
+ return;
+
+ tmp = readw(mmio + NV_ADMA_CTL);
+ writew(tmp | NV_ADMA_CTL_GO, mmio + NV_ADMA_CTL);
+
+ pp->flags &= ~NV_ADMA_PORT_REGISTER_MODE;
+}
+
+static int nv_adma_port_start(struct ata_port *ap)
+{
+ struct device *dev = ap->host->dev;
+ struct nv_adma_port_priv *pp;
+ int rc;
+ void *mem;
+ dma_addr_t mem_dma;
+ void __iomem *mmio = nv_adma_ctl_block(ap);
+ u16 tmp;
+
+ VPRINTK("ENTER\n");
+
+ rc = ata_port_start(ap);
+ if (rc)
+ return rc;
+
+ pp = kzalloc(sizeof(*pp), GFP_KERNEL);
+ if (!pp) {
+ rc = -ENOMEM;
+ goto err_out;
+ }
+
+ mem = dma_alloc_coherent(dev, NV_ADMA_PORT_PRIV_DMA_SZ,
+ &mem_dma, GFP_KERNEL);
+
+ if (!mem) {
+ rc = -ENOMEM;
+ goto err_out_kfree;
+ }
+ memset(mem, 0, NV_ADMA_PORT_PRIV_DMA_SZ);
+
+ /*
+ * First item in chunk of DMA memory:
+ * 128-byte command parameter block (CPB)
+ * one for each command tag
+ */
+ pp->cpb = mem;
+ pp->cpb_dma = mem_dma;
+
+ writel(mem_dma & 0xFFFFFFFF, mmio + NV_ADMA_CPB_BASE_LOW);
+ writel((mem_dma >> 16 ) >> 16, mmio + NV_ADMA_CPB_BASE_HIGH);
+
+ mem += NV_ADMA_MAX_CPBS * NV_ADMA_CPB_SZ;
+ mem_dma += NV_ADMA_MAX_CPBS * NV_ADMA_CPB_SZ;
+
+ /*
+ * Second item: block of ADMA_SGTBL_LEN s/g entries
+ */
+ pp->aprd = mem;
+ pp->aprd_dma = mem_dma;
+
+ ap->private_data = pp;
+
+ /* clear any outstanding interrupt conditions */
+ writew(0xffff, mmio + NV_ADMA_STAT);
+
+ /* initialize port variables */
+ pp->flags = NV_ADMA_PORT_REGISTER_MODE;
+
+ /* clear CPB fetch count */
+ writew(0, mmio + NV_ADMA_CPB_COUNT);
+
+ /* clear GO for register mode */
+ tmp = readw(mmio + NV_ADMA_CTL);
+ writew(tmp & ~NV_ADMA_CTL_GO, mmio + NV_ADMA_CTL);
+
+ tmp = readw(mmio + NV_ADMA_CTL);
+ writew(tmp | NV_ADMA_CTL_CHANNEL_RESET, mmio + NV_ADMA_CTL);
+ readl( mmio + NV_ADMA_CTL ); /* flush posted write */
+ udelay(1);
+ writew(tmp & ~NV_ADMA_CTL_CHANNEL_RESET, mmio + NV_ADMA_CTL);
+ readl( mmio + NV_ADMA_CTL ); /* flush posted write */
+
+ return 0;
+
+err_out_kfree:
+ kfree(pp);
+err_out:
+ ata_port_stop(ap);
+ return rc;
+}
+
+static void nv_adma_port_stop(struct ata_port *ap)
+{
+ struct device *dev = ap->host->dev;
+ struct nv_adma_port_priv *pp = ap->private_data;
+ void __iomem *mmio = nv_adma_ctl_block(ap);
+
+ VPRINTK("ENTER\n");
+
+ writew(0, mmio + NV_ADMA_CTL);
+
+ ap->private_data = NULL;
+ dma_free_coherent(dev, NV_ADMA_PORT_PRIV_DMA_SZ, pp->cpb, pp->cpb_dma);
+ kfree(pp);
+ ata_port_stop(ap);
+}
+
+
+static void nv_adma_setup_port(struct ata_probe_ent *probe_ent, unsigned int port)
+{
+ void __iomem *mmio = probe_ent->mmio_base;
+ struct ata_ioports *ioport = &probe_ent->port[port];
+
+ VPRINTK("ENTER\n");
+
+ mmio += NV_ADMA_PORT + port * NV_ADMA_PORT_SIZE;
+
+ ioport->cmd_addr = (unsigned long) mmio;
+ ioport->data_addr = (unsigned long) mmio + (ATA_REG_DATA * 4);
+ ioport->error_addr =
+ ioport->feature_addr = (unsigned long) mmio + (ATA_REG_ERR * 4);
+ ioport->nsect_addr = (unsigned long) mmio + (ATA_REG_NSECT * 4);
+ ioport->lbal_addr = (unsigned long) mmio + (ATA_REG_LBAL * 4);
+ ioport->lbam_addr = (unsigned long) mmio + (ATA_REG_LBAM * 4);
+ ioport->lbah_addr = (unsigned long) mmio + (ATA_REG_LBAH * 4);
+ ioport->device_addr = (unsigned long) mmio + (ATA_REG_DEVICE * 4);
+ ioport->status_addr =
+ ioport->command_addr = (unsigned long) mmio + (ATA_REG_STATUS * 4);
+ ioport->altstatus_addr =
+ ioport->ctl_addr = (unsigned long) mmio + 0x20;
+}
+
+static int nv_adma_host_init(struct ata_probe_ent *probe_ent)
+{
+ struct pci_dev *pdev = to_pci_dev(probe_ent->dev);
+ unsigned int i;
+ u32 tmp32;
+
+ VPRINTK("ENTER\n");
+
+ /* enable ADMA on the ports */
+ pci_read_config_dword(pdev, NV_MCP_SATA_CFG_20, &tmp32);
+ tmp32 |= NV_MCP_SATA_CFG_20_PORT0_EN |
+ NV_MCP_SATA_CFG_20_PORT0_PWB_EN |
+ NV_MCP_SATA_CFG_20_PORT1_EN |
+ NV_MCP_SATA_CFG_20_PORT1_PWB_EN;
+
+ pci_write_config_dword(pdev, NV_MCP_SATA_CFG_20, tmp32);
+
+ for (i = 0; i < probe_ent->n_ports; i++)
+ nv_adma_setup_port(probe_ent, i);
+
+ for (i = 0; i < probe_ent->n_ports; i++) {
+ void __iomem *mmio = __nv_adma_ctl_block(probe_ent->mmio_base, i);
+ u16 tmp;
+
+ /* enable interrupt, clear reset if not already clear */
+ tmp = readw(mmio + NV_ADMA_CTL);
+ writew(tmp | NV_ADMA_CTL_AIEN, mmio + NV_ADMA_CTL);
+ }
+
+ return 0;
+}
+
+static void nv_adma_fill_aprd(struct ata_queued_cmd *qc,
+ struct scatterlist *sg,
+ int idx,
+ struct nv_adma_prd *aprd)
+{
+ u32 flags;
+
+ memset(aprd, 0, sizeof(struct nv_adma_prd));
+
+ flags = 0;
+ if (qc->tf.flags & ATA_TFLAG_WRITE)
+ flags |= NV_APRD_WRITE;
+ if (idx == qc->n_elem - 1)
+ flags |= NV_APRD_END;
+ else if (idx != 4)
+ flags |= NV_APRD_CONT;
+
+ aprd->addr = cpu_to_le64(((u64)sg_dma_address(sg)));
+ aprd->len = cpu_to_le32(((u32)sg_dma_len(sg))); /* len in bytes */
+ aprd->flags = cpu_to_le32(flags);
+}
+
+static void nv_adma_fill_sg(struct ata_queued_cmd *qc, struct nv_adma_cpb *cpb)
+{
+ struct nv_adma_port_priv *pp = qc->ap->private_data;
+ unsigned int idx;
+ struct nv_adma_prd *aprd;
+ struct scatterlist *sg;
+
+ VPRINTK("ENTER\n");
+
+ idx = 0;
+
+ ata_for_each_sg(sg, qc) {
+ aprd = (idx < 5) ? &cpb->aprd[idx] : &pp->aprd[NV_ADMA_SGTBL_LEN * qc->tag + (idx-5)];
+ nv_adma_fill_aprd(qc, sg, idx, aprd);
+ idx++;
+ }
+ if (idx > 5)
+ cpb->next_aprd = cpu_to_le64(((u64)(pp->aprd_dma + NV_ADMA_SGTBL_SZ * qc->tag)));
+}
+
+static void nv_adma_qc_prep(struct ata_queued_cmd *qc)
+{
+ struct nv_adma_port_priv *pp = qc->ap->private_data;
+ struct nv_adma_cpb *cpb = &pp->cpb[qc->tag];
+ u8 ctl_flags = NV_CPB_CTL_CPB_VALID |
+ NV_CPB_CTL_APRD_VALID |
+ NV_CPB_CTL_IEN;
+
+ VPRINTK("qc->flags = 0x%lx\n", qc->flags);
+
+ if (!(qc->flags & ATA_QCFLAG_DMAMAP) ||
+ qc->tf.protocol == ATA_PROT_ATAPI_DMA) {
+ ata_qc_prep(qc);
+ return;
+ }
+
+ memset(cpb, 0, sizeof(struct nv_adma_cpb));
+
+ cpb->len = 3;
+ cpb->tag = qc->tag;
+ cpb->next_cpb_idx = 0;
+
+ /* turn on NCQ flags for NCQ commands */
+ if (qc->tf.protocol == ATA_PROT_NCQ)
+ ctl_flags |= NV_CPB_CTL_QUEUE | NV_CPB_CTL_FPDMA;
+
+ nv_adma_tf_to_cpb(&qc->tf, cpb->tf);
+
+ nv_adma_fill_sg(qc, cpb);
+
+ /* Be paranoid and don't let the device see NV_CPB_CTL_CPB_VALID until we are
+ finished filling in all of the contents */
+ wmb();
+ cpb->ctl_flags = ctl_flags;
+}
+
+static unsigned int nv_adma_qc_issue(struct ata_queued_cmd *qc)
+{
+ void __iomem *mmio = nv_adma_ctl_block(qc->ap);
+
+ VPRINTK("ENTER\n");
+
+ if (!(qc->flags & ATA_QCFLAG_DMAMAP) ||
+ qc->tf.protocol == ATA_PROT_ATAPI_DMA) {
+ /* use ATA register mode */
+ VPRINTK("no dmamap or ATAPI, using ATA register mode: 0x%lx\n", qc->flags);
+ nv_adma_register_mode(qc->ap);
+ return ata_qc_issue_prot(qc);
+ } else
+ nv_adma_mode(qc->ap);
+
+ /* write append register, command tag in lower 8 bits
+ and (number of cpbs to append -1) in top 8 bits */
+ wmb();
+ writew(qc->tag, mmio + NV_ADMA_APPEND);
+
+ DPRINTK("Issued tag %u\n",qc->tag);
+
+ return 0;
+}
+