[libata] sata_mv: Implement direct FIS transmission via mv_qc_issue_fis().

This is initially needed to work around NCQ errata,
whereby the READ_LOG_EXT command sometimes fails
when issued in the traditional (sff) fashion.

Portions of this code will likely be reused for
implementation of the target mode feature later on.

Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 116 insertions, 0 deletions

diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index 542e244f37ab..8cad3b2fe554 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -1822,6 +1822,105 @@ static u8 mv_sff_check_status(struct ata_port *ap)
 }
 
 /**
+ *      mv_send_fis - Send a FIS, using the "Vendor-Unique FIS" register
+ *      @fis: fis to be sent
+ *      @nwords: number of 32-bit words in the fis
+ */
+static unsigned int mv_send_fis(struct ata_port *ap, u32 *fis, int nwords)
+{
+        void __iomem *port_mmio = mv_ap_base(ap);
+        u32 ifctl, old_ifctl, ifstat;
+        int i, timeout = 200, final_word = nwords - 1;
+
+        /* Initiate FIS transmission mode */
+        old_ifctl = readl(port_mmio + SATA_IFCTL_OFS);
+        ifctl = 0x100 | (old_ifctl & 0xf);
+        writelfl(ifctl, port_mmio + SATA_IFCTL_OFS);
+
+        /* Send all words of the FIS except for the final word */
+        for (i = 0; i < final_word; ++i)
+                writel(fis[i], port_mmio + VENDOR_UNIQUE_FIS_OFS);
+
+        /* Flag end-of-transmission, and then send the final word */
+        writelfl(ifctl | 0x200, port_mmio + SATA_IFCTL_OFS);
+        writelfl(fis[final_word], port_mmio + VENDOR_UNIQUE_FIS_OFS);
+
+        /*
+         * Wait for FIS transmission to complete.
+         * This typically takes just a single iteration.
+         */
+        do {
+                ifstat = readl(port_mmio + SATA_IFSTAT_OFS);
+        } while (!(ifstat & 0x1000) && --timeout);
+
+        /* Restore original port configuration */
+        writelfl(old_ifctl, port_mmio + SATA_IFCTL_OFS);
+
+        /* See if it worked */
+        if ((ifstat & 0x3000) != 0x1000) {
+                ata_port_printk(ap, KERN_WARNING,
+                                "%s transmission error, ifstat=%08x\n",
+                                __func__, ifstat);
+                return AC_ERR_OTHER;
+        }
+        return 0;
+}
+
+/**
+ *      mv_qc_issue_fis - Issue a command directly as a FIS
+ *      @qc: queued command to start
+ *
+ *      Note that the ATA shadow registers are not updated
+ *      after command issue, so the device will appear "READY"
+ *      if polled, even while it is BUSY processing the command.
+ *
+ *      So we use a status hook to fake ATA_BUSY until the drive changes state.
+ *
+ *      Note: we don't get updated shadow regs on *completion*
+ *      of non-data commands. So avoid sending them via this function,
+ *      as they will appear to have completed immediately.
+ *
+ *      GEN_IIE has special registers that we could get the result tf from,
+ *      but earlier chipsets do not.  For now, we ignore those registers.
+ */
+static unsigned int mv_qc_issue_fis(struct ata_queued_cmd *qc)
+{
+        struct ata_port *ap = qc->ap;
+        struct mv_port_priv *pp = ap->private_data;
+        struct ata_link *link = qc->dev->link;
+        u32 fis[5];
+        int err = 0;
+
+        ata_tf_to_fis(&qc->tf, link->pmp, 1, (void *)fis);
+        err = mv_send_fis(ap, fis, sizeof(fis) / sizeof(fis[0]));
+        if (err)
+                return err;
+
+        switch (qc->tf.protocol) {
+        case ATAPI_PROT_PIO:
+                pp->pp_flags |= MV_PP_FLAG_FAKE_ATA_BUSY;
+                /* fall through */
+        case ATAPI_PROT_NODATA:
+                ap->hsm_task_state = HSM_ST_FIRST;
+                break;
+        case ATA_PROT_PIO:
+                pp->pp_flags |= MV_PP_FLAG_FAKE_ATA_BUSY;
+                if (qc->tf.flags & ATA_TFLAG_WRITE)
+                        ap->hsm_task_state = HSM_ST_FIRST;
+                else
+                        ap->hsm_task_state = HSM_ST;
+                break;
+        default:
+                ap->hsm_task_state = HSM_ST_LAST;
+                break;
+        }
+
+        if (qc->tf.flags & ATA_TFLAG_POLLING)
+                ata_pio_queue_task(ap, qc, 0);
+        return 0;
+}
+
+/**
  *      mv_qc_issue - Initiate a command to the host
  *      @qc: queued command to start
  *
@@ -1896,6 +1995,23 @@ static unsigned int mv_qc_issue(struct ata_queued_cmd *qc)
         mv_stop_edma(ap);
         mv_clear_and_enable_port_irqs(ap, mv_ap_base(ap), port_irqs);
         mv_pmp_select(ap, qc->dev->link->pmp);
+
+        if (qc->tf.command == ATA_CMD_READ_LOG_EXT) {
+                struct mv_host_priv *hpriv = ap->host->private_data;
+                /*
+                 * Workaround for 88SX60x1 FEr SATA#25 (part 2).
+                 * 
+                 * After any NCQ error, the READ_LOG_EXT command
+                 * from libata-eh *must* use mv_qc_issue_fis().
+                 * Otherwise it might fail, due to chip errata.
+                 *
+                 * Rather than special-case it, we'll just *always*
+                 * use this method here for READ_LOG_EXT, making for
+                 * easier testing.
+                 */
+                if (IS_GEN_II(hpriv))
+                        return mv_qc_issue_fis(qc);
+        }
         return ata_sff_qc_issue(qc);
 }