ata_piix: drop merged SCR access and use slave_link instead

Now that libata has slave_link, there's no need to keep ugly merged
SCR access.  Drop it and use slave_link instead.  This results in
simpler code and much better separate link handling for master and
slave.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 40 insertions, 127 deletions

diff --git a/drivers/ata/ata_piix.c b/drivers/ata/ata_piix.c
index 81387ff48937..9d8cb804ee2b 100644
--- a/drivers/ata/ata_piix.c
+++ b/drivers/ata/ata_piix.c
@@ -887,23 +887,9 @@ static void ich_set_dmamode(struct ata_port *ap, struct ata_device *adev)
  * Serial ATA Index/Data Pair Superset Registers access
  *
  * Beginning from ICH8, there's a sane way to access SCRs using index
- * and data register pair located at BAR5.  This creates an
- * interesting problem of mapping two SCRs to one port.
- *
- * Although they have separate SCRs, the master and slave aren't
- * independent enough to be treated as separate links - e.g. softreset
- * resets both.  Also, there's no protocol defined for hard resetting
- * singled device sharing the virtual port (no defined way to acquire
- * device signature).  This is worked around by merging the SCR values
- * into one sensible value and requesting follow-up SRST after
- * hardreset.
- *
- * SCR merging is perfomed in nibbles which is the unit contents in
- * SCRs are organized.  If two values are equal, the value is used.
- * When they differ, merge table which lists precedence of possible
- * values is consulted and the first match or the last entry when
- * nothing matches is used.  When there's no merge table for the
- * specific nibble, value from the first port is used.
+ * and data register pair located at BAR5 which means that we have
+ * separate SCRs for master and slave.  This is handled using libata
+ * slave_link facility.
  */
 static const int piix_sidx_map[] = {
         [SCR_STATUS]    = 0,
@@ -911,125 +897,38 @@ static const int piix_sidx_map[] = {
         [SCR_CONTROL]   = 1,
 };
 
-static void piix_sidpr_sel(struct ata_device *dev, unsigned int reg)
+static void piix_sidpr_sel(struct ata_link *link, unsigned int reg)
 {
-        struct ata_port *ap = dev->link->ap;
+        struct ata_port *ap = link->ap;
         struct piix_host_priv *hpriv = ap->host->private_data;
 
-        iowrite32(((ap->port_no * 2 + dev->devno) << 8) | piix_sidx_map[reg],
+        iowrite32(((ap->port_no * 2 + link->pmp) << 8) | piix_sidx_map[reg],
                   hpriv->sidpr + PIIX_SIDPR_IDX);
 }
 
-static int piix_sidpr_read(struct ata_device *dev, unsigned int reg)
-{
-        struct piix_host_priv *hpriv = dev->link->ap->host->private_data;
-
-        piix_sidpr_sel(dev, reg);
-        return ioread32(hpriv->sidpr + PIIX_SIDPR_DATA);
-}
-
-static void piix_sidpr_write(struct ata_device *dev, unsigned int reg, u32 val)
-{
-        struct piix_host_priv *hpriv = dev->link->ap->host->private_data;
-
-        piix_sidpr_sel(dev, reg);
-        iowrite32(val, hpriv->sidpr + PIIX_SIDPR_DATA);
-}
-
-static u32 piix_merge_scr(u32 val0, u32 val1, const int * const *merge_tbl)
-{
-        u32 val = 0;
-        int i, mi;
-
-        for (i = 0, mi = 0; i < 32 / 4; i++) {
-                u8 c0 = (val0 >> (i * 4)) & 0xf;
-                u8 c1 = (val1 >> (i * 4)) & 0xf;
-                u8 merged = c0;
-                const int *cur;
-
-                /* if no merge preference, assume the first value */
-                cur = merge_tbl[mi];
-                if (!cur)
-                        goto done;
-                mi++;
-
-                /* if two values equal, use it */
-                if (c0 == c1)
-                        goto done;
-
-                /* choose the first match or the last from the merge table */
-                while (*cur != -1) {
-                        if (c0 == *cur || c1 == *cur)
-                                break;
-                        cur++;
-                }
-                if (*cur == -1)
-                        cur--;
-                merged = *cur;
-        done:
-                val |= merged << (i * 4);
-        }
-
-        return val;
-}
-
 static int piix_sidpr_scr_read(struct ata_link *link,
                                unsigned int reg, u32 *val)
 {
-        struct ata_port *ap = link->ap;
-        const int * const sstatus_merge_tbl[] = {
-                /* DET */ (const int []){ 1, 3, 0, 4, 3, -1 },
-                /* SPD */ (const int []){ 2, 1, 0, -1 },
-                /* IPM */ (const int []){ 6, 2, 1, 0, -1 },
-                NULL,
-        };
-        const int * const scontrol_merge_tbl[] = {
-                /* DET */ (const int []){ 1, 0, 4, 0, -1 },
-                /* SPD */ (const int []){ 0, 2, 1, 0, -1 },
-                /* IPM */ (const int []){ 0, 1, 2, 3, 0, -1 },
-                NULL,
-        };
-        u32 v0, v1;
+        struct piix_host_priv *hpriv = link->ap->host->private_data;
 
         if (reg >= ARRAY_SIZE(piix_sidx_map))
                 return -EINVAL;
 
-        if (!(ap->flags & ATA_FLAG_SLAVE_POSS)) {
-                *val = piix_sidpr_read(&ap->link.device[0], reg);
-                return 0;
-        }
-
-        v0 = piix_sidpr_read(&ap->link.device[0], reg);
-        v1 = piix_sidpr_read(&ap->link.device[1], reg);
-
-        switch (reg) {
-        case SCR_STATUS:
-                *val = piix_merge_scr(v0, v1, sstatus_merge_tbl);
-                break;
-        case SCR_ERROR:
-                *val = v0 | v1;
-                break;
-        case SCR_CONTROL:
-                *val = piix_merge_scr(v0, v1, scontrol_merge_tbl);
-                break;
-        }
-
+        piix_sidpr_sel(link, reg);
+        *val = ioread32(hpriv->sidpr + PIIX_SIDPR_DATA);
         return 0;
 }
 
 static int piix_sidpr_scr_write(struct ata_link *link,
                                 unsigned int reg, u32 val)
 {
-        struct ata_port *ap = link->ap;
+        struct piix_host_priv *hpriv = link->ap->host->private_data;
 
         if (reg >= ARRAY_SIZE(piix_sidx_map))
                 return -EINVAL;
 
-        piix_sidpr_write(&ap->link.device[0], reg, val);
-
-        if (ap->flags & ATA_FLAG_SLAVE_POSS)
-                piix_sidpr_write(&ap->link.device[1], reg, val);
-
+        piix_sidpr_sel(link, reg);
+        iowrite32(val, hpriv->sidpr + PIIX_SIDPR_DATA);
         return 0;
 }
 
@@ -1370,28 +1269,28 @@ static const int *__devinit piix_init_sata_map(struct pci_dev *pdev,
         return map;
 }
 
-static void __devinit piix_init_sidpr(struct ata_host *host)
+static int __devinit piix_init_sidpr(struct ata_host *host)
 {
         struct pci_dev *pdev = to_pci_dev(host->dev);
         struct piix_host_priv *hpriv = host->private_data;
-        struct ata_device *dev0 = &host->ports[0]->link.device[0];
+        struct ata_link *link0 = &host->ports[0]->link;
         u32 scontrol;
-        int i;
+        int i, rc;
 
         /* check for availability */
         for (i = 0; i < 4; i++)
                 if (hpriv->map[i] == IDE)
-                        return;
+                        return 0;
 
         if (!(host->ports[0]->flags & PIIX_FLAG_SIDPR))
-                return;
+                return 0;
 
         if (pci_resource_start(pdev, PIIX_SIDPR_BAR) == 0 ||
             pci_resource_len(pdev, PIIX_SIDPR_BAR) != PIIX_SIDPR_LEN)
-                return;
+                return 0;
 
         if (pcim_iomap_regions(pdev, 1 << PIIX_SIDPR_BAR, DRV_NAME))
-                return;
+                return 0;
 
         hpriv->sidpr = pcim_iomap_table(pdev)[PIIX_SIDPR_BAR];
 
@@ -1399,7 +1298,7 @@ static void __devinit piix_init_sidpr(struct ata_host *host)
          * Give it a test drive by inhibiting power save modes which
          * we'll do anyway.
          */
-        scontrol = piix_sidpr_read(dev0, SCR_CONTROL);
+        piix_sidpr_scr_read(link0, SCR_CONTROL, &scontrol);
 
         /* if IPM is already 3, SCR access is probably working.  Don't
          * un-inhibit power save modes as BIOS might have inhibited
@@ -1407,18 +1306,30 @@ static void __devinit piix_init_sidpr(struct ata_host *host)
          */
         if ((scontrol & 0xf00) != 0x300) {
                 scontrol |= 0x300;
-                piix_sidpr_write(dev0, SCR_CONTROL, scontrol);
-                scontrol = piix_sidpr_read(dev0, SCR_CONTROL);
+                piix_sidpr_scr_write(link0, SCR_CONTROL, scontrol);
+                piix_sidpr_scr_read(link0, SCR_CONTROL, &scontrol);
 
                 if ((scontrol & 0xf00) != 0x300) {
                         dev_printk(KERN_INFO, host->dev, "SCR access via "
                                    "SIDPR is available but doesn't work\n");
-                        return;
+                        return 0;
                 }
         }
 
-        host->ports[0]->ops = &piix_sidpr_sata_ops;
-        host->ports[1]->ops = &piix_sidpr_sata_ops;
+        /* okay, SCRs available, set ops and ask libata for slave_link */
+        for (i = 0; i < 2; i++) {
+                struct ata_port *ap = host->ports[i];
+
+                ap->ops = &piix_sidpr_sata_ops;
+
+                if (ap->flags & ATA_FLAG_SLAVE_POSS) {
+                        rc = ata_slave_link_init(ap);
+                        if (rc)
+                                return rc;
+                }
+        }
+
+        return 0;
 }
 
 static void piix_iocfg_bit18_quirk(struct pci_dev *pdev)
@@ -1528,7 +1439,9 @@ static int __devinit piix_init_one(struct pci_dev *pdev,
         /* initialize controller */
         if (port_flags & ATA_FLAG_SATA) {
                 piix_init_pcs(host, piix_map_db_table[ent->driver_data]);
-                piix_init_sidpr(host);
+                rc = piix_init_sidpr(host);
+                if (rc)
+                        return rc;
         }
 
         /* apply IOCFG bit18 quirk */