libata: separate out ata_acpi_gtm_xfermask() from pacpi_discover_modes()

Finding out matching transfer mode from ACPI GTM values is useful for
other purposes too.  Separate out the function and timing tables from
pata_acpi::pacpi_discover_modes().

Other than checking shared-configuration bit after doing
ata_acpi_gtm() in pacpi_discover_modes() which should be safe, this
patch doesn't introduce any behavior change.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

3 files changed, 114 insertions, 55 deletions

diff --git a/drivers/ata/libata-acpi.c b/drivers/ata/libata-acpi.c
index ebc4dfcf2f19..d6697baf243d 100644
--- a/drivers/ata/libata-acpi.c
+++ b/drivers/ata/libata-acpi.c
@@ -441,6 +441,84 @@ static int ata_dev_get_GTF(struct ata_device *dev, struct ata_acpi_gtf **gtf)
         return rc;
 }
 
+/* Welcome to ACPI, bring a bucket */
+const unsigned int ata_acpi_pio_cycle[7] = {
+        600, 383, 240, 180, 120, 100, 80
+};
+EXPORT_SYMBOL_GPL(ata_acpi_pio_cycle);
+
+const unsigned int ata_acpi_mwdma_cycle[5] = {
+        480, 150, 120, 100, 80
+};
+EXPORT_SYMBOL_GPL(ata_acpi_mwdma_cycle);
+
+const unsigned int ata_acpi_udma_cycle[7] = {
+        120, 80, 60, 45, 30, 20, 15
+};
+EXPORT_SYMBOL_GPL(ata_acpi_udma_cycle);
+
+/**
+ * ata_acpi_gtm_xfermode - determine xfermode from GTM parameter
+ * @dev: target device
+ * @gtm: GTM parameter to use
+ *
+ * Determine xfermask for @dev from @gtm.
+ *
+ * LOCKING:
+ * None.
+ *
+ * RETURNS:
+ * Determined xfermask.
+ */
+unsigned long ata_acpi_gtm_xfermask(struct ata_device *dev,
+                                    const struct ata_acpi_gtm *gtm)
+{
+        int unit, i;
+        u32 t;
+        unsigned long mask = (0x7f << ATA_SHIFT_UDMA) | (0x7 << ATA_SHIFT_MWDMA) | (0x1F << ATA_SHIFT_PIO);
+
+        /* we always use the 0 slot for crap hardware */
+        unit = dev->devno;
+        if (!(gtm->flags & 0x10))
+                unit = 0;
+
+        /* start by scanning for PIO modes */
+        for (i = 0; i < 7; i++) {
+                t = gtm->drive[unit].pio;
+                if (t <= ata_acpi_pio_cycle[i]) {
+                        mask |= (2 << (ATA_SHIFT_PIO + i)) - 1;
+                        break;
+                }
+        }
+
+        /* See if we have MWDMA or UDMA data. We don't bother with
+         * MWDMA if UDMA is available as this means the BIOS set UDMA
+         * and our error changedown if it works is UDMA to PIO anyway.
+         */
+        if (gtm->flags & (1 << (2 * unit))) {
+                /* MWDMA */
+                for (i = 0; i < 5; i++) {
+                        t = gtm->drive[unit].dma;
+                        if (t <= ata_acpi_mwdma_cycle[i]) {
+                                mask |= (2 << (ATA_SHIFT_MWDMA + i)) - 1;
+                                break;
+                        }
+                }
+        } else {
+                /* UDMA */
+                for (i = 0; i < 7; i++) {
+                        t = gtm->drive[unit].dma;
+                        if (t <= ata_acpi_udma_cycle[i]) {
+                                mask |= (2 << (ATA_SHIFT_UDMA + i)) - 1;
+                                break;
+                        }
+                }
+        }
+
+        return mask;
+}
+EXPORT_SYMBOL_GPL(ata_acpi_gtm_xfermask);
+
 /**
  * ata_acpi_cbl_80wire          -       Check for 80 wire cable
  * @ap: Port to check
diff --git a/drivers/ata/pata_acpi.c b/drivers/ata/pata_acpi.c
index e4542ab9c7f8..a4737a3d31cb 100644
--- a/drivers/ata/pata_acpi.c
+++ b/drivers/ata/pata_acpi.c
@@ -81,17 +81,6 @@ static void pacpi_error_handler(struct ata_port *ap)
                                   NULL, ata_std_postreset);
 }
 
-/* Welcome to ACPI, bring a bucket */
-static const unsigned int pio_cycle[7] = {
-        600, 383, 240, 180, 120, 100, 80
-};
-static const unsigned int mwdma_cycle[5] = {
-        480, 150, 120, 100, 80
-};
-static const unsigned int udma_cycle[7] = {
-        120, 80, 60, 45, 30, 20, 15
-};
-
 /**
  *      pacpi_discover_modes    -       filter non ACPI modes
  *      @adev: ATA device
@@ -103,56 +92,20 @@ static const unsigned int udma_cycle[7] = {
 
 static unsigned long pacpi_discover_modes(struct ata_port *ap, struct ata_device *adev)
 {
-        int unit = adev->devno;
         struct pata_acpi *acpi = ap->private_data;
-        int i;
-        u32 t;
-        unsigned long mask = (0x7f << ATA_SHIFT_UDMA) | (0x7 << ATA_SHIFT_MWDMA) | (0x1F << ATA_SHIFT_PIO);
-
         struct ata_acpi_gtm probe;
+        unsigned int xfer_mask;
 
         probe = acpi->gtm;
 
-        /* We always use the 0 slot for crap hardware */
-        if (!(probe.flags & 0x10))
-                unit = 0;
-
         ata_acpi_gtm(ap, &probe);
 
-        /* Start by scanning for PIO modes */
-        for (i = 0; i < 7; i++) {
-                t = probe.drive[unit].pio;
-                if (t <= pio_cycle[i]) {
-                        mask |= (2 << (ATA_SHIFT_PIO + i)) - 1;
-                        break;
-                }
-        }
+        xfer_mask = ata_acpi_gtm_xfermask(adev, &probe);
 
-        /* See if we have MWDMA or UDMA data. We don't bother with MWDMA
-           if UDMA is availabe as this means the BIOS set UDMA and our
-           error changedown if it works is UDMA to PIO anyway */
-        if (probe.flags & (1 << (2 * unit))) {
-                /* MWDMA */
-                for (i = 0; i < 5; i++) {
-                        t = probe.drive[unit].dma;
-                        if (t <= mwdma_cycle[i]) {
-                                mask |= (2 << (ATA_SHIFT_MWDMA + i)) - 1;
-                                break;
-                        }
-                }
-        } else {
-                /* UDMA */
-                for (i = 0; i < 7; i++) {
-                        t = probe.drive[unit].dma;
-                        if (t <= udma_cycle[i]) {
-                                mask |= (2 << (ATA_SHIFT_UDMA + i)) - 1;
-                                break;
-                        }
-                }
-        }
-        if (mask & (0xF8 << ATA_SHIFT_UDMA))
+        if (xfer_mask & (0xF8 << ATA_SHIFT_UDMA))
                 ap->cbl = ATA_CBL_PATA80;
-        return mask;
+
+        return xfer_mask;
 }
 
 /**
@@ -185,7 +138,8 @@ static void pacpi_set_piomode(struct ata_port *ap, struct ata_device *adev)
                 unit = 0;
 
         /* Now stuff the nS values into the structure */
-        acpi->gtm.drive[unit].pio = pio_cycle[adev->pio_mode - XFER_PIO_0];
+        acpi->gtm.drive[unit].pio =
+                ata_acpi_pio_cycle[adev->pio_mode - XFER_PIO_0];
         ata_acpi_stm(ap, &acpi->gtm);
         /* See what mode we actually got */
         ata_acpi_gtm(ap, &acpi->gtm);
@@ -207,10 +161,12 @@ static void pacpi_set_dmamode(struct ata_port *ap, struct ata_device *adev)
 
         /* Now stuff the nS values into the structure */
         if (adev->dma_mode >= XFER_UDMA_0) {
-                acpi->gtm.drive[unit].dma = udma_cycle[adev->dma_mode - XFER_UDMA_0];
+                acpi->gtm.drive[unit].dma =
+                        ata_acpi_udma_cycle[adev->dma_mode - XFER_UDMA_0];
                 acpi->gtm.flags |= (1 << (2 * unit));
         } else {
-                acpi->gtm.drive[unit].dma = mwdma_cycle[adev->dma_mode - XFER_MW_DMA_0];
+                acpi->gtm.drive[unit].dma =
+                        ata_acpi_mwdma_cycle[adev->dma_mode - XFER_MW_DMA_0];
                 acpi->gtm.flags &= ~(1 << (2 * unit));
         }
         ata_acpi_stm(ap, &acpi->gtm);
diff --git a/include/linux/libata.h b/include/linux/libata.h
index bdb7c6e13993..8022e5b2224d 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -961,6 +961,10 @@ enum {
 
 /* libata-acpi.c */
 #ifdef CONFIG_ATA_ACPI
+extern const unsigned int ata_acpi_pio_cycle[7];
+extern const unsigned int ata_acpi_mwdma_cycle[5];
+extern const unsigned int ata_acpi_udma_cycle[7];
+
 static inline const struct ata_acpi_gtm *ata_acpi_init_gtm(struct ata_port *ap)
 {
         if (ap->pflags & ATA_PFLAG_INIT_GTM_VALID)
@@ -970,12 +974,33 @@ static inline const struct ata_acpi_gtm *ata_acpi_init_gtm(struct ata_port *ap)
 extern int ata_acpi_cbl_80wire(struct ata_port *ap);
 int ata_acpi_stm(struct ata_port *ap, const struct ata_acpi_gtm *stm);
 int ata_acpi_gtm(struct ata_port *ap, struct ata_acpi_gtm *stm);
+unsigned long ata_acpi_gtm_xfermask(struct ata_device *dev,
+                                    const struct ata_acpi_gtm *gtm);
+
 #else
 static inline const struct ata_acpi_gtm *ata_acpi_init_gtm(struct ata_port *ap)
 {
         return NULL;
 }
 static inline int ata_acpi_cbl_80wire(struct ata_port *ap) { return 0; }
+
+static inline int ata_acpi_stm(const struct ata_port *ap,
+                               struct ata_acpi_gtm *stm)
+{
+        return -ENOSYS;
+}
+
+static inline int ata_acpi_gtm(const struct ata_port *ap,
+                               struct ata_acpi_gtm *stm)
+{
+        return -ENOSYS;
+}
+
+static inline unsigned int ata_acpi_gtm_xfermask(struct ata_device *dev,
+                                        const struct ata_acpi_gtm *gtm)
+{
+        return 0;
+}
 #endif
 
 #ifdef CONFIG_PCI