libata: implement ata_timing_cycle2mode() and use it in libata-acpi and pata_acpi

libata-acpi is using separate timing tables for transfer modes
although libata-core has the complete ata_timing table.  Implement
ata_timing_cycle2mode() to look for matching mode given transfer type
and cycle duration and use it in libata-acpi and pata_acpi to replace
private timing tables.

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

4 files changed, 75 insertions, 57 deletions

diff --git a/drivers/ata/libata-acpi.c b/drivers/ata/libata-acpi.c
index 9f0b208afcf5..a6f1a6b56d8c 100644
--- a/drivers/ata/libata-acpi.c
+++ b/drivers/ata/libata-acpi.c
@@ -441,22 +441,6 @@ 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
@@ -473,49 +457,33 @@ EXPORT_SYMBOL_GPL(ata_acpi_udma_cycle);
 unsigned long ata_acpi_gtm_xfermask(struct ata_device *dev,
                                     const struct ata_acpi_gtm *gtm)
 {
-        unsigned long pio_mask = 0, mwdma_mask = 0, udma_mask = 0;
-        int unit, i;
-        u32 t;
+        unsigned long xfer_mask = 0;
+        unsigned int type;
+        int unit;
+        u8 mode;
 
         /* we always use the 0 slot for crap hardware */
         unit = dev->devno;
         if (!(gtm->flags & 0x10))
                 unit = 0;
 
-        /* Values larger than the longest cycle results in 0 mask
-         * while values equal to smaller than the shortest cycle
-         * results in mask which includes all supported modes.
-         * Disabled transfer method has the value of 0xffffffff which
-         * will always result in 0 mask.
-         */
-
-        /* start by scanning for PIO modes */
-        t = gtm->drive[unit].pio;
-        for (i = 0; i < ARRAY_SIZE(ata_acpi_pio_cycle); i++)
-                if (t > ata_acpi_pio_cycle[i])
-                        break;
-        pio_mask = (1 << i) - 1;
+        /* PIO */
+        mode = ata_timing_cycle2mode(ATA_SHIFT_PIO, gtm->drive[unit].pio);
+        xfer_mask |= ata_xfer_mode2mask(mode);
 
         /* 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.
          */
-        t = gtm->drive[unit].dma;
-        if (!(gtm->flags & (1 << (2 * unit)))) {
-                /* MWDMA */
-                for (i = 0; i < ARRAY_SIZE(ata_acpi_mwdma_cycle); i++)
-                        if (t > ata_acpi_mwdma_cycle[i])
-                                break;
-                mwdma_mask = (1 << i) - 1;
-        } else {
-                /* UDMA */
-                for (i = 0; i < ARRAY_SIZE(ata_acpi_udma_cycle); i++)
-                        if (t > ata_acpi_udma_cycle[i])
-                                break;
-                udma_mask = (1 << i) - 1;
-        }
+        if (!(gtm->flags & (1 << (2 * unit))))
+                type = ATA_SHIFT_MWDMA;
+        else
+                type = ATA_SHIFT_UDMA;
+
+        mode = ata_timing_cycle2mode(type, gtm->drive[unit].dma);
+        xfer_mask |= ata_xfer_mode2mask(mode);
 
-        return ata_pack_xfermask(pio_mask, mwdma_mask, udma_mask);
+        return xfer_mask;
 }
 EXPORT_SYMBOL_GPL(ata_acpi_gtm_xfermask);
 
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 62c4b328b0b6..f01c1734b1d0 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -2903,6 +2903,57 @@ int ata_timing_compute(struct ata_device *adev, unsigned short speed,
 }
 
 /**
+ *      ata_timing_cycle2mode - find xfer mode for the specified cycle duration
+ *      @xfer_shift: ATA_SHIFT_* value for transfer type to examine.
+ *      @cycle: cycle duration in ns
+ *
+ *      Return matching xfer mode for @cycle.  The returned mode is of
+ *      the transfer type specified by @xfer_shift.  If @cycle is too
+ *      slow for @xfer_shift, 0xff is returned.  If @cycle is faster
+ *      than the fastest known mode, the fasted mode is returned.
+ *
+ *      LOCKING:
+ *      None.
+ *
+ *      RETURNS:
+ *      Matching xfer_mode, 0xff if no match found.
+ */
+u8 ata_timing_cycle2mode(unsigned int xfer_shift, int cycle)
+{
+        u8 base_mode = 0xff, last_mode = 0xff;
+        const struct ata_xfer_ent *ent;
+        const struct ata_timing *t;
+
+        for (ent = ata_xfer_tbl; ent->shift >= 0; ent++)
+                if (ent->shift == xfer_shift)
+                        base_mode = ent->base;
+
+        for (t = ata_timing_find_mode(base_mode);
+             t && ata_xfer_mode2shift(t->mode) == xfer_shift; t++) {
+                unsigned short this_cycle;
+
+                switch (xfer_shift) {
+                case ATA_SHIFT_PIO:
+                case ATA_SHIFT_MWDMA:
+                        this_cycle = t->cycle;
+                        break;
+                case ATA_SHIFT_UDMA:
+                        this_cycle = t->udma;
+                        break;
+                default:
+                        return 0xff;
+                }
+
+                if (cycle > this_cycle)
+                        break;
+
+                last_mode = t->mode;
+        }
+
+        return last_mode;
+}
+
+/**
  *      ata_down_xfermask_limit - adjust dev xfer masks downward
  *      @dev: Device to adjust xfer masks
  *      @sel: ATA_DNXFER_* selector
@@ -7630,6 +7681,7 @@ EXPORT_SYMBOL_GPL(ata_pio_need_iordy);
 EXPORT_SYMBOL_GPL(ata_timing_find_mode);
 EXPORT_SYMBOL_GPL(ata_timing_compute);
 EXPORT_SYMBOL_GPL(ata_timing_merge);
+EXPORT_SYMBOL_GPL(ata_timing_cycle2mode);
 
 #ifdef CONFIG_PCI
 EXPORT_SYMBOL_GPL(pci_test_config_bits);
diff --git a/drivers/ata/pata_acpi.c b/drivers/ata/pata_acpi.c
index a4737a3d31cb..244098a80ce4 100644
--- a/drivers/ata/pata_acpi.c
+++ b/drivers/ata/pata_acpi.c
@@ -133,13 +133,14 @@ static void pacpi_set_piomode(struct ata_port *ap, struct ata_device *adev)
 {
         int unit = adev->devno;
         struct pata_acpi *acpi = ap->private_data;
+        const struct ata_timing *t;
 
         if (!(acpi->gtm.flags & 0x10))
                 unit = 0;
 
         /* Now stuff the nS values into the structure */
-        acpi->gtm.drive[unit].pio =
-                ata_acpi_pio_cycle[adev->pio_mode - XFER_PIO_0];
+        t = ata_timing_find_mode(adev->pio_mode);
+        acpi->gtm.drive[unit].pio = t->cycle;
         ata_acpi_stm(ap, &acpi->gtm);
         /* See what mode we actually got */
         ata_acpi_gtm(ap, &acpi->gtm);
@@ -155,18 +156,18 @@ static void pacpi_set_dmamode(struct ata_port *ap, struct ata_device *adev)
 {
         int unit = adev->devno;
         struct pata_acpi *acpi = ap->private_data;
+        const struct ata_timing *t;
 
         if (!(acpi->gtm.flags & 0x10))
                 unit = 0;
 
         /* Now stuff the nS values into the structure */
+        t = ata_timing_find_mode(adev->dma_mode);
         if (adev->dma_mode >= XFER_UDMA_0) {
-                acpi->gtm.drive[unit].dma =
-                        ata_acpi_udma_cycle[adev->dma_mode - XFER_UDMA_0];
+                acpi->gtm.drive[unit].dma = t->udma;
                 acpi->gtm.flags |= (1 << (2 * unit));
         } else {
-                acpi->gtm.drive[unit].dma =
-                        ata_acpi_mwdma_cycle[adev->dma_mode - XFER_MW_DMA_0];
+                acpi->gtm.drive[unit].dma = t->cycle;
                 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 8022e5b2224d..8ede93b5c7a6 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -941,6 +941,7 @@ extern int ata_timing_compute(struct ata_device *, unsigned short,
 extern void ata_timing_merge(const struct ata_timing *,
                              const struct ata_timing *, struct ata_timing *,
                              unsigned int);
+extern u8 ata_timing_cycle2mode(unsigned int xfer_shift, int cycle);
 
 enum {
         ATA_TIMING_SETUP        = (1 << 0),
@@ -961,10 +962,6 @@ 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)