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>

1 files changed, 52 insertions, 0 deletions

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);