[PATCH] libata: add xfer_mask handling functions
Add ata_pack_xfermask(), ata_xfer_mask2mode(), ata_xfer_mode2mask(),
ata_xfer_mode2shift() and ata_id_xfermask(). These functions will be
used by following patches to simplify xfer_mask handling.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 18418c8..9946618 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -231,6 +231,108 @@
return -1;
}
+/**
+ * ata_pack_xfermask - Pack pio, mwdma and udma masks into xfer_mask
+ * @pio_mask: pio_mask
+ * @mwdma_mask: mwdma_mask
+ * @udma_mask: udma_mask
+ *
+ * Pack @pio_mask, @mwdma_mask and @udma_mask into a single
+ * unsigned int xfer_mask.
+ *
+ * LOCKING:
+ * None.
+ *
+ * RETURNS:
+ * Packed xfer_mask.
+ */
+static unsigned int ata_pack_xfermask(unsigned int pio_mask,
+ unsigned int mwdma_mask,
+ unsigned int udma_mask)
+{
+ return ((pio_mask << ATA_SHIFT_PIO) & ATA_MASK_PIO) |
+ ((mwdma_mask << ATA_SHIFT_MWDMA) & ATA_MASK_MWDMA) |
+ ((udma_mask << ATA_SHIFT_UDMA) & ATA_MASK_UDMA);
+}
+
+static const struct ata_xfer_ent {
+ unsigned int shift, bits;
+ u8 base;
+} ata_xfer_tbl[] = {
+ { ATA_SHIFT_PIO, ATA_BITS_PIO, XFER_PIO_0 },
+ { ATA_SHIFT_MWDMA, ATA_BITS_MWDMA, XFER_MW_DMA_0 },
+ { ATA_SHIFT_UDMA, ATA_BITS_UDMA, XFER_UDMA_0 },
+ { -1, },
+};
+
+/**
+ * ata_xfer_mask2mode - Find matching XFER_* for the given xfer_mask
+ * @xfer_mask: xfer_mask of interest
+ *
+ * Return matching XFER_* value for @xfer_mask. Only the highest
+ * bit of @xfer_mask is considered.
+ *
+ * LOCKING:
+ * None.
+ *
+ * RETURNS:
+ * Matching XFER_* value, 0 if no match found.
+ */
+static u8 ata_xfer_mask2mode(unsigned int xfer_mask)
+{
+ int highbit = fls(xfer_mask) - 1;
+ const struct ata_xfer_ent *ent;
+
+ for (ent = ata_xfer_tbl; ent->shift >= 0; ent++)
+ if (highbit >= ent->shift && highbit < ent->shift + ent->bits)
+ return ent->base + highbit - ent->shift;
+ return 0;
+}
+
+/**
+ * ata_xfer_mode2mask - Find matching xfer_mask for XFER_*
+ * @xfer_mode: XFER_* of interest
+ *
+ * Return matching xfer_mask for @xfer_mode.
+ *
+ * LOCKING:
+ * None.
+ *
+ * RETURNS:
+ * Matching xfer_mask, 0 if no match found.
+ */
+static unsigned int ata_xfer_mode2mask(u8 xfer_mode)
+{
+ const struct ata_xfer_ent *ent;
+
+ for (ent = ata_xfer_tbl; ent->shift >= 0; ent++)
+ if (xfer_mode >= ent->base && xfer_mode < ent->base + ent->bits)
+ return 1 << (ent->shift + xfer_mode - ent->base);
+ return 0;
+}
+
+/**
+ * ata_xfer_mode2shift - Find matching xfer_shift for XFER_*
+ * @xfer_mode: XFER_* of interest
+ *
+ * Return matching xfer_shift for @xfer_mode.
+ *
+ * LOCKING:
+ * None.
+ *
+ * RETURNS:
+ * Matching xfer_shift, -1 if no match found.
+ */
+static int ata_xfer_mode2shift(unsigned int xfer_mode)
+{
+ const struct ata_xfer_ent *ent;
+
+ for (ent = ata_xfer_tbl; ent->shift >= 0; ent++)
+ if (xfer_mode >= ent->base && xfer_mode < ent->base + ent->bits)
+ return ent->shift;
+ return -1;
+}
+
static const char * const xfer_mode_str[] = {
"PIO0",
"PIO1",
@@ -682,6 +784,51 @@
id[93]);
}
+/**
+ * ata_id_xfermask - Compute xfermask from the given IDENTIFY data
+ * @id: IDENTIFY data to compute xfer mask from
+ *
+ * Compute the xfermask for this device. This is not as trivial
+ * as it seems if we must consider early devices correctly.
+ *
+ * FIXME: pre IDE drive timing (do we care ?).
+ *
+ * LOCKING:
+ * None.
+ *
+ * RETURNS:
+ * Computed xfermask
+ */
+static unsigned int ata_id_xfermask(const u16 *id)
+{
+ unsigned int pio_mask, mwdma_mask, udma_mask;
+
+ /* Usual case. Word 53 indicates word 64 is valid */
+ if (id[ATA_ID_FIELD_VALID] & (1 << 1)) {
+ pio_mask = id[ATA_ID_PIO_MODES] & 0x03;
+ pio_mask <<= 3;
+ pio_mask |= 0x7;
+ } else {
+ /* If word 64 isn't valid then Word 51 high byte holds
+ * the PIO timing number for the maximum. Turn it into
+ * a mask.
+ */
+ pio_mask = (2 << (id[ATA_ID_OLD_PIO_MODES] & 0xFF)) - 1 ;
+
+ /* But wait.. there's more. Design your standards by
+ * committee and you too can get a free iordy field to
+ * process. However its the speeds not the modes that
+ * are supported... Note drivers using the timing API
+ * will get this right anyway
+ */
+ }
+
+ mwdma_mask = id[ATA_ID_MWDMA_MODES] & 0x07;
+ udma_mask = id[ATA_ID_UDMA_MODES] & 0xff;
+
+ return ata_pack_xfermask(pio_mask, mwdma_mask, udma_mask);
+}
+
/*
* Compute the PIO modes available for this device. This is not as
* trivial as it seems if we must consider early devices correctly.