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[PATCH] libata: add xfer_mask handling functions

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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>
This commit is contained in:
Tejun Heo 2006-03-06 04:31:56 +09:00 committed by Jeff Garzik
parent 1da7b0d01b
commit cb95d562e4
1 changed files with 147 additions and 0 deletions
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147
drivers/scsi/libata-core.c
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@ -231,6 +231,108 @@ int ata_rwcmd_protocol(struct ata_queued_cmd *qc)
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 @@ static inline void ata_dump_id(const u16 *id)
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.