diff options
Diffstat (limited to 'drivers/ide/ide-dma.c')
| -rw-r--r-- | drivers/ide/ide-dma.c | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/drivers/ide/ide-dma.c b/drivers/ide/ide-dma.c index fd213088b06..f28fabb791f 100644 --- a/drivers/ide/ide-dma.c +++ b/drivers/ide/ide-dma.c @@ -705,6 +705,80 @@ int ide_use_dma(ide_drive_t *drive) EXPORT_SYMBOL_GPL(ide_use_dma); +static const u8 xfer_mode_bases[] = { + XFER_UDMA_0, + XFER_MW_DMA_0, + XFER_SW_DMA_0, +}; + +static unsigned int ide_get_mode_mask(ide_drive_t *drive, u8 base) +{ + struct hd_driveid *id = drive->id; + ide_hwif_t *hwif = drive->hwif; + unsigned int mask = 0; + + switch(base) { + case XFER_UDMA_0: + if ((id->field_valid & 4) == 0) + break; + + mask = id->dma_ultra & hwif->ultra_mask; + + if (hwif->udma_filter) + mask &= hwif->udma_filter(drive); + + if ((mask & 0x78) && (eighty_ninty_three(drive) == 0)) + mask &= 0x07; + break; + case XFER_MW_DMA_0: + mask = id->dma_mword & hwif->mwdma_mask; + break; + case XFER_SW_DMA_0: + mask = id->dma_1word & hwif->swdma_mask; + break; + default: + BUG(); + break; + } + + return mask; +} + +/** + * ide_max_dma_mode - compute DMA speed + * @drive: IDE device + * + * Checks the drive capabilities and returns the speed to use + * for the DMA transfer. Returns 0 if the drive is incapable + * of DMA transfers. + */ + +u8 ide_max_dma_mode(ide_drive_t *drive) +{ + ide_hwif_t *hwif = drive->hwif; + unsigned int mask; + int x, i; + u8 mode = 0; + + if (drive->media != ide_disk && hwif->atapi_dma == 0) + return 0; + + for (i = 0; i < ARRAY_SIZE(xfer_mode_bases); i++) { + mask = ide_get_mode_mask(drive, xfer_mode_bases[i]); + x = fls(mask) - 1; + if (x >= 0) { + mode = xfer_mode_bases[i] + x; + break; + } + } + + printk(KERN_DEBUG "%s: selected mode 0x%x\n", drive->name, mode); + + return mode; +} + +EXPORT_SYMBOL_GPL(ide_max_dma_mode); + void ide_dma_verbose(ide_drive_t *drive) { struct hd_driveid *id = drive->id; |