libata: beef up iterators

There currently are the following looping constructs.

* __ata_port_for_each_link() for all available links
* ata_port_for_each_link() for edge links
* ata_link_for_each_dev() for all devices
* ata_link_for_each_dev_reverse() for all devices in reverse order

Now there's a need for looping construct which is similar to
__ata_port_for_each_link() but iterates over PMP links before the host
link.  Instead of adding another one with long name, do the following
cleanup.

* Implement and export ata_link_next() and ata_dev_next() which take
  @mode parameter and can be used to build custom loop.
* Implement ata_for_each_link() and ata_for_each_dev() which take
  looping mode explicitly.

The following iteration modes are implemented.

* ATA_LITER_EDGE		: loop over edge links
* ATA_LITER_HOST_FIRST		: loop over all links, host link first
* ATA_LITER_PMP_FIRST		: loop over all links, PMP links first

* ATA_DITER_ENABLED		: loop over enabled devices
* ATA_DITER_ENABLED_REVERSE	: loop over enabled devices in reverse order
* ATA_DITER_ALL			: loop over all devices
* ATA_DITER_ALL_REVERSE		: loop over all devices in reverse order

This change removes exlicit device enabledness checks from many loops
and makes it clear which ones are iterated over in which direction.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 16 insertions, 18 deletions

diff --git a/drivers/ata/pata_it821x.c b/drivers/ata/pata_it821x.c
index 860ede526282..f828a29d7756 100644
--- a/drivers/ata/pata_it821x.c
+++ b/drivers/ata/pata_it821x.c
@@ -465,24 +465,22 @@ static int it821x_smart_set_mode(struct ata_link *link, struct ata_device **unus
 {
         struct ata_device *dev;
 
-        ata_link_for_each_dev(dev, link) {
-                if (ata_dev_enabled(dev)) {
-                        /* We don't really care */
-                        dev->pio_mode = XFER_PIO_0;
-                        dev->dma_mode = XFER_MW_DMA_0;
-                        /* We do need the right mode information for DMA or PIO
-                           and this comes from the current configuration flags */
-                        if (ata_id_has_dma(dev->id)) {
-                                ata_dev_printk(dev, KERN_INFO, "configured for DMA\n");
-                                dev->xfer_mode = XFER_MW_DMA_0;
-                                dev->xfer_shift = ATA_SHIFT_MWDMA;
-                                dev->flags &= ~ATA_DFLAG_PIO;
-                        } else {
-                                ata_dev_printk(dev, KERN_INFO, "configured for PIO\n");
-                                dev->xfer_mode = XFER_PIO_0;
-                                dev->xfer_shift = ATA_SHIFT_PIO;
-                                dev->flags |= ATA_DFLAG_PIO;
-                        }
+        ata_for_each_dev(dev, link, ENABLED) {
+                /* We don't really care */
+                dev->pio_mode = XFER_PIO_0;
+                dev->dma_mode = XFER_MW_DMA_0;
+                /* We do need the right mode information for DMA or PIO
+                   and this comes from the current configuration flags */
+                if (ata_id_has_dma(dev->id)) {
+                        ata_dev_printk(dev, KERN_INFO, "configured for DMA\n");
+                        dev->xfer_mode = XFER_MW_DMA_0;
+                        dev->xfer_shift = ATA_SHIFT_MWDMA;
+                        dev->flags &= ~ATA_DFLAG_PIO;
+                } else {
+                        ata_dev_printk(dev, KERN_INFO, "configured for PIO\n");
+                        dev->xfer_mode = XFER_PIO_0;
+                        dev->xfer_shift = ATA_SHIFT_PIO;
+                        dev->flags |= ATA_DFLAG_PIO;
                 }
         }
         return 0;