libata-link: implement and use link/device iterators

Multiple links and different number of devices per link should be
considered to iterate over links and devices.  This patch implements
and uses link and device iterators - ata_port_for_each_link() and
ata_link_for_each_dev() - and ata_link_max_devices().

This change makes a lot of functions iterate over only possible
devices instead of from dev 0 to dev ATA_MAX_DEVICES.  All such
changes have been examined and nothing should be broken.

While at it, add a separating comment before device helpers to
distinguish them better from link helpers and others.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 14 insertions, 3 deletions

diff --git a/include/linux/libata.h b/include/linux/libata.h
index ca4493125fa0..62fa8cf677a1 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -1030,15 +1030,26 @@ static inline unsigned int ata_dev_absent(const struct ata_device *dev)
 }
 
 /*
- * port helpers
+ * link helpers
  */
-static inline int ata_port_max_devices(const struct ata_port *ap)
+static inline int ata_link_max_devices(const struct ata_link *link)
 {
-        if (ap->flags & ATA_FLAG_SLAVE_POSS)
+        if (link->ap->flags & ATA_FLAG_SLAVE_POSS)
                 return 2;
         return 1;
 }
 
+#define ata_port_for_each_link(lk, ap) \
+        for ((lk) = &(ap)->link; (lk); (lk) = NULL)
+
+#define ata_link_for_each_dev(dev, link) \
+        for ((dev) = (link)->device; \
+             (dev) < (link)->device + ata_link_max_devices(link) || ((dev) = NULL); \
+             (dev)++)
+
+#define ata_link_for_each_dev_reverse(dev, link) \
+        for ((dev) = (link)->device + ata_link_max_devices(link) - 1; \
+             (dev) >= (link)->device || ((dev) = NULL); (dev)--)
 
 static inline u8 ata_chk_status(struct ata_port *ap)
 {