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authorTejun Heo <tj@kernel.org>2008-07-31 17:02:43 +0900
committerJeff Garzik <jgarzik@redhat.com>2008-09-29 00:25:28 -0400
commitb1c72916abbdd0a55015c87358536ca0ebaf6735 (patch)
tree1064fe92f2c3600dd6587c880d907020896b3348 /drivers/ata/libata.h
parentb5b3fa386b8f96c7fa92e507e5deddc2637924b4 (diff)
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libata: implement slave_link
Explanation taken from the comment of ata_slave_link_init(). In libata, a port contains links and a link contains devices. There is single host link but if a PMP is attached to it, there can be multiple fan-out links. On SATA, there's usually a single device connected to a link but PATA and SATA controllers emulating TF based interface can have two - master and slave. However, there are a few controllers which don't fit into this abstraction too well - SATA controllers which emulate TF interface with both master and slave devices but also have separate SCR register sets for each device. These controllers need separate links for physical link handling (e.g. onlineness, link speed) but should be treated like a traditional M/S controller for everything else (e.g. command issue, softreset). slave_link is libata's way of handling this class of controllers without impacting core layer too much. For anything other than physical link handling, the default host link is used for both master and slave. For physical link handling, separate @ap->slave_link is used. All dirty details are implemented inside libata core layer. From LLD's POV, the only difference is that prereset, hardreset and postreset are called once more for the slave link, so the reset sequence looks like the following. prereset(M) -> prereset(S) -> hardreset(M) -> hardreset(S) -> softreset(M) -> postreset(M) -> postreset(S) Note that softreset is called only for the master. Softreset resets both M/S by definition, so SRST on master should handle both (the standard method will work just fine). As slave_link excludes PMP support and only code paths which deal with the attributes of physical link are affected, all the changes are localized to libata.h, libata-core.c and libata-eh.c. * ata_is_host_link() updated so that slave_link is considered as host link too. * iterator extended to iterate over the slave_link when using the underbarred version. * force param handling updated such that devno 16 is mapped to the slave link/device. * ata_link_on/offline() updated to return the combined result from master and slave link. ata_phys_link_on/offline() are the direct versions. * EH autopsy and report are performed separately for master slave links. Reset is udpated to implement the above described reset sequence. Except for reset update, most changes are minor, many of them just modifying dev->link to ata_dev_phys_link(dev) or using phys online test instead. After this update, LLDs can take full advantage of per-dev SCR registers by simply turning on slave link. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Diffstat (limited to 'drivers/ata/libata.h')
-rw-r--r--drivers/ata/libata.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
index ade5c75b614..e96de96e302 100644
--- a/drivers/ata/libata.h
+++ b/drivers/ata/libata.h
@@ -70,6 +70,7 @@ extern int atapi_passthru16;
extern int libata_fua;
extern int libata_noacpi;
extern int libata_allow_tpm;
+extern struct ata_link *ata_dev_phys_link(struct ata_device *dev);
extern void ata_force_cbl(struct ata_port *ap);
extern u64 ata_tf_to_lba(const struct ata_taskfile *tf);
extern u64 ata_tf_to_lba48(const struct ata_taskfile *tf);
@@ -107,6 +108,8 @@ extern void ata_qc_issue(struct ata_queued_cmd *qc);
extern void __ata_qc_complete(struct ata_queued_cmd *qc);
extern int atapi_check_dma(struct ata_queued_cmd *qc);
extern void swap_buf_le16(u16 *buf, unsigned int buf_words);
+extern bool ata_phys_link_online(struct ata_link *link);
+extern bool ata_phys_link_offline(struct ata_link *link);
extern void ata_dev_init(struct ata_device *dev);
extern void ata_link_init(struct ata_port *ap, struct ata_link *link, int pmp);
extern int sata_link_init_spd(struct ata_link *link);