libata-pmp: implement Port Multiplier support

Implement Port Multiplier support.  To support PMP, a LLDD has to
supply ops->pmp_read() and pmp_write().  If non-null, ->pmp_attach and
->pmp_detach are called on PMP attach and detach, respectively.

->pmp_read/write() can be called while the port is frozen, so they
must be implemented by polling.  This patch supplies several helpers
to ease ->pmp_read/write() implementation.

Also, irq_handler and error_handler must be PMP aware.  Most of PMP
aware EH can be done by calling ata_pmp_do_eh() with appropriate
methods.  PMP EH uses separate set of reset methods and this patch
implements standard prereset, hardreset and postreset methods.

This patch only implements PMP support.  The next patch will integrate
PMP into the reset of libata and thus enable PMP support.

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

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
index ebe2298..a9b9c9e 100644
--- a/drivers/ata/libata.h
+++ b/drivers/ata/libata.h
@@ -153,6 +153,11 @@ extern void ata_schedule_scsi_eh(struct Scsi_Host *shost);
 extern void ata_scsi_dev_rescan(struct work_struct *work);
 extern int ata_bus_probe(struct ata_port *ap);
 
+/* libata-pmp.c */
+extern int sata_pmp_scr_read(struct ata_link *link, int reg, u32 *val);
+extern int sata_pmp_scr_write(struct ata_link *link, int reg, u32 val);
+extern int sata_pmp_attach(struct ata_device *dev);
+
 /* libata-eh.c */
 extern enum scsi_eh_timer_return ata_scsi_timed_out(struct scsi_cmnd *cmd);
 extern void ata_scsi_error(struct Scsi_Host *host);