ahci: implement aggressive SATA device sleep support

Device Sleep is a feature as described in AHCI 1.3.1 Technical Proposal.
This feature enables an HBA and SATA storage device to enter the DevSleep
interface state, enabling lower power SATA-based systems.

Aggressive Device Sleep enables the HBA to assert the DEVSLP signal as
soon as there are no commands outstanding to the device and the port
specific Device Sleep idle timer has expired. This enables autonomous
entry into the DevSleep interface state without waiting for software
in power sensitive systems.

This patch enables Aggressive Device Sleep only if both host controller
and device support it.

Tested on AMD reference board together with Device Sleep supported device
sample.

Signed-off-by: Shane Huang <shane.huang@amd.com>
Reviewed-by: Aaron Lu <aaron.lwe@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
index 50e4dff0604e..7148a58020b9 100644
--- a/drivers/ata/libata.h
+++ b/drivers/ata/libata.h
@@ -165,6 +165,8 @@ extern void ata_eh_about_to_do(struct ata_link *link, struct ata_device *dev,
                                unsigned int action);
 extern void ata_eh_done(struct ata_link *link, struct ata_device *dev,
                         unsigned int action);
+extern unsigned int ata_read_log_page(struct ata_device *dev, u8 log,
+                                      u8 page, void *buf, unsigned int sectors);
 extern void ata_eh_autopsy(struct ata_port *ap);
 const char *ata_get_cmd_descript(u8 command);
 extern void ata_eh_report(struct ata_port *ap);