[PATCH v6 2/3] ata: Use ACPI methods to power on disks

[Markus Probst <markus.probst@posteo.de>]

Some embedded devices have the ability to control whether power is
provided to the disks via the SATA power connector or not. If power
resources are defined on ATA ports / devices in ACPI, we should try to set
the power state to D0 before probing the disk to ensure that any power
supply or power gate that may exist is providing power to the disk.

An example for such devices would be newer synology NAS devices. Every
disk slot has its own SATA power connector. Whether the connector is
providing power is controlled via an gpio, which is *off by default*.
Also the disk loses power on reboots.

Add a new function, ata_acpi_port_power_on(), that will be used to power
on the SATA power connector if usable ACPI power resources on the
associated ATA port / device are found. It will be called right before
probing the port, therefore the disk will be powered on just in time.

Signed-off-by: Markus Probst <markus.probst@posteo.de>
---
 drivers/ata/libata-acpi.c | 41 +++++++++++++++++++++++++++++++++++++++
 drivers/ata/libata-core.c |  2 ++
 drivers/ata/libata.h      |  2 ++
 3 files changed, 45 insertions(+)

diff --git a/drivers/ata/libata-acpi.c b/drivers/ata/libata-acpi.c
index f2140fc06ba0..4782e0f22d7f 100644
--- a/drivers/ata/libata-acpi.c
+++ b/drivers/ata/libata-acpi.c
@@ -245,6 +245,47 @@ void ata_acpi_bind_dev(struct ata_device *dev)
 				   ata_acpi_dev_uevent);
 }
 
+/**
+ * ata_acpi_port_power_on - set the power state of the ata port to D0
+ * @ap: target ATA port
+ *
+ * This function is called at the beginning of ata_port_probe().
+ */
+void ata_acpi_port_power_on(struct ata_port *ap)
+{
+	acpi_handle handle;
+	int i;
+
+	/*
+	 * If ATA_FLAG_ACPI_SATA is set, the acpi fwnode is attached to the
+	 * ata_device instead of the ata_port.
+	 */
+	if (ap->flags & ATA_FLAG_ACPI_SATA) {
+		for (i = 0; i < ATA_MAX_DEVICES; i++) {
+			struct ata_device *dev = &ap->link.device[i];
+
+			if (!is_acpi_device_node(dev->tdev.fwnode))
+				continue;
+			handle = ACPI_HANDLE(&dev->tdev);
+			if (!acpi_bus_power_manageable(handle))
+				continue;
+			if (acpi_bus_set_power(handle, ACPI_STATE_D0))
+				ata_dev_err(dev,
+					    "acpi: failed to set power state to D0\n");
+		}
+		return;
+	}
+
+	if (!is_acpi_device_node(ap->tdev.fwnode))
+		return;
+	handle = ACPI_HANDLE(&ap->tdev);
+	if (!acpi_bus_power_manageable(handle))
+		return;
+
+	if (acpi_bus_set_power(handle, ACPI_STATE_D0))
+		ata_port_err(ap, "acpi: failed to set power state to D0\n");
+}
+
 /**
  * ata_acpi_dissociate - dissociate ATA host from ACPI objects
  * @host: target ATA host
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 2a210719c4ce..a6813ced3ec2 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -5901,6 +5901,8 @@ void ata_port_probe(struct ata_port *ap)
 	struct ata_eh_info *ehi = &ap->link.eh_info;
 	unsigned long flags;
 
+	ata_acpi_port_power_on(ap);
+
 	/* kick EH for boot probing */
 	spin_lock_irqsave(ap->lock, flags);
 
diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
index e5b977a8d3e1..8cc7227f2d94 100644
--- a/drivers/ata/libata.h
+++ b/drivers/ata/libata.h
@@ -130,6 +130,7 @@ extern void ata_acpi_on_disable(struct ata_device *dev);
 extern void ata_acpi_set_state(struct ata_port *ap, pm_message_t state);
 extern void ata_acpi_bind_port(struct ata_port *ap);
 extern void ata_acpi_bind_dev(struct ata_device *dev);
+extern void ata_acpi_port_power_on(struct ata_port *ap);
 extern acpi_handle ata_dev_acpi_handle(struct ata_device *dev);
 #else
 static inline void ata_acpi_dissociate(struct ata_host *host) { }
@@ -140,6 +141,7 @@ static inline void ata_acpi_set_state(struct ata_port *ap,
 				      pm_message_t state) { }
 static inline void ata_acpi_bind_port(struct ata_port *ap) {}
 static inline void ata_acpi_bind_dev(struct ata_device *dev) {}
+static inline void ata_acpi_port_power_on(struct ata_port *ap) {}
 #endif
 
 /* libata-scsi.c */
-- 
2.51.0