[PATCH v4 2/3] usb: xhci: implement device_suspend/device_resume entries

[Lu Baolu]

This patch implements device_suspend/device_resume entries for xHC driver.
device_suspend will be called when a USB device is about to suspend. It
will issue a stop endpoint command for each endpoint in this device. The
Suspend(SP) bit in the command TRB will set which will give xHC a hint
about the suspend. device_resume will be called when a USB device is just
resumed. It will ring doorbells of all endpoint unconditionally. XHC may
use these suspend/resume hints to optimize its operation.

Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
---
 drivers/usb/host/xhci-hub.c |  2 +-
 drivers/usb/host/xhci.c     | 38 ++++++++++++++++++++++++++++++++++++++
 drivers/usb/host/xhci.h     |  9 +++++++++
 3 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index 0827d7c..a83e82e 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -266,7 +266,7 @@ int xhci_find_slot_id_by_port(struct usb_hcd *hcd, struct xhci_hcd *xhci,
  * to complete.
  * suspend will set to 1, if suspend bit need to set in command.
  */
-static int xhci_stop_device(struct xhci_hcd *xhci, int slot_id, int suspend)
+int xhci_stop_device(struct xhci_hcd *xhci, int slot_id, int suspend)
 {
 	struct xhci_virt_device *virt_dev;
 	struct xhci_command *cmd;
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index ec8ac16..330961d 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -4680,6 +4680,38 @@ int xhci_disable_usb3_lpm_timeout(struct usb_hcd *hcd,
 		return ret;
 	return 0;
 }
+
+/*
+ * xHCI compatible host controller driver expects to be notified prior to
+ * selectively suspending a device. xHCI hcd could optimize the endpoint
+ * cache for power saving purpose. Refer to 4.15.1.1 of xHCI 1.1.
+ */
+void xhci_device_suspend(struct usb_hcd *hcd, struct usb_device *udev)
+{
+	struct xhci_hcd	*xhci;
+
+	xhci = hcd_to_xhci(hcd);
+	if (!xhci || !xhci->devs[udev->slot_id])
+		return;
+
+	xhci_stop_device(xhci, udev->slot_id, 1);
+}
+
+/*
+ * xHCI compatible host controller driver expects to be notified after a
+ * USB device is resumed. xHCI hcd could optimize the endpoint cache
+ * to reduce the latency. Refer to 4.15.1.1 of xHCI 1.1.
+ */
+void xhci_device_resume(struct usb_hcd *hcd, struct usb_device *udev)
+{
+	struct xhci_hcd	*xhci;
+
+	xhci = hcd_to_xhci(hcd);
+	if (!xhci || !xhci->devs[udev->slot_id])
+		return;
+
+	xhci_ring_device(xhci, udev->slot_id);
+}
 #else /* CONFIG_PM */
 
 int xhci_set_usb2_hardware_lpm(struct usb_hcd *hcd,
@@ -4976,6 +5008,12 @@ static const struct hc_driver xhci_hc_driver = {
 	.enable_usb3_lpm_timeout =	xhci_enable_usb3_lpm_timeout,
 	.disable_usb3_lpm_timeout =	xhci_disable_usb3_lpm_timeout,
 	.find_raw_port_number =	xhci_find_raw_port_number,
+
+	/*
+	 * call back when devices suspend or resume
+	 */
+	.device_suspend =	xhci_device_suspend,
+	.device_resume =	xhci_device_resume,
 };
 
 void xhci_init_driver(struct hc_driver *drv, int (*setup_fn)(struct usb_hcd *))
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 8e421b8..67c13c5 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1867,10 +1867,19 @@ u32 xhci_port_state_to_neutral(u32 state);
 int xhci_find_slot_id_by_port(struct usb_hcd *hcd, struct xhci_hcd *xhci,
 		u16 port);
 void xhci_ring_device(struct xhci_hcd *xhci, int slot_id);
+int xhci_stop_device(struct xhci_hcd *xhci, int slot_id, int suspend);
 
 /* xHCI contexts */
 struct xhci_input_control_ctx *xhci_get_input_control_ctx(struct xhci_container_ctx *ctx);
 struct xhci_slot_ctx *xhci_get_slot_ctx(struct xhci_hcd *xhci, struct xhci_container_ctx *ctx);
 struct xhci_ep_ctx *xhci_get_ep_ctx(struct xhci_hcd *xhci, struct xhci_container_ctx *ctx, unsigned int ep_index);
 
+#ifdef	CONFIG_PM
+void xhci_device_suspend(struct usb_hcd *hcd, struct usb_device *udev);
+void xhci_device_resume(struct usb_hcd *hcd, struct usb_device *udev);
+#else
+#define xhci_device_suspend	NULL
+#define xhci_device_resume	NULL
+#endif /* CONFIG_PM */
+
 #endif /* __LINUX_XHCI_HCD_H */
-- 
2.1.0

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