[PATCH v20 06/41] usb: host: xhci-sideband: Expose a sideband interrupter enable API

[Wesley Cheng <quic_wcheng@xxxxxxxxxxx>]

Some use cases maybe require that the secondary interrupter's events to
be handled by the OS.  In this case, configure the IMOD and the
skip_events property to enable the interrupter's events.  By default,
assume that the secondary interrupter doesn't want to enable OS event
handling.

Signed-off-by: Wesley Cheng <quic_wcheng@xxxxxxxxxxx>
---
 drivers/usb/host/xhci-sideband.c  | 28 ++++++++++++++++++++++++++++
 include/linux/usb/xhci-sideband.h |  2 ++
 2 files changed, 30 insertions(+)

diff --git a/drivers/usb/host/xhci-sideband.c b/drivers/usb/host/xhci-sideband.c
index 255feae33c6e..6fdae9840c11 100644
--- a/drivers/usb/host/xhci-sideband.c
+++ b/drivers/usb/host/xhci-sideband.c
@@ -237,6 +237,30 @@ xhci_sideband_get_event_buffer(struct xhci_sideband *sb)
 }
 EXPORT_SYMBOL_GPL(xhci_sideband_get_event_buffer);
 
+/**
+ * xhci_sideband_enable_interrupt - enable interrupt for secondary interrupter
+ * @sb: sideband instance for this usb device
+ * @imod_interval: number of event ring segments to allocate
+ *
+ * Enables OS owned event handling for a particular interrupter if client
+ * requests for it.  In addition, set the IMOD interval for this particular
+ * interrupter.
+ *
+ * Returns 0 on success, negative error otherwise
+ */
+int xhci_sideband_enable_interrupt(struct xhci_sideband *sb, u32 imod_interval)
+{
+	if (!sb || !sb->ir)
+		return -ENODEV;
+
+	xhci_set_interrupter_moderation(sb->ir, imod_interval);
+	sb->ir->skip_events = false;
+	xhci_enable_interrupter(sb->ir);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(xhci_sideband_enable_interrupt);
+
 /**
  * xhci_sideband_create_interrupter - creates a new interrupter for this sideband
  * @sb: sideband instance for this usb device
@@ -275,6 +299,8 @@ xhci_sideband_create_interrupter(struct xhci_sideband *sb, int num_seg,
 	}
 
 	sb->ir->ip_autoclear = ip_autoclear;
+	/* skip events for secondary interrupters by default */
+	sb->ir->skip_events = true;
 
 out:
 	mutex_unlock(&sb->mutex);
@@ -297,6 +323,8 @@ xhci_sideband_remove_interrupter(struct xhci_sideband *sb)
 		return;
 
 	mutex_lock(&sb->mutex);
+	if (!sb->ir->skip_events)
+		xhci_disable_interrupter(sb->ir);
 	xhci_remove_secondary_interrupter(xhci_to_hcd(sb->xhci), sb->ir);
 
 	sb->ir = NULL;
diff --git a/include/linux/usb/xhci-sideband.h b/include/linux/usb/xhci-sideband.h
index 1035dae43cee..a749ae307ba7 100644
--- a/include/linux/usb/xhci-sideband.h
+++ b/include/linux/usb/xhci-sideband.h
@@ -54,6 +54,8 @@ xhci_sideband_get_endpoint_buffer(struct xhci_sideband *sb,
 struct sg_table *
 xhci_sideband_get_event_buffer(struct xhci_sideband *sb);
 
+int xhci_sideband_enable_interrupt(struct xhci_sideband *sb, u32 imod_interval);
+
 int
 xhci_sideband_create_interrupter(struct xhci_sideband *sb, int num_seg,
 				 bool ip_autoclear);