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From: Wesley Cheng <quic_wcheng@quicinc.com>
To: <srinivas.kandagatla@linaro.org>, <mathias.nyman@intel.com>,
        <perex@perex.cz>, <conor+dt@kernel.org>, <corbet@lwn.net>,
        <lgirdwood@gmail.com>, <andersson@kernel.org>,
        <krzysztof.kozlowski+dt@linaro.org>, <gregkh@linuxfoundation.org>,
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        <konrad.dybcio@linaro.org>
CC: <linux-kernel@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <linux-sound@vger.kernel.org>, <linux-usb@vger.kernel.org>,
        <linux-arm-msm@vger.kernel.org>, <linux-doc@vger.kernel.org>,
        <alsa-devel@alsa-project.org>, Wesley Cheng <quic_wcheng@quicinc.com>
Subject: [PATCH v19 06/41] usb: host: xhci-sideband: Expose a sideband interrupter enable API
Date: Mon, 22 Apr 2024 15:48:31 -0700
Message-ID: <20240422224906.15868-7-quic_wcheng@quicinc.com>
In-Reply-To: <20240422224906.15868-1-quic_wcheng@quicinc.com>
References: <20240422224906.15868-1-quic_wcheng@quicinc.com>
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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@quicinc.com>
---
 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 0944bf31d772..504a6f1586b5 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);