[RFC PATCH 02/14] usb: gadget: Add callback to set lane and transfer rate

From: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
To: Felipe Balbi <balbi@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
	linux-usb@vger.kernel.org, Alan Stern <stern@rowland.harvard.edu>,
	Roger Quadros <rogerq@ti.com>, zhengbin <zhengbin13@huawei.com>
Cc: John Youn <John.Youn@synopsys.com>
Subject: [RFC PATCH 02/14] usb: gadget: Add callback to set lane and transfer rate
Date: Wed, 11 Dec 2019 18:49:12 -0800	[thread overview]
Message-ID: <25394a433bb79ddf36d0ec52bc998b164e373bf4.1576118671.git.thinhn@synopsys.com> (raw)
In-Reply-To: <cover.1576118671.git.thinhn@synopsys.com>

Introduce gadget opts udc_set_sublink_speed callback to set the lane
count and transfer rate (in lane speed mantissa of Gbps) for SuperSpeed
Plus capable gadgets. In the same way udc_set_speed, this function can
control the gadget's sublink attributes for SuperSpeed Plus.

Signed-off-by: Thinh Nguyen <thinhn@synopsys.com>
---
 drivers/usb/gadget/composite.c           |  2 ++
 drivers/usb/gadget/legacy/mass_storage.c |  2 ++
 drivers/usb/gadget/udc/core.c            | 38 +++++++++++++++++++++++++++++++-
 include/linux/usb/gadget.h               |  3 +++
 4 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 3b4f67000315..a4de5a8c0f19 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -2353,6 +2353,8 @@ int usb_composite_probe(struct usb_composite_driver *driver)
 	gadget_driver->function =  (char *) driver->name;
 	gadget_driver->driver.name = driver->name;
 	gadget_driver->max_speed = driver->max_speed;
+	gadget_driver->max_lane_count = driver->max_lane_count;
+	gadget_driver->max_lsm = driver->max_lsm;
 
 	return usb_gadget_probe_driver(gadget_driver);
 }
diff --git a/drivers/usb/gadget/legacy/mass_storage.c b/drivers/usb/gadget/legacy/mass_storage.c
index f18f77584fc2..a0912c5afffc 100644
--- a/drivers/usb/gadget/legacy/mass_storage.c
+++ b/drivers/usb/gadget/legacy/mass_storage.c
@@ -223,6 +223,8 @@ static struct usb_composite_driver msg_driver = {
 	.name		= "g_mass_storage",
 	.dev		= &msg_device_desc,
 	.max_speed	= USB_SPEED_SUPER_PLUS,
+	.max_lane_count	= 2,
+	.max_lsm	= 10,
 	.needs_serial	= 1,
 	.strings	= dev_strings,
 	.bind		= msg_bind,
diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index 51fa614b4079..a3b106a22a6e 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -1120,6 +1120,35 @@ static inline void usb_gadget_udc_set_speed(struct usb_udc *udc,
 	}
 }
 
+/**
+ * usb_gadget_udc_set_sublink_attr - tells usb device controller the sublink
+ *    attributes supported by the current driver
+ * @udc: The device we want to set maximum speed
+ * @lane_count: The maximum number of lanes to connect
+ * @lsm: The maximum lane speed mantissa in Gbps to run
+ *
+ * In the same way as usb_gadget_udc_set_speed(), this function can set the
+ * gadget's sublink attributes for SuperSpeed Plus.
+ *
+ * This call is issued by the UDC Class driver before calling
+ * usb_gadget_udc_start() in order to make sure that we don't try to
+ * connect on speeds the gadget driver doesn't support.
+ */
+static inline void usb_gadget_udc_set_sublink_attr(struct usb_udc *udc,
+						   unsigned int lane_count,
+						   unsigned int lsm)
+{
+	if (udc->gadget->ops->udc_set_sublink_attr) {
+		unsigned int rate;
+		unsigned int lanes;
+
+		rate = min(lsm, udc->gadget->max_lsm);
+		lanes = min(lane_count, udc->gadget->max_lane_count);
+		udc->gadget->ops->udc_set_sublink_attr(udc->gadget,
+						       lanes, rate);
+	}
+}
+
 /**
  * usb_udc_release - release the usb_udc struct
  * @dev: the dev member within usb_udc
@@ -1353,7 +1382,14 @@ static int udc_bind_to_driver(struct usb_udc *udc, struct usb_gadget_driver *dri
 	udc->dev.driver = &driver->driver;
 	udc->gadget->dev.driver = &driver->driver;
 
-	usb_gadget_udc_set_speed(udc, driver->max_speed);
+	if (udc->gadget->ops->udc_set_sublink_attr &&
+	    udc->gadget->max_speed == USB_SPEED_SUPER_PLUS &&
+	    driver->max_lsm && driver->max_lane_count &&
+	    driver->max_speed == USB_SPEED_SUPER_PLUS)
+		usb_gadget_udc_set_sublink_attr(udc, driver->max_lane_count,
+						driver->max_lsm);
+	else
+		usb_gadget_udc_set_speed(udc, driver->max_speed);
 
 	ret = driver->bind(udc->gadget, driver);
 	if (ret)
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index cb7531a6f784..a8ee2480b408 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -319,6 +319,9 @@ struct usb_gadget_ops {
 			struct usb_gadget_driver *);
 	int	(*udc_stop)(struct usb_gadget *);
 	void	(*udc_set_speed)(struct usb_gadget *, enum usb_device_speed);
+	void	(*udc_set_sublink_attr)(struct usb_gadget *,
+					unsigned int lane_count,
+					unsigned int lsm);
 	struct usb_ep *(*match_ep)(struct usb_gadget *,
 			struct usb_endpoint_descriptor *,
 			struct usb_ss_ep_comp_descriptor *);
-- 
2.11.0

