[PATCH] usb: dwc3: Support EBC feature of DWC_usb31

[Manan Aurora <maurora@google.com>]

Support configuration and use of bulk endpoints in the so-called EBC
mode described in the DBC_usb31 databook (appendix E)

Added a bit fifo_mode to usb_ep to indicate to the UDC driver that a
specific endpoint is to operate in the EBC (or equivalent) mode when
enabled

Added macros for bits 15 and 14 of DEPCFG parameter 1 to indicate EBC
mode and write back behaviour. These bits will be set to 1 when
configuring an EBC endpoint as described in the programming guide

Signed-off-by: Manan Aurora <maurora@google.com>
---
 drivers/usb/dwc3/core.h    | 1 +
 drivers/usb/dwc3/gadget.c  | 6 ++++++
 drivers/usb/dwc3/gadget.h  | 2 ++
 include/linux/usb/gadget.h | 4 ++++
 4 files changed, 13 insertions(+)

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index efe6caf4d0e8..c5b578188cd3 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -374,6 +374,7 @@
 /* Global HWPARAMS4 Register */
 #define DWC3_GHWPARAMS4_HIBER_SCRATCHBUFS(n)	(((n) & (0x0f << 13)) >> 13)
 #define DWC3_MAX_HIBER_SCRATCHBUFS		15
+#define DWC3_EXT_BUFF_CONTROL		BIT(21)
 
 /* Global HWPARAMS6 Register */
 #define DWC3_GHWPARAMS6_BCSUPPORT		BIT(14)
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 858fe4c299b7..47d2737d528b 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -673,6 +673,12 @@ static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action)
 		params.param1 |= DWC3_DEPCFG_BINTERVAL_M1(bInterval_m1);
 	}
 
+	if (dep->endpoint.fifo_mode) {
+		if (!(dwc->hwparams.hwparams4 & DWC3_EXT_BUFF_CONTROL))
+			return -EINVAL;
+		params.param1 |= DWC3_DEPCFG_EBC_HWO_NOWB | DWC3_DEPCFG_USE_EBC;
+	}
+
 	return dwc3_send_gadget_ep_cmd(dep, DWC3_DEPCMD_SETEPCONFIG, &params);
 }
 
diff --git a/drivers/usb/dwc3/gadget.h b/drivers/usb/dwc3/gadget.h
index 55a56cf67d73..fd7a4e94397e 100644
--- a/drivers/usb/dwc3/gadget.h
+++ b/drivers/usb/dwc3/gadget.h
@@ -26,6 +26,8 @@ struct dwc3;
 #define DWC3_DEPCFG_XFER_NOT_READY_EN	BIT(10)
 #define DWC3_DEPCFG_FIFO_ERROR_EN	BIT(11)
 #define DWC3_DEPCFG_STREAM_EVENT_EN	BIT(13)
+#define DWC3_DEPCFG_EBC_HWO_NOWB	BIT(14)
+#define DWC3_DEPCFG_USE_EBC		BIT(15)
 #define DWC3_DEPCFG_BINTERVAL_M1(n)	(((n) & 0xff) << 16)
 #define DWC3_DEPCFG_STREAM_CAPABLE	BIT(24)
 #define DWC3_DEPCFG_EP_NUMBER(n)	(((n) & 0x1f) << 25)
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 6532beb587b1..c526ae09bcee 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -209,6 +209,9 @@ struct usb_ep_caps {
  *	by this EP (0 - 16, actual number is 2^n)
  * @mult: multiplier, 'mult' value for SS Isoc EPs
  * @maxburst: the maximum number of bursts supported by this EP (for usb3)
+ * @fifo_mode: indicates that the control of this EP is handed off to an
+ *	hardware fifo device. Depends on hardware support eg. EBC feature
+ *	of DWC usb3.1 device or equivalent. Set before enabling the EP
  * @driver_data:for use by the gadget driver.
  * @address: used to identify the endpoint when finding descriptor that
  *	matches connection speed
@@ -236,6 +239,7 @@ struct usb_ep {
 	unsigned		max_streams:16;
 	unsigned		mult:2;
 	unsigned		maxburst:5;
+	unsigned		fifo_mode:1;
 	u8			address;
 	const struct usb_endpoint_descriptor	*desc;
 	const struct usb_ss_ep_comp_descriptor	*comp_desc;
-- 
2.42.0.820.g83a721a137-goog