libpayload: usb: Support MTK xHCI host controller

1. There is a mis-understanding to calculate the value of TD Size
   in Normal TRB. For MTK's xHCI controller it defines a number of
   packets that remain to be transferred for a TD after processing
   all Max packets in all previous TRBs, that means don't include the
   current TRB's.
2. To minimize the scheduling effort for synchronous endpoints in xHC,
   the MTK architecture defines some extra SW scheduling parameters for
   HW. According to these parameters provided by SW, the xHC can easily
   decide whether a synchronous endpoint should be scheduled in a specific
   uFrame. The extra SW scheduling parameters are put into reserved DWs
   in Slot and Endpoint Context. But in coreboot synchronous transfer can
   be ignored, so only two fields are set to a default value 1 to support
   bulk and interrupt transfers, and others are set to zero.
3. For control transfer, it is better to read back doorbell register or add
   a memory barrier after ringing the doorbell to flush posted write.
   Otherwise the first command will be aborted on MTK's xHCI controller.
4. Before send commands to a port, the Port Power in PORTSC register should
   be set to 1 on MTK's xHCI so a hook function of enable_port in
   generic_hub_ops_t struct is provided.

Change-Id: Ie8878b50c048907ebf939b3f6657535a54877fde
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 738609c11f16264c6e6429d478b2040cb391fe41
Original-Change-Id: Id9156892699e2e42a166c77fbf6690049abe953b
Original-Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Original-Reviewed-on: https://chromium-review.googlesource.com/265362
Original-Reviewed-by: Julius Werner <jwerner@chromium.org>
Original-Commit-Queue: Yidi Lin <yidi.lin@mediatek.com>
Original-Tested-by: Yidi Lin <yidi.lin@mediatek.com>
Reviewed-on: http://review.coreboot.org/10389
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins)

payloads/libpayload/Config.in

@@ -495,6 +495,12 @@ config USB_XHCI
 	  Select this option if you want to use USB 3.0
 	  NOTE: This option is not (fully) implemented yet
 
+config USB_XHCI_MTK_QUIRK
+	bool "Support for USB xHCI controllers on MTK SoC"
+	depends on USB_XHCI
+	help
+	  Select this option if you want to use USB 3.0 on MTK platform.
+
 config USB_DWC2
 	bool "Support for USB DesignWare HCD controllers"
 	depends on USB && !USB_HID

payloads/libpayload/drivers/usb/xhci.c

@@ -370,6 +370,8 @@ xhci_reinit (hci_t *controller)
 	xhci->ev_ring_table[0].seg_base_hi = 0;
 	xhci->ev_ring_table[0].seg_size = EVENT_RING_SIZE;
 
+	/* pass event ring table to hardware */
+	wmb();
 	/* Initialize primary interrupter */
 	xhci->hcrreg->intrrs[0].erstsz = 1;
 	xhci_update_event_dq(xhci);
@@ -510,6 +512,7 @@ xhci_enqueue_trb(transfer_ring_t *const tr)
 		xhci_spew("Handling LINK pointer\n");
 		const int tc = TRB_GET(TC, tr->cur);
 		TRB_SET(CH, tr->cur, chain);
+		wmb();
 		TRB_SET(C, tr->cur, tr->pcs);
 		tr->cur = phys_to_virt(tr->cur->ptr_low);
 		if (tc)
@@ -535,7 +538,7 @@ xhci_enqueue_td(transfer_ring_t *const tr, const int ep, const size_t mps,
 			cur_length = length;
 			packets = 0;
 			length = 0;
-		} else {
+		} else if (!IS_ENABLED(CONFIG_LP_XHCI_MTK_QUIRK)) {
 			packets -= (residue + cur_length) / mps;
 			residue = (residue + cur_length) % mps;
 			length -= cur_length;
@@ -548,6 +551,18 @@ xhci_enqueue_td(transfer_ring_t *const tr, const int ep, const size_t mps,
 		TRB_SET(TDS, trb, MIN(TRB_MAX_TD_SIZE, packets));
 		TRB_SET(CH, trb, 1);
 
+		if (length && IS_ENABLED(CONFIG_LP_XHCI_MTK_QUIRK)) {
+			/*
+			 * For MTK's xHCI controller, TDS defines a number of
+			 * packets that remain to be transferred for a TD after
+			 * processing all Max packets in all previous TRBs, that
+			 * means don't include the current TRB's.
+			 */
+			packets -= (residue + cur_length) / mps;
+			residue = (residue + cur_length) % mps;
+			length -= cur_length;
+		}
+
 		/* Check for first, data stage TRB */
 		if (!trb_count && ep == 1) {
 			TRB_SET(DIR, trb, dir);

payloads/libpayload/drivers/usb/xhci_commands.c

@@ -47,6 +47,8 @@ xhci_post_command(xhci_t *const xhci)
 	TRB_SET(C, xhci->cr.cur, xhci->cr.pcs);
 	++xhci->cr.cur;
 
+	/* pass command trb to hardware */
+	wmb();
 	/* Ring the doorbell */
 	xhci->dbreg[0] = 0;
 

payloads/libpayload/drivers/usb/xhci_devconf.c

@@ -313,6 +313,16 @@ xhci_finish_ep_config(const endpoint_t *const ep, inputctx_t *const ic)
 	EC_SET(AVRTRB,	epctx, avrtrb);
 	EC_SET(MXESIT,  epctx, EC_GET(MPS, epctx) * EC_GET(MBS, epctx));
 
+	if (IS_ENABLED(CONFIG_LP_USB_XHCI_MTK_QUIRK)) {
+		/* The MTK xHCI defines some extra SW parameters which are
+		 * put into reserved DWs in Slot and Endpoint Contexts for
+		 * synchronous endpoints. But for non-isochronous transfers,
+		 * it is enough to set the following two fields to 1, and others
+		 * are set to 0.
+		 */
+		EC_SET(BPKTS, epctx, 1);
+		EC_SET(BBM, epctx, 1);
+	}
 	return 0;
 }
 

payloads/libpayload/drivers/usb/xhci_private.h

@@ -33,6 +33,8 @@
 
 //#define USB_DEBUG
 #include <usb/usb.h>
+#include <arch/barrier.h>
+#include <kconfig.h>
 
 //#define XHCI_DUMPS
 #define xhci_debug(fmt, args...) usb_debug("%s: " fmt, __func__, ## args)
@@ -242,6 +244,13 @@ typedef volatile struct slotctx {
 #define EC_MXESIT_FIELD		f5		/* MXESIT - Max ESIT Payload */
 #define EC_MXESIT_START		16
 #define EC_MXESIT_LEN		16
+#define EC_BPKTS_FIELD		rsvd[0]		/* BPKTS - packets tx in scheduled uframe */
+#define EC_BPKTS_START		0
+#define EC_BPKTS_LEN		6
+#define EC_BBM_FIELD		rsvd[0]		/* BBM - burst mode for scheduling */
+#define EC_BBM_START		11
+#define EC_BBM_LEN		1
+
 #define EC_MASK(tok)		MASK(EC_##tok##_START, EC_##tok##_LEN)
 #define EC_GET(tok, ec)		(((ec)->EC_##tok##_FIELD & EC_MASK(tok)) \
 				 >> EC_##tok##_START)

payloads/libpayload/drivers/usb/xhci_rh.c

@@ -119,6 +119,24 @@ xhci_rh_reset_port(usbdev_t *const dev, const int port)
 	return 0;
 }
 
+static int
+xhci_rh_enable_port(usbdev_t *const dev, int port)
+{
+	if (IS_ENABLED(CONFIG_LP_USB_XHCI_MTK_QUIRK)) {
+		xhci_t *const xhci = XHCI_INST(dev->controller);
+		volatile u32 *const portsc =
+			&xhci->opreg->prs[port - 1].portsc;
+
+		/*
+		 * Before sending commands to a port, the Port Power in
+		 * PORTSC register should be enabled on MTK's xHCI.
+		 */
+		*portsc = (*portsc & PORTSC_RW_MASK) | PORTSC_PP;
+	}
+	return 0;
+}
+
+
 static const generic_hub_ops_t xhci_rh_ops = {
 	.hub_status_changed	= xhci_rh_hub_status_changed,
 	.port_status_changed	= xhci_rh_port_status_changed,
@@ -126,7 +144,7 @@ static const generic_hub_ops_t xhci_rh_ops = {
 	.port_in_reset		= xhci_rh_port_in_reset,
 	.port_enabled		= xhci_rh_port_enabled,
 	.port_speed		= xhci_rh_port_speed,
-	.enable_port		= NULL,
+	.enable_port		= xhci_rh_enable_port,
 	.disable_port		= NULL,
 	.start_port_reset	= NULL,
 	.reset_port		= xhci_rh_reset_port,