[PATCH v3 1/1] usb: dwc2: Fix the write to W1C fields in HPRT register

[teik.heng.chong at intel.com]

From: Teik Heng Chong <teik.heng.chong at intel.com>

Fix the write to the HPRT register which treat W1C fields
as if they were mere RW. This leads to unintended clearing of such fields

This bug was found during the testing on Simics model. Referring to
specification DesignWare Cores USB 2.0 Hi-Speed On-The-Go (OTG)
Databook (3.30a)"5.3.4.8 Host Port Control and Status Register (HPRT)", the
HPRT.PrtPwr is cleared by this mistake. In the Linux driver (contrary to
U-Boot), HPRT is always read using dwc2_read_hprt0 helper function which
clears W1C bits. So after write back those bits are zeroes.

Signed-off-by: Teik Heng Chong <teik.heng.chong at intel.com>

---

V2->V3
- update commit message
---
 drivers/usb/host/dwc2.c | 34 ++++++++--------------------------
 drivers/usb/host/dwc2.h |  4 ++++
 2 files changed, 12 insertions(+), 26 deletions(-)

diff --git a/drivers/usb/host/dwc2.c b/drivers/usb/host/dwc2.c
index 23060fc369..9818f9be94 100644
--- a/drivers/usb/host/dwc2.c
+++ b/drivers/usb/host/dwc2.c
@@ -315,9 +315,7 @@ static void dwc_otg_core_host_init(struct udevice *dev,
 
 	/* Turn on the vbus power. */
 	if (readl(&regs->gintsts) & DWC2_GINTSTS_CURMODE_HOST) {
-		hprt0 = readl(&regs->hprt0);
-		hprt0 &= ~(DWC2_HPRT0_PRTENA | DWC2_HPRT0_PRTCONNDET);
-		hprt0 &= ~(DWC2_HPRT0_PRTENCHNG | DWC2_HPRT0_PRTOVRCURRCHNG);
+		hprt0 = readl(&regs->hprt0) & ~DWC2_HPRT0_W1C_MASK;
 		if (!(hprt0 & DWC2_HPRT0_PRTPWR)) {
 			hprt0 |= DWC2_HPRT0_PRTPWR;
 			writel(hprt0, &regs->hprt0);
@@ -748,7 +746,7 @@ static int dwc_otg_submit_rh_msg_out(struct dwc2_priv *priv,
 	case (USB_REQ_CLEAR_FEATURE << 8) | USB_RECIP_OTHER | USB_TYPE_CLASS:
 		switch (wValue) {
 		case USB_PORT_FEAT_C_CONNECTION:
-			setbits_le32(&regs->hprt0, DWC2_HPRT0_PRTCONNDET);
+			clrsetbits_le32(&regs->hprt0, DWC2_HPRT0_W1C_MASK, DWC2_HPRT0_PRTCONNDET);
 			break;
 		}
 		break;
@@ -759,21 +757,13 @@ static int dwc_otg_submit_rh_msg_out(struct dwc2_priv *priv,
 			break;
 
 		case USB_PORT_FEAT_RESET:
-			clrsetbits_le32(&regs->hprt0, DWC2_HPRT0_PRTENA |
-					DWC2_HPRT0_PRTCONNDET |
-					DWC2_HPRT0_PRTENCHNG |
-					DWC2_HPRT0_PRTOVRCURRCHNG,
-					DWC2_HPRT0_PRTRST);
+			clrsetbits_le32(&regs->hprt0, DWC2_HPRT0_W1C_MASK, DWC2_HPRT0_PRTRST);
 			mdelay(50);
-			clrbits_le32(&regs->hprt0, DWC2_HPRT0_PRTRST);
+			clrbits_le32(&regs->hprt0, DWC2_HPRT0_W1C_MASK | DWC2_HPRT0_PRTRST);
 			break;
 
 		case USB_PORT_FEAT_POWER:
-			clrsetbits_le32(&regs->hprt0, DWC2_HPRT0_PRTENA |
-					DWC2_HPRT0_PRTCONNDET |
-					DWC2_HPRT0_PRTENCHNG |
-					DWC2_HPRT0_PRTOVRCURRCHNG,
-					DWC2_HPRT0_PRTRST);
+			clrsetbits_le32(&regs->hprt0, DWC2_HPRT0_W1C_MASK, DWC2_HPRT0_PRTRST);
 			break;
 
 		case USB_PORT_FEAT_ENABLE:
@@ -1213,14 +1203,9 @@ static int dwc2_init_common(struct udevice *dev, struct dwc2_priv *priv)
 		dwc_otg_core_host_init(dev, regs);
 	}
 
-	clrsetbits_le32(&regs->hprt0, DWC2_HPRT0_PRTENA |
-			DWC2_HPRT0_PRTCONNDET | DWC2_HPRT0_PRTENCHNG |
-			DWC2_HPRT0_PRTOVRCURRCHNG,
-			DWC2_HPRT0_PRTRST);
+	clrsetbits_le32(&regs->hprt0, DWC2_HPRT0_W1C_MASK, DWC2_HPRT0_PRTRST);
 	mdelay(50);
-	clrbits_le32(&regs->hprt0, DWC2_HPRT0_PRTENA | DWC2_HPRT0_PRTCONNDET |
-		     DWC2_HPRT0_PRTENCHNG | DWC2_HPRT0_PRTOVRCURRCHNG |
-		     DWC2_HPRT0_PRTRST);
+	clrbits_le32(&regs->hprt0, DWC2_HPRT0_W1C_MASK | DWC2_HPRT0_PRTRST);
 
 	for (i = 0; i < MAX_DEVICE; i++) {
 		for (j = 0; j < MAX_ENDPOINT; j++) {
@@ -1246,10 +1231,7 @@ static int dwc2_init_common(struct udevice *dev, struct dwc2_priv *priv)
 static void dwc2_uninit_common(struct dwc2_core_regs *regs)
 {
 	/* Put everything in reset. */
-	clrsetbits_le32(&regs->hprt0, DWC2_HPRT0_PRTENA |
-			DWC2_HPRT0_PRTCONNDET | DWC2_HPRT0_PRTENCHNG |
-			DWC2_HPRT0_PRTOVRCURRCHNG,
-			DWC2_HPRT0_PRTRST);
+	clrsetbits_le32(&regs->hprt0, DWC2_HPRT0_W1C_MASK, DWC2_HPRT0_PRTRST);
 }
 
 #if !CONFIG_IS_ENABLED(DM_USB)
diff --git a/drivers/usb/host/dwc2.h b/drivers/usb/host/dwc2.h
index a6f562fe60..6f022e33a1 100644
--- a/drivers/usb/host/dwc2.h
+++ b/drivers/usb/host/dwc2.h
@@ -543,6 +543,10 @@ struct dwc2_core_regs {
 #define DWC2_HPRT0_PRTSPD_LOW				(2 << 17)
 #define DWC2_HPRT0_PRTSPD_MASK				(0x3 << 17)
 #define DWC2_HPRT0_PRTSPD_OFFSET			17
+#define DWC2_HPRT0_W1C_MASK				(DWC2_HPRT0_PRTCONNDET | \
+							DWC2_HPRT0_PRTENA | \
+							DWC2_HPRT0_PRTENCHNG | \
+							DWC2_HPRT0_PRTOVRCURRCHNG)
 #define DWC2_HAINT_CH0					(1 << 0)
 #define DWC2_HAINT_CH0_OFFSET				0
 #define DWC2_HAINT_CH1					(1 << 1)
-- 
2.25.1