usb: dwc2: Update Core Reset programming flow.

Starting from core version 4.20a Core Reset flow is changed.
Introduced new bit in GRSTCTL register - GRSTCTL_CSFTRST_DONE.
Core Reset new programming flow steps are follow:
1. Set GRSTCTL_CSFTRST bit.
2. Wait for bit GRSTCTL_CSFTRST_DONE is set.
3. Clear GRSTCTL_CSFTRST and GRSTCTL_CSFTRST_DONE bits.

Check core version functionality separated from dwc2_get_hwparams() to
new dwc2_check_core_version() function because Core Reset flow depend
on SNPSID.
Signed-off-by: Minas Harutyunyan <hminas@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

drivers/usb/dwc2/core.c

@@ -524,10 +524,25 @@ int dwc2_core_reset(struct dwc2_hsotg *hsotg, bool skip_wait)
 	greset |= GRSTCTL_CSFTRST;
 	dwc2_writel(hsotg, greset, GRSTCTL);
 
-	if (dwc2_hsotg_wait_bit_clear(hsotg, GRSTCTL, GRSTCTL_CSFTRST, 10000)) {
-		dev_warn(hsotg->dev, "%s: HANG! Soft Reset timeout GRSTCTL GRSTCTL_CSFTRST\n",
-			 __func__);
-		return -EBUSY;
+	if ((hsotg->hw_params.snpsid & DWC2_CORE_REV_MASK) <
+		(DWC2_CORE_REV_4_20a & DWC2_CORE_REV_MASK)) {
+		if (dwc2_hsotg_wait_bit_clear(hsotg, GRSTCTL,
+					      GRSTCTL_CSFTRST, 10000)) {
+			dev_warn(hsotg->dev, "%s: HANG! Soft Reset timeout GRSTCTL_CSFTRST\n",
+				 __func__);
+			return -EBUSY;
+		}
+	} else {
+		if (dwc2_hsotg_wait_bit_set(hsotg, GRSTCTL,
+					    GRSTCTL_CSFTRST_DONE, 10000)) {
+			dev_warn(hsotg->dev, "%s: HANG! Soft Reset timeout GRSTCTL_CSFTRST_DONE\n",
+				 __func__);
+			return -EBUSY;
+		}
+		greset = dwc2_readl(hsotg, GRSTCTL);
+		greset &= ~GRSTCTL_CSFTRST;
+		greset |= GRSTCTL_CSFTRST_DONE;
+		dwc2_writel(hsotg, greset, GRSTCTL);
 	}
 
 	/* Wait for AHB master IDLE state */

drivers/usb/dwc2/core.h

@@ -1103,8 +1103,10 @@ struct dwc2_hsotg {
 #define DWC2_CORE_REV_3_00a	0x4f54300a
 #define DWC2_CORE_REV_3_10a	0x4f54310a
 #define DWC2_CORE_REV_4_00a	0x4f54400a
+#define DWC2_CORE_REV_4_20a	0x4f54420a
 #define DWC2_FS_IOT_REV_1_00a	0x5531100a
 #define DWC2_HS_IOT_REV_1_00a	0x5532100a
+#define DWC2_CORE_REV_MASK	0x0000ffff
 
 	/* DWC OTG HW Core ID */
 #define DWC2_OTG_ID		0x4f540000
@@ -1309,6 +1311,8 @@ void dwc2_force_dr_mode(struct dwc2_hsotg *hsotg);
 
 bool dwc2_is_controller_alive(struct dwc2_hsotg *hsotg);
 
+int dwc2_check_core_version(struct dwc2_hsotg *hsotg);
+
 /*
  * Common core Functions.
  * The following functions support managing the DWC_otg controller in either

drivers/usb/dwc2/hw.h

@@ -126,6 +126,7 @@
 #define GRSTCTL				HSOTG_REG(0x010)
 #define GRSTCTL_AHBIDLE			BIT(31)
 #define GRSTCTL_DMAREQ			BIT(30)
+#define GRSTCTL_CSFTRST_DONE		BIT(29)
 #define GRSTCTL_TXFNUM_MASK		(0x1f << 6)
 #define GRSTCTL_TXFNUM_SHIFT		6
 #define GRSTCTL_TXFNUM_LIMIT		0x1f

drivers/usb/dwc2/params.c

@@ -782,25 +782,6 @@ int dwc2_get_hwparams(struct dwc2_hsotg *hsotg)
 	u32 hwcfg1, hwcfg2, hwcfg3, hwcfg4;
 	u32 grxfsiz;
 
-	/*
-	 * Attempt to ensure this device is really a DWC_otg Controller.
-	 * Read and verify the GSNPSID register contents. The value should be
-	 * 0x45f4xxxx, 0x5531xxxx or 0x5532xxxx
-	 */
-
-	hw->snpsid = dwc2_readl(hsotg, GSNPSID);
-	if ((hw->snpsid & GSNPSID_ID_MASK) != DWC2_OTG_ID &&
-	    (hw->snpsid & GSNPSID_ID_MASK) != DWC2_FS_IOT_ID &&
-	    (hw->snpsid & GSNPSID_ID_MASK) != DWC2_HS_IOT_ID) {
-		dev_err(hsotg->dev, "Bad value for GSNPSID: 0x%08x\n",
-			hw->snpsid);
-		return -ENODEV;
-	}
-
-	dev_dbg(hsotg->dev, "Core Release: %1x.%1x%1x%1x (snpsid=%x)\n",
-		hw->snpsid >> 12 & 0xf, hw->snpsid >> 8 & 0xf,
-		hw->snpsid >> 4 & 0xf, hw->snpsid & 0xf, hw->snpsid);
-
 	hwcfg1 = dwc2_readl(hsotg, GHWCFG1);
 	hwcfg2 = dwc2_readl(hsotg, GHWCFG2);
 	hwcfg3 = dwc2_readl(hsotg, GHWCFG3);

drivers/usb/dwc2/platform.c

@@ -362,6 +362,37 @@ static bool dwc2_check_core_endianness(struct dwc2_hsotg *hsotg)
 	return true;
 }
 
+/**
+ * Check core version
+ *
+ * @hsotg: Programming view of the DWC_otg controller
+ *
+ */
+int dwc2_check_core_version(struct dwc2_hsotg *hsotg)
+{
+	struct dwc2_hw_params *hw = &hsotg->hw_params;
+
+	/*
+	 * Attempt to ensure this device is really a DWC_otg Controller.
+	 * Read and verify the GSNPSID register contents. The value should be
+	 * 0x45f4xxxx, 0x5531xxxx or 0x5532xxxx
+	 */
+
+	hw->snpsid = dwc2_readl(hsotg, GSNPSID);
+	if ((hw->snpsid & GSNPSID_ID_MASK) != DWC2_OTG_ID &&
+	    (hw->snpsid & GSNPSID_ID_MASK) != DWC2_FS_IOT_ID &&
+	    (hw->snpsid & GSNPSID_ID_MASK) != DWC2_HS_IOT_ID) {
+		dev_err(hsotg->dev, "Bad value for GSNPSID: 0x%08x\n",
+			hw->snpsid);
+		return -ENODEV;
+	}
+
+	dev_dbg(hsotg->dev, "Core Release: %1x.%1x%1x%1x (snpsid=%x)\n",
+		hw->snpsid >> 12 & 0xf, hw->snpsid >> 8 & 0xf,
+		hw->snpsid >> 4 & 0xf, hw->snpsid & 0xf, hw->snpsid);
+	return 0;
+}
+
 /**
  * dwc2_driver_probe() - Called when the DWC_otg core is bound to the DWC_otg
  * driver
@@ -444,6 +475,14 @@ static int dwc2_driver_probe(struct platform_device *dev)
 		of_property_read_bool(dev->dev.of_node,
 				      "snps,need-phy-for-wake");
 
+	/*
+	 * Before performing any core related operations
+	 * check core version.
+	 */
+	retval = dwc2_check_core_version(hsotg);
+	if (retval)
+		goto error;
+
 	/*
 	 * Reset before dwc2_get_hwparams() then it could get power-on real
 	 * reset value form registers.