From 9cc14ca0aae53c16d10ffea49848ac61a5015562 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <zajec5@gmail.com>
Date: Sun, 21 Jun 2015 11:10:49 +0200
Subject: [PATCH] xhci: add Broadcom specific fake doorbell
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This fixes problem with controller seeing devices only in some small
percentage of cold boots.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
---
 drivers/usb/host/xhci.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)

--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -122,6 +122,64 @@ int xhci_halt(struct xhci_hcd *xhci)
 	return ret;
 }
 
+#ifdef CONFIG_ARCH_BCM_5301X
+int xhci_fake_doorbell(struct xhci_hcd *xhci, int slot_id)
+{
+	unsigned int temp1, ret;
+
+	/* alloc a virt device for slot */
+	if (!xhci_alloc_virt_device(xhci, slot_id, 0, GFP_NOIO)) {
+		xhci_warn(xhci, "Could not allocate xHCI USB device data structures\n");
+		return 1;
+        }
+
+	/* ring fake doorbell for slot_id ep 0 */
+	xhci_ring_ep_doorbell(xhci, slot_id, 0, 0);
+	mdelay(1);
+
+	/* read the status register to check if HSE is set or not? */
+	temp1 = readl(&xhci->op_regs->status);
+	xhci_dbg(xhci, "op reg status = %x\n",temp1);
+
+	/* clear HSE if set */
+	if(temp1 & STS_FATAL) {
+		xhci_dbg(xhci, "HSE problem detected\n");
+		temp1 &= ~(0x1fff);
+		temp1 |= STS_FATAL;
+		xhci_dbg(xhci, "temp1=%x\n",temp1);
+		writel(temp1, &xhci->op_regs->status);
+		mdelay(1);
+		temp1 = readl(&xhci->op_regs->status);
+		xhci_dbg(xhci, "After clear op reg status=%x\n", temp1);
+	}
+
+	/* Free virt device */
+	xhci_free_virt_device(xhci, slot_id);
+
+	/* Run the controller if needed */
+	temp1 = readl(&xhci->op_regs->command);
+	if (temp1 & CMD_RUN)
+		return 0;
+	temp1 |= (CMD_RUN);
+
+	writel(temp1, &xhci->op_regs->command);
+	/*
+	 * Wait for the HCHalted Status bit to be 0 to indicate the host is running.
+	 */
+	ret = xhci_handshake(xhci, &xhci->op_regs->status,
+			     STS_HALT, 0, XHCI_MAX_HALT_USEC);
+
+	if (ret == -ETIMEDOUT) {
+		xhci_err(xhci, "Host took too long to start, "
+				"waited %u microseconds.\n",
+				XHCI_MAX_HALT_USEC);
+		return 1;
+	}
+
+	return 0;
+}
+#endif /* CONFIG_ARCH_BCM_5301X */
+
 /*
  * Set the run bit and wait for the host to be running.
  */
@@ -146,6 +204,10 @@ static int xhci_start(struct xhci_hcd *x
 		xhci_err(xhci, "Host took too long to start, "
 				"waited %u microseconds.\n",
 				XHCI_MAX_HALT_USEC);
+#ifdef CONFIG_ARCH_BCM_5301X
+	xhci_fake_doorbell(xhci, 1);
+#endif /* CONFIG_ARCH_BCM_5301X */
+
 	if (!ret)
 		xhci->xhc_state &= ~XHCI_STATE_HALTED;
 	return ret;
