[PATCH v2] USB: ehci-pci: USB host controller support for Intel Quark X1000

["Chen, Alvin" <alvin.chen@intel.com>]

From: Bryan O'Donoghue <bryan.odonoghue@intel.com>

The EHCI packet buffer in/out threshold is programmable for Intel Quark X1000 USB host
controller, and the default value is 0x20 dwords. The in/out threshold can be programmed
to 0x80 dwords, but only when isochronous/interrupt transactions are not initiated by
the USB host controller. This patch is to reconfigure the packet buffer in/out threshold
as maximal as possible, and it is 0x7F dwords since the USB host controller initiates
isochronous/interrupt transactions.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@intel.com>
Signed-off-by: Alvin (Weike) Chen <alvin.chen@intel.com>
---
changelog v2:
*Change the function name from 'usb_is_intel_qrk' to 'usb_is_intel_quark_x1000'.
*Move the functions 'usb_is_intel_quark_x1000' and 'usb_set_qrk_bulk_thresh'
 from 'pci-quirks.c' to 'ehci-pci.c'.
*Remove unnecessary kernel message in the function of 'usb_set_qrk_bulk_thresh'.
*Remove 'unlikely' in the functions of 'ehci_pci_reinit'.
*Add white space after 'if'.
*Update the descriptions to make it more clearly.
*Add Micros to avoid magic number.

 drivers/usb/host/ehci-pci.c |   45 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/drivers/usb/host/ehci-pci.c b/drivers/usb/host/ehci-pci.c
index 3e86bf4..ca29f34 100644
--- a/drivers/usb/host/ehci-pci.c
+++ b/drivers/usb/host/ehci-pci.c
@@ -35,6 +35,47 @@ static const char hcd_name[] = "ehci-pci";
 #define PCI_DEVICE_ID_INTEL_CE4100_USB	0x2e70
 
 /*-------------------------------------------------------------------------*/
+#define PCI_DEVICE_ID_INTEL_QUARK_X1000_SOC		0x0939
+static inline bool usb_is_intel_quark_x1000(struct pci_dev *pdev)
+{
+	return pdev->vendor == PCI_VENDOR_ID_INTEL &&
+		pdev->device == PCI_DEVICE_ID_INTEL_QUARK_X1000_SOC;
+
+}
+
+/* Register offset of in/out threshold */
+#define EHCI_INSNREG01		    0x84
+/* The maximal threshold is 0x80 Dword */
+#define EHCI_MAX_THRESHOLD      0X80
+/* Lower word is 'in' threshold, and higher word is 'out' threshold*/
+#define EHCI_INSNREG01_THRESH \
+	((EHCI_MAX_THRESHOLD - 1)<<16 | (EHCI_MAX_THRESHOLD - 1))
+static void usb_set_qrk_bulk_thresh(struct pci_dev *pdev)
+{
+	void __iomem *base, *op_reg_base;
+	u8 cap_length;
+	u32 val;
+	u16 cmd;
+
+	if (!pci_resource_start(pdev, 0))
+		return;
+
+	if (pci_read_config_word(pdev, PCI_COMMAND, &cmd)
+		|| !(cmd & PCI_COMMAND_MEMORY))
+		return;
+
+	base = pci_ioremap_bar(pdev, 0);
+	if (base == NULL)
+		return;
+
+	cap_length = readb(base);
+	op_reg_base = base + cap_length;
+
+	val = EHCI_INSNREG01_THRESH;
+	writel(val, op_reg_base + EHCI_INSNREG01);
+
+	iounmap(base);
+}
 
 /* called after powerup, by probe or system-pm "wakeup" */
 static int ehci_pci_reinit(struct ehci_hcd *ehci, struct pci_dev *pdev)
@@ -50,6 +91,10 @@ static int ehci_pci_reinit(struct ehci_hcd *ehci, struct pci_dev *pdev)
 	if (!retval)
 		ehci_dbg(ehci, "MWI active\n");
 
+	/* Reset the threshold limit */
+	if (usb_is_intel_quark_x1000(pdev))
+		usb_set_qrk_bulk_thresh(pdev);
+
 	return 0;
 }
 
-- 
1.7.9.5