PCI: work around IvyBridge internal graphics FLR erratum

For IvyBridge Mobile platform, a system hang may occur if a FLR (Function
Level Reset) is asserted to internal graphics.

This quirk is a workaround for the IVB FLR errata issue.  We are
disabling the FLR reset handshake between the PCH and CPU display, then
manually powering down the panel power sequencing and resetting the PCH
display.

Signed-off-by: Xudong Hao <xudong.hao@intel.com>
Signed-off-by: Kay, Allen M <allen.m.kay@intel.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/quirks.c

@@ -3085,16 +3085,74 @@ static int reset_intel_82599_sfp_virtfn(struct pci_dev *dev, int probe)
 	return 0;
 }
 
+#include "../gpu/drm/i915/i915_reg.h"
+#define MSG_CTL			0x45010
+#define NSDE_PWR_STATE		0xd0100
+#define IGD_OPERATION_TIMEOUT	10000     /* set timeout 10 seconds */
+
+static int reset_ivb_igd(struct pci_dev *dev, int probe)
+{
+	void __iomem *mmio_base;
+	unsigned long timeout;
+	u32 val;
+
+	if (probe)
+		return 0;
+
+	mmio_base = pci_iomap(dev, 0, 0);
+	if (!mmio_base)
+		return -ENOMEM;
+
+	iowrite32(0x00000002, mmio_base + MSG_CTL);
+
+	/*
+	 * Clobbering SOUTH_CHICKEN2 register is fine only if the next
+	 * driver loaded sets the right bits. However, this's a reset and
+	 * the bits have been set by i915 previously, so we clobber
+	 * SOUTH_CHICKEN2 register directly here.
+	 */
+	iowrite32(0x00000005, mmio_base + SOUTH_CHICKEN2);
+
+	val = ioread32(mmio_base + PCH_PP_CONTROL) & 0xfffffffe;
+	iowrite32(val, mmio_base + PCH_PP_CONTROL);
+
+	timeout = jiffies + msecs_to_jiffies(IGD_OPERATION_TIMEOUT);
+	do {
+		val = ioread32(mmio_base + PCH_PP_STATUS);
+		if ((val & 0xb0000000) == 0)
+			goto reset_complete;
+		msleep(10);
+	} while (time_before(jiffies, timeout));
+	dev_warn(&dev->dev, "timeout during reset\n");
+
+reset_complete:
+	iowrite32(0x00000002, mmio_base + NSDE_PWR_STATE);
+
+	pci_iounmap(dev, mmio_base);
+	return 0;
+}
+
 #define PCI_DEVICE_ID_INTEL_82599_SFP_VF   0x10ed
+#define PCI_DEVICE_ID_INTEL_IVB_M_VGA      0x0156
+#define PCI_DEVICE_ID_INTEL_IVB_M2_VGA     0x0166
 
 static const struct pci_dev_reset_methods pci_dev_reset_methods[] = {
 	{ PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82599_SFP_VF,
 		 reset_intel_82599_sfp_virtfn },
+	{ PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_IVB_M_VGA,
+		reset_ivb_igd },
+	{ PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_IVB_M2_VGA,
+		reset_ivb_igd },
 	{ PCI_VENDOR_ID_INTEL, PCI_ANY_ID,
 		reset_intel_generic_dev },
 	{ 0 }
 };
 
+/*
+ * These device-specific reset methods are here rather than in a driver
+ * because when a host assigns a device to a guest VM, the host may need
+ * to reset the device but probably doesn't have a driver for it.
+ */
 int pci_dev_specific_reset(struct pci_dev *dev, int probe)
 {
 	const struct pci_dev_reset_methods *i;