diff --git a/arch/x86/cpu/pci.c b/arch/x86/cpu/pci.c
index c6218250e1..0ccde194d9 100644
--- a/arch/x86/cpu/pci.c
+++ b/arch/x86/cpu/pci.c
@@ -16,6 +16,10 @@
 #include <asm/io.h>
 #include <asm/pci.h>
 
+/*
+ * TODO(sjg@chromium.org): Drop the first parameter from each of these
+ * functions since it is not used.
+ */
 int pci_x86_read_config(struct udevice *bus, pci_dev_t bdf, uint offset,
 			ulong *valuep, enum pci_size_t size)
 {
@@ -54,6 +58,21 @@ int pci_x86_write_config(struct udevice *bus, pci_dev_t bdf, uint offset,
 	return 0;
 }
 
+int pci_x86_clrset_config(struct udevice *bus, pci_dev_t bdf, uint offset,
+			  ulong clr, ulong set, enum pci_size_t size)
+{
+	ulong value;
+	int ret;
+
+	ret = pci_x86_read_config(bus, bdf, offset, &value, size);
+	if (ret)
+		return ret;
+	value &= ~clr;
+	value |= set;
+
+	return pci_x86_write_config(bus, bdf, offset, value, size);
+}
+
 void pci_assign_irqs(int bus, int device, u8 irq[4])
 {
 	pci_dev_t bdf;
diff --git a/arch/x86/include/asm/pci.h b/arch/x86/include/asm/pci.h
index 118ac937d9..fb1edf3df7 100644
--- a/arch/x86/include/asm/pci.h
+++ b/arch/x86/include/asm/pci.h
@@ -17,12 +17,52 @@
 
 #ifndef __ASSEMBLY__
 
+/**
+ * pci_x86_read_config() - Read a configuration value from a device
+ *
+ * This function can be called before PCI is set up in driver model.
+ *
+ * @bus:	Bus to read from (ignored, can be NULL)
+ * @bdf:	PCI device address: bus, device and function -see PCI_BDF()
+ * @offset:	Register offset to read
+ * @valuep:	Place to put the returned value
+ * @size:	Access size
+ * @return 0 if OK, -ve on error
+ */
 int pci_x86_read_config(struct udevice *bus, pci_dev_t bdf, uint offset,
 			ulong *valuep, enum pci_size_t size);
 
+/**
+ * pci_bus_write_config() - Write a configuration value to a device
+ *
+ * This function can be called before PCI is set up in driver model.
+ *
+ * @bus:	Bus to read from (ignored, can be NULL)
+ * @bdf:	PCI device address: bus, device and function -see PCI_BDF()
+ * @offset:	Register offset to write
+ * @value:	Value to write
+ * @size:	Access size
+ * @return 0 if OK, -ve on error
+ */
 int pci_x86_write_config(struct udevice *bus, pci_dev_t bdf, uint offset,
 			 ulong value, enum pci_size_t size);
 
+/**
+ * pci_bus_clrset_config32() - Update a configuration value for a device
+ *
+ * The register at @offset is updated to (oldvalue & ~clr) | set. This function
+ * can be called before PCI is set up in driver model.
+ *
+ * @bus:	Bus to read from (ignored, can be NULL)
+ * @bdf:	PCI device address: bus, device and function -see PCI_BDF()
+ * @offset:	Register offset to update
+ * @clr:	Bits to clear
+ * @set:	Bits to set
+ * @return 0 if OK, -ve on error
+ */
+int pci_x86_clrset_config(struct udevice *bus, pci_dev_t bdf, uint offset,
+			  ulong clr, ulong set, enum pci_size_t size);
+
 /**
  * Assign IRQ number to a PCI device
  *