1 files changed, 59 insertions, 0 deletions
diff --git a/arch/x86/pci/early.c b/arch/x86/pci/early.c
new file mode 100644
index 000000000..f5fc953e5
--- /dev/null
+++ b/arch/x86/pci/early.c
@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kernel.h>
+#include <linux/pci.h>
+#include <asm/pci-direct.h>
+#include <asm/io.h>
+#include <asm/pci_x86.h>
+
+/* Direct PCI access. This is used for PCI accesses in early boot before
+   the PCI subsystem works. */
+
+u32 read_pci_config(u8 bus, u8 slot, u8 func, u8 offset)
+{
+	u32 v;
+	outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
+	v = inl(0xcfc);
+	return v;
+}
+
+u8 read_pci_config_byte(u8 bus, u8 slot, u8 func, u8 offset)
+{
+	u8 v;
+	outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
+	v = inb(0xcfc + (offset&3));
+	return v;
+}
+
+u16 read_pci_config_16(u8 bus, u8 slot, u8 func, u8 offset)
+{
+	u16 v;
+	outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
+	v = inw(0xcfc + (offset&2));
+	return v;
+}
+
+void write_pci_config(u8 bus, u8 slot, u8 func, u8 offset,
+				    u32 val)
+{
+	outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
+	outl(val, 0xcfc);
+}
+
+void write_pci_config_byte(u8 bus, u8 slot, u8 func, u8 offset, u8 val)
+{
+	outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
+	outb(val, 0xcfc + (offset&3));
+}
+
+void write_pci_config_16(u8 bus, u8 slot, u8 func, u8 offset, u16 val)
+{
+	outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
+	outw(val, 0xcfc + (offset&2));
+}
+
+int early_pci_allowed(void)
+{
+	return (pci_probe & (PCI_PROBE_CONF1|PCI_PROBE_NOEARLY)) ==
+			PCI_PROBE_CONF1;
+}
+