1 files changed, 64 insertions, 0 deletions
diff --git a/arch/sh/drivers/pci/fixups-sdk7786.c b/arch/sh/drivers/pci/fixups-sdk7786.c
new file mode 100644
index 0000000000..6972af7b4e
--- /dev/null
+++ b/arch/sh/drivers/pci/fixups-sdk7786.c
@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * SDK7786 FPGA PCIe mux handling
+ *
+ * Copyright (C) 2010  Paul Mundt
+ */
+#define pr_fmt(fmt) "PCI: " fmt
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/pci.h>
+#include <mach/fpga.h>
+
+/*
+ * The SDK7786 FPGA supports mangling of most of the slots in some way or
+ * another. Slots 3/4 are special in that only one can be supported at a
+ * time, and both appear on port 3 to the PCI bus scan. Enabling slot 4
+ * (the horizontal edge connector) will disable slot 3 entirely.
+ *
+ * Misconfigurations can be detected through the FPGA via the slot
+ * resistors to determine card presence. Hotplug remains unsupported.
+ */
+static unsigned int slot4en __initdata;
+
+char *__init pcibios_setup(char *str)
+{
+	if (strcmp(str, "slot4en") == 0) {
+		slot4en = 1;
+		return NULL;
+	}
+
+	return str;
+}
+
+static int __init sdk7786_pci_init(void)
+{
+	u16 data = fpga_read_reg(PCIECR);
+
+	/*
+	 * Enable slot #4 if it's been specified on the command line.
+	 *
+	 * Optionally reroute if slot #4 has a card present while slot #3
+	 * does not, regardless of command line value.
+	 *
+	 * Card presence is logically inverted.
+	 */
+	slot4en ?: (!(data & PCIECR_PRST4) && (data & PCIECR_PRST3));
+	if (slot4en) {
+		pr_info("Activating PCIe slot#4 (disabling slot#3)\n");
+
+		data &= ~PCIECR_PCIEMUX1;
+		fpga_write_reg(data, PCIECR);
+
+		/* Warn about forced rerouting if slot#3 is occupied */
+		if ((data & PCIECR_PRST3) == 0) {
+			pr_warn("Unreachable card detected in slot#3\n");
+			return -EBUSY;
+		}
+	} else
+		pr_info("PCIe slot#4 disabled\n");
+
+	return 0;
+}
+postcore_initcall(sdk7786_pci_init);