// 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_warning("Unreachable card detected in slot#3\n"); return -EBUSY; } } else pr_info("PCIe slot#4 disabled\n"); return 0; } postcore_initcall(sdk7786_pci_init);