| Paul Mundt | 61a46766 | 2010-10-14 07:37:01 +0900 | [diff] [blame] | 1 | /* |
| 2 | * SDK7786 FPGA PCIe mux handling |
| 3 | * |
| 4 | * Copyright (C) 2010 Paul Mundt |
| 5 | * |
| 6 | * This file is subject to the terms and conditions of the GNU General Public |
| 7 | * License. See the file "COPYING" in the main directory of this archive |
| 8 | * for more details. |
| 9 | */ |
| 10 | #define pr_fmt(fmt) "PCI: " fmt |
| 11 | |
| 12 | #include <linux/init.h> |
| Paul Mundt | 61a46766 | 2010-10-14 07:37:01 +0900 | [diff] [blame] | 13 | #include <linux/kernel.h> |
| 14 | #include <linux/pci.h> |
| 15 | #include <mach/fpga.h> |
| 16 | |
| 17 | /* |
| 18 | * The SDK7786 FPGA supports mangling of most of the slots in some way or |
| 19 | * another. Slots 3/4 are special in that only one can be supported at a |
| 20 | * time, and both appear on port 3 to the PCI bus scan. Enabling slot 4 |
| 21 | * (the horizontal edge connector) will disable slot 3 entirely. |
| 22 | * |
| 23 | * Misconfigurations can be detected through the FPGA via the slot |
| 24 | * resistors to determine card presence. Hotplug remains unsupported. |
| 25 | */ |
| 26 | static unsigned int slot4en __devinitdata; |
| 27 | |
| 28 | char *__devinit pcibios_setup(char *str) |
| 29 | { |
| 30 | if (strcmp(str, "slot4en") == 0) { |
| 31 | slot4en = 1; |
| 32 | return NULL; |
| 33 | } |
| 34 | |
| 35 | return str; |
| 36 | } |
| 37 | |
| 38 | static int __init sdk7786_pci_init(void) |
| 39 | { |
| 40 | u16 data = fpga_read_reg(PCIECR); |
| 41 | |
| 42 | /* |
| 43 | * Enable slot #4 if it's been specified on the command line. |
| 44 | * |
| 45 | * Optionally reroute if slot #4 has a card present while slot #3 |
| 46 | * does not, regardless of command line value. |
| 47 | * |
| 48 | * Card presence is logically inverted. |
| 49 | */ |
| 50 | slot4en ?: (!(data & PCIECR_PRST4) && (data & PCIECR_PRST3)); |
| 51 | if (slot4en) { |
| 52 | pr_info("Activating PCIe slot#4 (disabling slot#3)\n"); |
| 53 | |
| 54 | data &= ~PCIECR_PCIEMUX1; |
| 55 | fpga_write_reg(data, PCIECR); |
| 56 | |
| 57 | /* Warn about forced rerouting if slot#3 is occupied */ |
| 58 | if ((data & PCIECR_PRST3) == 0) { |
| 59 | pr_warning("Unreachable card detected in slot#3\n"); |
| 60 | return -EBUSY; |
| 61 | } |
| 62 | } else |
| 63 | pr_info("PCIe slot#4 disabled\n"); |
| 64 | |
| 65 | return 0; |
| 66 | } |
| 67 | postcore_initcall(sdk7786_pci_init); |