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