b6b77b2d5f
The SDK7786 FPGA has secondary control over the PCIe clocks, specifically relating to the slots and oscillator. This ties the FPGA clocks in to the clock framework and balances the refcounting similar to how the primary on-chip clocks are managed. While the on-chip clocks are per-port, the FPGA clock enable/disable is global for the entire block. Signed-off-by: Paul Mundt <lethal@linux-sh.org>
68 lines
1.7 KiB
C
68 lines
1.7 KiB
C
/*
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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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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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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 __devinitdata;
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char *__devinit 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_warning("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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