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// 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);
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