65 lines
1.6 KiB
C
65 lines
1.6 KiB
C
// 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_warn("Unreachable card detected in slot#3\n");
|
|
return -EBUSY;
|
|
}
|
|
} else
|
|
pr_info("PCIe slot#4 disabled\n");
|
|
|
|
return 0;
|
|
}
|
|
postcore_initcall(sdk7786_pci_init);
|