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61a46766 PM |
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> | |
61a46766 PM |
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 | */ | |
ce8dd71a | 26 | static unsigned int slot4en __initdata; |
61a46766 | 27 | |
ce8dd71a | 28 | char *__init pcibios_setup(char *str) |
61a46766 PM |
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); |