1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * PCI operations for the Sega Dreamcast
4 *
5 * Copyright (C) 2001, 2002 M. R. Brown
6 * Copyright (C) 2002, 2003 Paul Mundt
7 */
8
9 #include <linux/sched.h>
10 #include <linux/kernel.h>
11 #include <linux/param.h>
12 #include <linux/interrupt.h>
13 #include <linux/init.h>
14 #include <linux/irq.h>
15 #include <linux/pci.h>
16 #include <linux/module.h>
17 #include <linux/io.h>
18 #include <mach/pci.h>
19
20 /*
21 * The !gapspci_config_access case really shouldn't happen, ever, unless
22 * someone implicitly messes around with the last devfn value.. otherwise we
23 * only support a single device anyways, and if we didn't have a BBA, we
24 * wouldn't make it terribly far through the PCI setup anyways.
25 *
26 * Also, we could very easily support both Type 0 and Type 1 configurations
27 * here, but since it doesn't seem that there is any such implementation in
28 * existence, we don't bother.
29 *
30 * I suppose if someone actually gets around to ripping the chip out of
31 * the BBA and hanging some more devices off of it, then this might be
32 * something to take into consideration. However, due to the cost of the BBA,
33 * and the general lack of activity by DC hardware hackers, this doesn't seem
34 * likely to happen anytime soon.
35 */
gapspci_config_access(unsigned char bus,unsigned int devfn)36 static int gapspci_config_access(unsigned char bus, unsigned int devfn)
37 {
38 return (bus == 0) && (devfn == 0);
39 }
40
41 /*
42 * We can also actually read and write in b/w/l sizes! Thankfully this part
43 * was at least done right, and we don't have to do the stupid masking and
44 * shifting that we do on the 7751! Small wonders never cease to amaze.
45 */
gapspci_read(struct pci_bus * bus,unsigned int devfn,int where,int size,u32 * val)46 static int gapspci_read(struct pci_bus *bus, unsigned int devfn, int where, int size, u32 *val)
47 {
48 *val = 0xffffffff;
49
50 if (!gapspci_config_access(bus->number, devfn))
51 return PCIBIOS_DEVICE_NOT_FOUND;
52
53 switch (size) {
54 case 1: *val = inb(GAPSPCI_BBA_CONFIG+where); break;
55 case 2: *val = inw(GAPSPCI_BBA_CONFIG+where); break;
56 case 4: *val = inl(GAPSPCI_BBA_CONFIG+where); break;
57 }
58
59 return PCIBIOS_SUCCESSFUL;
60 }
61
gapspci_write(struct pci_bus * bus,unsigned int devfn,int where,int size,u32 val)62 static int gapspci_write(struct pci_bus *bus, unsigned int devfn, int where, int size, u32 val)
63 {
64 if (!gapspci_config_access(bus->number, devfn))
65 return PCIBIOS_DEVICE_NOT_FOUND;
66
67 switch (size) {
68 case 1: outb(( u8)val, GAPSPCI_BBA_CONFIG+where); break;
69 case 2: outw((u16)val, GAPSPCI_BBA_CONFIG+where); break;
70 case 4: outl((u32)val, GAPSPCI_BBA_CONFIG+where); break;
71 }
72
73 return PCIBIOS_SUCCESSFUL;
74 }
75
76 struct pci_ops gapspci_pci_ops = {
77 .read = gapspci_read,
78 .write = gapspci_write,
79 };
80