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