1/*
2 * drivers/pci/rom.c
3 *
4 * (C) Copyright 2004 Jon Smirl <jonsmirl@yahoo.com>
5 * (C) Copyright 2004 Silicon Graphics, Inc. Jesse Barnes <jbarnes@sgi.com>
6 *
7 * PCI ROM access routines
8 */
9#include <linux/kernel.h>
10#include <linux/export.h>
11#include <linux/pci.h>
12#include <linux/slab.h>
13
14#include "pci.h"
15
16/**
17 * pci_enable_rom - enable ROM decoding for a PCI device
18 * @pdev: PCI device to enable
19 *
20 * Enable ROM decoding on @dev.  This involves simply turning on the last
21 * bit of the PCI ROM BAR.  Note that some cards may share address decoders
22 * between the ROM and other resources, so enabling it may disable access
23 * to MMIO registers or other card memory.
24 */
25int pci_enable_rom(struct pci_dev *pdev)
26{
27	struct resource *res = pdev->resource + PCI_ROM_RESOURCE;
28	struct pci_bus_region region;
29	u32 rom_addr;
30
31	if (!res->flags)
32		return -1;
33
34	pcibios_resource_to_bus(pdev->bus, &region, res);
35	pci_read_config_dword(pdev, pdev->rom_base_reg, &rom_addr);
36	rom_addr &= ~PCI_ROM_ADDRESS_MASK;
37	rom_addr |= region.start | PCI_ROM_ADDRESS_ENABLE;
38	pci_write_config_dword(pdev, pdev->rom_base_reg, rom_addr);
39	return 0;
40}
41EXPORT_SYMBOL_GPL(pci_enable_rom);
42
43/**
44 * pci_disable_rom - disable ROM decoding for a PCI device
45 * @pdev: PCI device to disable
46 *
47 * Disable ROM decoding on a PCI device by turning off the last bit in the
48 * ROM BAR.
49 */
50void pci_disable_rom(struct pci_dev *pdev)
51{
52	u32 rom_addr;
53	pci_read_config_dword(pdev, pdev->rom_base_reg, &rom_addr);
54	rom_addr &= ~PCI_ROM_ADDRESS_ENABLE;
55	pci_write_config_dword(pdev, pdev->rom_base_reg, rom_addr);
56}
57EXPORT_SYMBOL_GPL(pci_disable_rom);
58
59/**
60 * pci_get_rom_size - obtain the actual size of the ROM image
61 * @pdev: target PCI device
62 * @rom: kernel virtual pointer to image of ROM
63 * @size: size of PCI window
64 *  return: size of actual ROM image
65 *
66 * Determine the actual length of the ROM image.
67 * The PCI window size could be much larger than the
68 * actual image size.
69 */
70size_t pci_get_rom_size(struct pci_dev *pdev, void __iomem *rom, size_t size)
71{
72	void __iomem *image;
73	int last_image;
74	unsigned length;
75
76	image = rom;
77	do {
78		void __iomem *pds;
79		/* Standard PCI ROMs start out with these bytes 55 AA */
80		if (readb(image) != 0x55) {
81			dev_err(&pdev->dev, "Invalid ROM contents\n");
82			break;
83		}
84		if (readb(image + 1) != 0xAA)
85			break;
86		/* get the PCI data structure and check its signature */
87		pds = image + readw(image + 24);
88		if (readb(pds) != 'P')
89			break;
90		if (readb(pds + 1) != 'C')
91			break;
92		if (readb(pds + 2) != 'I')
93			break;
94		if (readb(pds + 3) != 'R')
95			break;
96		last_image = readb(pds + 21) & 0x80;
97		length = readw(pds + 16);
98		image += length * 512;
99	} while (length && !last_image);
100
101	/* never return a size larger than the PCI resource window */
102	/* there are known ROMs that get the size wrong */
103	return min((size_t)(image - rom), size);
104}
105
106/**
107 * pci_map_rom - map a PCI ROM to kernel space
108 * @pdev: pointer to pci device struct
109 * @size: pointer to receive size of pci window over ROM
110 *
111 * Return: kernel virtual pointer to image of ROM
112 *
113 * Map a PCI ROM into kernel space. If ROM is boot video ROM,
114 * the shadow BIOS copy will be returned instead of the
115 * actual ROM.
116 */
117void __iomem *pci_map_rom(struct pci_dev *pdev, size_t *size)
118{
119	struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
120	loff_t start;
121	void __iomem *rom;
122
123	/*
124	 * IORESOURCE_ROM_SHADOW set on x86, x86_64 and IA64 supports legacy
125	 * memory map if the VGA enable bit of the Bridge Control register is
126	 * set for embedded VGA.
127	 */
128	if (res->flags & IORESOURCE_ROM_SHADOW) {
129		/* primary video rom always starts here */
130		start = (loff_t)0xC0000;
131		*size = 0x20000; /* cover C000:0 through E000:0 */
132	} else {
133		if (res->flags &
134			(IORESOURCE_ROM_COPY | IORESOURCE_ROM_BIOS_COPY)) {
135			*size = pci_resource_len(pdev, PCI_ROM_RESOURCE);
136			return (void __iomem *)(unsigned long)
137				pci_resource_start(pdev, PCI_ROM_RESOURCE);
138		} else {
139			/* assign the ROM an address if it doesn't have one */
140			if (res->parent == NULL &&
141			    pci_assign_resource(pdev, PCI_ROM_RESOURCE))
142				return NULL;
143			start = pci_resource_start(pdev, PCI_ROM_RESOURCE);
144			*size = pci_resource_len(pdev, PCI_ROM_RESOURCE);
145			if (*size == 0)
146				return NULL;
147
148			/* Enable ROM space decodes */
149			if (pci_enable_rom(pdev))
150				return NULL;
151		}
152	}
153
154	rom = ioremap(start, *size);
155	if (!rom) {
156		/* restore enable if ioremap fails */
157		if (!(res->flags & (IORESOURCE_ROM_ENABLE |
158				    IORESOURCE_ROM_SHADOW |
159				    IORESOURCE_ROM_COPY)))
160			pci_disable_rom(pdev);
161		return NULL;
162	}
163
164	/*
165	 * Try to find the true size of the ROM since sometimes the PCI window
166	 * size is much larger than the actual size of the ROM.
167	 * True size is important if the ROM is going to be copied.
168	 */
169	*size = pci_get_rom_size(pdev, rom, *size);
170	return rom;
171}
172EXPORT_SYMBOL(pci_map_rom);
173
174/**
175 * pci_unmap_rom - unmap the ROM from kernel space
176 * @pdev: pointer to pci device struct
177 * @rom: virtual address of the previous mapping
178 *
179 * Remove a mapping of a previously mapped ROM
180 */
181void pci_unmap_rom(struct pci_dev *pdev, void __iomem *rom)
182{
183	struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
184
185	if (res->flags & (IORESOURCE_ROM_COPY | IORESOURCE_ROM_BIOS_COPY))
186		return;
187
188	iounmap(rom);
189
190	/* Disable again before continuing, leave enabled if pci=rom */
191	if (!(res->flags & (IORESOURCE_ROM_ENABLE | IORESOURCE_ROM_SHADOW)))
192		pci_disable_rom(pdev);
193}
194EXPORT_SYMBOL(pci_unmap_rom);
195
196/**
197 * pci_cleanup_rom - free the ROM copy created by pci_map_rom_copy
198 * @pdev: pointer to pci device struct
199 *
200 * Free the copied ROM if we allocated one.
201 */
202void pci_cleanup_rom(struct pci_dev *pdev)
203{
204	struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
205
206	if (res->flags & IORESOURCE_ROM_COPY) {
207		kfree((void *)(unsigned long)res->start);
208		res->flags |= IORESOURCE_UNSET;
209		res->flags &= ~IORESOURCE_ROM_COPY;
210		res->start = 0;
211		res->end = 0;
212	}
213}
214
215/**
216 * pci_platform_rom - provides a pointer to any ROM image provided by the
217 * platform
218 * @pdev: pointer to pci device struct
219 * @size: pointer to receive size of pci window over ROM
220 */
221void __iomem *pci_platform_rom(struct pci_dev *pdev, size_t *size)
222{
223	if (pdev->rom && pdev->romlen) {
224		*size = pdev->romlen;
225		return phys_to_virt((phys_addr_t)pdev->rom);
226	}
227
228	return NULL;
229}
230EXPORT_SYMBOL(pci_platform_rom);
231