xref: /openbmc/linux/drivers/pci/rom.c (revision 9ac8d3fb)
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/pci.h>
11 #include <linux/slab.h>
12 
13 #include "pci.h"
14 
15 /**
16  * pci_enable_rom - enable ROM decoding for a PCI device
17  * @pdev: PCI device to enable
18  *
19  * Enable ROM decoding on @dev.  This involves simply turning on the last
20  * bit of the PCI ROM BAR.  Note that some cards may share address decoders
21  * between the ROM and other resources, so enabling it may disable access
22  * to MMIO registers or other card memory.
23  */
24 int pci_enable_rom(struct pci_dev *pdev)
25 {
26 	struct resource *res = pdev->resource + PCI_ROM_RESOURCE;
27 	struct pci_bus_region region;
28 	u32 rom_addr;
29 
30 	if (!res->flags)
31 		return -1;
32 
33 	pcibios_resource_to_bus(pdev, &region, res);
34 	pci_read_config_dword(pdev, pdev->rom_base_reg, &rom_addr);
35 	rom_addr &= ~PCI_ROM_ADDRESS_MASK;
36 	rom_addr |= region.start | PCI_ROM_ADDRESS_ENABLE;
37 	pci_write_config_dword(pdev, pdev->rom_base_reg, rom_addr);
38 	return 0;
39 }
40 
41 /**
42  * pci_disable_rom - disable ROM decoding for a PCI device
43  * @pdev: PCI device to disable
44  *
45  * Disable ROM decoding on a PCI device by turning off the last bit in the
46  * ROM BAR.
47  */
48 void pci_disable_rom(struct pci_dev *pdev)
49 {
50 	u32 rom_addr;
51 	pci_read_config_dword(pdev, pdev->rom_base_reg, &rom_addr);
52 	rom_addr &= ~PCI_ROM_ADDRESS_ENABLE;
53 	pci_write_config_dword(pdev, pdev->rom_base_reg, rom_addr);
54 }
55 
56 /**
57  * pci_get_rom_size - obtain the actual size of the ROM image
58  * @rom: kernel virtual pointer to image of ROM
59  * @size: size of PCI window
60  *  return: size of actual ROM image
61  *
62  * Determine the actual length of the ROM image.
63  * The PCI window size could be much larger than the
64  * actual image size.
65  */
66 size_t pci_get_rom_size(void __iomem *rom, size_t size)
67 {
68 	void __iomem *image;
69 	int last_image;
70 
71 	image = rom;
72 	do {
73 		void __iomem *pds;
74 		/* Standard PCI ROMs start out with these bytes 55 AA */
75 		if (readb(image) != 0x55)
76 			break;
77 		if (readb(image + 1) != 0xAA)
78 			break;
79 		/* get the PCI data structure and check its signature */
80 		pds = image + readw(image + 24);
81 		if (readb(pds) != 'P')
82 			break;
83 		if (readb(pds + 1) != 'C')
84 			break;
85 		if (readb(pds + 2) != 'I')
86 			break;
87 		if (readb(pds + 3) != 'R')
88 			break;
89 		last_image = readb(pds + 21) & 0x80;
90 		/* this length is reliable */
91 		image += readw(pds + 16) * 512;
92 	} while (!last_image);
93 
94 	/* never return a size larger than the PCI resource window */
95 	/* there are known ROMs that get the size wrong */
96 	return min((size_t)(image - rom), size);
97 }
98 
99 /**
100  * pci_map_rom - map a PCI ROM to kernel space
101  * @pdev: pointer to pci device struct
102  * @size: pointer to receive size of pci window over ROM
103  * @return: kernel virtual pointer to image of ROM
104  *
105  * Map a PCI ROM into kernel space. If ROM is boot video ROM,
106  * the shadow BIOS copy will be returned instead of the
107  * actual ROM.
108  */
109 void __iomem *pci_map_rom(struct pci_dev *pdev, size_t *size)
110 {
111 	struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
112 	loff_t start;
113 	void __iomem *rom;
114 
115 	/*
116 	 * IORESOURCE_ROM_SHADOW set on x86, x86_64 and IA64 supports legacy
117 	 * memory map if the VGA enable bit of the Bridge Control register is
118 	 * set for embedded VGA.
119 	 */
120 	if (res->flags & IORESOURCE_ROM_SHADOW) {
121 		/* primary video rom always starts here */
122 		start = (loff_t)0xC0000;
123 		*size = 0x20000; /* cover C000:0 through E000:0 */
124 	} else {
125 		if (res->flags &
126 			(IORESOURCE_ROM_COPY | IORESOURCE_ROM_BIOS_COPY)) {
127 			*size = pci_resource_len(pdev, PCI_ROM_RESOURCE);
128 			return (void __iomem *)(unsigned long)
129 				pci_resource_start(pdev, PCI_ROM_RESOURCE);
130 		} else {
131 			/* assign the ROM an address if it doesn't have one */
132 			if (res->parent == NULL &&
133 			    pci_assign_resource(pdev,PCI_ROM_RESOURCE))
134 				return NULL;
135 			start = pci_resource_start(pdev, PCI_ROM_RESOURCE);
136 			*size = pci_resource_len(pdev, PCI_ROM_RESOURCE);
137 			if (*size == 0)
138 				return NULL;
139 
140 			/* Enable ROM space decodes */
141 			if (pci_enable_rom(pdev))
142 				return NULL;
143 		}
144 	}
145 
146 	rom = ioremap(start, *size);
147 	if (!rom) {
148 		/* restore enable if ioremap fails */
149 		if (!(res->flags & (IORESOURCE_ROM_ENABLE |
150 				    IORESOURCE_ROM_SHADOW |
151 				    IORESOURCE_ROM_COPY)))
152 			pci_disable_rom(pdev);
153 		return NULL;
154 	}
155 
156 	/*
157 	 * Try to find the true size of the ROM since sometimes the PCI window
158 	 * size is much larger than the actual size of the ROM.
159 	 * True size is important if the ROM is going to be copied.
160 	 */
161 	*size = pci_get_rom_size(rom, *size);
162 	return rom;
163 }
164 
165 #if 0
166 /**
167  * pci_map_rom_copy - map a PCI ROM to kernel space, create a copy
168  * @pdev: pointer to pci device struct
169  * @size: pointer to receive size of pci window over ROM
170  * @return: kernel virtual pointer to image of ROM
171  *
172  * Map a PCI ROM into kernel space. If ROM is boot video ROM,
173  * the shadow BIOS copy will be returned instead of the
174  * actual ROM.
175  */
176 void __iomem *pci_map_rom_copy(struct pci_dev *pdev, size_t *size)
177 {
178 	struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
179 	void __iomem *rom;
180 
181 	rom = pci_map_rom(pdev, size);
182 	if (!rom)
183 		return NULL;
184 
185 	if (res->flags & (IORESOURCE_ROM_COPY | IORESOURCE_ROM_SHADOW |
186 			  IORESOURCE_ROM_BIOS_COPY))
187 		return rom;
188 
189 	res->start = (unsigned long)kmalloc(*size, GFP_KERNEL);
190 	if (!res->start)
191 		return rom;
192 
193 	res->end = res->start + *size;
194 	memcpy_fromio((void*)(unsigned long)res->start, rom, *size);
195 	pci_unmap_rom(pdev, rom);
196 	res->flags |= IORESOURCE_ROM_COPY;
197 
198 	return (void __iomem *)(unsigned long)res->start;
199 }
200 #endif  /*  0  */
201 
202 /**
203  * pci_unmap_rom - unmap the ROM from kernel space
204  * @pdev: pointer to pci device struct
205  * @rom: virtual address of the previous mapping
206  *
207  * Remove a mapping of a previously mapped ROM
208  */
209 void pci_unmap_rom(struct pci_dev *pdev, void __iomem *rom)
210 {
211 	struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
212 
213 	if (res->flags & (IORESOURCE_ROM_COPY | IORESOURCE_ROM_BIOS_COPY))
214 		return;
215 
216 	iounmap(rom);
217 
218 	/* Disable again before continuing, leave enabled if pci=rom */
219 	if (!(res->flags & (IORESOURCE_ROM_ENABLE | IORESOURCE_ROM_SHADOW)))
220 		pci_disable_rom(pdev);
221 }
222 
223 #if 0
224 /**
225  * pci_remove_rom - disable the ROM and remove its sysfs attribute
226  * @pdev: pointer to pci device struct
227  *
228  * Remove the rom file in sysfs and disable ROM decoding.
229  */
230 void pci_remove_rom(struct pci_dev *pdev)
231 {
232 	struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
233 
234 	if (pci_resource_len(pdev, PCI_ROM_RESOURCE))
235 		sysfs_remove_bin_file(&pdev->dev.kobj, pdev->rom_attr);
236 	if (!(res->flags & (IORESOURCE_ROM_ENABLE |
237 			    IORESOURCE_ROM_SHADOW |
238 			    IORESOURCE_ROM_BIOS_COPY |
239 			    IORESOURCE_ROM_COPY)))
240 		pci_disable_rom(pdev);
241 }
242 #endif  /*  0  */
243 
244 /**
245  * pci_cleanup_rom - free the ROM copy created by pci_map_rom_copy
246  * @pdev: pointer to pci device struct
247  *
248  * Free the copied ROM if we allocated one.
249  */
250 void pci_cleanup_rom(struct pci_dev *pdev)
251 {
252 	struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
253 	if (res->flags & IORESOURCE_ROM_COPY) {
254 		kfree((void*)(unsigned long)res->start);
255 		res->flags &= ~IORESOURCE_ROM_COPY;
256 		res->start = 0;
257 		res->end = 0;
258 	}
259 }
260 
261 EXPORT_SYMBOL(pci_map_rom);
262 EXPORT_SYMBOL(pci_unmap_rom);
263 EXPORT_SYMBOL_GPL(pci_enable_rom);
264 EXPORT_SYMBOL_GPL(pci_disable_rom);
265