xref: /openbmc/linux/drivers/pci/rom.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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 static 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 static 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_map_rom - map a PCI ROM to kernel space
58  * @pdev: pointer to pci device struct
59  * @size: pointer to receive size of pci window over ROM
60  * @return: kernel virtual pointer to image of ROM
61  *
62  * Map a PCI ROM into kernel space. If ROM is boot video ROM,
63  * the shadow BIOS copy will be returned instead of the
64  * actual ROM.
65  */
66 void __iomem *pci_map_rom(struct pci_dev *pdev, size_t *size)
67 {
68 	struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
69 	loff_t start;
70 	void __iomem *rom;
71 	void __iomem *image;
72 	int last_image;
73 
74 	/*
75 	 * IORESOURCE_ROM_SHADOW set on x86, x86_64 and IA64 supports legacy
76 	 * memory map if the VGA enable bit of the Bridge Control register is
77 	 * set for embedded VGA.
78 	 */
79 	if (res->flags & IORESOURCE_ROM_SHADOW) {
80 		/* primary video rom always starts here */
81 		start = (loff_t)0xC0000;
82 		*size = 0x20000; /* cover C000:0 through E000:0 */
83 	} else {
84 		if (res->flags &
85 			(IORESOURCE_ROM_COPY | IORESOURCE_ROM_BIOS_COPY)) {
86 			*size = pci_resource_len(pdev, PCI_ROM_RESOURCE);
87 			return (void __iomem *)(unsigned long)
88 				pci_resource_start(pdev, PCI_ROM_RESOURCE);
89 		} else {
90 			/* assign the ROM an address if it doesn't have one */
91 			if (res->parent == NULL &&
92 			    pci_assign_resource(pdev,PCI_ROM_RESOURCE))
93 				return NULL;
94 			start = pci_resource_start(pdev, PCI_ROM_RESOURCE);
95 			*size = pci_resource_len(pdev, PCI_ROM_RESOURCE);
96 			if (*size == 0)
97 				return NULL;
98 
99 			/* Enable ROM space decodes */
100 			if (pci_enable_rom(pdev))
101 				return NULL;
102 		}
103 	}
104 
105 	rom = ioremap(start, *size);
106 	if (!rom) {
107 		/* restore enable if ioremap fails */
108 		if (!(res->flags & (IORESOURCE_ROM_ENABLE |
109 				    IORESOURCE_ROM_SHADOW |
110 				    IORESOURCE_ROM_COPY)))
111 			pci_disable_rom(pdev);
112 		return NULL;
113 	}
114 
115 	/*
116 	 * Try to find the true size of the ROM since sometimes the PCI window
117 	 * size is much larger than the actual size of the ROM.
118 	 * True size is important if the ROM is going to be copied.
119 	 */
120 	image = rom;
121 	do {
122 		void __iomem *pds;
123 		/* Standard PCI ROMs start out with these bytes 55 AA */
124 		if (readb(image) != 0x55)
125 			break;
126 		if (readb(image + 1) != 0xAA)
127 			break;
128 		/* get the PCI data structure and check its signature */
129 		pds = image + readw(image + 24);
130 		if (readb(pds) != 'P')
131 			break;
132 		if (readb(pds + 1) != 'C')
133 			break;
134 		if (readb(pds + 2) != 'I')
135 			break;
136 		if (readb(pds + 3) != 'R')
137 			break;
138 		last_image = readb(pds + 21) & 0x80;
139 		/* this length is reliable */
140 		image += readw(pds + 16) * 512;
141 	} while (!last_image);
142 
143 	/* never return a size larger than the PCI resource window */
144 	/* there are known ROMs that get the size wrong */
145 	*size = min((size_t)(image - rom), *size);
146 
147 	return rom;
148 }
149 
150 /**
151  * pci_map_rom_copy - map a PCI ROM to kernel space, create a copy
152  * @pdev: pointer to pci device struct
153  * @size: pointer to receive size of pci window over ROM
154  * @return: kernel virtual pointer to image of ROM
155  *
156  * Map a PCI ROM into kernel space. If ROM is boot video ROM,
157  * the shadow BIOS copy will be returned instead of the
158  * actual ROM.
159  */
160 void __iomem *pci_map_rom_copy(struct pci_dev *pdev, size_t *size)
161 {
162 	struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
163 	void __iomem *rom;
164 
165 	rom = pci_map_rom(pdev, size);
166 	if (!rom)
167 		return NULL;
168 
169 	if (res->flags & (IORESOURCE_ROM_COPY | IORESOURCE_ROM_SHADOW |
170 			  IORESOURCE_ROM_BIOS_COPY))
171 		return rom;
172 
173 	res->start = (unsigned long)kmalloc(*size, GFP_KERNEL);
174 	if (!res->start)
175 		return rom;
176 
177 	res->end = res->start + *size;
178 	memcpy_fromio((void*)(unsigned long)res->start, rom, *size);
179 	pci_unmap_rom(pdev, rom);
180 	res->flags |= IORESOURCE_ROM_COPY;
181 
182 	return (void __iomem *)(unsigned long)res->start;
183 }
184 
185 /**
186  * pci_unmap_rom - unmap the ROM from kernel space
187  * @pdev: pointer to pci device struct
188  * @rom: virtual address of the previous mapping
189  *
190  * Remove a mapping of a previously mapped ROM
191  */
192 void pci_unmap_rom(struct pci_dev *pdev, void __iomem *rom)
193 {
194 	struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
195 
196 	if (res->flags & (IORESOURCE_ROM_COPY | IORESOURCE_ROM_BIOS_COPY))
197 		return;
198 
199 	iounmap(rom);
200 
201 	/* Disable again before continuing, leave enabled if pci=rom */
202 	if (!(res->flags & (IORESOURCE_ROM_ENABLE | IORESOURCE_ROM_SHADOW)))
203 		pci_disable_rom(pdev);
204 }
205 
206 /**
207  * pci_remove_rom - disable the ROM and remove its sysfs attribute
208  * @pdev: pointer to pci device struct
209  *
210  * Remove the rom file in sysfs and disable ROM decoding.
211  */
212 void pci_remove_rom(struct pci_dev *pdev)
213 {
214 	struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
215 
216 	if (pci_resource_len(pdev, PCI_ROM_RESOURCE))
217 		sysfs_remove_bin_file(&pdev->dev.kobj, pdev->rom_attr);
218 	if (!(res->flags & (IORESOURCE_ROM_ENABLE |
219 			    IORESOURCE_ROM_SHADOW |
220 			    IORESOURCE_ROM_BIOS_COPY |
221 			    IORESOURCE_ROM_COPY)))
222 		pci_disable_rom(pdev);
223 }
224 
225 /**
226  * pci_cleanup_rom - internal routine for freeing the ROM copy created
227  * by pci_map_rom_copy called from remove.c
228  * @pdev: pointer to pci device struct
229  *
230  * Free the copied ROM if we allocated one.
231  */
232 void pci_cleanup_rom(struct pci_dev *pdev)
233 {
234 	struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
235 	if (res->flags & IORESOURCE_ROM_COPY) {
236 		kfree((void*)(unsigned long)res->start);
237 		res->flags &= ~IORESOURCE_ROM_COPY;
238 		res->start = 0;
239 		res->end = 0;
240 	}
241 }
242 
243 EXPORT_SYMBOL(pci_map_rom);
244 EXPORT_SYMBOL(pci_map_rom_copy);
245 EXPORT_SYMBOL(pci_unmap_rom);
246 EXPORT_SYMBOL(pci_remove_rom);
247