1 // SPDX-License-Identifier: GPL-2.0
3 * BIOS32 and PCI BIOS handling.
7 #include <linux/init.h>
8 #include <linux/slab.h>
9 #include <linux/module.h>
10 #include <linux/uaccess.h>
12 #include <asm/pci_x86.h>
13 #include <asm/e820/types.h>
14 #include <asm/pci-functions.h>
15 #include <asm/set_memory.h>
17 /* BIOS32 signature: "_32_" */
18 #define BIOS32_SIGNATURE (('_' << 0) + ('3' << 8) + ('2' << 16) + ('_' << 24))
20 /* PCI signature: "PCI " */
21 #define PCI_SIGNATURE (('P' << 0) + ('C' << 8) + ('I' << 16) + (' ' << 24))
23 /* PCI service signature: "$PCI" */
24 #define PCI_SERVICE (('$' << 0) + ('P' << 8) + ('C' << 16) + ('I' << 24))
26 /* PCI BIOS hardware mechanism flags */
27 #define PCIBIOS_HW_TYPE1 0x01
28 #define PCIBIOS_HW_TYPE2 0x02
29 #define PCIBIOS_HW_TYPE1_SPEC 0x10
30 #define PCIBIOS_HW_TYPE2_SPEC 0x20
34 /* According to the BIOS specification at:
35 * http://members.datafast.net.au/dft0802/specs/bios21.pdf, we could
36 * restrict the x zone to some pages and make it ro. But this may be
37 * broken on some bios, complex to handle with static_protections.
38 * We could make the 0xe0000-0x100000 range rox, but this can break
41 * So we let's an rw and x hole when pcibios is used. This shouldn't
42 * happen for modern system with mmconfig, and if you don't want it
43 * you could disable pcibios...
45 static inline void set_bios_x(void)
48 set_memory_x(PAGE_OFFSET + BIOS_BEGIN, (BIOS_END - BIOS_BEGIN) >> PAGE_SHIFT);
49 if (__supported_pte_mask & _PAGE_NX)
50 printk(KERN_INFO "PCI: PCI BIOS area is rw and x. Use pci=nobios if you want it NX.\n");
54 * This is the standard structure used to identify the entry point
55 * to the BIOS32 Service Directory, as documented in
56 * Standard BIOS 32-bit Service Directory Proposal
57 * Revision 0.4 May 24, 1993
58 * Phoenix Technologies Ltd.
60 * and the PCI BIOS specification.
65 unsigned long signature; /* _32_ */
66 unsigned long entry; /* 32 bit physical address */
67 unsigned char revision; /* Revision level, 0 */
68 unsigned char length; /* Length in paragraphs should be 01 */
69 unsigned char checksum; /* All bytes must add up to zero */
70 unsigned char reserved[5]; /* Must be zero */
76 * Physical address of the service directory. I don't know if we're
77 * allowed to have more than one of these or not, so just in case
78 * we'll make pcibios_present() take a memory start parameter and store
83 unsigned long address;
84 unsigned short segment;
85 } bios32_indirect __initdata = { 0, __KERNEL_CS };
88 * Returns the entry point for the given service, NULL on error
91 static unsigned long __init bios32_service(unsigned long service)
93 unsigned char return_code; /* %al */
94 unsigned long address; /* %ebx */
95 unsigned long length; /* %ecx */
96 unsigned long entry; /* %edx */
99 local_irq_save(flags);
100 __asm__("lcall *(%%edi); cld"
101 : "=a" (return_code),
107 "D" (&bios32_indirect));
108 local_irq_restore(flags);
110 switch (return_code) {
112 return address + entry;
113 case 0x80: /* Not present */
114 printk(KERN_WARNING "bios32_service(0x%lx): not present\n", service);
116 default: /* Shouldn't happen */
117 printk(KERN_WARNING "bios32_service(0x%lx): returned 0x%x -- BIOS bug!\n",
118 service, return_code);
124 unsigned long address;
125 unsigned short segment;
126 } pci_indirect __ro_after_init = {
128 .segment = __KERNEL_CS,
131 static int pci_bios_present __ro_after_init;
133 static int __init check_pcibios(void)
135 u32 signature, eax, ebx, ecx;
136 u8 status, major_ver, minor_ver, hw_mech;
137 unsigned long flags, pcibios_entry;
139 if ((pcibios_entry = bios32_service(PCI_SERVICE))) {
140 pci_indirect.address = pcibios_entry + PAGE_OFFSET;
142 local_irq_save(flags);
144 "lcall *(%%edi); cld\n\t"
152 : "1" (PCIBIOS_PCI_BIOS_PRESENT),
155 local_irq_restore(flags);
157 status = (eax >> 8) & 0xff;
158 hw_mech = eax & 0xff;
159 major_ver = (ebx >> 8) & 0xff;
160 minor_ver = ebx & 0xff;
161 if (pcibios_last_bus < 0)
162 pcibios_last_bus = ecx & 0xff;
163 DBG("PCI: BIOS probe returned s=%02x hw=%02x ver=%02x.%02x l=%02x\n",
164 status, hw_mech, major_ver, minor_ver, pcibios_last_bus);
165 if (status || signature != PCI_SIGNATURE) {
166 printk (KERN_ERR "PCI: BIOS BUG #%x[%08x] found\n",
170 printk(KERN_INFO "PCI: PCI BIOS revision %x.%02x entry at 0x%lx, last bus=%d\n",
171 major_ver, minor_ver, pcibios_entry, pcibios_last_bus);
172 #ifdef CONFIG_PCI_DIRECT
173 if (!(hw_mech & PCIBIOS_HW_TYPE1))
174 pci_probe &= ~PCI_PROBE_CONF1;
175 if (!(hw_mech & PCIBIOS_HW_TYPE2))
176 pci_probe &= ~PCI_PROBE_CONF2;
183 static int pci_bios_read(unsigned int seg, unsigned int bus,
184 unsigned int devfn, int reg, int len, u32 *value)
186 unsigned long result = 0;
188 unsigned long bx = (bus << 8) | devfn;
189 u16 number = 0, mask = 0;
192 if (!value || (bus > 255) || (devfn > 255) || (reg > 255))
195 raw_spin_lock_irqsave(&pci_config_lock, flags);
199 number = PCIBIOS_READ_CONFIG_BYTE;
203 number = PCIBIOS_READ_CONFIG_WORD;
207 number = PCIBIOS_READ_CONFIG_DWORD;
211 __asm__("lcall *(%%esi); cld\n\t"
220 "S" (&pci_indirect));
222 * Zero-extend the result beyond 8 or 16 bits, do not trust the
223 * BIOS having done it:
228 raw_spin_unlock_irqrestore(&pci_config_lock, flags);
230 return (int)((result & 0xff00) >> 8);
233 static int pci_bios_write(unsigned int seg, unsigned int bus,
234 unsigned int devfn, int reg, int len, u32 value)
236 unsigned long result = 0;
238 unsigned long bx = (bus << 8) | devfn;
242 if ((bus > 255) || (devfn > 255) || (reg > 255))
245 raw_spin_lock_irqsave(&pci_config_lock, flags);
249 number = PCIBIOS_WRITE_CONFIG_BYTE;
252 number = PCIBIOS_WRITE_CONFIG_WORD;
255 number = PCIBIOS_WRITE_CONFIG_DWORD;
259 __asm__("lcall *(%%esi); cld\n\t"
268 "S" (&pci_indirect));
270 raw_spin_unlock_irqrestore(&pci_config_lock, flags);
272 return (int)((result & 0xff00) >> 8);
277 * Function table for BIOS32 access
280 static const struct pci_raw_ops pci_bios_access = {
281 .read = pci_bios_read,
282 .write = pci_bios_write
286 * Try to find PCI BIOS.
289 static const struct pci_raw_ops *__init pci_find_bios(void)
296 * Follow the standard procedure for locating the BIOS32 Service
297 * directory by scanning the permissible address range from
298 * 0xe0000 through 0xfffff for a valid BIOS32 structure.
301 for (check = (union bios32 *) __va(0xe0000);
302 check <= (union bios32 *) __va(0xffff0);
305 if (probe_kernel_address(&check->fields.signature, sig))
308 if (check->fields.signature != BIOS32_SIGNATURE)
310 length = check->fields.length * 16;
314 for (i = 0; i < length ; ++i)
315 sum += check->chars[i];
318 if (check->fields.revision != 0) {
319 printk("PCI: unsupported BIOS32 revision %d at 0x%p\n",
320 check->fields.revision, check);
323 DBG("PCI: BIOS32 Service Directory structure at 0x%p\n", check);
324 if (check->fields.entry >= 0x100000) {
325 printk("PCI: BIOS32 entry (0x%p) in high memory, "
326 "cannot use.\n", check);
329 unsigned long bios32_entry = check->fields.entry;
330 DBG("PCI: BIOS32 Service Directory entry at 0x%lx\n",
332 bios32_indirect.address = bios32_entry + PAGE_OFFSET;
335 return &pci_bios_access;
337 break; /* Hopefully more than one BIOS32 cannot happen... */
344 * BIOS Functions for IRQ Routing
347 struct irq_routing_options {
349 struct irq_info *table;
351 } __attribute__((packed));
353 struct irq_routing_table * pcibios_get_irq_routing_table(void)
355 struct irq_routing_options opt;
356 struct irq_routing_table *rt = NULL;
360 if (!pci_bios_present)
362 page = __get_free_page(GFP_KERNEL);
365 opt.table = (struct irq_info *) page;
366 opt.size = PAGE_SIZE;
367 opt.segment = __KERNEL_DS;
369 DBG("PCI: Fetching IRQ routing table... ");
370 __asm__("push %%es\n\t"
373 "lcall *(%%esi); cld\n\t"
381 : "0" (PCIBIOS_GET_ROUTING_OPTIONS),
387 DBG("OK ret=%d, size=%d, map=%x\n", ret, opt.size, map);
389 printk(KERN_ERR "PCI: Error %02x when fetching IRQ routing table.\n", (ret >> 8) & 0xff);
391 rt = kmalloc(sizeof(struct irq_routing_table) + opt.size, GFP_KERNEL);
393 memset(rt, 0, sizeof(struct irq_routing_table));
394 rt->size = opt.size + sizeof(struct irq_routing_table);
395 rt->exclusive_irqs = map;
396 memcpy(rt->slots, (void *) page, opt.size);
397 printk(KERN_INFO "PCI: Using BIOS Interrupt Routing Table\n");
403 EXPORT_SYMBOL(pcibios_get_irq_routing_table);
405 int pcibios_set_irq_routing(struct pci_dev *dev, int pin, int irq)
409 __asm__("lcall *(%%esi); cld\n\t"
414 : "0" (PCIBIOS_SET_PCI_HW_INT),
415 "b" ((dev->bus->number << 8) | dev->devfn),
416 "c" ((irq << 8) | (pin + 10)),
417 "S" (&pci_indirect));
418 return !(ret & 0xff00);
420 EXPORT_SYMBOL(pcibios_set_irq_routing);
422 void __init pci_pcbios_init(void)
424 if ((pci_probe & PCI_PROBE_BIOS)
425 && ((raw_pci_ops = pci_find_bios()))) {
426 pci_bios_present = 1;