1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * BIOS32 and PCI BIOS handling. 4 */ 5 6 #include <linux/bits.h> 7 #include <linux/bitfield.h> 8 #include <linux/pci.h> 9 #include <linux/init.h> 10 #include <linux/slab.h> 11 #include <linux/module.h> 12 #include <linux/uaccess.h> 13 14 #include <asm/pci_x86.h> 15 #include <asm/e820/types.h> 16 #include <asm/pci-functions.h> 17 #include <asm/set_memory.h> 18 19 /* BIOS32 signature: "_32_" */ 20 #define BIOS32_SIGNATURE (('_' << 0) + ('3' << 8) + ('2' << 16) + ('_' << 24)) 21 22 /* PCI signature: "PCI " */ 23 #define PCI_SIGNATURE (('P' << 0) + ('C' << 8) + ('I' << 16) + (' ' << 24)) 24 25 /* PCI service signature: "$PCI" */ 26 #define PCI_SERVICE (('$' << 0) + ('P' << 8) + ('C' << 16) + ('I' << 24)) 27 28 /* PCI BIOS hardware mechanism flags */ 29 #define PCIBIOS_HW_TYPE1 0x01 30 #define PCIBIOS_HW_TYPE2 0x02 31 #define PCIBIOS_HW_TYPE1_SPEC 0x10 32 #define PCIBIOS_HW_TYPE2_SPEC 0x20 33 34 /* 35 * Returned in EAX: 36 * - AH: return code 37 */ 38 #define PCIBIOS_RETURN_CODE GENMASK(15, 8) 39 40 int pcibios_enabled; 41 42 static u8 pcibios_get_return_code(u32 eax) 43 { 44 return FIELD_GET(PCIBIOS_RETURN_CODE, eax); 45 } 46 47 /* According to the BIOS specification at: 48 * http://members.datafast.net.au/dft0802/specs/bios21.pdf, we could 49 * restrict the x zone to some pages and make it ro. But this may be 50 * broken on some bios, complex to handle with static_protections. 51 * We could make the 0xe0000-0x100000 range rox, but this can break 52 * some ISA mapping. 53 * 54 * So we let's an rw and x hole when pcibios is used. This shouldn't 55 * happen for modern system with mmconfig, and if you don't want it 56 * you could disable pcibios... 57 */ 58 static inline void set_bios_x(void) 59 { 60 pcibios_enabled = 1; 61 set_memory_x(PAGE_OFFSET + BIOS_BEGIN, (BIOS_END - BIOS_BEGIN) >> PAGE_SHIFT); 62 if (__supported_pte_mask & _PAGE_NX) 63 printk(KERN_INFO "PCI: PCI BIOS area is rw and x. Use pci=nobios if you want it NX.\n"); 64 } 65 66 /* 67 * This is the standard structure used to identify the entry point 68 * to the BIOS32 Service Directory, as documented in 69 * Standard BIOS 32-bit Service Directory Proposal 70 * Revision 0.4 May 24, 1993 71 * Phoenix Technologies Ltd. 72 * Norwood, MA 73 * and the PCI BIOS specification. 74 */ 75 76 union bios32 { 77 struct { 78 unsigned long signature; /* _32_ */ 79 unsigned long entry; /* 32 bit physical address */ 80 unsigned char revision; /* Revision level, 0 */ 81 unsigned char length; /* Length in paragraphs should be 01 */ 82 unsigned char checksum; /* All bytes must add up to zero */ 83 unsigned char reserved[5]; /* Must be zero */ 84 } fields; 85 char chars[16]; 86 }; 87 88 /* 89 * Physical address of the service directory. I don't know if we're 90 * allowed to have more than one of these or not, so just in case 91 * we'll make pcibios_present() take a memory start parameter and store 92 * the array there. 93 */ 94 95 static struct { 96 unsigned long address; 97 unsigned short segment; 98 } bios32_indirect __initdata = { 0, __KERNEL_CS }; 99 100 /* 101 * Returns the entry point for the given service, NULL on error 102 */ 103 104 static unsigned long __init bios32_service(unsigned long service) 105 { 106 unsigned char return_code; /* %al */ 107 unsigned long address; /* %ebx */ 108 unsigned long length; /* %ecx */ 109 unsigned long entry; /* %edx */ 110 unsigned long flags; 111 112 local_irq_save(flags); 113 __asm__("lcall *(%%edi); cld" 114 : "=a" (return_code), 115 "=b" (address), 116 "=c" (length), 117 "=d" (entry) 118 : "0" (service), 119 "1" (0), 120 "D" (&bios32_indirect)); 121 local_irq_restore(flags); 122 123 switch (return_code) { 124 case 0: 125 return address + entry; 126 case 0x80: /* Not present */ 127 printk(KERN_WARNING "bios32_service(0x%lx): not present\n", service); 128 return 0; 129 default: /* Shouldn't happen */ 130 printk(KERN_WARNING "bios32_service(0x%lx): returned 0x%x -- BIOS bug!\n", 131 service, return_code); 132 return 0; 133 } 134 } 135 136 static struct { 137 unsigned long address; 138 unsigned short segment; 139 } pci_indirect __ro_after_init = { 140 .address = 0, 141 .segment = __KERNEL_CS, 142 }; 143 144 static int pci_bios_present __ro_after_init; 145 146 static int __init check_pcibios(void) 147 { 148 u32 signature, eax, ebx, ecx; 149 u8 status, major_ver, minor_ver, hw_mech; 150 unsigned long flags, pcibios_entry; 151 152 if ((pcibios_entry = bios32_service(PCI_SERVICE))) { 153 pci_indirect.address = pcibios_entry + PAGE_OFFSET; 154 155 local_irq_save(flags); 156 __asm__( 157 "lcall *(%%edi); cld\n\t" 158 "jc 1f\n\t" 159 "xor %%ah, %%ah\n" 160 "1:" 161 : "=d" (signature), 162 "=a" (eax), 163 "=b" (ebx), 164 "=c" (ecx) 165 : "1" (PCIBIOS_PCI_BIOS_PRESENT), 166 "D" (&pci_indirect) 167 : "memory"); 168 local_irq_restore(flags); 169 170 status = pcibios_get_return_code(eax); 171 hw_mech = eax & 0xff; 172 major_ver = (ebx >> 8) & 0xff; 173 minor_ver = ebx & 0xff; 174 if (pcibios_last_bus < 0) 175 pcibios_last_bus = ecx & 0xff; 176 DBG("PCI: BIOS probe returned s=%02x hw=%02x ver=%02x.%02x l=%02x\n", 177 status, hw_mech, major_ver, minor_ver, pcibios_last_bus); 178 if (status || signature != PCI_SIGNATURE) { 179 printk (KERN_ERR "PCI: BIOS BUG #%x[%08x] found\n", 180 status, signature); 181 return 0; 182 } 183 printk(KERN_INFO "PCI: PCI BIOS revision %x.%02x entry at 0x%lx, last bus=%d\n", 184 major_ver, minor_ver, pcibios_entry, pcibios_last_bus); 185 #ifdef CONFIG_PCI_DIRECT 186 if (!(hw_mech & PCIBIOS_HW_TYPE1)) 187 pci_probe &= ~PCI_PROBE_CONF1; 188 if (!(hw_mech & PCIBIOS_HW_TYPE2)) 189 pci_probe &= ~PCI_PROBE_CONF2; 190 #endif 191 return 1; 192 } 193 return 0; 194 } 195 196 static int pci_bios_read(unsigned int seg, unsigned int bus, 197 unsigned int devfn, int reg, int len, u32 *value) 198 { 199 unsigned long result = 0; 200 unsigned long flags; 201 unsigned long bx = (bus << 8) | devfn; 202 u16 number = 0, mask = 0; 203 204 WARN_ON(seg); 205 if (!value || (bus > 255) || (devfn > 255) || (reg > 255)) 206 return -EINVAL; 207 208 raw_spin_lock_irqsave(&pci_config_lock, flags); 209 210 switch (len) { 211 case 1: 212 number = PCIBIOS_READ_CONFIG_BYTE; 213 mask = 0xff; 214 break; 215 case 2: 216 number = PCIBIOS_READ_CONFIG_WORD; 217 mask = 0xffff; 218 break; 219 case 4: 220 number = PCIBIOS_READ_CONFIG_DWORD; 221 break; 222 } 223 224 __asm__("lcall *(%%esi); cld\n\t" 225 "jc 1f\n\t" 226 "xor %%ah, %%ah\n" 227 "1:" 228 : "=c" (*value), 229 "=a" (result) 230 : "1" (number), 231 "b" (bx), 232 "D" ((long)reg), 233 "S" (&pci_indirect)); 234 /* 235 * Zero-extend the result beyond 8 or 16 bits, do not trust the 236 * BIOS having done it: 237 */ 238 if (mask) 239 *value &= mask; 240 241 raw_spin_unlock_irqrestore(&pci_config_lock, flags); 242 243 return pcibios_get_return_code(result); 244 } 245 246 static int pci_bios_write(unsigned int seg, unsigned int bus, 247 unsigned int devfn, int reg, int len, u32 value) 248 { 249 unsigned long result = 0; 250 unsigned long flags; 251 unsigned long bx = (bus << 8) | devfn; 252 u16 number = 0; 253 254 WARN_ON(seg); 255 if ((bus > 255) || (devfn > 255) || (reg > 255)) 256 return -EINVAL; 257 258 raw_spin_lock_irqsave(&pci_config_lock, flags); 259 260 switch (len) { 261 case 1: 262 number = PCIBIOS_WRITE_CONFIG_BYTE; 263 break; 264 case 2: 265 number = PCIBIOS_WRITE_CONFIG_WORD; 266 break; 267 case 4: 268 number = PCIBIOS_WRITE_CONFIG_DWORD; 269 break; 270 } 271 272 __asm__("lcall *(%%esi); cld\n\t" 273 "jc 1f\n\t" 274 "xor %%ah, %%ah\n" 275 "1:" 276 : "=a" (result) 277 : "0" (number), 278 "c" (value), 279 "b" (bx), 280 "D" ((long)reg), 281 "S" (&pci_indirect)); 282 283 raw_spin_unlock_irqrestore(&pci_config_lock, flags); 284 285 return pcibios_get_return_code(result); 286 } 287 288 289 /* 290 * Function table for BIOS32 access 291 */ 292 293 static const struct pci_raw_ops pci_bios_access = { 294 .read = pci_bios_read, 295 .write = pci_bios_write 296 }; 297 298 /* 299 * Try to find PCI BIOS. 300 */ 301 302 static const struct pci_raw_ops *__init pci_find_bios(void) 303 { 304 union bios32 *check; 305 unsigned char sum; 306 int i, length; 307 308 /* 309 * Follow the standard procedure for locating the BIOS32 Service 310 * directory by scanning the permissible address range from 311 * 0xe0000 through 0xfffff for a valid BIOS32 structure. 312 */ 313 314 for (check = (union bios32 *) __va(0xe0000); 315 check <= (union bios32 *) __va(0xffff0); 316 ++check) { 317 long sig; 318 if (get_kernel_nofault(sig, &check->fields.signature)) 319 continue; 320 321 if (check->fields.signature != BIOS32_SIGNATURE) 322 continue; 323 length = check->fields.length * 16; 324 if (!length) 325 continue; 326 sum = 0; 327 for (i = 0; i < length ; ++i) 328 sum += check->chars[i]; 329 if (sum != 0) 330 continue; 331 if (check->fields.revision != 0) { 332 printk("PCI: unsupported BIOS32 revision %d at 0x%p\n", 333 check->fields.revision, check); 334 continue; 335 } 336 DBG("PCI: BIOS32 Service Directory structure at 0x%p\n", check); 337 if (check->fields.entry >= 0x100000) { 338 printk("PCI: BIOS32 entry (0x%p) in high memory, " 339 "cannot use.\n", check); 340 return NULL; 341 } else { 342 unsigned long bios32_entry = check->fields.entry; 343 DBG("PCI: BIOS32 Service Directory entry at 0x%lx\n", 344 bios32_entry); 345 bios32_indirect.address = bios32_entry + PAGE_OFFSET; 346 set_bios_x(); 347 if (check_pcibios()) 348 return &pci_bios_access; 349 } 350 break; /* Hopefully more than one BIOS32 cannot happen... */ 351 } 352 353 return NULL; 354 } 355 356 /* 357 * BIOS Functions for IRQ Routing 358 */ 359 360 struct irq_routing_options { 361 u16 size; 362 struct irq_info *table; 363 u16 segment; 364 } __attribute__((packed)); 365 366 struct irq_routing_table * pcibios_get_irq_routing_table(void) 367 { 368 struct irq_routing_options opt; 369 struct irq_routing_table *rt = NULL; 370 int ret, map; 371 unsigned long page; 372 373 if (!pci_bios_present) 374 return NULL; 375 page = __get_free_page(GFP_KERNEL); 376 if (!page) 377 return NULL; 378 opt.table = (struct irq_info *) page; 379 opt.size = PAGE_SIZE; 380 opt.segment = __KERNEL_DS; 381 382 DBG("PCI: Fetching IRQ routing table... "); 383 __asm__("push %%es\n\t" 384 "push %%ds\n\t" 385 "pop %%es\n\t" 386 "lcall *(%%esi); cld\n\t" 387 "pop %%es\n\t" 388 "jc 1f\n\t" 389 "xor %%ah, %%ah\n" 390 "1:" 391 : "=a" (ret), 392 "=b" (map), 393 "=m" (opt) 394 : "0" (PCIBIOS_GET_ROUTING_OPTIONS), 395 "1" (0), 396 "D" ((long) &opt), 397 "S" (&pci_indirect), 398 "m" (opt) 399 : "memory"); 400 DBG("OK ret=%d, size=%d, map=%x\n", ret, opt.size, map); 401 ret = pcibios_get_return_code(ret); 402 if (ret) { 403 printk(KERN_ERR "PCI: Error %02x when fetching IRQ routing table.\n", ret); 404 } else if (opt.size) { 405 rt = kmalloc(sizeof(struct irq_routing_table) + opt.size, GFP_KERNEL); 406 if (rt) { 407 memset(rt, 0, sizeof(struct irq_routing_table)); 408 rt->size = opt.size + sizeof(struct irq_routing_table); 409 rt->exclusive_irqs = map; 410 memcpy(rt->slots, (void *) page, opt.size); 411 printk(KERN_INFO "PCI: Using BIOS Interrupt Routing Table\n"); 412 } 413 } 414 free_page(page); 415 return rt; 416 } 417 EXPORT_SYMBOL(pcibios_get_irq_routing_table); 418 419 int pcibios_set_irq_routing(struct pci_dev *dev, int pin, int irq) 420 { 421 int ret; 422 423 __asm__("lcall *(%%esi); cld\n\t" 424 "jc 1f\n\t" 425 "xor %%ah, %%ah\n" 426 "1:" 427 : "=a" (ret) 428 : "0" (PCIBIOS_SET_PCI_HW_INT), 429 "b" ((dev->bus->number << 8) | dev->devfn), 430 "c" ((irq << 8) | (pin + 10)), 431 "S" (&pci_indirect)); 432 return pcibios_get_return_code(ret) == PCIBIOS_SUCCESSFUL; 433 } 434 EXPORT_SYMBOL(pcibios_set_irq_routing); 435 436 void __init pci_pcbios_init(void) 437 { 438 if ((pci_probe & PCI_PROBE_BIOS) 439 && ((raw_pci_ops = pci_find_bios()))) { 440 pci_bios_present = 1; 441 } 442 } 443 444