1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2018 Marvell 4 * 5 * Author: Thomas Petazzoni <thomas.petazzoni@bootlin.com> 6 * 7 * This file helps PCI controller drivers implement a fake root port 8 * PCI bridge when the HW doesn't provide such a root port PCI 9 * bridge. 10 * 11 * It emulates a PCI bridge by providing a fake PCI configuration 12 * space (and optionally a PCIe capability configuration space) in 13 * memory. By default the read/write operations simply read and update 14 * this fake configuration space in memory. However, PCI controller 15 * drivers can provide through the 'struct pci_sw_bridge_ops' 16 * structure a set of operations to override or complement this 17 * default behavior. 18 */ 19 20 #include <linux/pci.h> 21 #include "pci-bridge-emul.h" 22 23 #define PCI_BRIDGE_CONF_END PCI_STD_HEADER_SIZEOF 24 #define PCI_CAP_PCIE_SIZEOF (PCI_EXP_SLTSTA2 + 2) 25 #define PCI_CAP_PCIE_START PCI_BRIDGE_CONF_END 26 #define PCI_CAP_PCIE_END (PCI_CAP_PCIE_START + PCI_CAP_PCIE_SIZEOF) 27 28 /** 29 * struct pci_bridge_reg_behavior - register bits behaviors 30 * @ro: Read-Only bits 31 * @rw: Read-Write bits 32 * @w1c: Write-1-to-Clear bits 33 * 34 * Reads and Writes will be filtered by specified behavior. All other bits not 35 * declared are assumed 'Reserved' and will return 0 on reads, per PCIe 5.0: 36 * "Reserved register fields must be read only and must return 0 (all 0's for 37 * multi-bit fields) when read". 38 */ 39 struct pci_bridge_reg_behavior { 40 /* Read-only bits */ 41 u32 ro; 42 43 /* Read-write bits */ 44 u32 rw; 45 46 /* Write-1-to-clear bits */ 47 u32 w1c; 48 }; 49 50 static const 51 struct pci_bridge_reg_behavior pci_regs_behavior[PCI_STD_HEADER_SIZEOF / 4] = { 52 [PCI_VENDOR_ID / 4] = { .ro = ~0 }, 53 [PCI_COMMAND / 4] = { 54 .rw = (PCI_COMMAND_IO | PCI_COMMAND_MEMORY | 55 PCI_COMMAND_MASTER | PCI_COMMAND_PARITY | 56 PCI_COMMAND_SERR), 57 .ro = ((PCI_COMMAND_SPECIAL | PCI_COMMAND_INVALIDATE | 58 PCI_COMMAND_VGA_PALETTE | PCI_COMMAND_WAIT | 59 PCI_COMMAND_FAST_BACK) | 60 (PCI_STATUS_CAP_LIST | PCI_STATUS_66MHZ | 61 PCI_STATUS_FAST_BACK | PCI_STATUS_DEVSEL_MASK) << 16), 62 .w1c = PCI_STATUS_ERROR_BITS << 16, 63 }, 64 [PCI_CLASS_REVISION / 4] = { .ro = ~0 }, 65 66 /* 67 * Cache Line Size register: implement as read-only, we do not 68 * pretend implementing "Memory Write and Invalidate" 69 * transactions" 70 * 71 * Latency Timer Register: implemented as read-only, as "A 72 * bridge that is not capable of a burst transfer of more than 73 * two data phases on its primary interface is permitted to 74 * hardwire the Latency Timer to a value of 16 or less" 75 * 76 * Header Type: always read-only 77 * 78 * BIST register: implemented as read-only, as "A bridge that 79 * does not support BIST must implement this register as a 80 * read-only register that returns 0 when read" 81 */ 82 [PCI_CACHE_LINE_SIZE / 4] = { .ro = ~0 }, 83 84 /* 85 * Base Address registers not used must be implemented as 86 * read-only registers that return 0 when read. 87 */ 88 [PCI_BASE_ADDRESS_0 / 4] = { .ro = ~0 }, 89 [PCI_BASE_ADDRESS_1 / 4] = { .ro = ~0 }, 90 91 [PCI_PRIMARY_BUS / 4] = { 92 /* Primary, secondary and subordinate bus are RW */ 93 .rw = GENMASK(24, 0), 94 /* Secondary latency is read-only */ 95 .ro = GENMASK(31, 24), 96 }, 97 98 [PCI_IO_BASE / 4] = { 99 /* The high four bits of I/O base/limit are RW */ 100 .rw = (GENMASK(15, 12) | GENMASK(7, 4)), 101 102 /* The low four bits of I/O base/limit are RO */ 103 .ro = (((PCI_STATUS_66MHZ | PCI_STATUS_FAST_BACK | 104 PCI_STATUS_DEVSEL_MASK) << 16) | 105 GENMASK(11, 8) | GENMASK(3, 0)), 106 107 .w1c = PCI_STATUS_ERROR_BITS << 16, 108 }, 109 110 [PCI_MEMORY_BASE / 4] = { 111 /* The high 12-bits of mem base/limit are RW */ 112 .rw = GENMASK(31, 20) | GENMASK(15, 4), 113 114 /* The low four bits of mem base/limit are RO */ 115 .ro = GENMASK(19, 16) | GENMASK(3, 0), 116 }, 117 118 [PCI_PREF_MEMORY_BASE / 4] = { 119 /* The high 12-bits of pref mem base/limit are RW */ 120 .rw = GENMASK(31, 20) | GENMASK(15, 4), 121 122 /* The low four bits of pref mem base/limit are RO */ 123 .ro = GENMASK(19, 16) | GENMASK(3, 0), 124 }, 125 126 [PCI_PREF_BASE_UPPER32 / 4] = { 127 .rw = ~0, 128 }, 129 130 [PCI_PREF_LIMIT_UPPER32 / 4] = { 131 .rw = ~0, 132 }, 133 134 [PCI_IO_BASE_UPPER16 / 4] = { 135 .rw = ~0, 136 }, 137 138 [PCI_CAPABILITY_LIST / 4] = { 139 .ro = GENMASK(7, 0), 140 }, 141 142 [PCI_ROM_ADDRESS1 / 4] = { 143 .rw = GENMASK(31, 11) | BIT(0), 144 }, 145 146 /* 147 * Interrupt line (bits 7:0) are RW, interrupt pin (bits 15:8) 148 * are RO, and bridge control (31:16) are a mix of RW, RO, 149 * reserved and W1C bits 150 */ 151 [PCI_INTERRUPT_LINE / 4] = { 152 /* Interrupt line is RW */ 153 .rw = (GENMASK(7, 0) | 154 ((PCI_BRIDGE_CTL_PARITY | 155 PCI_BRIDGE_CTL_SERR | 156 PCI_BRIDGE_CTL_ISA | 157 PCI_BRIDGE_CTL_VGA | 158 PCI_BRIDGE_CTL_MASTER_ABORT | 159 PCI_BRIDGE_CTL_BUS_RESET | 160 BIT(8) | BIT(9) | BIT(11)) << 16)), 161 162 /* Interrupt pin is RO */ 163 .ro = (GENMASK(15, 8) | ((PCI_BRIDGE_CTL_FAST_BACK) << 16)), 164 165 .w1c = BIT(10) << 16, 166 }, 167 }; 168 169 static const 170 struct pci_bridge_reg_behavior pcie_cap_regs_behavior[PCI_CAP_PCIE_SIZEOF / 4] = { 171 [PCI_CAP_LIST_ID / 4] = { 172 /* 173 * Capability ID, Next Capability Pointer and 174 * Capabilities register are all read-only. 175 */ 176 .ro = ~0, 177 }, 178 179 [PCI_EXP_DEVCAP / 4] = { 180 .ro = ~0, 181 }, 182 183 [PCI_EXP_DEVCTL / 4] = { 184 /* Device control register is RW */ 185 .rw = GENMASK(15, 0), 186 187 /* 188 * Device status register has bits 6 and [3:0] W1C, [5:4] RO, 189 * the rest is reserved 190 */ 191 .w1c = (BIT(6) | GENMASK(3, 0)) << 16, 192 .ro = GENMASK(5, 4) << 16, 193 }, 194 195 [PCI_EXP_LNKCAP / 4] = { 196 /* All bits are RO, except bit 23 which is reserved */ 197 .ro = lower_32_bits(~BIT(23)), 198 }, 199 200 [PCI_EXP_LNKCTL / 4] = { 201 /* 202 * Link control has bits [15:14], [11:3] and [1:0] RW, the 203 * rest is reserved. 204 * 205 * Link status has bits [13:0] RO, and bits [15:14] 206 * W1C. 207 */ 208 .rw = GENMASK(15, 14) | GENMASK(11, 3) | GENMASK(1, 0), 209 .ro = GENMASK(13, 0) << 16, 210 .w1c = GENMASK(15, 14) << 16, 211 }, 212 213 [PCI_EXP_SLTCAP / 4] = { 214 .ro = ~0, 215 }, 216 217 [PCI_EXP_SLTCTL / 4] = { 218 /* 219 * Slot control has bits [14:0] RW, the rest is 220 * reserved. 221 * 222 * Slot status has bits 8 and [4:0] W1C, bits [7:5] RO, the 223 * rest is reserved. 224 */ 225 .rw = GENMASK(14, 0), 226 .w1c = (PCI_EXP_SLTSTA_ABP | PCI_EXP_SLTSTA_PFD | 227 PCI_EXP_SLTSTA_MRLSC | PCI_EXP_SLTSTA_PDC | 228 PCI_EXP_SLTSTA_CC | PCI_EXP_SLTSTA_DLLSC) << 16, 229 .ro = (PCI_EXP_SLTSTA_MRLSS | PCI_EXP_SLTSTA_PDS | 230 PCI_EXP_SLTSTA_EIS) << 16, 231 }, 232 233 [PCI_EXP_RTCTL / 4] = { 234 /* 235 * Root control has bits [4:0] RW, the rest is 236 * reserved. 237 * 238 * Root capabilities has bit 0 RO, the rest is reserved. 239 */ 240 .rw = (PCI_EXP_RTCTL_SECEE | PCI_EXP_RTCTL_SENFEE | 241 PCI_EXP_RTCTL_SEFEE | PCI_EXP_RTCTL_PMEIE | 242 PCI_EXP_RTCTL_CRSSVE), 243 .ro = PCI_EXP_RTCAP_CRSVIS << 16, 244 }, 245 246 [PCI_EXP_RTSTA / 4] = { 247 /* 248 * Root status has bits 17 and [15:0] RO, bit 16 W1C, the rest 249 * is reserved. 250 */ 251 .ro = GENMASK(15, 0) | PCI_EXP_RTSTA_PENDING, 252 .w1c = PCI_EXP_RTSTA_PME, 253 }, 254 }; 255 256 /* 257 * Initialize a pci_bridge_emul structure to represent a fake PCI 258 * bridge configuration space. The caller needs to have initialized 259 * the PCI configuration space with whatever values make sense 260 * (typically at least vendor, device, revision), the ->ops pointer, 261 * and optionally ->data and ->has_pcie. 262 */ 263 int pci_bridge_emul_init(struct pci_bridge_emul *bridge, 264 unsigned int flags) 265 { 266 BUILD_BUG_ON(sizeof(bridge->conf) != PCI_BRIDGE_CONF_END); 267 268 bridge->conf.class_revision |= cpu_to_le32(PCI_CLASS_BRIDGE_PCI << 16); 269 bridge->conf.header_type = PCI_HEADER_TYPE_BRIDGE; 270 bridge->conf.cache_line_size = 0x10; 271 bridge->conf.status = cpu_to_le16(PCI_STATUS_CAP_LIST); 272 bridge->pci_regs_behavior = kmemdup(pci_regs_behavior, 273 sizeof(pci_regs_behavior), 274 GFP_KERNEL); 275 if (!bridge->pci_regs_behavior) 276 return -ENOMEM; 277 278 if (bridge->has_pcie) { 279 bridge->conf.capabilities_pointer = PCI_CAP_PCIE_START; 280 bridge->pcie_conf.cap_id = PCI_CAP_ID_EXP; 281 /* Set PCIe v2, root port, slot support */ 282 bridge->pcie_conf.cap = 283 cpu_to_le16(PCI_EXP_TYPE_ROOT_PORT << 4 | 2 | 284 PCI_EXP_FLAGS_SLOT); 285 bridge->pcie_cap_regs_behavior = 286 kmemdup(pcie_cap_regs_behavior, 287 sizeof(pcie_cap_regs_behavior), 288 GFP_KERNEL); 289 if (!bridge->pcie_cap_regs_behavior) { 290 kfree(bridge->pci_regs_behavior); 291 return -ENOMEM; 292 } 293 } 294 295 if (flags & PCI_BRIDGE_EMUL_NO_PREFETCHABLE_BAR) { 296 bridge->pci_regs_behavior[PCI_PREF_MEMORY_BASE / 4].ro = ~0; 297 bridge->pci_regs_behavior[PCI_PREF_MEMORY_BASE / 4].rw = 0; 298 } 299 300 return 0; 301 } 302 EXPORT_SYMBOL_GPL(pci_bridge_emul_init); 303 304 /* 305 * Cleanup a pci_bridge_emul structure that was previously initialized 306 * using pci_bridge_emul_init(). 307 */ 308 void pci_bridge_emul_cleanup(struct pci_bridge_emul *bridge) 309 { 310 if (bridge->has_pcie) 311 kfree(bridge->pcie_cap_regs_behavior); 312 kfree(bridge->pci_regs_behavior); 313 } 314 EXPORT_SYMBOL_GPL(pci_bridge_emul_cleanup); 315 316 /* 317 * Should be called by the PCI controller driver when reading the PCI 318 * configuration space of the fake bridge. It will call back the 319 * ->ops->read_base or ->ops->read_pcie operations. 320 */ 321 int pci_bridge_emul_conf_read(struct pci_bridge_emul *bridge, int where, 322 int size, u32 *value) 323 { 324 int ret; 325 int reg = where & ~3; 326 pci_bridge_emul_read_status_t (*read_op)(struct pci_bridge_emul *bridge, 327 int reg, u32 *value); 328 __le32 *cfgspace; 329 const struct pci_bridge_reg_behavior *behavior; 330 331 if (bridge->has_pcie && reg >= PCI_CAP_PCIE_END) { 332 *value = 0; 333 return PCIBIOS_SUCCESSFUL; 334 } 335 336 if (!bridge->has_pcie && reg >= PCI_BRIDGE_CONF_END) { 337 *value = 0; 338 return PCIBIOS_SUCCESSFUL; 339 } 340 341 if (bridge->has_pcie && reg >= PCI_CAP_PCIE_START) { 342 reg -= PCI_CAP_PCIE_START; 343 read_op = bridge->ops->read_pcie; 344 cfgspace = (__le32 *) &bridge->pcie_conf; 345 behavior = bridge->pcie_cap_regs_behavior; 346 } else { 347 read_op = bridge->ops->read_base; 348 cfgspace = (__le32 *) &bridge->conf; 349 behavior = bridge->pci_regs_behavior; 350 } 351 352 if (read_op) 353 ret = read_op(bridge, reg, value); 354 else 355 ret = PCI_BRIDGE_EMUL_NOT_HANDLED; 356 357 if (ret == PCI_BRIDGE_EMUL_NOT_HANDLED) 358 *value = le32_to_cpu(cfgspace[reg / 4]); 359 360 /* 361 * Make sure we never return any reserved bit with a value 362 * different from 0. 363 */ 364 *value &= behavior[reg / 4].ro | behavior[reg / 4].rw | 365 behavior[reg / 4].w1c; 366 367 if (size == 1) 368 *value = (*value >> (8 * (where & 3))) & 0xff; 369 else if (size == 2) 370 *value = (*value >> (8 * (where & 3))) & 0xffff; 371 else if (size != 4) 372 return PCIBIOS_BAD_REGISTER_NUMBER; 373 374 return PCIBIOS_SUCCESSFUL; 375 } 376 EXPORT_SYMBOL_GPL(pci_bridge_emul_conf_read); 377 378 /* 379 * Should be called by the PCI controller driver when writing the PCI 380 * configuration space of the fake bridge. It will call back the 381 * ->ops->write_base or ->ops->write_pcie operations. 382 */ 383 int pci_bridge_emul_conf_write(struct pci_bridge_emul *bridge, int where, 384 int size, u32 value) 385 { 386 int reg = where & ~3; 387 int mask, ret, old, new, shift; 388 void (*write_op)(struct pci_bridge_emul *bridge, int reg, 389 u32 old, u32 new, u32 mask); 390 __le32 *cfgspace; 391 const struct pci_bridge_reg_behavior *behavior; 392 393 if (bridge->has_pcie && reg >= PCI_CAP_PCIE_END) 394 return PCIBIOS_SUCCESSFUL; 395 396 if (!bridge->has_pcie && reg >= PCI_BRIDGE_CONF_END) 397 return PCIBIOS_SUCCESSFUL; 398 399 shift = (where & 0x3) * 8; 400 401 if (size == 4) 402 mask = 0xffffffff; 403 else if (size == 2) 404 mask = 0xffff << shift; 405 else if (size == 1) 406 mask = 0xff << shift; 407 else 408 return PCIBIOS_BAD_REGISTER_NUMBER; 409 410 ret = pci_bridge_emul_conf_read(bridge, reg, 4, &old); 411 if (ret != PCIBIOS_SUCCESSFUL) 412 return ret; 413 414 if (bridge->has_pcie && reg >= PCI_CAP_PCIE_START) { 415 reg -= PCI_CAP_PCIE_START; 416 write_op = bridge->ops->write_pcie; 417 cfgspace = (__le32 *) &bridge->pcie_conf; 418 behavior = bridge->pcie_cap_regs_behavior; 419 } else { 420 write_op = bridge->ops->write_base; 421 cfgspace = (__le32 *) &bridge->conf; 422 behavior = bridge->pci_regs_behavior; 423 } 424 425 /* Keep all bits, except the RW bits */ 426 new = old & (~mask | ~behavior[reg / 4].rw); 427 428 /* Update the value of the RW bits */ 429 new |= (value << shift) & (behavior[reg / 4].rw & mask); 430 431 /* Clear the W1C bits */ 432 new &= ~((value << shift) & (behavior[reg / 4].w1c & mask)); 433 434 cfgspace[reg / 4] = cpu_to_le32(new); 435 436 if (write_op) 437 write_op(bridge, reg, old, new, mask); 438 439 return PCIBIOS_SUCCESSFUL; 440 } 441 EXPORT_SYMBOL_GPL(pci_bridge_emul_conf_write); 442