1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * Copyright 2019 Google Inc 4 * 5 * This program is free software; you can redistribute it and/or 6 * modify it under the terms of the GNU General Public License 7 * as published by the Free Software Foundation; either version 8 * 2 of the License, or (at your option) any later version. 9 * 10 * Provides a simple driver to control the ASPEED P2A interface which allows 11 * the host to read and write to various regions of the BMC's memory. 12 */ 13 14 #include <linux/fs.h> 15 #include <linux/io.h> 16 #include <linux/mfd/syscon.h> 17 #include <linux/miscdevice.h> 18 #include <linux/mm.h> 19 #include <linux/module.h> 20 #include <linux/mutex.h> 21 #include <linux/of_address.h> 22 #include <linux/of_device.h> 23 #include <linux/platform_device.h> 24 #include <linux/regmap.h> 25 #include <linux/slab.h> 26 #include <linux/uaccess.h> 27 28 #include <linux/aspeed-p2a-ctrl.h> 29 30 #define DEVICE_NAME "aspeed-p2a-ctrl" 31 32 /* SCU2C is a Misc. Control Register. */ 33 #define SCU2C 0x2c 34 /* SCU180 is the PCIe Configuration Setting Control Register. */ 35 #define SCU180 0x180 36 /* Bit 1 controls the P2A bridge, while bit 0 controls the entire VGA device 37 * on the PCI bus. 38 */ 39 #define SCU180_ENP2A BIT(1) 40 41 /* The ast2400/2500 both have six ranges. */ 42 #define P2A_REGION_COUNT 6 43 44 struct region { 45 u64 min; 46 u64 max; 47 u32 bit; 48 }; 49 50 struct aspeed_p2a_model_data { 51 /* min, max, bit */ 52 struct region regions[P2A_REGION_COUNT]; 53 }; 54 55 struct aspeed_p2a_ctrl { 56 struct miscdevice miscdev; 57 struct regmap *regmap; 58 59 const struct aspeed_p2a_model_data *config; 60 61 /* Access to these needs to be locked, held via probe, mapping ioctl, 62 * and release, remove. 63 */ 64 struct mutex tracking; 65 u32 readers; 66 u32 readerwriters[P2A_REGION_COUNT]; 67 68 phys_addr_t mem_base; 69 resource_size_t mem_size; 70 }; 71 72 struct aspeed_p2a_user { 73 struct file *file; 74 struct aspeed_p2a_ctrl *parent; 75 76 /* The entire memory space is opened for reading once the bridge is 77 * enabled, therefore this needs only to be tracked once per user. 78 * If any user has it open for read, the bridge must stay enabled. 79 */ 80 u32 read; 81 82 /* Each entry of the array corresponds to a P2A Region. If the user 83 * opens for read or readwrite, the reference goes up here. On 84 * release, this array is walked and references adjusted accordingly. 85 */ 86 u32 readwrite[P2A_REGION_COUNT]; 87 }; 88 89 static void aspeed_p2a_enable_bridge(struct aspeed_p2a_ctrl *p2a_ctrl) 90 { 91 regmap_update_bits(p2a_ctrl->regmap, 92 SCU180, SCU180_ENP2A, SCU180_ENP2A); 93 } 94 95 static void aspeed_p2a_disable_bridge(struct aspeed_p2a_ctrl *p2a_ctrl) 96 { 97 regmap_update_bits(p2a_ctrl->regmap, SCU180, SCU180_ENP2A, 0); 98 } 99 100 static int aspeed_p2a_mmap(struct file *file, struct vm_area_struct *vma) 101 { 102 unsigned long vsize; 103 pgprot_t prot; 104 struct aspeed_p2a_user *priv = file->private_data; 105 struct aspeed_p2a_ctrl *ctrl = priv->parent; 106 107 if (ctrl->mem_base == 0 && ctrl->mem_size == 0) 108 return -EINVAL; 109 110 vsize = vma->vm_end - vma->vm_start; 111 prot = vma->vm_page_prot; 112 113 if (vma->vm_pgoff + vsize > ctrl->mem_base + ctrl->mem_size) 114 return -EINVAL; 115 116 /* ast2400/2500 AHB accesses are not cache coherent */ 117 prot = pgprot_noncached(prot); 118 119 if (remap_pfn_range(vma, vma->vm_start, 120 (ctrl->mem_base >> PAGE_SHIFT) + vma->vm_pgoff, 121 vsize, prot)) 122 return -EAGAIN; 123 124 return 0; 125 } 126 127 static bool aspeed_p2a_region_acquire(struct aspeed_p2a_user *priv, 128 struct aspeed_p2a_ctrl *ctrl, 129 struct aspeed_p2a_ctrl_mapping *map) 130 { 131 int i; 132 u64 base, end; 133 bool matched = false; 134 135 base = map->addr; 136 end = map->addr + (map->length - 1); 137 138 /* If the value is a legal u32, it will find a match. */ 139 for (i = 0; i < P2A_REGION_COUNT; i++) { 140 const struct region *curr = &ctrl->config->regions[i]; 141 142 /* If the top of this region is lower than your base, skip it. 143 */ 144 if (curr->max < base) 145 continue; 146 147 /* If the bottom of this region is higher than your end, bail. 148 */ 149 if (curr->min > end) 150 break; 151 152 /* Lock this and update it, therefore it someone else is 153 * closing their file out, this'll preserve the increment. 154 */ 155 mutex_lock(&ctrl->tracking); 156 ctrl->readerwriters[i] += 1; 157 mutex_unlock(&ctrl->tracking); 158 159 /* Track with the user, so when they close their file, we can 160 * decrement properly. 161 */ 162 priv->readwrite[i] += 1; 163 164 /* Enable the region as read-write. */ 165 regmap_update_bits(ctrl->regmap, SCU2C, curr->bit, 0); 166 matched = true; 167 } 168 169 return matched; 170 } 171 172 static long aspeed_p2a_ioctl(struct file *file, unsigned int cmd, 173 unsigned long data) 174 { 175 struct aspeed_p2a_user *priv = file->private_data; 176 struct aspeed_p2a_ctrl *ctrl = priv->parent; 177 void __user *arg = (void __user *)data; 178 struct aspeed_p2a_ctrl_mapping map; 179 180 if (copy_from_user(&map, arg, sizeof(map))) 181 return -EFAULT; 182 183 switch (cmd) { 184 case ASPEED_P2A_CTRL_IOCTL_SET_WINDOW: 185 /* If they want a region to be read-only, since the entire 186 * region is read-only once enabled, we just need to track this 187 * user wants to read from the bridge, and if it's not enabled. 188 * Enable it. 189 */ 190 if (map.flags == ASPEED_P2A_CTRL_READ_ONLY) { 191 mutex_lock(&ctrl->tracking); 192 ctrl->readers += 1; 193 mutex_unlock(&ctrl->tracking); 194 195 /* Track with the user, so when they close their file, 196 * we can decrement properly. 197 */ 198 priv->read += 1; 199 } else if (map.flags == ASPEED_P2A_CTRL_READWRITE) { 200 /* If we don't acquire any region return error. */ 201 if (!aspeed_p2a_region_acquire(priv, ctrl, &map)) { 202 return -EINVAL; 203 } 204 } else { 205 /* Invalid map flags. */ 206 return -EINVAL; 207 } 208 209 aspeed_p2a_enable_bridge(ctrl); 210 return 0; 211 case ASPEED_P2A_CTRL_IOCTL_GET_MEMORY_CONFIG: 212 /* This is a request for the memory-region and corresponding 213 * length that is used by the driver for mmap. 214 */ 215 216 map.flags = 0; 217 map.addr = ctrl->mem_base; 218 map.length = ctrl->mem_size; 219 220 return copy_to_user(arg, &map, sizeof(map)) ? -EFAULT : 0; 221 } 222 223 return -EINVAL; 224 } 225 226 227 /* 228 * When a user opens this file, we create a structure to track their mappings. 229 * 230 * A user can map a region as read-only (bridge enabled), or read-write (bit 231 * flipped, and bridge enabled). Either way, this tracking is used, s.t. when 232 * they release the device references are handled. 233 * 234 * The bridge is not enabled until a user calls an ioctl to map a region, 235 * simply opening the device does not enable it. 236 */ 237 static int aspeed_p2a_open(struct inode *inode, struct file *file) 238 { 239 struct aspeed_p2a_user *priv; 240 241 priv = kmalloc(sizeof(*priv), GFP_KERNEL); 242 if (!priv) 243 return -ENOMEM; 244 245 priv->file = file; 246 priv->read = 0; 247 memset(priv->readwrite, 0, sizeof(priv->readwrite)); 248 249 /* The file's private_data is initialized to the p2a_ctrl. */ 250 priv->parent = file->private_data; 251 252 /* Set the file's private_data to the user's data. */ 253 file->private_data = priv; 254 255 return 0; 256 } 257 258 /* 259 * This will close the users mappings. It will go through what they had opened 260 * for readwrite, and decrement those counts. If at the end, this is the last 261 * user, it'll close the bridge. 262 */ 263 static int aspeed_p2a_release(struct inode *inode, struct file *file) 264 { 265 int i; 266 u32 bits = 0; 267 bool open_regions = false; 268 struct aspeed_p2a_user *priv = file->private_data; 269 270 /* Lock others from changing these values until everything is updated 271 * in one pass. 272 */ 273 mutex_lock(&priv->parent->tracking); 274 275 priv->parent->readers -= priv->read; 276 277 for (i = 0; i < P2A_REGION_COUNT; i++) { 278 priv->parent->readerwriters[i] -= priv->readwrite[i]; 279 280 if (priv->parent->readerwriters[i] > 0) 281 open_regions = true; 282 else 283 bits |= priv->parent->config->regions[i].bit; 284 } 285 286 /* Setting a bit to 1 disables the region, so let's just OR with the 287 * above to disable any. 288 */ 289 290 /* Note, if another user is trying to ioctl, they can't grab tracking, 291 * and therefore can't grab either register mutex. 292 * If another user is trying to close, they can't grab tracking either. 293 */ 294 regmap_update_bits(priv->parent->regmap, SCU2C, bits, bits); 295 296 /* If parent->readers is zero and open windows is 0, disable the 297 * bridge. 298 */ 299 if (!open_regions && priv->parent->readers == 0) 300 aspeed_p2a_disable_bridge(priv->parent); 301 302 mutex_unlock(&priv->parent->tracking); 303 304 kfree(priv); 305 306 return 0; 307 } 308 309 static const struct file_operations aspeed_p2a_ctrl_fops = { 310 .owner = THIS_MODULE, 311 .mmap = aspeed_p2a_mmap, 312 .unlocked_ioctl = aspeed_p2a_ioctl, 313 .open = aspeed_p2a_open, 314 .release = aspeed_p2a_release, 315 }; 316 317 /* The regions are controlled by SCU2C */ 318 static void aspeed_p2a_disable_all(struct aspeed_p2a_ctrl *p2a_ctrl) 319 { 320 int i; 321 u32 value = 0; 322 323 for (i = 0; i < P2A_REGION_COUNT; i++) 324 value |= p2a_ctrl->config->regions[i].bit; 325 326 regmap_update_bits(p2a_ctrl->regmap, SCU2C, value, value); 327 328 /* Disable the bridge. */ 329 aspeed_p2a_disable_bridge(p2a_ctrl); 330 } 331 332 static int aspeed_p2a_ctrl_probe(struct platform_device *pdev) 333 { 334 struct aspeed_p2a_ctrl *misc_ctrl; 335 struct device *dev; 336 struct resource resm; 337 struct device_node *node; 338 int rc = 0; 339 340 dev = &pdev->dev; 341 342 misc_ctrl = devm_kzalloc(dev, sizeof(*misc_ctrl), GFP_KERNEL); 343 if (!misc_ctrl) 344 return -ENOMEM; 345 346 mutex_init(&misc_ctrl->tracking); 347 348 /* optional. */ 349 node = of_parse_phandle(dev->of_node, "memory-region", 0); 350 if (node) { 351 rc = of_address_to_resource(node, 0, &resm); 352 of_node_put(node); 353 if (rc) { 354 dev_err(dev, "Couldn't address to resource for reserved memory\n"); 355 return -ENODEV; 356 } 357 358 misc_ctrl->mem_size = resource_size(&resm); 359 misc_ctrl->mem_base = resm.start; 360 } 361 362 misc_ctrl->regmap = syscon_node_to_regmap(pdev->dev.parent->of_node); 363 if (IS_ERR(misc_ctrl->regmap)) { 364 dev_err(dev, "Couldn't get regmap\n"); 365 return -ENODEV; 366 } 367 368 misc_ctrl->config = of_device_get_match_data(dev); 369 370 dev_set_drvdata(&pdev->dev, misc_ctrl); 371 372 aspeed_p2a_disable_all(misc_ctrl); 373 374 misc_ctrl->miscdev.minor = MISC_DYNAMIC_MINOR; 375 misc_ctrl->miscdev.name = DEVICE_NAME; 376 misc_ctrl->miscdev.fops = &aspeed_p2a_ctrl_fops; 377 misc_ctrl->miscdev.parent = dev; 378 379 rc = misc_register(&misc_ctrl->miscdev); 380 if (rc) 381 dev_err(dev, "Unable to register device\n"); 382 383 return rc; 384 } 385 386 static int aspeed_p2a_ctrl_remove(struct platform_device *pdev) 387 { 388 struct aspeed_p2a_ctrl *p2a_ctrl = dev_get_drvdata(&pdev->dev); 389 390 misc_deregister(&p2a_ctrl->miscdev); 391 392 return 0; 393 } 394 395 #define SCU2C_DRAM BIT(25) 396 #define SCU2C_SPI BIT(24) 397 #define SCU2C_SOC BIT(23) 398 #define SCU2C_FLASH BIT(22) 399 400 static const struct aspeed_p2a_model_data ast2400_model_data = { 401 .regions = { 402 {0x00000000, 0x17FFFFFF, SCU2C_FLASH}, 403 {0x18000000, 0x1FFFFFFF, SCU2C_SOC}, 404 {0x20000000, 0x2FFFFFFF, SCU2C_FLASH}, 405 {0x30000000, 0x3FFFFFFF, SCU2C_SPI}, 406 {0x40000000, 0x5FFFFFFF, SCU2C_DRAM}, 407 {0x60000000, 0xFFFFFFFF, SCU2C_SOC}, 408 } 409 }; 410 411 static const struct aspeed_p2a_model_data ast2500_model_data = { 412 .regions = { 413 {0x00000000, 0x0FFFFFFF, SCU2C_FLASH}, 414 {0x10000000, 0x1FFFFFFF, SCU2C_SOC}, 415 {0x20000000, 0x3FFFFFFF, SCU2C_FLASH}, 416 {0x40000000, 0x5FFFFFFF, SCU2C_SOC}, 417 {0x60000000, 0x7FFFFFFF, SCU2C_SPI}, 418 {0x80000000, 0xFFFFFFFF, SCU2C_DRAM}, 419 } 420 }; 421 422 static const struct of_device_id aspeed_p2a_ctrl_match[] = { 423 { .compatible = "aspeed,ast2400-p2a-ctrl", 424 .data = &ast2400_model_data }, 425 { .compatible = "aspeed,ast2500-p2a-ctrl", 426 .data = &ast2500_model_data }, 427 { }, 428 }; 429 430 static struct platform_driver aspeed_p2a_ctrl_driver = { 431 .driver = { 432 .name = DEVICE_NAME, 433 .of_match_table = aspeed_p2a_ctrl_match, 434 }, 435 .probe = aspeed_p2a_ctrl_probe, 436 .remove = aspeed_p2a_ctrl_remove, 437 }; 438 439 module_platform_driver(aspeed_p2a_ctrl_driver); 440 441 MODULE_DEVICE_TABLE(of, aspeed_p2a_ctrl_match); 442 MODULE_LICENSE("GPL"); 443 MODULE_AUTHOR("Patrick Venture <venture@google.com>"); 444 MODULE_DESCRIPTION("Control for aspeed 2400/2500 P2A VGA HOST to BMC mappings"); 445