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1// SPDX-License-Identifier: GPL-2.0+2/*3 * Copyright 2019 Google Inc4 *5 * This program is free software; you can redistribute it and/or6 * modify it under the terms of the GNU General Public License7 * as published by the Free Software Foundation; either version8 * 2 of the License, or (at your option) any later version.9 *10 * Provides a simple driver to control the ASPEED P2A interface which allows11 * 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.h>22#include <linux/of_address.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 0x2c34/* SCU180 is the PCIe Configuration Setting Control Register. */35#define SCU180 0x18036/* Bit 1 controls the P2A bridge, while bit 0 controls the entire VGA device37 * 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 643 44struct region {45 u64 min;46 u64 max;47 u32 bit;48};49 50struct aspeed_p2a_model_data {51 /* min, max, bit */52 struct region regions[P2A_REGION_COUNT];53};54 55struct 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 72struct 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 is77 * 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 user83 * opens for read or readwrite, the reference goes up here. On84 * release, this array is walked and references adjusted accordingly.85 */86 u32 readwrite[P2A_REGION_COUNT];87};88 89static 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 95static 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 100static 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 + vma_pages(vma) > ctrl->mem_size >> PAGE_SHIFT)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 127static 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 is153 * 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 can160 * 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 172static 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 entire186 * region is read-only once enabled, we just need to track this187 * 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 corresponding213 * 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 (bit231 * flipped, and bridge enabled). Either way, this tracking is used, s.t. when232 * 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 */237static 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 opened260 * for readwrite, and decrement those counts. If at the end, this is the last261 * user, it'll close the bridge.262 */263static 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 updated271 * 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 else283 bits |= priv->parent->config->regions[i].bit;284 }285 286 /* Setting a bit to 1 disables the region, so let's just OR with the287 * 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 the297 * 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 309static 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 */318static 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 332static 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 386static void 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}392 393#define SCU2C_DRAM BIT(25)394#define SCU2C_SPI BIT(24)395#define SCU2C_SOC BIT(23)396#define SCU2C_FLASH BIT(22)397 398static const struct aspeed_p2a_model_data ast2400_model_data = {399 .regions = {400 {0x00000000, 0x17FFFFFF, SCU2C_FLASH},401 {0x18000000, 0x1FFFFFFF, SCU2C_SOC},402 {0x20000000, 0x2FFFFFFF, SCU2C_FLASH},403 {0x30000000, 0x3FFFFFFF, SCU2C_SPI},404 {0x40000000, 0x5FFFFFFF, SCU2C_DRAM},405 {0x60000000, 0xFFFFFFFF, SCU2C_SOC},406 }407};408 409static const struct aspeed_p2a_model_data ast2500_model_data = {410 .regions = {411 {0x00000000, 0x0FFFFFFF, SCU2C_FLASH},412 {0x10000000, 0x1FFFFFFF, SCU2C_SOC},413 {0x20000000, 0x3FFFFFFF, SCU2C_FLASH},414 {0x40000000, 0x5FFFFFFF, SCU2C_SOC},415 {0x60000000, 0x7FFFFFFF, SCU2C_SPI},416 {0x80000000, 0xFFFFFFFF, SCU2C_DRAM},417 }418};419 420static const struct of_device_id aspeed_p2a_ctrl_match[] = {421 { .compatible = "aspeed,ast2400-p2a-ctrl",422 .data = &ast2400_model_data },423 { .compatible = "aspeed,ast2500-p2a-ctrl",424 .data = &ast2500_model_data },425 { },426};427 428static struct platform_driver aspeed_p2a_ctrl_driver = {429 .driver = {430 .name = DEVICE_NAME,431 .of_match_table = aspeed_p2a_ctrl_match,432 },433 .probe = aspeed_p2a_ctrl_probe,434 .remove_new = aspeed_p2a_ctrl_remove,435};436 437module_platform_driver(aspeed_p2a_ctrl_driver);438 439MODULE_DEVICE_TABLE(of, aspeed_p2a_ctrl_match);440MODULE_LICENSE("GPL");441MODULE_AUTHOR("Patrick Venture <venture@google.com>");442MODULE_DESCRIPTION("Control for aspeed 2400/2500 P2A VGA HOST to BMC mappings");443