drivers/pci/hotplug/fakephp.c

   1 /*
   2  * Fake PCI Hot Plug Controller Driver
   3  *
   4  * Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
   5  * Copyright (C) 2003 IBM Corp.
   6  * Copyright (C) 2003 Rolf Eike Beer <eike-kernel@sf-tec.de>
   7  *
   8  * Based on ideas and code from:
   9  *      Vladimir Kondratiev <vladimir.kondratiev@intel.com>
  10  *      Rolf Eike Beer <eike-kernel@sf-tec.de>
  11  *
  12  * All rights reserved.
  13  *
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation, version 2 of the License.
  17  *
  18  * Send feedback to <greg@kroah.com>
  19  */
  20
  21 /*
  22  *
  23  * This driver will "emulate" removing PCI devices from the system.  If
  24  * the "power" file is written to with "0" then the specified PCI device
  25  * will be completely removed from the kernel.
  26  *
  27  * WARNING, this does NOT turn off the power to the PCI device.  This is
  28  * a "logical" removal, not a physical or electrical removal.
  29  *
  30  * Use this module at your own risk, you have been warned!
  31  *
  32  * Enabling PCI devices is left as an exercise for the reader...
  33  *
  34  */
  35 #include <linux/kernel.h>
  36 #include <linux/module.h>
  37 #include <linux/pci.h>
  38 #include <linux/pci_hotplug.h>
  39 #include <linux/init.h>
  40 #include <linux/string.h>
  41 #include <linux/slab.h>
  42 #include <linux/workqueue.h>
  43 #include "../pci.h"
  44
  45 #if !defined(MODULE)
  46         #define MY_NAME "fakephp"
  47 #else
  48         #define MY_NAME THIS_MODULE->name
  49 #endif
  50
  51 #define dbg(format, arg...)                                     \
  52         do {                                                    \
  53                 if (debug)                                      \
  54                         printk(KERN_DEBUG "%s: " format,        \
  55                                 MY_NAME , ## arg);              \
  56         } while (0)
  57 #define err(format, arg...) printk(KERN_ERR "%s: " format, MY_NAME , ## arg)
  58 #define info(format, arg...) printk(KERN_INFO "%s: " format, MY_NAME , ## arg)
  59
  60 #define DRIVER_AUTHOR   "Greg Kroah-Hartman <greg@kroah.com>"
  61 #define DRIVER_DESC     "Fake PCI Hot Plug Controller Driver"
  62
  63 struct dummy_slot {
  64         struct list_head node;
  65         struct hotplug_slot *slot;
  66         struct pci_dev *dev;
  67         struct work_struct remove_work;
  68         unsigned long removed;
  69 };
  70
  71 static int debug;
  72 static LIST_HEAD(slot_list);
  73 static struct workqueue_struct *dummyphp_wq;
  74
  75 static void pci_rescan_worker(struct work_struct *work);
  76 static DECLARE_WORK(pci_rescan_work, pci_rescan_worker);
  77
  78 static int enable_slot (struct hotplug_slot *slot);
  79 static int disable_slot (struct hotplug_slot *slot);
  80
  81 static struct hotplug_slot_ops dummy_hotplug_slot_ops = {
  82         .owner                  = THIS_MODULE,
  83         .enable_slot            = enable_slot,
  84         .disable_slot           = disable_slot,
  85 };
  86
  87 static void dummy_release(struct hotplug_slot *slot)
  88 {
  89         struct dummy_slot *dslot = slot->private;
  90
  91         list_del(&dslot->node);
  92         kfree(dslot->slot->info);
  93         kfree(dslot->slot);
  94         pci_dev_put(dslot->dev);
  95         kfree(dslot);
  96 }
  97
  98 static int add_slot(struct pci_dev *dev)
  99 {
 100         struct dummy_slot *dslot;
 101         struct hotplug_slot *slot;
 102         int retval = -ENOMEM;
 103
 104         slot = kzalloc(sizeof(struct hotplug_slot), GFP_KERNEL);
 105         if (!slot)
 106                 goto error;
 107
 108         slot->info = kzalloc(sizeof(struct hotplug_slot_info), GFP_KERNEL);
 109         if (!slot->info)
 110                 goto error_slot;
 111
 112         slot->info->power_status = 1;
 113         slot->info->max_bus_speed = PCI_SPEED_UNKNOWN;
 114         slot->info->cur_bus_speed = PCI_SPEED_UNKNOWN;
 115
 116         slot->name = &dev->dev.bus_id[0];
 117         dbg("slot->name = %s\n", slot->name);
 118
 119         dslot = kzalloc(sizeof(struct dummy_slot), GFP_KERNEL);
 120         if (!dslot)
 121                 goto error_info;
 122
 123         slot->ops = &dummy_hotplug_slot_ops;
 124         slot->release = &dummy_release;
 125         slot->private = dslot;
 126
 127         retval = pci_hp_register(slot);
 128         if (retval) {
 129                 err("pci_hp_register failed with error %d\n", retval);
 130                 goto error_dslot;
 131         }
 132
 133         dslot->slot = slot;
 134         dslot->dev = pci_dev_get(dev);
 135         list_add (&dslot->node, &slot_list);
 136         return retval;
 137
 138 error_dslot:
 139         kfree(dslot);
 140 error_info:
 141         kfree(slot->info);
 142 error_slot:
 143         kfree(slot);
 144 error:
 145         return retval;
 146 }
 147
 148 static int __init pci_scan_buses(void)
 149 {
 150         struct pci_dev *dev = NULL;
 151         int retval = 0;
 152
 153         while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
 154                 retval = add_slot(dev);
 155                 if (retval) {
 156                         pci_dev_put(dev);
 157                         break;
 158                 }
 159         }
 160
 161         return retval;
 162 }
 163
 164 static void remove_slot(struct dummy_slot *dslot)
 165 {
 166         int retval;
 167
 168         dbg("removing slot %s\n", dslot->slot->name);
 169         retval = pci_hp_deregister(dslot->slot);
 170         if (retval)
 171                 err("Problem unregistering a slot %s\n", dslot->slot->name);
 172 }
 173
 174 /* called from the single-threaded workqueue handler to remove a slot */
 175 static void remove_slot_worker(struct work_struct *work)
 176 {
 177         struct dummy_slot *dslot =
 178                 container_of(work, struct dummy_slot, remove_work);
 179         remove_slot(dslot);
 180 }
 181
 182 /**
 183  * pci_rescan_slot - Rescan slot
 184  * @temp: Device template. Should be set: bus and devfn.
 185  *
 186  * Tries hard not to re-enable already existing devices;
 187  * also handles scanning of subfunctions.
 188  */
 189 static void pci_rescan_slot(struct pci_dev *temp)
 190 {
 191         struct pci_bus *bus = temp->bus;
 192         struct pci_dev *dev;
 193         int func;
 194         int retval;
 195         u8 hdr_type;
 196
 197         if (!pci_read_config_byte(temp, PCI_HEADER_TYPE, &hdr_type)) {
 198                 temp->hdr_type = hdr_type & 0x7f;
 199                 if ((dev = pci_get_slot(bus, temp->devfn)) != NULL)
 200                         pci_dev_put(dev);
 201                 else {
 202                         dev = pci_scan_single_device(bus, temp->devfn);
 203                         if (dev) {
 204                                 dbg("New device on %s function %x:%x\n",
 205                                         bus->name, temp->devfn >> 3,
 206                                         temp->devfn & 7);
 207                                 retval = pci_bus_add_device(dev);
 208                                 if (retval)
 209                                         dev_err(&dev->dev, "error adding "
 210                                                 "device, continuing.\n");
 211                                 else
 212                                         add_slot(dev);
 213                         }
 214                 }
 215                 /* multifunction device? */
 216                 if (!(hdr_type & 0x80))
 217                         return;
 218
 219                 /* continue scanning for other functions */
 220                 for (func = 1, temp->devfn++; func < 8; func++, temp->devfn++) {
 221                         if (pci_read_config_byte(temp, PCI_HEADER_TYPE, &hdr_type))
 222                                 continue;
 223                         temp->hdr_type = hdr_type & 0x7f;
 224
 225                         if ((dev = pci_get_slot(bus, temp->devfn)) != NULL)
 226                                 pci_dev_put(dev);
 227                         else {
 228                                 dev = pci_scan_single_device(bus, temp->devfn);
 229                                 if (dev) {
 230                                         dbg("New device on %s function %x:%x\n",
 231                                                 bus->name, temp->devfn >> 3,
 232                                                 temp->devfn & 7);
 233                                         retval = pci_bus_add_device(dev);
 234                                         if (retval)
 235                                                 dev_err(&dev->dev, "error adding "
 236                                                         "device, continuing.\n");
 237                                         else
 238                                                 add_slot(dev);
 239                                 }
 240                         }
 241                 }
 242         }
 243 }
 244
 245
 246 /**
 247  * pci_rescan_bus - Rescan PCI bus
 248  * @bus: the PCI bus to rescan
 249  *
 250  * Call pci_rescan_slot for each possible function of the bus.
 251  */
 252 static void pci_rescan_bus(const struct pci_bus *bus)
 253 {
 254         unsigned int devfn;
 255         struct pci_dev *dev;
 256         dev = alloc_pci_dev();
 257         if (!dev)
 258                 return;
 259
 260         dev->bus = (struct pci_bus*)bus;
 261         dev->sysdata = bus->sysdata;
 262         for (devfn = 0; devfn < 0x100; devfn += 8) {
 263                 dev->devfn = devfn;
 264                 pci_rescan_slot(dev);
 265         }
 266         kfree(dev);
 267 }
 268
 269 /* recursively scan all buses */
 270 static void pci_rescan_buses(const struct list_head *list)
 271 {
 272         const struct list_head *l;
 273         list_for_each(l,list) {
 274                 const struct pci_bus *b = pci_bus_b(l);
 275                 pci_rescan_bus(b);
 276                 pci_rescan_buses(&b->children);
 277         }
 278 }
 279
 280 /* initiate rescan of all pci buses */
 281 static inline void pci_rescan(void) {
 282         pci_rescan_buses(&pci_root_buses);
 283 }
 284
 285 /* called from the single-threaded workqueue handler to rescan all pci buses */
 286 static void pci_rescan_worker(struct work_struct *work)
 287 {
 288         pci_rescan();
 289 }
 290
 291 static int enable_slot(struct hotplug_slot *hotplug_slot)
 292 {
 293         /* mis-use enable_slot for rescanning of the pci bus */
 294         cancel_work_sync(&pci_rescan_work);
 295         queue_work(dummyphp_wq, &pci_rescan_work);
 296         return -ENODEV;
 297 }
 298
 299 /* find the hotplug_slot for the pci_dev */
 300 static struct hotplug_slot *get_slot_from_dev(struct pci_dev *dev)
 301 {
 302         struct dummy_slot *dslot;
 303
 304         list_for_each_entry(dslot, &slot_list, node) {
 305                 if (dslot->dev == dev)
 306                         return dslot->slot;
 307         }
 308         return NULL;
 309 }
 310
 311
 312 static int disable_slot(struct hotplug_slot *slot)
 313 {
 314         struct dummy_slot *dslot;
 315         struct hotplug_slot *hslot;
 316         struct pci_dev *dev;
 317         int func;
 318
 319         if (!slot)
 320                 return -ENODEV;
 321         dslot = slot->private;
 322
 323         dbg("%s - physical_slot = %s\n", __FUNCTION__, slot->name);
 324
 325         /* don't disable bridged devices just yet, we can't handle them easily... */
 326         if (dslot->dev->subordinate) {
 327                 err("Can't remove PCI devices with other PCI devices behind it yet.\n");
 328                 return -ENODEV;
 329         }
 330         if (test_and_set_bit(0, &dslot->removed)) {
 331                 dbg("Slot already scheduled for removal\n");
 332                 return -ENODEV;
 333         }
 334         /* search for subfunctions and disable them first */
 335         if (!(dslot->dev->devfn & 7)) {
 336                 for (func = 1; func < 8; func++) {
 337                         dev = pci_get_slot(dslot->dev->bus,
 338                                         dslot->dev->devfn + func);
 339                         if (dev) {
 340                                 hslot = get_slot_from_dev(dev);
 341                                 if (hslot)
 342                                         disable_slot(hslot);
 343                                 else {
 344                                         err("Hotplug slot not found for subfunction of PCI device\n");
 345                                         return -ENODEV;
 346                                 }
 347                                 pci_dev_put(dev);
 348                         } else
 349                                 dbg("No device in slot found\n");
 350                 }
 351         }
 352
 353         /* remove the device from the pci core */
 354         pci_remove_bus_device(dslot->dev);
 355
 356         /* queue work item to blow away this sysfs entry and other parts. */
 357         INIT_WORK(&dslot->remove_work, remove_slot_worker);
 358         queue_work(dummyphp_wq, &dslot->remove_work);
 359
 360         return 0;
 361 }
 362
 363 static void cleanup_slots (void)
 364 {
 365         struct list_head *tmp;
 366         struct list_head *next;
 367         struct dummy_slot *dslot;
 368
 369         destroy_workqueue(dummyphp_wq);
 370         list_for_each_safe (tmp, next, &slot_list) {
 371                 dslot = list_entry (tmp, struct dummy_slot, node);
 372                 remove_slot(dslot);
 373         }
 374
 375 }
 376
 377 static int __init dummyphp_init(void)
 378 {
 379         info(DRIVER_DESC "\n");
 380
 381         dummyphp_wq = create_singlethread_workqueue(MY_NAME);
 382         if (!dummyphp_wq)
 383                 return -ENOMEM;
 384
 385         return pci_scan_buses();
 386 }
 387
 388
 389 static void __exit dummyphp_exit(void)
 390 {
 391         cleanup_slots();
 392 }
 393
 394 module_init(dummyphp_init);
 395 module_exit(dummyphp_exit);
 396
 397 MODULE_AUTHOR(DRIVER_AUTHOR);
 398 MODULE_DESCRIPTION(DRIVER_DESC);
 399 MODULE_LICENSE("GPL");
 400 module_param(debug, bool, S_IRUGO | S_IWUSR);
 401 MODULE_PARM_DESC(debug, "Debugging mode enabled or not");
 402