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 int dup_slots;
  73 static LIST_HEAD(slot_list);
  74 static struct workqueue_struct *dummyphp_wq;
  75
  76 static void pci_rescan_worker(struct work_struct *work);
  77 static DECLARE_WORK(pci_rescan_work, pci_rescan_worker);
  78
  79 static int enable_slot (struct hotplug_slot *slot);
  80 static int disable_slot (struct hotplug_slot *slot);
  81
  82 static struct hotplug_slot_ops dummy_hotplug_slot_ops = {
  83         .owner                  = THIS_MODULE,
  84         .enable_slot            = enable_slot,
  85         .disable_slot           = disable_slot,
  86 };
  87
  88 static void dummy_release(struct hotplug_slot *slot)
  89 {
  90         struct dummy_slot *dslot = slot->private;
  91
  92         list_del(&dslot->node);
  93         kfree(dslot->slot->info);
  94         kfree(dslot->slot);
  95         pci_dev_put(dslot->dev);
  96         kfree(dslot);
  97 }
  98
  99 #define SLOT_NAME_SIZE  8
 100
 101 static int add_slot(struct pci_dev *dev)
 102 {
 103         struct dummy_slot *dslot;
 104         struct hotplug_slot *slot;
 105         char name[SLOT_NAME_SIZE];
 106         int retval = -ENOMEM;
 107         static int count = 1;
 108
 109         slot = kzalloc(sizeof(struct hotplug_slot), GFP_KERNEL);
 110         if (!slot)
 111                 goto error;
 112
 113         slot->info = kzalloc(sizeof(struct hotplug_slot_info), GFP_KERNEL);
 114         if (!slot->info)
 115                 goto error_slot;
 116
 117         slot->info->power_status = 1;
 118         slot->info->max_bus_speed = PCI_SPEED_UNKNOWN;
 119         slot->info->cur_bus_speed = PCI_SPEED_UNKNOWN;
 120
 121         dslot = kzalloc(sizeof(struct dummy_slot), GFP_KERNEL);
 122         if (!dslot)
 123                 goto error_info;
 124
 125         if (dup_slots)
 126                 snprintf(name, SLOT_NAME_SIZE, "fake");
 127         else
 128                 snprintf(name, SLOT_NAME_SIZE, "fake%d", count++);
 129         dbg("slot->name = %s\n", name);
 130         slot->ops = &dummy_hotplug_slot_ops;
 131         slot->release = &dummy_release;
 132         slot->private = dslot;
 133
 134         retval = pci_hp_register(slot, dev->bus, PCI_SLOT(dev->devfn), name);
 135         if (retval) {
 136                 err("pci_hp_register failed with error %d\n", retval);
 137                 goto error_dslot;
 138         }
 139
 140         dbg("slot->name = %s\n", hotplug_slot_name(slot));
 141         dslot->slot = slot;
 142         dslot->dev = pci_dev_get(dev);
 143         list_add (&dslot->node, &slot_list);
 144         return retval;
 145
 146 error_dslot:
 147         kfree(dslot);
 148 error_info:
 149         kfree(slot->info);
 150 error_slot:
 151         kfree(slot);
 152 error:
 153         return retval;
 154 }
 155
 156 static int __init pci_scan_buses(void)
 157 {
 158         struct pci_dev *dev = NULL;
 159         int lastslot = 0;
 160
 161         while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
 162                 if (PCI_FUNC(dev->devfn) > 0 &&
 163                                 lastslot == PCI_SLOT(dev->devfn))
 164                         continue;
 165                 lastslot = PCI_SLOT(dev->devfn);
 166                 add_slot(dev);
 167         }
 168
 169         return 0;
 170 }
 171
 172 static void remove_slot(struct dummy_slot *dslot)
 173 {
 174         int retval;
 175
 176         dbg("removing slot %s\n", hotplug_slot_name(dslot->slot));
 177         retval = pci_hp_deregister(dslot->slot);
 178         if (retval)
 179                 err("Problem unregistering a slot %s\n",
 180                         hotplug_slot_name(dslot->slot));
 181 }
 182
 183 /* called from the single-threaded workqueue handler to remove a slot */
 184 static void remove_slot_worker(struct work_struct *work)
 185 {
 186         struct dummy_slot *dslot =
 187                 container_of(work, struct dummy_slot, remove_work);
 188         remove_slot(dslot);
 189 }
 190
 191 /**
 192  * pci_rescan_slot - Rescan slot
 193  * @temp: Device template. Should be set: bus and devfn.
 194  *
 195  * Tries hard not to re-enable already existing devices;
 196  * also handles scanning of subfunctions.
 197  */
 198 static void pci_rescan_slot(struct pci_dev *temp)
 199 {
 200         struct pci_bus *bus = temp->bus;
 201         struct pci_dev *dev;
 202         int func;
 203         int retval;
 204         u8 hdr_type;
 205
 206         if (!pci_read_config_byte(temp, PCI_HEADER_TYPE, &hdr_type)) {
 207                 temp->hdr_type = hdr_type & 0x7f;
 208                 if ((dev = pci_get_slot(bus, temp->devfn)) != NULL)
 209                         pci_dev_put(dev);
 210                 else {
 211                         dev = pci_scan_single_device(bus, temp->devfn);
 212                         if (dev) {
 213                                 dbg("New device on %s function %x:%x\n",
 214                                         bus->name, temp->devfn >> 3,
 215                                         temp->devfn & 7);
 216                                 retval = pci_bus_add_device(dev);
 217                                 if (retval)
 218                                         dev_err(&dev->dev, "error adding "
 219                                                 "device, continuing.\n");
 220                                 else
 221                                         add_slot(dev);
 222                         }
 223                 }
 224                 /* multifunction device? */
 225                 if (!(hdr_type & 0x80))
 226                         return;
 227
 228                 /* continue scanning for other functions */
 229                 for (func = 1, temp->devfn++; func < 8; func++, temp->devfn++) {
 230                         if (pci_read_config_byte(temp, PCI_HEADER_TYPE, &hdr_type))
 231                                 continue;
 232                         temp->hdr_type = hdr_type & 0x7f;
 233
 234                         if ((dev = pci_get_slot(bus, temp->devfn)) != NULL)
 235                                 pci_dev_put(dev);
 236                         else {
 237                                 dev = pci_scan_single_device(bus, temp->devfn);
 238                                 if (dev) {
 239                                         dbg("New device on %s function %x:%x\n",
 240                                                 bus->name, temp->devfn >> 3,
 241                                                 temp->devfn & 7);
 242                                         retval = pci_bus_add_device(dev);
 243                                         if (retval)
 244                                                 dev_err(&dev->dev, "error adding "
 245                                                         "device, continuing.\n");
 246                                         else
 247                                                 add_slot(dev);
 248                                 }
 249                         }
 250                 }
 251         }
 252 }
 253
 254
 255 /**
 256  * pci_rescan_bus - Rescan PCI bus
 257  * @bus: the PCI bus to rescan
 258  *
 259  * Call pci_rescan_slot for each possible function of the bus.
 260  */
 261 static void pci_rescan_bus(const struct pci_bus *bus)
 262 {
 263         unsigned int devfn;
 264         struct pci_dev *dev;
 265         dev = alloc_pci_dev();
 266         if (!dev)
 267                 return;
 268
 269         dev->bus = (struct pci_bus*)bus;
 270         dev->sysdata = bus->sysdata;
 271         for (devfn = 0; devfn < 0x100; devfn += 8) {
 272                 dev->devfn = devfn;
 273                 pci_rescan_slot(dev);
 274         }
 275         kfree(dev);
 276 }
 277
 278 /* recursively scan all buses */
 279 static void pci_rescan_buses(const struct list_head *list)
 280 {
 281         const struct list_head *l;
 282         list_for_each(l,list) {
 283                 const struct pci_bus *b = pci_bus_b(l);
 284                 pci_rescan_bus(b);
 285                 pci_rescan_buses(&b->children);
 286         }
 287 }
 288
 289 /* initiate rescan of all pci buses */
 290 static inline void pci_rescan(void) {
 291         pci_rescan_buses(&pci_root_buses);
 292 }
 293
 294 /* called from the single-threaded workqueue handler to rescan all pci buses */
 295 static void pci_rescan_worker(struct work_struct *work)
 296 {
 297         pci_rescan();
 298 }
 299
 300 static int enable_slot(struct hotplug_slot *hotplug_slot)
 301 {
 302         /* mis-use enable_slot for rescanning of the pci bus */
 303         cancel_work_sync(&pci_rescan_work);
 304         queue_work(dummyphp_wq, &pci_rescan_work);
 305         return 0;
 306 }
 307
 308 static int disable_slot(struct hotplug_slot *slot)
 309 {
 310         struct dummy_slot *dslot;
 311         struct pci_dev *dev;
 312         int func;
 313
 314         if (!slot)
 315                 return -ENODEV;
 316         dslot = slot->private;
 317
 318         dbg("%s - physical_slot = %s\n", __func__, hotplug_slot_name(slot));
 319
 320         for (func = 7; func >= 0; func--) {
 321                 dev = pci_get_slot(dslot->dev->bus, dslot->dev->devfn + func);
 322                 if (!dev)
 323                         continue;
 324
 325                 if (test_and_set_bit(0, &dslot->removed)) {
 326                         dbg("Slot already scheduled for removal\n");
 327                         pci_dev_put(dev);
 328                         return -ENODEV;
 329                 }
 330
 331                 /* remove the device from the pci core */
 332                 pci_remove_bus_device(dev);
 333
 334                 /* queue work item to blow away this sysfs entry and other
 335                  * parts.
 336                  */
 337                 INIT_WORK(&dslot->remove_work, remove_slot_worker);
 338                 queue_work(dummyphp_wq, &dslot->remove_work);
 339
 340                 pci_dev_put(dev);
 341         }
 342         return 0;
 343 }
 344
 345 static void cleanup_slots (void)
 346 {
 347         struct list_head *tmp;
 348         struct list_head *next;
 349         struct dummy_slot *dslot;
 350
 351         destroy_workqueue(dummyphp_wq);
 352         list_for_each_safe (tmp, next, &slot_list) {
 353                 dslot = list_entry (tmp, struct dummy_slot, node);
 354                 remove_slot(dslot);
 355         }
 356
 357 }
 358
 359 static int __init dummyphp_init(void)
 360 {
 361         info(DRIVER_DESC "\n");
 362
 363         dummyphp_wq = create_singlethread_workqueue(MY_NAME);
 364         if (!dummyphp_wq)
 365                 return -ENOMEM;
 366
 367         return pci_scan_buses();
 368 }
 369
 370
 371 static void __exit dummyphp_exit(void)
 372 {
 373         cleanup_slots();
 374 }
 375
 376 module_init(dummyphp_init);
 377 module_exit(dummyphp_exit);
 378
 379 MODULE_AUTHOR(DRIVER_AUTHOR);
 380 MODULE_DESCRIPTION(DRIVER_DESC);
 381 MODULE_LICENSE("GPL");
 382 module_param(debug, bool, S_IRUGO | S_IWUSR);
 383 MODULE_PARM_DESC(debug, "Debugging mode enabled or not");
 384 module_param(dup_slots, bool, S_IRUGO | S_IWUSR);
 385 MODULE_PARM_DESC(dup_slots, "Force duplicate slot names for debugging");