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         char name[8];
  70 };
  71
  72 static int debug;
  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 static int add_slot(struct pci_dev *dev)
 100 {
 101         struct dummy_slot *dslot;
 102         struct hotplug_slot *slot;
 103         int retval = -ENOMEM;
 104         static int count = 1;
 105
 106         slot = kzalloc(sizeof(struct hotplug_slot), GFP_KERNEL);
 107         if (!slot)
 108                 goto error;
 109
 110         slot->info = kzalloc(sizeof(struct hotplug_slot_info), GFP_KERNEL);
 111         if (!slot->info)
 112                 goto error_slot;
 113
 114         slot->info->power_status = 1;
 115         slot->info->max_bus_speed = PCI_SPEED_UNKNOWN;
 116         slot->info->cur_bus_speed = PCI_SPEED_UNKNOWN;
 117
 118         dslot = kzalloc(sizeof(struct dummy_slot), GFP_KERNEL);
 119         if (!dslot)
 120                 goto error_info;
 121
 122         slot->name = dslot->name;
 123         snprintf(slot->name, sizeof(dslot->name), "fake%d", count++);
 124         dbg("slot->name = %s\n", slot->name);
 125         slot->ops = &dummy_hotplug_slot_ops;
 126         slot->release = &dummy_release;
 127         slot->private = dslot;
 128
 129         retval = pci_hp_register(slot, dev->bus, PCI_SLOT(dev->devfn));
 130         if (retval) {
 131                 err("pci_hp_register failed with error %d\n", retval);
 132                 goto error_dslot;
 133         }
 134
 135         dslot->slot = slot;
 136         dslot->dev = pci_dev_get(dev);
 137         list_add (&dslot->node, &slot_list);
 138         return retval;
 139
 140 error_dslot:
 141         kfree(dslot);
 142 error_info:
 143         kfree(slot->info);
 144 error_slot:
 145         kfree(slot);
 146 error:
 147         return retval;
 148 }
 149
 150 static int __init pci_scan_buses(void)
 151 {
 152         struct pci_dev *dev = NULL;
 153         int lastslot = 0;
 154
 155         while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
 156                 if (PCI_FUNC(dev->devfn) > 0 &&
 157                                 lastslot == PCI_SLOT(dev->devfn))
 158                         continue;
 159                 lastslot = PCI_SLOT(dev->devfn);
 160                 add_slot(dev);
 161         }
 162
 163         return 0;
 164 }
 165
 166 static void remove_slot(struct dummy_slot *dslot)
 167 {
 168         int retval;
 169
 170         dbg("removing slot %s\n", dslot->slot->name);
 171         retval = pci_hp_deregister(dslot->slot);
 172         if (retval)
 173                 err("Problem unregistering a slot %s\n", dslot->slot->name);
 174 }
 175
 176 /* called from the single-threaded workqueue handler to remove a slot */
 177 static void remove_slot_worker(struct work_struct *work)
 178 {
 179         struct dummy_slot *dslot =
 180                 container_of(work, struct dummy_slot, remove_work);
 181         remove_slot(dslot);
 182 }
 183
 184 /**
 185  * pci_rescan_slot - Rescan slot
 186  * @temp: Device template. Should be set: bus and devfn.
 187  *
 188  * Tries hard not to re-enable already existing devices;
 189  * also handles scanning of subfunctions.
 190  */
 191 static void pci_rescan_slot(struct pci_dev *temp)
 192 {
 193         struct pci_bus *bus = temp->bus;
 194         struct pci_dev *dev;
 195         int func;
 196         int retval;
 197         u8 hdr_type;
 198
 199         if (!pci_read_config_byte(temp, PCI_HEADER_TYPE, &hdr_type)) {
 200                 temp->hdr_type = hdr_type & 0x7f;
 201                 if ((dev = pci_get_slot(bus, temp->devfn)) != NULL)
 202                         pci_dev_put(dev);
 203                 else {
 204                         dev = pci_scan_single_device(bus, temp->devfn);
 205                         if (dev) {
 206                                 dbg("New device on %s function %x:%x\n",
 207                                         bus->name, temp->devfn >> 3,
 208                                         temp->devfn & 7);
 209                                 retval = pci_bus_add_device(dev);
 210                                 if (retval)
 211                                         dev_err(&dev->dev, "error adding "
 212                                                 "device, continuing.\n");
 213                                 else
 214                                         add_slot(dev);
 215                         }
 216                 }
 217                 /* multifunction device? */
 218                 if (!(hdr_type & 0x80))
 219                         return;
 220
 221                 /* continue scanning for other functions */
 222                 for (func = 1, temp->devfn++; func < 8; func++, temp->devfn++) {
 223                         if (pci_read_config_byte(temp, PCI_HEADER_TYPE, &hdr_type))
 224                                 continue;
 225                         temp->hdr_type = hdr_type & 0x7f;
 226
 227                         if ((dev = pci_get_slot(bus, temp->devfn)) != NULL)
 228                                 pci_dev_put(dev);
 229                         else {
 230                                 dev = pci_scan_single_device(bus, temp->devfn);
 231                                 if (dev) {
 232                                         dbg("New device on %s function %x:%x\n",
 233                                                 bus->name, temp->devfn >> 3,
 234                                                 temp->devfn & 7);
 235                                         retval = pci_bus_add_device(dev);
 236                                         if (retval)
 237                                                 dev_err(&dev->dev, "error adding "
 238                                                         "device, continuing.\n");
 239                                         else
 240                                                 add_slot(dev);
 241                                 }
 242                         }
 243                 }
 244         }
 245 }
 246
 247
 248 /**
 249  * pci_rescan_bus - Rescan PCI bus
 250  * @bus: the PCI bus to rescan
 251  *
 252  * Call pci_rescan_slot for each possible function of the bus.
 253  */
 254 static void pci_rescan_bus(const struct pci_bus *bus)
 255 {
 256         unsigned int devfn;
 257         struct pci_dev *dev;
 258         dev = alloc_pci_dev();
 259         if (!dev)
 260                 return;
 261
 262         dev->bus = (struct pci_bus*)bus;
 263         dev->sysdata = bus->sysdata;
 264         for (devfn = 0; devfn < 0x100; devfn += 8) {
 265                 dev->devfn = devfn;
 266                 pci_rescan_slot(dev);
 267         }
 268         kfree(dev);
 269 }
 270
 271 /* recursively scan all buses */
 272 static void pci_rescan_buses(const struct list_head *list)
 273 {
 274         const struct list_head *l;
 275         list_for_each(l,list) {
 276                 const struct pci_bus *b = pci_bus_b(l);
 277                 pci_rescan_bus(b);
 278                 pci_rescan_buses(&b->children);
 279         }
 280 }
 281
 282 /* initiate rescan of all pci buses */
 283 static inline void pci_rescan(void) {
 284         pci_rescan_buses(&pci_root_buses);
 285 }
 286
 287 /* called from the single-threaded workqueue handler to rescan all pci buses */
 288 static void pci_rescan_worker(struct work_struct *work)
 289 {
 290         pci_rescan();
 291 }
 292
 293 static int enable_slot(struct hotplug_slot *hotplug_slot)
 294 {
 295         /* mis-use enable_slot for rescanning of the pci bus */
 296         cancel_work_sync(&pci_rescan_work);
 297         queue_work(dummyphp_wq, &pci_rescan_work);
 298         return 0;
 299 }
 300
 301 static int disable_slot(struct hotplug_slot *slot)
 302 {
 303         struct dummy_slot *dslot;
 304         struct pci_dev *dev;
 305         int func;
 306
 307         if (!slot)
 308                 return -ENODEV;
 309         dslot = slot->private;
 310
 311         dbg("%s - physical_slot = %s\n", __func__, slot->name);
 312
 313         for (func = 7; func >= 0; func--) {
 314                 dev = pci_get_slot(dslot->dev->bus, dslot->dev->devfn + func);
 315                 if (!dev)
 316                         continue;
 317
 318                 if (test_and_set_bit(0, &dslot->removed)) {
 319                         dbg("Slot already scheduled for removal\n");
 320                         return -ENODEV;
 321                 }
 322
 323                 /* queue work item to blow away this sysfs entry and other
 324                  * parts.
 325                  */
 326                 INIT_WORK(&dslot->remove_work, remove_slot_worker);
 327                 queue_work(dummyphp_wq, &dslot->remove_work);
 328
 329                 /* blow away this sysfs entry and other parts. */
 330                 remove_slot(dslot);
 331
 332                 pci_dev_put(dev);
 333         }
 334         return 0;
 335 }
 336
 337 static void cleanup_slots (void)
 338 {
 339         struct list_head *tmp;
 340         struct list_head *next;
 341         struct dummy_slot *dslot;
 342
 343         destroy_workqueue(dummyphp_wq);
 344         list_for_each_safe (tmp, next, &slot_list) {
 345                 dslot = list_entry (tmp, struct dummy_slot, node);
 346                 remove_slot(dslot);
 347         }
 348
 349 }
 350
 351 static int __init dummyphp_init(void)
 352 {
 353         info(DRIVER_DESC "\n");
 354
 355         dummyphp_wq = create_singlethread_workqueue(MY_NAME);
 356         if (!dummyphp_wq)
 357                 return -ENOMEM;
 358
 359         return pci_scan_buses();
 360 }
 361
 362
 363 static void __exit dummyphp_exit(void)
 364 {
 365         cleanup_slots();
 366 }
 367
 368 module_init(dummyphp_init);
 369 module_exit(dummyphp_exit);
 370
 371 MODULE_AUTHOR(DRIVER_AUTHOR);
 372 MODULE_DESCRIPTION(DRIVER_DESC);
 373 MODULE_LICENSE("GPL");
 374 module_param(debug, bool, S_IRUGO | S_IWUSR);
 375 MODULE_PARM_DESC(debug, "Debugging mode enabled or not");
 376