drivers/usb/storage/libusual.c

   1 /*
   2  * libusual
   3  *
   4  * The libusual contains the table of devices common for ub and usb-storage.
   5  */
   6 #include <linux/kernel.h>
   7 #include <linux/module.h>
   8 #include <linux/usb.h>
   9 #include <linux/usb_usual.h>
  10 #include <linux/vmalloc.h>
  11 #include <linux/kthread.h>
  12 #include <linux/mutex.h>
  13
  14 /*
  15  */
  16 #define USU_MOD_FL_THREAD   1   /* Thread is running */
  17 #define USU_MOD_FL_PRESENT  2   /* The module is loaded */
  18
  19 struct mod_status {
  20         unsigned long fls;
  21 };
  22
  23 static struct mod_status stat[3];
  24 static DEFINE_SPINLOCK(usu_lock);
  25
  26 /*
  27  */
  28 #define USB_US_DEFAULT_BIAS     USB_US_TYPE_STOR
  29 static atomic_t usu_bias = ATOMIC_INIT(USB_US_DEFAULT_BIAS);
  30
  31 #define BIAS_NAME_SIZE  (sizeof("usb-storage"))
  32 static const char *bias_names[3] = { "none", "usb-storage", "ub" };
  33
  34 static DEFINE_MUTEX(usu_probe_mutex);
  35 static DECLARE_COMPLETION(usu_end_notify);
  36 static atomic_t total_threads = ATOMIC_INIT(0);
  37
  38 static int usu_probe_thread(void *arg);
  39
  40 /*
  41  * The table.
  42  */
  43 #define UNUSUAL_DEV(id_vendor, id_product, bcdDeviceMin, bcdDeviceMax, \
  44                     vendorName, productName,useProtocol, useTransport, \
  45                     initFunction, flags) \
  46 { USB_DEVICE_VER(id_vendor, id_product, bcdDeviceMin,bcdDeviceMax), \
  47   .driver_info = (flags)|(USB_US_TYPE_STOR<<24) }
  48
  49 #define USUAL_DEV(useProto, useTrans, useType) \
  50 { USB_INTERFACE_INFO(USB_CLASS_MASS_STORAGE, useProto, useTrans), \
  51   .driver_info = ((useType)<<24) }
  52
  53 struct usb_device_id storage_usb_ids [] = {
  54 #       include "unusual_devs.h"
  55         { } /* Terminating entry */
  56 };
  57
  58 #undef USUAL_DEV
  59 #undef UNUSUAL_DEV
  60
  61 MODULE_DEVICE_TABLE(usb, storage_usb_ids);
  62 EXPORT_SYMBOL_GPL(storage_usb_ids);
  63
  64 /*
  65  * @type: the module type as an integer
  66  */
  67 void usb_usual_set_present(int type)
  68 {
  69         struct mod_status *st;
  70         unsigned long flags;
  71
  72         if (type <= 0 || type >= 3)
  73                 return;
  74         st = &stat[type];
  75         spin_lock_irqsave(&usu_lock, flags);
  76         st->fls |= USU_MOD_FL_PRESENT;
  77         spin_unlock_irqrestore(&usu_lock, flags);
  78 }
  79 EXPORT_SYMBOL_GPL(usb_usual_set_present);
  80
  81 void usb_usual_clear_present(int type)
  82 {
  83         struct mod_status *st;
  84         unsigned long flags;
  85
  86         if (type <= 0 || type >= 3)
  87                 return;
  88         st = &stat[type];
  89         spin_lock_irqsave(&usu_lock, flags);
  90         st->fls &= ~USU_MOD_FL_PRESENT;
  91         spin_unlock_irqrestore(&usu_lock, flags);
  92 }
  93 EXPORT_SYMBOL_GPL(usb_usual_clear_present);
  94
  95 /*
  96  * Match the calling driver type against the table.
  97  * Returns: 0 if the device matches.
  98  */
  99 int usb_usual_check_type(const struct usb_device_id *id, int caller_type)
 100 {
 101         int id_type = USB_US_TYPE(id->driver_info);
 102
 103         if (caller_type <= 0 || caller_type >= 3)
 104                 return -EINVAL;
 105
 106         /* Drivers grab fixed assignment devices */
 107         if (id_type == caller_type)
 108                 return 0;
 109         /* Drivers grab devices biased to them */
 110         if (id_type == USB_US_TYPE_NONE && caller_type == atomic_read(&usu_bias))
 111                 return 0;
 112         return -ENODEV;
 113 }
 114 EXPORT_SYMBOL_GPL(usb_usual_check_type);
 115
 116 /*
 117  */
 118 static int usu_probe(struct usb_interface *intf,
 119                          const struct usb_device_id *id)
 120 {
 121         int rc;
 122         unsigned long type;
 123         struct task_struct* task;
 124         unsigned long flags;
 125
 126         type = USB_US_TYPE(id->driver_info);
 127         if (type == 0)
 128                 type = atomic_read(&usu_bias);
 129
 130         spin_lock_irqsave(&usu_lock, flags);
 131         if ((stat[type].fls & (USU_MOD_FL_THREAD|USU_MOD_FL_PRESENT)) != 0) {
 132                 spin_unlock_irqrestore(&usu_lock, flags);
 133                 return -ENXIO;
 134         }
 135         stat[type].fls |= USU_MOD_FL_THREAD;
 136         spin_unlock_irqrestore(&usu_lock, flags);
 137
 138         task = kthread_run(usu_probe_thread, (void*)type, "libusual_%ld", type);
 139         if (IS_ERR(task)) {
 140                 rc = PTR_ERR(task);
 141                 printk(KERN_WARNING "libusual: "
 142                     "Unable to start the thread for %s: %d\n",
 143                     bias_names[type], rc);
 144                 spin_lock_irqsave(&usu_lock, flags);
 145                 stat[type].fls &= ~USU_MOD_FL_THREAD;
 146                 spin_unlock_irqrestore(&usu_lock, flags);
 147                 return rc;      /* Not being -ENXIO causes a message printed */
 148         }
 149         atomic_inc(&total_threads);
 150
 151         return -ENXIO;
 152 }
 153
 154 static void usu_disconnect(struct usb_interface *intf)
 155 {
 156         ;       /* We should not be here. */
 157 }
 158
 159 static struct usb_driver usu_driver = {
 160         .name =         "libusual",
 161         .probe =        usu_probe,
 162         .disconnect =   usu_disconnect,
 163         .id_table =     storage_usb_ids,
 164 };
 165
 166 /*
 167  * A whole new thread for a purpose of request_module seems quite stupid.
 168  * The request_module forks once inside again. However, if we attempt
 169  * to load a storage module from our own modprobe thread, that module
 170  * references our symbols, which cannot be resolved until our module is
 171  * initialized. I wish there was a way to wait for the end of initialization.
 172  * The module notifier reports MODULE_STATE_COMING only.
 173  * So, we wait until module->init ends as the next best thing.
 174  */
 175 static int usu_probe_thread(void *arg)
 176 {
 177         int type = (unsigned long) arg;
 178         struct mod_status *st = &stat[type];
 179         int rc;
 180         unsigned long flags;
 181
 182         mutex_lock(&usu_probe_mutex);
 183         rc = request_module(bias_names[type]);
 184         spin_lock_irqsave(&usu_lock, flags);
 185         if (rc == 0 && (st->fls & USU_MOD_FL_PRESENT) == 0) {
 186                 /*
 187                  * This should not happen, but let us keep tabs on it.
 188                  */
 189                 printk(KERN_NOTICE "libusual: "
 190                     "modprobe for %s succeeded, but module is not present\n",
 191                     bias_names[type]);
 192         }
 193         st->fls &= ~USU_MOD_FL_THREAD;
 194         spin_unlock_irqrestore(&usu_lock, flags);
 195         mutex_unlock(&usu_probe_mutex);
 196
 197         complete_and_exit(&usu_end_notify, 0);
 198 }
 199
 200 /*
 201  */
 202 static int __init usb_usual_init(void)
 203 {
 204         int rc;
 205
 206         mutex_lock(&usu_probe_mutex);
 207         rc = usb_register(&usu_driver);
 208         mutex_unlock(&usu_probe_mutex);
 209         return rc;
 210 }
 211
 212 static void __exit usb_usual_exit(void)
 213 {
 214         /*
 215          * We do not check for any drivers present, because
 216          * they keep us pinned with symbol references.
 217          */
 218
 219         usb_deregister(&usu_driver);
 220
 221         while (atomic_read(&total_threads) > 0) {
 222                 wait_for_completion(&usu_end_notify);
 223                 atomic_dec(&total_threads);
 224         }
 225 }
 226
 227 /*
 228  * Validate and accept the bias parameter.
 229  */
 230 static int usu_set_bias(const char *bias_s, struct kernel_param *kp)
 231 {
 232         int i;
 233         int len;
 234         int bias_n = 0;
 235
 236         len = strlen(bias_s);
 237         if (len == 0)
 238                 return -EDOM;
 239         if (bias_s[len-1] == '\n')
 240                 --len;
 241
 242         for (i = 1; i < 3; i++) {
 243                 if (strncmp(bias_s, bias_names[i], len) == 0) {
 244                         bias_n = i;
 245                         break;
 246                 }
 247         }
 248         if (bias_n == 0)
 249                 return -EINVAL;
 250
 251         atomic_set(&usu_bias, bias_n);
 252         return 0;
 253 }
 254
 255 static int usu_get_bias(char *buffer, struct kernel_param *kp)
 256 {
 257         return strlen(strcpy(buffer, bias_names[atomic_read(&usu_bias)]));
 258 }
 259
 260 module_init(usb_usual_init);
 261 module_exit(usb_usual_exit);
 262
 263 module_param_call(bias, usu_set_bias, usu_get_bias, NULL, S_IRUGO|S_IWUSR);
 264 __MODULE_PARM_TYPE(bias, "string");
 265 MODULE_PARM_DESC(bias, "Bias to usb-storage or ub");
 266
 267 MODULE_LICENSE("GPL");