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
  13 /*
  14  */
  15 #define USU_MOD_FL_THREAD   1   /* Thread is running */
  16 #define USU_MOD_FL_PRESENT  2   /* The module is loaded */
  17
  18 struct mod_status {
  19         unsigned long fls;
  20 };
  21
  22 static struct mod_status stat[3];
  23 static DEFINE_SPINLOCK(usu_lock);
  24
  25 /*
  26  */
  27 #define USB_US_DEFAULT_BIAS     USB_US_TYPE_STOR
  28 static atomic_t usu_bias = ATOMIC_INIT(USB_US_DEFAULT_BIAS);
  29
  30 #define BIAS_NAME_SIZE  (sizeof("usb-storage"))
  31 static const char *bias_names[3] = { "none", "usb-storage", "ub" };
  32
  33 static DECLARE_MUTEX_LOCKED(usu_init_notify);
  34 static DECLARE_COMPLETION(usu_end_notify);
  35 static atomic_t total_threads = ATOMIC_INIT(0);
  36
  37 static int usu_probe_thread(void *arg);
  38
  39 /*
  40  * The table.
  41  */
  42 #define UNUSUAL_DEV(id_vendor, id_product, bcdDeviceMin, bcdDeviceMax, \
  43                     vendorName, productName,useProtocol, useTransport, \
  44                     initFunction, flags) \
  45 { USB_DEVICE_VER(id_vendor, id_product, bcdDeviceMin,bcdDeviceMax), \
  46   .driver_info = (flags)|(USB_US_TYPE_STOR<<24) }
  47
  48 #define USUAL_DEV(useProto, useTrans, useType) \
  49 { USB_INTERFACE_INFO(USB_CLASS_MASS_STORAGE, useProto, useTrans), \
  50   .driver_info = ((useType)<<24) }
  51
  52 struct usb_device_id storage_usb_ids [] = {
  53 #       include "unusual_devs.h"
  54         { } /* Terminating entry */
  55 };
  56
  57 #undef USUAL_DEV
  58 #undef UNUSUAL_DEV
  59
  60 MODULE_DEVICE_TABLE(usb, storage_usb_ids);
  61 EXPORT_SYMBOL_GPL(storage_usb_ids);
  62
  63 /*
  64  * @type: the module type as an integer
  65  */
  66 void usb_usual_set_present(int type)
  67 {
  68         struct mod_status *st;
  69         unsigned long flags;
  70
  71         if (type <= 0 || type >= 3)
  72                 return;
  73         st = &stat[type];
  74         spin_lock_irqsave(&usu_lock, flags);
  75         st->fls |= USU_MOD_FL_PRESENT;
  76         spin_unlock_irqrestore(&usu_lock, flags);
  77 }
  78 EXPORT_SYMBOL_GPL(usb_usual_set_present);
  79
  80 void usb_usual_clear_present(int type)
  81 {
  82         struct mod_status *st;
  83         unsigned long flags;
  84
  85         if (type <= 0 || type >= 3)
  86                 return;
  87         st = &stat[type];
  88         spin_lock_irqsave(&usu_lock, flags);
  89         st->fls &= ~USU_MOD_FL_PRESENT;
  90         spin_unlock_irqrestore(&usu_lock, flags);
  91 }
  92 EXPORT_SYMBOL_GPL(usb_usual_clear_present);
  93
  94 /*
  95  * Match the calling driver type against the table.
  96  * Returns: 0 if the device matches.
  97  */
  98 int usb_usual_check_type(const struct usb_device_id *id, int caller_type)
  99 {
 100         int id_type = USB_US_TYPE(id->driver_info);
 101
 102         if (caller_type <= 0 || caller_type >= 3)
 103                 return -EINVAL;
 104
 105         /* Drivers grab fixed assignment devices */
 106         if (id_type == caller_type)
 107                 return 0;
 108         /* Drivers grab devices biased to them */
 109         if (id_type == USB_US_TYPE_NONE && caller_type == atomic_read(&usu_bias))
 110                 return 0;
 111         return -ENODEV;
 112 }
 113 EXPORT_SYMBOL_GPL(usb_usual_check_type);
 114
 115 /*
 116  */
 117 static int usu_probe(struct usb_interface *intf,
 118                          const struct usb_device_id *id)
 119 {
 120         int rc;
 121         unsigned long type;
 122         struct task_struct* task;
 123         unsigned long flags;
 124
 125         type = USB_US_TYPE(id->driver_info);
 126         if (type == 0)
 127                 type = atomic_read(&usu_bias);
 128
 129         spin_lock_irqsave(&usu_lock, flags);
 130         if ((stat[type].fls & (USU_MOD_FL_THREAD|USU_MOD_FL_PRESENT)) != 0) {
 131                 spin_unlock_irqrestore(&usu_lock, flags);
 132                 return -ENXIO;
 133         }
 134         stat[type].fls |= USU_MOD_FL_THREAD;
 135         spin_unlock_irqrestore(&usu_lock, flags);
 136
 137         task = kthread_run(usu_probe_thread, (void*)type, "libusual_%d", type);
 138         if (IS_ERR(task)) {
 139                 rc = PTR_ERR(task);
 140                 printk(KERN_WARNING "libusual: "
 141                     "Unable to start the thread for %s: %d\n",
 142                     bias_names[type], rc);
 143                 spin_lock_irqsave(&usu_lock, flags);
 144                 stat[type].fls &= ~USU_MOD_FL_THREAD;
 145                 spin_unlock_irqrestore(&usu_lock, flags);
 146                 return rc;      /* Not being -ENXIO causes a message printed */
 147         }
 148         atomic_inc(&total_threads);
 149
 150         return -ENXIO;
 151 }
 152
 153 static void usu_disconnect(struct usb_interface *intf)
 154 {
 155         ;       /* We should not be here. */
 156 }
 157
 158 static struct usb_driver usu_driver = {
 159         .name =         "libusual",
 160         .probe =        usu_probe,
 161         .disconnect =   usu_disconnect,
 162         .id_table =     storage_usb_ids,
 163 };
 164
 165 /*
 166  * A whole new thread for a purpose of request_module seems quite stupid.
 167  * The request_module forks once inside again. However, if we attempt
 168  * to load a storage module from our own modprobe thread, that module
 169  * references our symbols, which cannot be resolved until our module is
 170  * initialized. I wish there was a way to wait for the end of initialization.
 171  * The module notifier reports MODULE_STATE_COMING only.
 172  * So, we wait until module->init ends as the next best thing.
 173  */
 174 static int usu_probe_thread(void *arg)
 175 {
 176         int type = (unsigned long) arg;
 177         struct mod_status *st = &stat[type];
 178         int rc;
 179         unsigned long flags;
 180
 181         /* A completion does not work here because it's counted. */
 182         down(&usu_init_notify);
 183         up(&usu_init_notify);
 184
 185         rc = request_module(bias_names[type]);
 186         spin_lock_irqsave(&usu_lock, flags);
 187         if (rc == 0 && (st->fls & USU_MOD_FL_PRESENT) == 0) {
 188                 /*
 189                  * This should not happen, but let us keep tabs on it.
 190                  */
 191                 printk(KERN_NOTICE "libusual: "
 192                     "modprobe for %s succeeded, but module is not present\n",
 193                     bias_names[type]);
 194         }
 195         st->fls &= ~USU_MOD_FL_THREAD;
 196         spin_unlock_irqrestore(&usu_lock, flags);
 197
 198         complete_and_exit(&usu_end_notify, 0);
 199 }
 200
 201 /*
 202  */
 203 static int __init usb_usual_init(void)
 204 {
 205         int rc;
 206
 207         rc = usb_register(&usu_driver);
 208         up(&usu_init_notify);
 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");