drivers/staging/meilhaus/medlock.h

   1 /**
   2  * @file medlock.h
   3  *
   4  * @brief Provides the device lock class.
   5  * @note Copyright (C) 2006 Meilhaus Electronic GmbH (support@meilhaus.de)
   6  * @author Guenter Gebhardt
   7  */
   8
   9 #ifndef _MEDLOCK_H_
  10 #define _MEDLOCK_H_
  11
  12 #include <linux/spinlock.h>
  13
  14 #ifdef __KERNEL__
  15
  16 /**
  17  * @brief The device lock class.
  18  */
  19 typedef struct me_dlock {
  20         struct file *filep;             /**< Pointer to file structure holding the device. */
  21         int count;                              /**< Number of tasks which are inside the device. */
  22         spinlock_t spin_lock;   /**< Spin lock protecting the attributes from concurrent access. */
  23 } me_dlock_t;
  24
  25 /**
  26  * @brief Tries to enter a device.
  27  *
  28  * @param dlock The device lock instance.
  29  * @param filep The file structure identifying the calling process.
  30  *
  31  * @return 0 on success.
  32  */
  33 int me_dlock_enter(struct me_dlock *dlock, struct file *filep);
  34
  35 /**
  36  * @brief Exits a device.
  37  *
  38  * @param dlock The device lock instance.
  39  * @param filep The file structure identifying the calling process.
  40  *
  41  * @return 0 on success.
  42  */
  43 int me_dlock_exit(struct me_dlock *dlock, struct file *filep);
  44
  45 /**
  46  * @brief Tries to perform a locking action on a device.
  47  *
  48  * @param dlock The device lock instance.
  49  * @param filep The file structure identifying the calling process.
  50  * @param The action to be done.
  51  * @param flags Flags from user space.
  52  * @param slist The subdevice list of the device.
  53  *
  54  * @return 0 on success.
  55  */
  56 int me_dlock_lock(struct me_dlock *dlock,
  57                   struct file *filep, int lock, int flags, me_slist_t * slist);
  58
  59 /**
  60  * @brief Initializes a lock structure.
  61  *
  62  * @param dlock The lock structure to initialize.
  63  * @return 0 on success.
  64  */
  65 int me_dlock_init(me_dlock_t * dlock);
  66
  67 /**
  68  * @brief Deinitializes a lock structure.
  69  *
  70  * @param dlock The lock structure to deinitialize.
  71  * @return 0 on success.
  72  */
  73 void me_dlock_deinit(me_dlock_t * dlock);
  74
  75 #endif
  76 #endif