i386/linux/linux-2.3.21/drivers/scsi/scsi_module.c

   1 /*
   2  *  scsi_module.c Copyright (1994, 1995) Eric Youngdale.
   3  *
   4  * Support for loading low-level scsi drivers using the linux kernel loadable
   5  * module interface.
   6  *
   7  * To use, the host adapter should first define and initialize the variable
   8  * driver_template (datatype Scsi_Host_Template), and then include this file.
   9  * This should also be wrapped in a #ifdef MODULE/#endif.
  10  *
  11  * The low -level driver must also define a release function which will
  12  * free any irq assignments, release any dma channels, release any I/O
  13  * address space that might be reserved, and otherwise clean up after itself.
  14  * The idea is that the same driver should be able to be reloaded without
  15  * any difficulty.  This makes debugging new drivers easier, as you should
  16  * be able to load the driver, test it, unload, modify and reload.
  17  *
  18  * One *very* important caveat.  If the driver may need to do DMA on the
  19  * ISA bus, you must have unchecked_isa_dma set in the device template,
  20  * even if this might be changed during the detect routine.  This is
  21  * because the shpnt structure will be allocated in a special way so that
  22  * it will be below the appropriate DMA limit - thus if your driver uses
  23  * the hostdata field of shpnt, and the board must be able to access this
  24  * via DMA, the shpnt structure must be in a DMA accessible region of
  25  * memory.  This comment would be relevant for something like the buslogic
  26  * driver where there are many boards, only some of which do DMA onto the
  27  * ISA bus.  There is no convenient way of specifying whether the host
  28  * needs to be in a ISA DMA accessible region of memory when you call
  29  * scsi_register.
  30  */
  31
  32 #include <linux/module.h>
  33
  34 int init_module(void)
  35 {
  36         driver_template.module = &__this_module;
  37         scsi_register_module(MODULE_SCSI_HA, &driver_template);
  38         if (driver_template.present)
  39                 return 0;
  40
  41         scsi_unregister_module(MODULE_SCSI_HA, &driver_template);
  42         return -1;
  43 }
  44
  45 void cleanup_module(void)
  46 {
  47         scsi_unregister_module(MODULE_SCSI_HA, &driver_template);
  48 }
  49
  50 /*
  51  * Overrides for Emacs so that we almost follow Linus's tabbing style.
  52  * Emacs will notice this stuff at the end of the file and automatically
  53  * adjust the settings for this buffer only.  This must remain at the end
  54  * of the file.
  55  * ---------------------------------------------------------------------------
  56  * Local variables:
  57  * c-indent-level: 4
  58  * c-brace-imaginary-offset: 0
  59  * c-brace-offset: -4
  60  * c-argdecl-indent: 4
  61  * c-label-offset: -4
  62  * c-continued-statement-offset: 4
  63  * c-continued-brace-offset: 0
  64  * indent-tabs-mode: nil
  65  * tab-width: 8
  66  * End:
  67  */