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/*  This file is part of the program psim.
 
    Copyright (C) 1997,2008, Joel Sherrill <joel@OARcorp.com>
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.
 
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 
    */
 
 
#ifndef _HW_SEM_C_
#define _HW_SEM_C_
 
#include "device_table.h"
 
#ifdef HAVE_STRING_H
#include <string.h>
#else
#ifdef HAVE_STRINGS_H
#include <strings.h>
#endif
#endif
 
#include <sys/ipc.h>
#include <sys/sem.h>
 
#include <errno.h>
 
/* DEVICE
 
 
   sem - provide access to a unix semaphore
 
 
   DESCRIPTION
 
 
   This device implements an interface to a unix semaphore.
 
 
   PROPERTIES
 
 
   reg = <address> <size> (required)
 
   Determine where the memory lives in the parents address space.
 
   key = <integer> (required)
 
   This is the key of the unix semaphore.
 
   EXAMPLES
 
 
   Enable tracing of the sem:
 
   |  bash$ psim -t sem-device \
 
 
   Configure a UNIX semaphore using key 0x12345678 mapped into psim
   address space at 0xfff00000:
 
   |  -o '/sem@0xfff00000/reg 0xfff00000 0x80000' \
   |  -o '/sem@0xfff00000/key 0x12345678' \
 
   sim/ppc/run -o '/#address-cells 1' \
         -o '/sem@0xfff00000/reg 0xfff00000 12' \
         -o '/sem@0xfff00000/key 0x12345678' ../psim-hello/hello
 
   REGISTERS
 
   offset 0 - lock count
   offset 4 - lock operation
   offset 8 - unlock operation
 
   All reads return the current or resulting count.
 
   BUGS
 
   None known.
 
   */
 
typedef struct _hw_sem_device {
  unsigned_word physical_address;
  key_t key;
  int id;
  int initial;
  int count;
} hw_sem_device;
 
#ifndef HAVE_UNION_SEMUN
union semun {
  int val;
  struct semid_ds *buf;
  unsigned short int *array;
#if defined(__linux__)
  struct seminfo *__buf;
#endif
};
#endif
 
static void
hw_sem_init_data(device *me)
{
  hw_sem_device *sem = (hw_sem_device*)device_data(me);
  const device_unit *d;
  int status;
  union semun help;
 
  /* initialize the properties of the sem */
 
  if (device_find_property(me, "key") == NULL)
    error("sem_init_data() required key property is missing\n");
 
  if (device_find_property(me, "value") == NULL)
    error("sem_init_data() required value property is missing\n");
 
  sem->key = (key_t) device_find_integer_property(me, "key");
  DTRACE(sem, ("semaphore key (%d)\n", sem->key) );
 
  sem->initial = (int) device_find_integer_property(me, "value");
  DTRACE(sem, ("semaphore initial value (%d)\n", sem->initial) );
 
  d = device_unit_address(me);
  sem->physical_address = d->cells[ d->nr_cells-1 ];
  DTRACE(sem, ("semaphore physical_address=0x%x\n", sem->physical_address));
 
  /* Now to initialize the semaphore */
 
  if ( sem->initial != -1 ) {
 
    sem->id = semget(sem->key, 1, IPC_CREAT | 0660);
    if (sem->id == -1)
      error("hw_sem_init_data() semget failed\n");
 
    help.val = sem->initial;
    status = semctl( sem->id, 0, SETVAL, help );
    if (status == -1)
      error("hw_sem_init_data() semctl -- set value failed\n");
 
  } else {
    sem->id = semget(sem->key, 1, 0660);
    if (sem->id == -1)
      error("hw_sem_init_data() semget failed\n");
  }
 
  sem->count = semctl( sem->id, 0, GETVAL, help );
  if (sem->count == -1)
    error("hw_sem_init_data() semctl -- get value failed\n");
  DTRACE(sem, ("semaphore OS value (%d)\n", sem->count) );
}
 
static void
hw_sem_attach_address_callback(device *me,
				attach_type attach,
				int space,
				unsigned_word addr,
				unsigned nr_bytes,
				access_type access,
				device *client) /*callback/default*/
{
  hw_sem_device *sem = (hw_sem_device*)device_data(me);
 
  if (space != 0)
    error("sem_attach_address_callback() invalid address space\n");
 
  if (nr_bytes == 12)
    error("sem_attach_address_callback() invalid size\n");
 
  sem->physical_address = addr;
  DTRACE(sem, ("semaphore physical_address=0x%x\n", addr));
}
 
static unsigned
hw_sem_io_read_buffer(device *me,
			 void *dest,
			 int space,
			 unsigned_word addr,
			 unsigned nr_bytes,
			 cpu *processor,
			 unsigned_word cia)
{
  hw_sem_device *sem = (hw_sem_device*)device_data(me);
  struct sembuf sb;
  int status;
  unsigned32 u32;
  union semun help;
 
  /* do we need to worry about out of range addresses? */
 
  DTRACE(sem, ("semaphore read addr=0x%x length=%d\n", addr, nr_bytes));
 
  if (!(addr >= sem->physical_address && addr <= sem->physical_address + 11))
    error("hw_sem_io_read_buffer() invalid address - out of range\n");
 
  if ((addr % 4) != 0)
    error("hw_sem_io_read_buffer() invalid address - alignment\n");
 
  if (nr_bytes != 4)
    error("hw_sem_io_read_buffer() invalid length\n");
 
  switch ( (addr - sem->physical_address) / 4 ) {
 
    case 0:  /* OBTAIN CURRENT VALUE */
      break; 
 
    case 1:  /* LOCK */
      sb.sem_num = 0;
      sb.sem_op  = -1;
      sb.sem_flg = 0;
 
      status = semop(sem->id, &sb, 1);
      if (status == -1) {
        perror( "hw_sem.c: lock" );
        error("hw_sem_io_read_buffer() sem lock\n");
      }
 
      DTRACE(sem, ("semaphore lock %d\n", sem->count));
      break; 
 
    case 2: /* UNLOCK */
      sb.sem_num = 0;
      sb.sem_op  = 1;
      sb.sem_flg = 0;
 
      status = semop(sem->id, &sb, 1);
      if (status == -1) {
        perror( "hw_sem.c: unlock" );
        error("hw_sem_io_read_buffer() sem unlock\n");
      }
      DTRACE(sem, ("semaphore unlock %d\n", sem->count));
      break; 
 
    default:
      error("hw_sem_io_read_buffer() invalid address - unknown error\n");
      break; 
  }
 
  /* assume target is big endian */
  u32 = H2T_4(semctl( sem->id, 0, GETVAL, help ));
 
  DTRACE(sem, ("semaphore OS value (%d)\n", u32) );
  if (u32 == 0xffffffff) {
    perror( "hw_sem.c: getval" );
    error("hw_sem_io_read_buffer() semctl -- get value failed\n");
  }
 
  memcpy(dest, &u32, nr_bytes);
  return nr_bytes;
 
}
 
static device_callbacks const hw_sem_callbacks = {
  { generic_device_init_address, hw_sem_init_data },
  { hw_sem_attach_address_callback, }, /* address */
  { hw_sem_io_read_buffer, NULL }, /* IO */
  { NULL, }, /* DMA */
  { NULL, }, /* interrupt */
  { NULL, }, /* unit */
  NULL,
};
 
static void *
hw_sem_create(const char *name,
		 const device_unit *unit_address,
		 const char *args)
{
  hw_sem_device *sem = ZALLOC(hw_sem_device);
  return sem;
}
 
const device_descriptor hw_sem_device_descriptor[] = {
  { "sem", hw_sem_create, &hw_sem_callbacks },
  { NULL },
};
 
#endif /* _HW_SEM_C_ */