/****************************************************************************
 *.Copyright (c) 2006 DST Technologies Inc.  All Rights Reserved.   
 *
 * Module:      LLD_OSUTIL
 *
 * Description: Unified APIs for Lowest Level Driver 
 *
 * Notes:       This module implements APIs to interface with the following
 *              device objects:
 *              - OS specific Utilities
 *
 ***************************************************************************/
#include "lld_os.h"
#include "lld_local.h"
#include <linux/interrupt.h>

/*==============================
 * Local defines
 *=============================*/
/*
 * This returns 1 if the address is from user-address-space
 * It's used because some of the functions can be called with
 * args from user-space or from kernel-space memory
 */
#define FROM_USER_SPACE(addr) (((DS_U32) (addr)) >= PAGE_OFFSET ? 0 : 1)

#define PUSH_PID        DS_U32 PidSave=current_filp; current_filp=KERNEL_PID;
#define POP_PID         current_filp=PidSave;

/*==============================
 * Local prototypes
 *=============================*/


/*==============================
 * External declarations
 *=============================*/
extern DS_U32 current_filp;

/*^^***************************************************************************
 * void lld_delay (milliseconds)
 *
 * Description:
 *          Delays execution of caller for some milliseconds
 *          This should NOT be used from interrupt handlers !
 *
 * Entry :  number of milliseconds to delay
 *
 * Return:  nothing
 *
 **************************************************************************^^*/
void lld_delay (DS_U32 millisec) 
{
    PUSH_PID;
#if KERNEL_2_4_0
    current->state = TASK_INTERRUPTIBLE;
    schedule_timeout ((HZ / 1000) * millisec);
#elif 1
    current->state = TASK_INTERRUPTIBLE;
    schedule_timeout ((HZ / 1000) * millisec);
#else    
    current->timeout = (HZ / 1000) * millisec; 
    current->state = TASK_INTERRUPTIBLE;
    schedule ();
    current->timeout = 0;
#endif
    POP_PID;
}

/*^^***************************************************************************
 * void lld_os_disable_ints (void)
 *
 * Description:
 *          disables system interrupts
 *
 * Entry :  none
 *
 * Return:  previous interrupt flag state
 *
 **************************************************************************^^*/
DS_U32 lld_os_disable_ints (void)
{
    DS_U32 flags;    

#if KERNEL_2_4_0
    save_flags(flags);
    cli ();
#else
    local_save_flags(flags);
    local_irq_disable ();
#endif
    return (flags);
}

/*^^***************************************************************************
 * void lld_os_restore_ints (DS_U32 flags)
 *
 * Description:
 *          restores interrupt state
 *
 * Entry :  none
 *
 * Return:  none
 *
 **************************************************************************^^*/
void lld_os_restore_ints (DS_U32 flags)
{
#if KERNEL_2_4_0
    restore_flags(flags);
#else
    local_irq_restore(flags);
#endif
}
        
/*^^***************************************************************************
 * void lld_os_enable_ints (void)
 *
 * Description:
 *          Enable interrupts
 *
 * Entry :  none
 *
 * Return:  none
 *
 **************************************************************************^^*/
void lld_os_enable_ints (void)
{
#if KERNEL_2_4_0
    sti();
#else
    local_irq_enable();
#endif
}
        
/*^^***************************************************************************
 * void* lld_os_malloc (DS_U32 cbsize)
 *
 * Description:
 *          allocates a block of kernel memory
 *
 * Entry :  cbsize = size in bytes
 *
 * Return:  pointer to allocated kernel memory block
 *
 **************************************************************************^^*/
void* lld_os_malloc (DS_U32 cbsize)
{
    return kmalloc (cbsize, GFP_KERNEL);
}

/*^^***************************************************************************
 * void lld_os_free (void *pmemory)
 *
 * Description:
 *          frees a previously allocated block of kernel memory
 *
 * Entry :  pointer to allocated kernel memory block
 *
 * Return:  none
 *
 **************************************************************************^^*/
void lld_os_free (void *pmemory)
{
    kfree (pmemory);
}

/*^^***************************************************************************
 * void lld_os_copy_from_user (DS_S8 *pdest, DS_S8* psrc, DS_U32 cbsize)
 *
 * Description:
 *          copys the contents of user memory to kernel memory
 *
 * Entry :  pdest  = kernel mode destination pointer
 *          psrc   = user mode source pointer
 *          cbsize = size in bytes
 *
 * Return:  none
 *
 **************************************************************************^^*/
void lld_os_copy_from_user (DS_S8 *pdest, DS_S8* psrc, DS_U32 cbsize)
{
    if (FROM_USER_SPACE(psrc))
    {
        copy_from_user (pdest, psrc, cbsize);
    }
    else
    {
        memcpy (pdest, psrc, cbsize);
    }
}

/*^^***************************************************************************
 * void lld_os_copy_to_user (DS_S8 *pdest, DS_S8* psrc, DS_U32 cbsize)
 *
 * Description:
 *          copys the contents of kernel memory to user memory
 *
 * Entry :  pdest  = user mode destination pointer
 *          psrc   = kernel mode source pointer
 *          cbsize = size in bytes
 *
 * Return:  none
 *
 **************************************************************************^^*/
void lld_os_copy_to_user (DS_S8 *pdest, DS_S8* psrc, DS_U32 cbsize)
{
    if (FROM_USER_SPACE(pdest))
    {
        copy_to_user (pdest, psrc, cbsize);
    }
    else
    {
        memcpy (pdest, psrc, cbsize);
    }
}

/*^^***************************************************************************
 * DS_BOOL lld_os_init_lock (DS_U32 lock, DS_U32 Init)
 *
 * Description:
 *          initialize os specific semaphore type object
 *
 * Entry :  lock = Pointer to os specific semaphore id
 *          Init = initialization value
 *
 * Return:  _TRUE_ or _FALSE_
 *
 **************************************************************************^^*/
DS_BOOL lld_os_init_lock (DS_U32 lock, DS_U32 Init)
{
    sema_init ((struct semaphore*)lock, Init);
    return (_TRUE_);
}

/*^^***************************************************************************
 * DS_BOOL lld_os_get_lock (DS_U32 lock)
 *
 * Description:
 *          locks an os specific semaphore type object
 *
 * Entry :  lock = os specific semaphore id
 *
 * Return:  _TRUE_ or _FALSE_
 *
 **************************************************************************^^*/
DS_BOOL lld_os_get_lock (DS_U32 lock)
{
    PUSH_PID;
    down((struct semaphore*)lock);
    POP_PID;
    return (_TRUE_);
}

/*^^***************************************************************************
 * lld_os_release_lock
 *
 * Description:
 *          unlocks an os specific semaphore type object
 *
 * Entry :  lock = os specific semaphore id
 *
 * Return:  _TRUE_ or _FALSE_
 *
 **************************************************************************^^*/
DS_BOOL lld_os_release_lock (DS_U32 lock)
{
    up((struct semaphore*)lock);
    return (_TRUE_);
}

/*^^***************************************************************************
 * lld_os_get_usermode_process_id
 *
 * Description:
 *          get current user mode process id.
 *
 * Entry :  none
 *
 * Return:  current user mode process id
 *
 **************************************************************************^^*/
DS_U32 lld_os_get_usermode_process_id (void)
{
    return ((DS_U32)current_filp);
}

/*^^***************************************************************************
 * DS_BOOL lld_os_signal_detected (void)
 *
 * Description:
 *
 * Entry:   None 
 *
 * Return:  _TRUE_ if the current task received an OS signal (e.g. Ctrl-C)
 *
 * Notes:
 *
 **************************************************************************^^*/
DS_BOOL lld_os_signal_detected (void)
{
    return (signal_pending(current));
}

/*^^***************************************************************************
 * DS_BOOL lld_check_wait_q (WAIT_Q *WaitQPtr)
 *
 * Description:
 *
 * Entry:   WaitQPtr = Wait queue pointer
 *
 * Return:  _TRUE_ if the queue contains any sleeping tasks
 *
 * Notes:
 *
 **************************************************************************^^*/
DS_BOOL lld_check_wait_q (WAIT_Q *WaitQPtr)
{
    return (waitqueue_active(WaitQPtr));
}

/*^^***************************************************************************
 * void lld_wait_for_interrupt (WAIT_Q *WaitQPtr)
 *
 * Description:
 *          Enable interrupts and wait on WaitQPtr for wake up
 *
 * Entry:   WaitQPtr = Wait queue pointer
 *
 * Return:  Interrupt occured
 *
 * Notes:   Interrupts can be disabled before calling this function
 *
 **************************************************************************^^*/
void lld_wait_for_interrupt (WAIT_Q *WaitQPtr)
{
    DECLARE_WAITQUEUE(wait, current);
    PUSH_PID;
    add_wait_queue(WaitQPtr, &wait);
    __set_current_state(TASK_INTERRUPTIBLE);
    lld_os_enable_ints();
    schedule();
    remove_wait_queue(WaitQPtr, &wait);
    set_current_state(TASK_RUNNING);
    POP_PID;
}

/*^^***************************************************************************
 * DS_U32 lld_init_wait_q (WAIT_Q *WaitQPtr)
 *
 * Description: Initialize wait queue
 *
 * Entry:   WaitQPtr = Wait queue pointer
 *
 * Return:  0
 *
 * Notes:
 *
 **************************************************************************^^*/
DS_U32 lld_init_wait_q (WAIT_Q *WaitQPtr)
{
#if 1
    init_waitqueue_head (WaitQPtr);
#else
    *WaitQPtr = NULL;
#endif
    return (0);
}

/*^^***************************************************************************
 * DS_U32 lld_wait_on_q (WAIT_Q *WaitQPtr)
 *
 * Description: Wait on queue for wake up signal
 *
 * Entry:   WaitQPtr = Wait queue pointer
 *
 * Return:  Wake up signal received
 *
 * Notes:
 *
 **************************************************************************^^*/
DS_U32 lld_wait_on_q (WAIT_Q *WaitQPtr)
{
    PUSH_PID;
    interruptible_sleep_on (WaitQPtr);
    POP_PID;
    return (0);
}

/*^^***************************************************************************
 * DS_U32 lld_timeout_wait_on_q (WAIT_Q *WaitQPtr, DS_U32 TimeOut)
 *
 * Description: Wait on queue with timeout
 *
 * Entry:   WaitQPtr = Wait queue pointer
 *
 * Return:  
 *
 * Notes:
 *
 **************************************************************************^^*/
DS_U32 lld_timeout_wait_on_q (WAIT_Q *WaitQPtr, DS_U32 TimeOut)
{
    DS_U32 i;
    PUSH_PID;
    i = (DS_U32)(interruptible_sleep_on_timeout (WaitQPtr, TimeOut));
    POP_PID;
    return (i);
}

/*^^***************************************************************************
 * DS_U32 lld_wakeup_wait_q (WAIT_Q *WaitQPtr)
 *
 * Description: Wake up waiting interruptible taks in a queue
 *
 * Entry:   WaitQPtr = Wait queue pointer
 *
 * Return:  
 *
 * Notes:
 *
 **************************************************************************^^*/
DS_U32 lld_wakeup_wait_q (WAIT_Q *WaitQPtr)
{
    PUSH_PID;
    wake_up_interruptible (WaitQPtr);
    POP_PID;
    return (0);
}

/*^^***************************************************************************
 * DS_U32 lld_force_wakeup_wait_q (WAIT_Q *WaitQPtr)
 *
 * Description: Wake up any tasks in a queue
 *
 * Entry:   WaitQPtr = Wait queue pointer
 *
 * Return:  
 *
 * Notes:
 *
 **************************************************************************^^*/
DS_U32 lld_force_wakeup_wait_q (WAIT_Q *WaitQPtr)
{
    PUSH_PID;
    wake_up (WaitQPtr);
    POP_PID;
    return (0);
}