//////////////////////////////////////////////////////////////////////////////////////
// File     : timer_driver.c
// Date     : 23/05/2013
// Author   : alain greiner
// Copyright (c) UPMC-LIP6
//////////////////////////////////////////////////////////////////////////////////////
// The timer_driver.c and timer_driver.h files are part ot the GIET-VM nano-kernel.
// This driver supports the SoCLib vci_multi_timer component.
//
// It can exist several multi_timers in the architecture (at most one per cluster),
// and each one can contain several timers (called channels).
//
// There is two types of timers: 
// - "system" timers : one per processor, used for context switch.
//   local_id in [0, NB_PROCS_MAX-1],
// - "user" timers : requested by the task in the mapping_info data structure.
//   For each user timer, the timer_id is stored in the context of the task.
// The global index is cluster_id * (NB_PROCS_MAX + NB_TIM_CHANNELS) + local_id
//
// The NB_PROCS_MAX and NB_TIM_CHANNELS values must be defined in the
// hard_config.h file.
//
// The register offsets must be defined in the hwr_mapping.h file.
/////////////////////////////////////////////////////////////////////////////////////
// The virtual base address of the segment associated to a channel is:
//
//     seg_tim_base + cluster_id * vseg_cluster_increment + TIMER_SPAN * timer_id
//
// The seg_tim_base and vseg_cluster_increment values must be defined 
// in the giet_vsegs.ld file.
/////////////////////////////////////////////////////////////////////////////////////

#include <giet_config.h>
#include <tim_driver.h>
#include <utils.h>

#if !defined(NB_CLUSTERS) 
# error: You must define NB_CLUSTERS in the hard_config.h file
#endif

#if (NB_CLUSTERS > 256)
# error: NB_CLUSTERS cannot be larger than 256!
#endif

#if !defined(NB_PROCS_MAX) 
# error: You must define NB_PROCS_MAX in the hard_config.h file
#endif

#if (NB_PROCS_MAX > 8)
# error: NB_PROCS_MAX cannot be larger than 8!
#endif

#if !defined(NB_TIM_CHANNELS)
#define NB_TIM_CHANNELS 0
#endif

#if ( (NB_TIM_CHANNELS + NB_PROC_MAX) > 32 )
# error: NB_TIM_CHANNELS + NB_PROCS_MAX cannot be larger than 32
#endif

#if !defined( USE_XICU )
# error: You must define USE_XICU in the hard_config.h file
#endif

///////////////////  Timer global variables ////////////////////////////////////////

#define in_unckdata __attribute__((section (".unckdata")))

#if (NB_TIM_CHANNELS > 0)
in_unckdata volatile unsigned char _user_timer_event[NB_CLUSTERS * NB_TIM_CHANNELS] 
                            = { [0 ... ((NB_CLUSTERS * NB_TIM_CHANNELS) - 1)] = 0 };
#endif

////////////////////////////////////////////////////////////////////////////////////
//     _timer_start()
// This function activates a timer in the vci_timer component
// by writing in the proper register the period value.
// It can be used by both the kernel to initialise a "system" timer,
// or by a task (through a system call) to configure an "user" timer.
// Returns 0 if success, > 0 if error.
//////////////////////////////////////////////////////////////////////////////
unsigned int _timer_start( unsigned int cluster_id, 
                           unsigned int local_id, 
                           unsigned int period) 
{
    // parameters checking 
    if (cluster_id >= NB_CLUSTERS)    return 1;
    if (local_id >= NB_TIM_CHANNELS)  return 1;

    unsigned int* timer_address = (unsigned int *) ((unsigned int)&seg_tim_base + 
                                  (cluster_id * (unsigned int)&vseg_cluster_increment));

    timer_address[local_id * TIMER_SPAN + TIMER_PERIOD] = period;
    timer_address[local_id * TIMER_SPAN + TIMER_MODE] = 0x3;
    return 0;
}

//////////////////////////////////////////////////////////////////////////////
//     _timer_stop()
// This function desactivates a timer in the vci_timer component
// by writing in the proper register.
// Returns 0 if success, > 0 if error.
//////////////////////////////////////////////////////////////////////////////
unsigned int _timer_stop( unsigned int cluster_id, 
                          unsigned int local_id) 
{
    // parameters checking 
    if (cluster_id >= NB_CLUSTERS)    return 1;
    if (local_id >= NB_TIM_CHANNELS)  return 1;

    unsigned int* timer_address = (unsigned int *) ((unsigned int)&seg_tim_base + 
                                  (cluster_id * (unsigned int)&vseg_cluster_increment));

    timer_address[local_id * TIMER_SPAN + TIMER_MODE] = 0;
    return 0;
}

//////////////////////////////////////////////////////////////////////////////
//     _timer_reset_irq()
// This function acknowlegge a timer interrupt in the vci_timer  
// component by writing in the proper register.
// It can be used by both the isr_switch() for a "system" timer, 
// or by the _isr_timer() for an "user" timer.
// Returns 0 if success, > 0 if error.
//////////////////////////////////////////////////////////////////////////////
unsigned int _timer_reset_irq( unsigned int cluster_id, 
                               unsigned int local_id ) 
{
    // parameters checking 
    if (cluster_id >= NB_CLUSTERS)    return 1;
    if (local_id >= NB_TIM_CHANNELS)  return 1;

    unsigned int * timer_address = (unsigned int *) ((unsigned int)&seg_tim_base + 
                                   (cluster_id * (unsigned int)&vseg_cluster_increment));

    timer_address[local_id * TIMER_SPAN + TIMER_RESETIRQ] = 0;
    return 0;
}

/////////////////////////////////////////////////////////////////////////////
//     _timer_reset_cpt()
// This function resets the timer counter. To do so, we re-write the period
// in the proper register, what causes the count to restart.
// The period value is read from the same (TIMER_PERIOD) register,
// this is why in appearance we do nothing useful (read a value
// from a register and write this value in the same register)
// This function is called during a context switch (user or preemptive)
//////////////////////////////////////////////////////////////////////i//////
unsigned int _timer_reset_cpt( unsigned int cluster_id, 
                               unsigned int local_id) 
{
    // parameters checking 
    if (cluster_id >= NB_CLUSTERS)    return 1;
    if (local_id >= NB_TIM_CHANNELS)  return 1;

    // We suppose that the TIMER_MODE register value is 0x3
    unsigned int * timer_address = (unsigned int *) ((unsigned int)&seg_tim_base + 
                                   (cluster_id * (unsigned int)&vseg_cluster_increment));

    unsigned int period = timer_address[local_id * TIMER_SPAN + TIMER_PERIOD];
    timer_address[local_id * TIMER_SPAN + TIMER_PERIOD] = period;
    return 0;
}


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