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/* SPDX-License-Identifier: copyleft-next-0.3.1 */
/* Copyright 2021 - 2022, Kim Kuparinen < kimi.h.kuparinen@gmail.com > */
/**
* @file timers.c
* Timer syscall implementations.
*/
#include <kmi/timer.h>
#include <kmi/uapi.h>
#include <arch/timer.h>
/**
* Convert arch-specific register values \p ticks and \p mult to \ref ticks_t.
*
* If we're on a 32bit system, one register can't contain a tick value,
* so we use two registers and combine them into one value and let the compiler
* handle the rest.
*
* @param ticks Register width tick value.
* @param mult Register width repeat value.
* @return Corresponding \ref ticks_t value.
*/
static ticks_t scaled_ticks(sys_arg_t ticks, sys_arg_t mult)
{
#if defined(_LP64)
UNUSED(mult);
return ticks;
#else
return (ticks_t)ticks * (ticks_t)mult;
#endif
}
/**
* Timebase syscall handler.
*
* @param t Current tcb.
* @return \ref OK and timebase in second argument if 64bit, otherwise high 32
* bits of timebase in second argument and low 32 bits in third argument.
*/
SYSCALL_DEFINE0(timebase)(struct tcb *t)
{
ticks_t tm = secs_to_ticks(1);
#if defined(_LP64)
return_args(t, SYS_RET2(OK, tm));
#else
return_args(t, SYS_RET3(OK, tm >> 32, tm));
#endif
}
/**
* Current ticks syscall handler.
*
* Note that most platforms allow user level read access to hardware timers, and
* should be preferred over this syscall on such platforms. Still, for
* completeness sake.
*
* @param t Current tcb.
* @return \ref OK and the current ticks when on 64bit systems, otherwise high
* 32 bits of ticks in second argument and low 32 bits in third.
*/
SYSCALL_DEFINE0(ticks)(struct tcb *t)
{
ticks_t tm = current_ticks();
#if defined(_LP64)
return_args(t, SYS_RET2(OK, tm));
#else
return_args(t, SYS_RET3(OK, tm >> 32, tm));
#endif
}
/**
* Relative timer request syscall handler.
*
* \note On 64bit systems, \p mult is ignored as \p ticks register is large
* enough to contain essentially any timepoint we want. A couple thousand years
* when the clock runs at 5GHz, if I'm not completely mistaken.
*
* @param t Current tcb.
* @param ticks Number of ticks from now.
* @param mult Multiply \c ticks by this value.
* @return \ref OK and \c cid of created timer.
*/
SYSCALL_DEFINE2(req_rel_timer)(struct tcb *t, sys_arg_t ticks, sys_arg_t mult)
{
return_args(t,
SYS_RET2(OK,
new_rel_timer(t->tid, scaled_ticks(ticks, mult))));
}
/**
* Absolute timer request syscall handler.
*
* @param t Current tcb.
* @param ticks Absolute timepoint relative to some start point defined at boot.
* @param mult Multiply \c ticks by this value.
* @return \ref OK and \c cid of created timer.
* \see req_rel_timer().
*/
SYSCALL_DEFINE2(req_abs_timer)(struct tcb *t, sys_arg_t ticks, sys_arg_t mult)
{
return_args(t,
SYS_RET2(OK,
new_abs_timer(t->tid, scaled_ticks(ticks, mult))));
}
/**
* Free timer request syscall handler.
*
* @param t Current tcb.
* @param cid \c cid of timer to free.
* @return \ref ERR_NF and \c 0if no timer could be found with \c cid, \ref OK
* and 0 otherwise.
*/
SYSCALL_DEFINE1(free_timer)(struct tcb *t, sys_arg_t cid)
{
struct timer *timer = find_timer(cid);
if (!timer)
return_args(t, SYS_RET1(ERR_NF));
remove_timer(timer);
return_args(t, SYS_RET1(OK));
}
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