timer_gptimer_tick.c
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/*
* Copyright (c) 2017, Cobham Gaisler AB
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Mini driver for supporting BCC / C library time functionality.
*/
#include <sys/time.h>
#include "bcc/bcc_param.h"
#include "bcc/regs/gptimer.h"
#include "timer_custom.h"
enum {
US_PER_S = (1000 * 1000),
GPTIMER_RESOLUTION = US_PER_S,
};
struct timer_tick_priv {
struct bcc_isr_node isr;
volatile struct timeval tickval;
uint32_t interrupt_ack_mask;
uint32_t usec_per_tick;
};
static struct timer_tick_priv priv;
/* Fill in a timeval: can be used by gettimeofday(). */
static void __bcc_timer_tick_get_timeval(
struct timeval *tv
)
{
time_t sec;
suseconds_t usec;
int plevel;
plevel = bcc_int_disable();
sec = priv.tickval.tv_sec;
usec = priv.tickval.tv_usec;
bcc_int_enable(plevel);
tv->tv_sec = sec;
tv->tv_usec = usec;
}
static uint32_t __bcc_timer_tick_get_us(void)
{
struct timeval tv;
__bcc_timer_tick_get_timeval(&tv);
return tv.tv_sec * US_PER_S + tv.tv_usec;
}
static void __bcc_timer_tick_isr(
void *arg,
int source
)
{
(void) source;
volatile struct gptimer_timer_regs *tmr = arg;
uint32_t ctrl;
ctrl = tmr->ctrl;
if (0 == (ctrl & GPTIMER_CTRL_IP)) {
/* Spurious interrupt */
return;
}
/* Clear pending */
tmr->ctrl = ctrl & priv.interrupt_ack_mask;
priv.tickval.tv_usec += priv.usec_per_tick;
while (US_PER_S <= priv.tickval.tv_usec) {
priv.tickval.tv_usec -= US_PER_S;
priv.tickval.tv_sec++;
}
}
/* Public function for initializing this driver. */
int bcc_timer_tick_init_period(
uint32_t usec_per_tick
)
{
if (
(0 == __bcc_timer_handle) ||
(0 == __bcc_timer_interrupt)
) {
return BCC_NOT_AVAILABLE;
}
/* Service can be enabled only once. */
if (__bcc_timer_custom_get_timeval) { return BCC_FAIL; }
/* Default to 100 tick interrupts per second */
if (0 == usec_per_tick) {
usec_per_tick = 10 * 1000;
}
priv.usec_per_tick = usec_per_tick;
/* Get initial values from timer. */
{
uint32_t us;
us = bcc_timer_get_us();
priv.tickval.tv_sec = us / US_PER_S;
priv.tickval.tv_usec = us % US_PER_S;
}
volatile struct gptimer_regs *regs = (void *) __bcc_timer_handle;
volatile struct gptimer_timer_regs *tmr = ®s->timer[0];
int intsource = __bcc_timer_interrupt;
bcc_int_mask(intsource);
#if 0
bcc_int_clear(intsource);
#endif
/* Stop timer and probe how CTRL_IP is cleared. */
tmr->ctrl = GPTIMER_CTRL_IP;
if (tmr->ctrl & GPTIMER_CTRL_IP) {
/* IP bit is cleared by setting it to 0. */
priv.interrupt_ack_mask = ~GPTIMER_CTRL_IP;
} else {
/* IP bit is cleared by setting it to 1. */
priv.interrupt_ack_mask = ~0;
}
/* Assume timer scaler value configured for 1 MHz. */
tmr->counter = 0;
tmr->reload = priv.usec_per_tick - 1;
tmr->ctrl = (
GPTIMER_CTRL_IP |
GPTIMER_CTRL_IE |
GPTIMER_CTRL_LD |
GPTIMER_CTRL_RS |
GPTIMER_CTRL_EN
) & priv.interrupt_ack_mask;
int ret;
priv.isr.source = intsource;
priv.isr.handler = __bcc_timer_tick_isr;
priv.isr.arg = (void *) tmr;
ret = bcc_isr_register_node(&priv.isr);
if (BCC_OK != ret) {
return ret;
}
/* Install vectors to override some simple BCC time functionality. */
__bcc_timer_custom_get_us = __bcc_timer_tick_get_us;
__bcc_timer_custom_get_timeval = __bcc_timer_tick_get_timeval;
bcc_int_unmask(intsource);
return BCC_OK;
}