/**
* @file
*
* Clock Tick Device Driver
*
* History:
* + Original driver was go32 clock by Joel Sherrill
* + go32 clock driver hardware code was inserted into new
* boilerplate when the pc386 BSP by:
* Pedro Miguel Da Cruz Neto Romano <pmcnr@camoes.rnl.ist.utl.pt>
* Jose Rufino <ruf@asterix.ist.utl.pt>
* + Reworked by Joel Sherrill to use clock driver template.
* This removes all boilerplate and leave original hardware
* code I developed for the go32 BSP.
*/
/*
* COPYRIGHT (c) 1989-2012.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#include <bsp.h>
#include <bsp/irq-generic.h>
#include <bspopts.h>
#include <libcpu/cpuModel.h>
#include <assert.h>
#include <rtems/timecounter.h>
#define CLOCK_VECTOR 0
volatile uint32_t pc386_microseconds_per_isr;
volatile uint32_t pc386_isrs_per_tick;
uint32_t pc386_clock_click_count;
/* forward declaration */
void Clock_isr(void *param);
static void clockOff(void);
static void Clock_isr_handler(void *param);
/*
* Roughly the number of cycles per second. Note that these
* will be wildly inaccurate if the chip speed changes due to power saving
* or thermal modes.
*
* NOTE: These are only used when the TSC method is used.
*/
static uint64_t pc586_tsc_frequency;
static struct timecounter pc386_tc;
/* this driver may need to count ISRs per tick */
#define CLOCK_DRIVER_ISRS_PER_TICK 1
#define CLOCK_DRIVER_ISRS_PER_TICK_VALUE pc386_isrs_per_tick
extern volatile uint32_t Clock_driver_ticks;
#define READ_8254( _lsb, _msb ) \
do { outport_byte(TIMER_MODE, TIMER_SEL0|TIMER_LATCH); \
inport_byte(TIMER_CNTR0, _lsb); \
inport_byte(TIMER_CNTR0, _msb); \
} while (0)
#ifdef RTEMS_SMP
#define Clock_driver_support_at_tick() \
_SMP_Send_message_broadcast(SMP_MESSAGE_CLOCK_TICK)
#endif
static uint32_t pc386_get_timecount_tsc(struct timecounter *tc)
{
return (uint32_t)rdtsc();
}
static uint32_t pc386_get_timecount_i8254(struct timecounter *tc)
{
uint32_t irqs;
uint8_t lsb, msb;
rtems_interrupt_lock_context lock_context;
/*
* Fetch all the data in an interrupt critical section.
*/
rtems_interrupt_lock_acquire(&rtems_i386_i8254_access_lock, &lock_context);
READ_8254(lsb, msb);
irqs = Clock_driver_ticks;
rtems_interrupt_lock_release(&rtems_i386_i8254_access_lock, &lock_context);
return (irqs + 1) * pc386_microseconds_per_isr - ((msb << 8) | lsb);
}
/*
* Calibrate CPU cycles per tick. Interrupts should be disabled.
*/
static void calibrate_tsc(void)
{
uint64_t begin_time;
uint8_t then_lsb, then_msb, now_lsb, now_msb;
uint32_t i;
/*
* We just reset the timer, so we know we're at the beginning of a tick.
*/
/*
* Count cycles. Watching the timer introduces a several microsecond
* uncertaintity, so let it cook for a while and divide by the number of
* ticks actually executed.
*/
begin_time = rdtsc();
for (i = rtems_clock_get_ticks_per_second() * pc386_isrs_per_tick;
i != 0; --i ) {
/* We know we've just completed a tick when timer goes from low to high */
then_lsb = then_msb = 0xff;
do {
READ_8254(now_lsb, now_msb);
if ((then_msb < now_msb) ||
((then_msb == now_msb) && (then_lsb < now_lsb)))
break;
then_lsb = now_lsb;
then_msb = now_msb;
} while (1);
}
pc586_tsc_frequency = rdtsc() - begin_time;
#if 0
printk( "CPU clock at %u MHz\n", (uint32_t)(pc586_tsc_frequency / 1000000));
#endif
}
static void clockOn(void)
{
rtems_interrupt_lock_context lock_context;
pc386_isrs_per_tick = 1;
pc386_microseconds_per_isr = rtems_configuration_get_microseconds_per_tick();
while (US_TO_TICK(pc386_microseconds_per_isr) > 65535) {
pc386_isrs_per_tick *= 10;
pc386_microseconds_per_isr /= 10;
}
pc386_clock_click_count = US_TO_TICK(pc386_microseconds_per_isr);
#if 0
printk( "configured usecs per tick=%d \n",
rtems_configuration_get_microseconds_per_tick() );
printk( "Microseconds per ISR =%d\n", pc386_microseconds_per_isr );
printk( "final ISRs per=%d\n", pc386_isrs_per_tick );
printk( "final timer counts=%d\n", pc386_clock_click_count );
#endif
rtems_interrupt_lock_acquire(&rtems_i386_i8254_access_lock, &lock_context);
outport_byte(TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_RATEGEN);
outport_byte(TIMER_CNTR0, pc386_clock_click_count >> 0 & 0xff);
outport_byte(TIMER_CNTR0, pc386_clock_click_count >> 8 & 0xff);
rtems_interrupt_lock_release(&rtems_i386_i8254_access_lock, &lock_context);
bsp_interrupt_vector_enable( BSP_PERIODIC_TIMER - BSP_IRQ_VECTOR_BASE );
/*
* Now calibrate cycles per tick. Do this every time we
* turn the clock on in case the CPU clock speed has changed.
*/
if ( x86_has_tsc() )
calibrate_tsc();
}
static void clockOff(void)
{
rtems_interrupt_lock_context lock_context;
rtems_interrupt_lock_acquire(&rtems_i386_i8254_access_lock, &lock_context);
/* reset timer mode to standard (BIOS) value */
outport_byte(TIMER_MODE, TIMER_SEL0 | TIMER_16BIT | TIMER_RATEGEN);
outport_byte(TIMER_CNTR0, 0);
outport_byte(TIMER_CNTR0, 0);
rtems_interrupt_lock_release(&rtems_i386_i8254_access_lock, &lock_context);
} /* Clock_exit */
bool Clock_isr_enabled = false;
static void Clock_isr_handler(void *param)
{
if ( Clock_isr_enabled )
Clock_isr( param );
}
void Clock_driver_install_handler(void)
{
rtems_status_code status;
status = rtems_interrupt_handler_install(
BSP_PERIODIC_TIMER,
"ckinit",
RTEMS_INTERRUPT_UNIQUE,
Clock_isr_handler,
NULL
);
assert(status == RTEMS_SUCCESSFUL);
clockOn();
}
#define Clock_driver_support_set_interrupt_affinity(online_processors) \
do { \
/* FIXME: Is there a way to do this on x86? */ \
(void) online_processors; \
} while (0)
void Clock_driver_support_initialize_hardware(void)
{
bool use_tsc = false;
bool use_8254 = false;
#if (CLOCK_DRIVER_USE_TSC == 1)
use_tsc = true;
#endif
#if (CLOCK_DRIVER_USE_8254 == 1)
use_8254 = true;
#endif
if ( !use_tsc && !use_8254 ) {
if ( x86_has_tsc() ) use_tsc = true;
else use_8254 = true;
}
if ( use_8254 ) {
/* printk( "Use 8254\n" ); */
pc386_tc.tc_get_timecount = pc386_get_timecount_i8254;
pc386_tc.tc_counter_mask = 0xffffffff;
pc386_tc.tc_frequency = TIMER_TICK;
} else {
/* printk( "Use TSC\n" ); */
pc386_tc.tc_get_timecount = pc386_get_timecount_tsc;
pc386_tc.tc_counter_mask = 0xffffffff;
pc386_tc.tc_frequency = pc586_tsc_frequency;
}
pc386_tc.tc_quality = RTEMS_TIMECOUNTER_QUALITY_CLOCK_DRIVER;
rtems_timecounter_install(&pc386_tc);
Clock_isr_enabled = true;
}
#define Clock_driver_support_shutdown_hardware() \
do { \
rtems_status_code status; \
clockOff(); \
status = rtems_interrupt_handler_remove( \
BSP_PERIODIC_TIMER, \
Clock_isr_handler, \
NULL \
); \
assert(status == RTEMS_SUCCESSFUL); \
} while (0)
#include "../../../shared/clockdrv_shell.h"
