/**
* @file
*
* @ingroup powerpc_shared
*
* @brief Source file for a clock driver.
*/
/*
* Copyright (c) 2008-2013 embedded brains GmbH. All rights reserved.
*
* embedded brains GmbH
* Obere Lagerstr. 30
* 82178 Puchheim
* Germany
* <rtems@embedded-brains.de>
*
* 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 <rtems.h>
#include <rtems/clockdrv.h>
#include <libcpu/powerpc-utility.h>
#include <bsp/vectors.h>
#define RTEMS_STATUS_CHECKS_USE_PRINTK
#include <rtems/status-checks.h>
/*
* This variable must be defined in the BSP and valid before clock driver
* initialization.
*/
extern uint32_t bsp_time_base_frequency;
#define PPC405_PIT 0x3db
#define PPC_CLOCK_DECREMENTER_MAX UINT32_MAX
volatile uint32_t Clock_driver_ticks = 0;
rtems_device_major_number rtems_clock_major = UINT32_MAX;
rtems_device_minor_number rtems_clock_minor = UINT32_MAX;
static uint32_t ppc_clock_decrementer_value = PPC_CLOCK_DECREMENTER_MAX;
static uint32_t ppc_clock_next_time_base;
static uint64_t ppc_clock_factor;
static void ppc_clock_no_tick(void)
{
/* Do nothing */
}
static void (*ppc_clock_tick)(void) = ppc_clock_no_tick;
static int ppc_clock_exception_handler( BSP_Exception_frame *frame, unsigned number)
{
uint32_t delta = ppc_clock_decrementer_value;
uint32_t next = ppc_clock_next_time_base;
uint32_t dec = 0;
uint32_t now = 0;
uint32_t msr = 0;
do {
/* Increment clock ticks */
Clock_driver_ticks += 1;
/* Enable external exceptions */
msr = ppc_external_exceptions_enable();
/* Call clock ticker */
ppc_clock_tick();
/* Restore machine state */
ppc_external_exceptions_disable( msr);
/* Next time base */
next += delta;
/* Current time */
now = ppc_time_base();
/* New decrementer value */
dec = next - now;
} while (dec > delta);
/* Set decrementer */
ppc_set_decrementer_register( dec);
/* Expected next time base */
ppc_clock_next_time_base = next;
return 0;
}
static int ppc_clock_exception_handler_first( BSP_Exception_frame *frame, unsigned number)
{
/* We have to clear the first pending decrementer exception this way */
if (ppc_decrementer_register() >= 0x80000000) {
ppc_clock_exception_handler( frame, number);
}
ppc_exc_set_handler( ASM_DEC_VECTOR, ppc_clock_exception_handler);
return 0;
}
static int ppc_clock_exception_handler_booke( BSP_Exception_frame *frame, unsigned number)
{
uint32_t msr;
/* Acknowledge decrementer request */
PPC_SET_SPECIAL_PURPOSE_REGISTER( BOOKE_TSR, BOOKE_TSR_DIS);
/* Increment clock ticks */
Clock_driver_ticks += 1;
/* Enable external exceptions */
msr = ppc_external_exceptions_enable();
/* Call clock ticker */
ppc_clock_tick();
/* Restore machine state */
ppc_external_exceptions_disable( msr);
return 0;
}
static int ppc_clock_exception_handler_ppc405(BSP_Exception_frame *frame, unsigned number)
{
uint32_t msr;
/* Acknowledge PIT request */
PPC_SET_SPECIAL_PURPOSE_REGISTER(PPC405_TSR, BOOKE_TSR_DIS);
/* Increment clock ticks */
Clock_driver_ticks += 1;
/* Enable external exceptions */
msr = ppc_external_exceptions_enable();
/* Call clock ticker */
ppc_clock_tick();
/* Restore machine state */
ppc_external_exceptions_disable(msr);
return 0;
}
static uint32_t ppc_clock_nanoseconds_since_last_tick(void)
{
uint64_t k = ppc_clock_factor;
uint32_t c = ppc_decrementer_register();
uint32_t i = ppc_clock_decrementer_value + 1;
return (uint32_t) (((i - c) * k) >> 32);
}
static uint32_t ppc_clock_nanoseconds_since_last_tick_ppc405(void)
{
uint64_t k = ppc_clock_factor;
uint32_t i = ppc_clock_decrementer_value;
uint32_t c = i - PPC_SPECIAL_PURPOSE_REGISTER(PPC405_PIT);
if ((PPC_SPECIAL_PURPOSE_REGISTER(PPC405_TSR) & BOOKE_TSR_DIS) != 0) {
c = i - PPC_SPECIAL_PURPOSE_REGISTER(PPC405_PIT) + i;
}
return (uint32_t) ((c * k) >> 32);
}
void Clock_exit(void)
{
/* Set the decrementer to the maximum value */
ppc_set_decrementer_register( PPC_CLOCK_DECREMENTER_MAX);
/* Use default clock handler */
ppc_clock_tick = ppc_clock_no_tick;
}
rtems_device_driver Clock_initialize( rtems_device_major_number major, rtems_device_minor_number minor, void *arg)
{
uint64_t frequency = bsp_time_base_frequency;
uint64_t us_per_tick = rtems_configuration_get_microseconds_per_tick();
uint32_t interval = (uint32_t) ((frequency * us_per_tick) / 1000000);
/* Make major/minor available to others such as shared memory driver */
rtems_clock_major = major;
rtems_clock_minor = minor;
/*
* Set default ticker.
*
* The function rtems_clock_tick() returns a status code. This value
* will be discarded since the RTEMS documentation claims that it is
* always successful.
*/
ppc_clock_tick = (void (*)(void)) rtems_clock_tick;
/* Factor for nano seconds extension */
ppc_clock_factor = (1000000000ULL << 32) / frequency;
if (ppc_cpu_is_bookE() != PPC_BOOKE_405) {
/* Decrementer value */
ppc_clock_decrementer_value = interval - 1;
/* Check decrementer value */
if (ppc_clock_decrementer_value == 0) {
ppc_clock_decrementer_value = PPC_CLOCK_DECREMENTER_MAX;
RTEMS_SYSLOG_ERROR( "decrementer value would be zero, will be set to maximum value instead\n");
}
/* Set the nanoseconds since last tick handler */
rtems_clock_set_nanoseconds_extension( ppc_clock_nanoseconds_since_last_tick);
if (ppc_cpu_is_bookE()) {
/* Set decrementer auto-reload value */
PPC_SET_SPECIAL_PURPOSE_REGISTER( BOOKE_DECAR, ppc_clock_decrementer_value);
/* Install exception handler */
ppc_exc_set_handler( ASM_BOOKE_DEC_VECTOR, ppc_clock_exception_handler_booke);
/* Enable decrementer and auto-reload */
PPC_SET_SPECIAL_PURPOSE_REGISTER_BITS( BOOKE_TCR, BOOKE_TCR_DIE | BOOKE_TCR_ARE);
} else {
/* Here the decrementer value is actually the interval */
++ppc_clock_decrementer_value;
/* Initialize next time base */
ppc_clock_next_time_base = ppc_time_base() + ppc_clock_decrementer_value;
/* Install exception handler */
ppc_exc_set_handler( ASM_DEC_VECTOR, ppc_clock_exception_handler_first);
}
/* Set the decrementer value */
ppc_set_decrementer_register( ppc_clock_decrementer_value);
} else {
/* PIT interval value */
ppc_clock_decrementer_value = interval;
/* Set the nanoseconds since last tick handler */
rtems_clock_set_nanoseconds_extension(ppc_clock_nanoseconds_since_last_tick_ppc405);
/* Install exception handler */
ppc_exc_set_handler(ASM_BOOKE_DEC_VECTOR, ppc_clock_exception_handler_ppc405);
/* Enable PIT and auto-reload */
PPC_SET_SPECIAL_PURPOSE_REGISTER_BITS(PPC405_TCR, BOOKE_TCR_DIE | BOOKE_TCR_ARE);
/* Set PIT auto-reload and initial value */
PPC_SET_SPECIAL_PURPOSE_REGISTER(PPC405_PIT, interval);
}
return RTEMS_SUCCESSFUL;
}
