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arm/raspberrypi: use GPU/system timer as clock source.

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It has advantage that it is designed as free-running counter
with compare registers and can easily serve for for both
timecounter and tick interrupt.
This commit is contained in:
Pavel Pisa
2016-09-07 20:29:39 +02:00
parent 40f49d11cf
commit 5d369c8572
1 changed files with 65 additions and 39 deletions
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c/src/lib/libbsp/arm/raspberrypi/clock/clockdrv.c
+65 -39
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@@ -10,6 +10,7 @@
* BCM2835 Clock driver
*
* Copyright (c) 2013 Alan Cudmore
* Copyright (c) 2016 Pavel Pisa
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
@@ -21,71 +22,96 @@
#include <rtems.h>
#include <bsp.h>
#include <bsp/irq.h>
#include <bsp/irq-generic.h>
#include <bsp/raspberrypi.h>
#include <rtems/timecounter.h>
/* This is defined in ../../../shared/clockdrv_shell.h */
void Clock_isr(rtems_irq_hdl_param arg);
static void raspberrypi_clock_at_tick(void)
static struct timecounter raspberrypi_tc;
static uint32_t raspberrypi_clock_get_timecount(struct timecounter *tc)
{
BCM2835_REG(BCM2835_TIMER_CLI) = 0;
return BCM2835_REG(BCM2835_GPU_TIMER_CLO);
}
static void raspberrypi_clock_handler_install(void)
static void raspberrypi_clock_at_tick(void)
{
uint32_t act_val;
uint32_t next_cmp = BCM2835_REG(BCM2835_GPU_TIMER_C3);
next_cmp += rtems_configuration_get_microseconds_per_tick();
BCM2835_REG(BCM2835_GPU_TIMER_C3) = next_cmp;
act_val = BCM2835_REG(BCM2835_GPU_TIMER_CLO);
/*
* Clear interrupt only if there is time left to the next tick.
* If time of the next tick has already passed then interrupt
* request stays active and fires immediately after current tick
* processing is finished.
*/
if ((int32_t)(next_cmp - act_val) > 0)
BCM2835_REG(BCM2835_GPU_TIMER_CS) = BCM2835_GPU_TIMER_CS_M3;
}
static void raspberrypi_clock_handler_install_isr(
rtems_isr_entry clock_isr
)
{
rtems_status_code sc = RTEMS_SUCCESSFUL;
sc = rtems_interrupt_handler_install(
BCM2835_IRQ_ID_TIMER_0,
"Clock",
RTEMS_INTERRUPT_UNIQUE,
(rtems_interrupt_handler) Clock_isr,
NULL
);
if (sc != RTEMS_SUCCESSFUL) {
if (clock_isr != NULL) {
sc = rtems_interrupt_handler_install(
BCM2835_IRQ_ID_GPU_TIMER_M3,
"Clock",
RTEMS_INTERRUPT_UNIQUE,
(rtems_interrupt_handler) clock_isr,
NULL
);
} else {
/* Remove interrupt handler */
sc = rtems_interrupt_handler_remove(
BCM2835_IRQ_ID_GPU_TIMER_M3,
(rtems_interrupt_handler) Clock_isr,
NULL
);
}
if ( sc != RTEMS_SUCCESSFUL ) {
rtems_fatal_error_occurred(0xdeadbeef);
}
}
static void raspberrypi_clock_initialize(void)
static void raspberrypi_clock_initialize_hardware(void)
{
BCM2835_REG(BCM2835_TIMER_CTL) = 0x003E0000;
BCM2835_REG(BCM2835_TIMER_LOD) =
rtems_configuration_get_microseconds_per_tick() - 1;
BCM2835_REG(BCM2835_TIMER_RLD) =
rtems_configuration_get_microseconds_per_tick() - 1;
BCM2835_REG(BCM2835_TIMER_DIV) = BCM2835_TIMER_PRESCALE;
BCM2835_REG(BCM2835_TIMER_CLI) = 0;
BCM2835_REG(BCM2835_TIMER_CTL) = 0x003E00A2;
uint32_t next_cmp = BCM2835_REG(BCM2835_GPU_TIMER_CLO);
next_cmp += rtems_configuration_get_microseconds_per_tick();
BCM2835_REG(BCM2835_GPU_TIMER_C3) = next_cmp;
BCM2835_REG(BCM2835_GPU_TIMER_CS) = BCM2835_GPU_TIMER_CS_M3;
raspberrypi_tc.tc_get_timecount = raspberrypi_clock_get_timecount;
raspberrypi_tc.tc_counter_mask = 0xffffffff;
raspberrypi_tc.tc_frequency = 1000000; /* 1 MHz */
raspberrypi_tc.tc_quality = RTEMS_TIMECOUNTER_QUALITY_CLOCK_DRIVER;
rtems_timecounter_install(&raspberrypi_tc);
}
static void raspberrypi_clock_cleanup(void)
{
rtems_status_code sc = RTEMS_SUCCESSFUL;
/* Remove interrupt handler */
sc = rtems_interrupt_handler_remove(
BCM2835_IRQ_ID_TIMER_0,
(rtems_interrupt_handler) Clock_isr,
NULL
);
if (sc != RTEMS_SUCCESSFUL) {
rtems_fatal_error_occurred(0xdeadbeef);
}
bsp_interrupt_vector_disable(BCM2835_IRQ_ID_GPU_TIMER_M3);
}
#define Clock_driver_support_at_tick() raspberrypi_clock_at_tick()
#define Clock_driver_support_initialize_hardware() raspberrypi_clock_initialize()
#define Clock_driver_support_install_isr(isr, old_isr) \
do { \
raspberrypi_clock_handler_install(); \
old_isr = NULL; \
} while (0)
#define Clock_driver_support_initialize_hardware() raspberrypi_clock_initialize_hardware()
#define Clock_driver_support_shutdown_hardware() raspberrypi_clock_cleanup()
#define CLOCK_DRIVER_USE_DUMMY_TIMECOUNTER
#define Clock_driver_support_install_isr(clock_isr, old_isr) \
do { \
raspberrypi_clock_handler_install_isr(clock_isr); \
old_isr = NULL; \
} while (0)
#define CLOCK_DRIVER_USE_ONLY_BOOT_PROCESSOR 1
#include "../../../shared/clockdrv_shell.h"