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authorPavel Pisa <pisa@cmp.felk.cvut.cz>2016-09-03 14:10:52 +0200
committerPavel Pisa <pisa@cmp.felk.cvut.cz>2016-09-07 20:29:39 +0200
commit5d369c85725062d2e716742180887068f1b2ccaa (patch)
tree92445d2228333f93aa7957ec53100df61e7844cd
parentarm/raspberrypi: correct and extend definitions for GPU timer. (diff)
downloadrtems-5d369c85725062d2e716742180887068f1b2ccaa.tar.bz2
arm/raspberrypi: use GPU/system timer as clock source.
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.
-rw-r--r--c/src/lib/libbsp/arm/raspberrypi/clock/clockdrv.c98
1 files changed, 62 insertions, 36 deletions
diff --git a/c/src/lib/libbsp/arm/raspberrypi/clock/clockdrv.c b/c/src/lib/libbsp/arm/raspberrypi/clock/clockdrv.c
index 4ce795fb30..72c85b1669 100644
--- a/c/src/lib/libbsp/arm/raspberrypi/clock/clockdrv.c
+++ b/c/src/lib/libbsp/arm/raspberrypi/clock/clockdrv.c
@@ -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 struct timecounter raspberrypi_tc;
+
+static uint32_t raspberrypi_clock_get_timecount(struct timecounter *tc)
+{
+ return BCM2835_REG(BCM2835_GPU_TIMER_CLO);
+}
+
static void raspberrypi_clock_at_tick(void)
{
- BCM2835_REG(BCM2835_TIMER_CLI) = 0;
+ 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(void)
+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_initialize_hardware() raspberrypi_clock_initialize_hardware()
-#define Clock_driver_support_install_isr(isr, old_isr) \
+#define Clock_driver_support_shutdown_hardware() raspberrypi_clock_cleanup()
+
+#define Clock_driver_support_install_isr(clock_isr, old_isr) \
do { \
- raspberrypi_clock_handler_install(); \
+ raspberrypi_clock_handler_install_isr(clock_isr); \
old_isr = NULL; \
} while (0)
-#define Clock_driver_support_shutdown_hardware() raspberrypi_clock_cleanup()
-
-#define CLOCK_DRIVER_USE_DUMMY_TIMECOUNTER
+#define CLOCK_DRIVER_USE_ONLY_BOOT_PROCESSOR 1
#include "../../../shared/clockdrv_shell.h"