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risc-v/bl808: Implement Timer with OpenSBI

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The implementation of the RISC-V Timer for BL808 SoC is incomplete. This PR implements the BL808 RISC-V Timer by calling OpenSBI. The code is derived from NuttX for RISC-V QEMU.

The implementation of `up_timer_initialize` with OpenSBI is explained in this article: https://lupyuen.github.io/articles/nim#appendix-opensbi-timer-for-nuttx
This commit is contained in:
Lee Lup Yuen 2024-01-04 07:30:51 +08:00 committed by Petro Karashchenko
parent fc53497ea2
commit 31ef9cd13c
1 changed files with 13 additions and 50 deletions
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63
arch/risc-v/src/bl808/bl808_timerisr.c
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@ -29,62 +29,16 @@
#include <time.h>
#include <debug.h>
#include <nuttx/arch.h>
#include <nuttx/clock.h>
#include <nuttx/init.h>
#include <nuttx/spinlock.h>
#include <nuttx/timers/arch_alarm.h>
#include <arch/board/board.h>
#include "riscv_internal.h"
#include "riscv_mtimer.h"
#include "riscv_percpu.h"
#include "hardware/bl808_memorymap.h"
/****************************************************************************
* Private Data
* Pre-processor Definitions
****************************************************************************/
static uint32_t g_stimer_pending = false;
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: bl808_ssoft_interrupt
*
* Description:
* This function is S-mode software interrupt handler to proceed
* the OS timer
*
****************************************************************************/
static int bl808_ssoft_interrupt(int irq, void *context, void *arg)
{
/* Cleaer Supervisor Software Interrupt */
CLEAR_CSR(sip, SIP_SSIP);
if (g_stimer_pending)
{
g_stimer_pending = false;
/* Proceed the OS timer */
nxsched_process_timer();
}
#ifdef CONFIG_SMP
else
{
/* We assume IPI has been issued */
riscv_pause_handler(irq, context, arg);
}
#endif
return 0;
}
#define MTIMER_FREQ 1000000
/****************************************************************************
* Public Functions
@ -101,6 +55,15 @@ static int bl808_ssoft_interrupt(int irq, void *context, void *arg)
void up_timer_initialize(void)
{
irq_attach(RISCV_IRQ_SSOFT, bl808_ssoft_interrupt, NULL);
up_enable_irq(RISCV_IRQ_SSOFT);
struct oneshot_lowerhalf_s *lower;
/* Initialize the OpenSBI Timer. mtime and mtimecmp are unused for
* OpenSBI.
*/
lower = riscv_mtimer_initialize(0, 0, RISCV_IRQ_STIMER, MTIMER_FREQ);
DEBUGASSERT(lower != NULL);
up_alarm_set_lowerhalf(lower);
}