blob: 19dbb3e8501aa870274409b9f456aca04916038c [file] [log] [blame]
/*
* Copyright (c) 2018 Foundries.io Ltd
*
* SPDX-License-Identifier: Apache-2.0
*/
#define DT_DRV_COMPAT openisa_rv32m1_lptmr
#include <zephyr/device.h>
#include <zephyr/zephyr.h>
#include <zephyr/sys/util.h>
#include <zephyr/drivers/timer/system_timer.h>
#include <soc.h>
/*
* This is just a getting started point.
*
* Assumptions and limitations:
*
* - system clock based on an LPTMR instance, clocked by SIRC output
* SIRCDIV3, prescaler divide-by-1, SIRC at 8MHz
* - no tickless
*/
#define CYCLES_PER_SEC sys_clock_hw_cycles_per_sec()
#define CYCLES_PER_TICK (CYCLES_PER_SEC / CONFIG_SYS_CLOCK_TICKS_PER_SEC)
#if defined(CONFIG_TEST)
const int32_t z_sys_timer_irq_for_test = DT_IRQN(DT_ALIAS(system_lptmr));
#endif
/*
* As a simplifying assumption, we only support a clock ticking at the
* SIRC reset rate of 8MHz.
*/
#if defined(CONFIG_TIMER_READS_ITS_FREQUENCY_AT_RUNTIME) || \
(MHZ(8) != CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC)
#error "system timer misconfiguration; unsupported clock rate"
#endif
#define SYSTEM_TIMER_INSTANCE \
((LPTMR_Type *)(DT_INST_REG_ADDR(0)))
#define SIRC_RANGE_8MHZ SCG_SIRCCFG_RANGE(1)
#define SIRCDIV3_DIVIDE_BY_1 1
#define PCS_SOURCE_SIRCDIV3 0
struct device; /* forward declaration; type is not used. */
static volatile uint32_t cycle_count;
static void lptmr_irq_handler(const struct device *unused)
{
ARG_UNUSED(unused);
SYSTEM_TIMER_INSTANCE->CSR |= LPTMR_CSR_TCF(1); /* Rearm timer. */
cycle_count += CYCLES_PER_TICK; /* Track cycles. */
sys_clock_announce(1); /* Poke the scheduler. */
}
uint32_t sys_clock_cycle_get_32(void)
{
return cycle_count + SYSTEM_TIMER_INSTANCE->CNR;
}
/*
* Since we're not tickless, this is identically zero.
*/
uint32_t sys_clock_elapsed(void)
{
return 0;
}
static int sys_clock_driver_init(const struct device *unused)
{
uint32_t csr, psr, sircdiv; /* LPTMR registers */
ARG_UNUSED(unused);
IRQ_CONNECT(DT_INST_IRQN(0),
0, lptmr_irq_handler, NULL, 0);
if ((SCG->SIRCCSR & SCG_SIRCCSR_SIRCEN_MASK) == SCG_SIRCCSR_SIRCEN(0)) {
/*
* SIRC is on by default, so something else turned it off.
*
* This is incompatible with this driver, which is SIRC-based.
*/
return -ENODEV;
}
/* Disable the timer and clear any pending IRQ. */
csr = SYSTEM_TIMER_INSTANCE->CSR;
csr &= ~LPTMR_CSR_TEN(0);
csr |= LPTMR_CSR_TFC(1);
SYSTEM_TIMER_INSTANCE->CSR = csr;
/*
* Set up the timer clock source and configure the timer.
*/
/*
* SIRCDIV3 is the SIRC divider for LPTMR (SoC dependent).
* Pass it directly through without any divider.
*/
sircdiv = SCG->SIRCDIV;
sircdiv &= ~SCG_SIRCDIV_SIRCDIV3_MASK;
sircdiv |= SCG_SIRCDIV_SIRCDIV3(SIRCDIV3_DIVIDE_BY_1);
SCG->SIRCDIV = sircdiv;
/*
* TMS = 0: time counter mode, not pulse counter
* TCF = 0: reset counter register on reaching compare value
* TDRE = 0: disable DMA request
*/
csr &= ~(LPTMR_CSR_TMS(1) | LPTMR_CSR_TFC(1) | LPTMR_CSR_TDRE(1));
/*
* TIE = 1: enable interrupt
*/
csr |= LPTMR_CSR_TIE(1);
SYSTEM_TIMER_INSTANCE->CSR = csr;
/*
* PCS = 0: clock source is SIRCDIV3 (SoC dependent)
* PBYP = 1: bypass the prescaler
*/
psr = SYSTEM_TIMER_INSTANCE->PSR;
psr &= ~LPTMR_PSR_PCS_MASK;
psr |= (LPTMR_PSR_PBYP(1) | LPTMR_PSR_PCS(PCS_SOURCE_SIRCDIV3));
SYSTEM_TIMER_INSTANCE->PSR = psr;
/*
* Set compare register to the proper tick count. The check
* here makes sure SIRC is left at its default reset value to
* make the defconfig setting work properly.
*
* TODO: be smarter to meet arbitrary Kconfig settings.
*/
if ((SCG->SIRCCFG & SCG_SIRCCFG_RANGE_MASK) != SIRC_RANGE_8MHZ) {
return -EINVAL;
}
SYSTEM_TIMER_INSTANCE->CMR = CYCLES_PER_TICK;
/*
* Enable interrupts and the timer. There's no need to clear the
* TFC bit in the csr variable, as it's already clear.
*/
irq_enable(DT_INST_IRQN(0));
csr = SYSTEM_TIMER_INSTANCE->CSR;
csr |= LPTMR_CSR_TEN(1);
SYSTEM_TIMER_INSTANCE->CSR = csr;
return 0;
}
SYS_INIT(sys_clock_driver_init, PRE_KERNEL_2,
CONFIG_SYSTEM_CLOCK_INIT_PRIORITY);