blob: a223d8e1533f2fe947097348cc72a6e24bc261e8 [file] [log] [blame]
/*
* Copyright (c) 2019-2020 Cobham Gaisler AB
*
* SPDX-License-Identifier: Apache-2.0
*/
/*
* This driver uses two independent GPTIMER subtimers in the following way:
* - subtimer 0 generates periodic interrupts and the ISR announces ticks.
* - subtimer 1 is used as up-counter.
*/
#define DT_DRV_COMPAT gaisler_gptimer
#include <zephyr/device.h>
#include <zephyr/drivers/timer/system_timer.h>
#include <zephyr/irq.h>
#include <zephyr/sys_clock.h>
/* GPTIMER subtimer increments each microsecond. */
#define PRESCALER (CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC / 1000000)
/* GPTIMER Timer instance */
struct gptimer_timer_regs {
uint32_t counter;
uint32_t reload;
uint32_t ctrl;
uint32_t latch;
};
/* A GPTIMER can have maximum of 7 subtimers. */
#define GPTIMER_MAX_SUBTIMERS 7
/* GPTIMER common registers */
struct gptimer_regs {
uint32_t scaler_value;
uint32_t scaler_reload;
uint32_t cfg;
uint32_t latch_cfg;
struct gptimer_timer_regs timer[GPTIMER_MAX_SUBTIMERS];
};
#define GPTIMER_CTRL_WN (1 << 7)
#define GPTIMER_CTRL_IP (1 << 4)
#define GPTIMER_CTRL_IE (1 << 3)
#define GPTIMER_CTRL_LD (1 << 2)
#define GPTIMER_CTRL_RS (1 << 1)
#define GPTIMER_CTRL_EN (1 << 0)
#define GPTIMER_CFG_EL (1 << 11)
#define GPTIMER_CFG_DF (1 << 9)
#define GPTIMER_CFG_SI (1 << 8)
#define GPTIMER_CFG_IRQ (0x1f << 3)
#define GPTIMER_CFG_TIMERS (7 << 0)
static volatile struct gptimer_regs *get_regs(void)
{
return (struct gptimer_regs *) DT_INST_REG_ADDR(0);
}
static int get_timer_irq(void)
{
return DT_INST_IRQN(0);
}
static uint32_t gptimer_ctrl_clear_ip;
static void timer_isr(const void *unused)
{
ARG_UNUSED(unused);
volatile struct gptimer_regs *regs = get_regs();
volatile struct gptimer_timer_regs *tmr = &regs->timer[0];
uint32_t ctrl;
ctrl = tmr->ctrl;
if ((ctrl & GPTIMER_CTRL_IP) == 0) {
return; /* interrupt not for us */
}
/* Clear pending */
tmr->ctrl = GPTIMER_CTRL_IE | GPTIMER_CTRL_RS |
GPTIMER_CTRL_EN | gptimer_ctrl_clear_ip;
sys_clock_announce(1);
}
uint32_t sys_clock_elapsed(void)
{
return 0;
}
uint32_t sys_clock_cycle_get_32(void)
{
volatile struct gptimer_regs *regs = get_regs();
volatile struct gptimer_timer_regs *tmr = &regs->timer[1];
uint32_t counter = tmr->counter;
return (0 - counter) * PRESCALER;
}
static void init_downcounter(volatile struct gptimer_timer_regs *tmr)
{
tmr->reload = 0xFFFFFFFF;
tmr->ctrl = GPTIMER_CTRL_LD | GPTIMER_CTRL_RS | GPTIMER_CTRL_EN;
}
static int sys_clock_driver_init(void)
{
const int timer_interrupt = get_timer_irq();
volatile struct gptimer_regs *regs = get_regs();
volatile struct gptimer_timer_regs *tmr = &regs->timer[0];
init_downcounter(&regs->timer[1]);
/* Stop timer and probe how CTRL_IP is cleared (write 1 or 0). */
tmr->ctrl = GPTIMER_CTRL_IP;
if ((tmr->ctrl & GPTIMER_CTRL_IP) == 0) {
/* IP bit is cleared by setting it to 1. */
gptimer_ctrl_clear_ip = GPTIMER_CTRL_IP;
}
/* Configure timer scaler for 1 MHz subtimer tick */
regs->scaler_reload = PRESCALER - 1;
tmr->reload = 1000000U / CONFIG_SYS_CLOCK_TICKS_PER_SEC - 1;
tmr->ctrl = GPTIMER_CTRL_IE | GPTIMER_CTRL_LD | GPTIMER_CTRL_RS |
GPTIMER_CTRL_EN;
irq_connect_dynamic(timer_interrupt, 0, timer_isr, NULL, 0);
irq_enable(timer_interrupt);
return 0;
}
SYS_INIT(sys_clock_driver_init, PRE_KERNEL_2,
CONFIG_SYSTEM_CLOCK_INIT_PRIORITY);