timer-imx-sysctr.c
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/*
* Copyright 2017 NXP
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*/
#include <linux/interrupt.h>
#include <linux/clockchips.h>
#include <linux/clocksource.h>
#include <linux/delay.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/sched_clock.h>
#define CNTCV_LO 0x8
#define CNTCV_HI 0xc
#define CMPCV_LO 0x20
#define CMPCV_HI 0x24
#define CMPCR 0x2c
#define SYS_CTR_EN 0x1
#define SYS_CTR_IRQ_MASK 0x2
static void __iomem *sys_ctr_rd_base;
static void __iomem *sys_ctr_cmp_base;
static struct clock_event_device clockevent_sysctr;
static inline void sysctr_timer_enable(bool enable)
{
u32 val;
val = readl(sys_ctr_cmp_base + CMPCR);
val &= ~SYS_CTR_EN;
if (enable)
val |= SYS_CTR_EN;
writel(val, sys_ctr_cmp_base + CMPCR);
}
static void sysctr_irq_acknowledge(void)
{
u32 val;
/* clear th enable bit(EN=0) to clear the ISTAT */
val = readl(sys_ctr_cmp_base + CMPCR);
val &= ~SYS_CTR_EN;
writel(val, sys_ctr_cmp_base + CMPCR);
}
static inline u64 sysctr_read_counter(void)
{
u32 cnt_hi, tmp_hi, cnt_lo;
do {
cnt_hi = readl_relaxed(sys_ctr_rd_base + CNTCV_HI);
cnt_lo = readl_relaxed(sys_ctr_rd_base + CNTCV_LO);
tmp_hi = readl_relaxed(sys_ctr_rd_base + CNTCV_HI);
} while (tmp_hi != cnt_hi);
return ((u64) cnt_hi << 32) | cnt_lo;
}
static u64 notrace sysctr_read_sched_clock(void)
{
return sysctr_read_counter();
}
static u64 sysctr_clocksourc_read(struct clocksource *cs)
{
return sysctr_read_counter();
}
static int __init sysctr_clocksource_init(unsigned int rate)
{
sched_clock_register(sysctr_read_sched_clock, 56, rate);
return clocksource_mmio_init(sys_ctr_rd_base, "imx sysctr",
rate, 200, 56, sysctr_clocksourc_read);
}
static int sysctr_set_next_event(unsigned long delta,
struct clock_event_device *evt)
{
u32 cmp_hi, cmp_lo;
u64 next;
sysctr_timer_enable(false);
next = sysctr_read_counter();
next += delta;
cmp_hi = (next >> 32) & 0x00fffff;
cmp_lo = next & 0xffffffff;
writel_relaxed(cmp_hi, sys_ctr_cmp_base + CMPCV_HI);
writel_relaxed(cmp_lo, sys_ctr_cmp_base + CMPCV_LO);
sysctr_timer_enable(true);
return 0;
}
static int sysctr_set_state_oneshot(struct clock_event_device *evt)
{
/* enable timer */
sysctr_timer_enable(true);
return 0;
}
static int sysctr_set_state_shutdown(struct clock_event_device *evt)
{
/* disable the timer */
sysctr_timer_enable(false);
return 0;
}
static irqreturn_t sysctr_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = &clockevent_sysctr;
sysctr_irq_acknowledge();
evt->event_handler(evt);
return IRQ_HANDLED;
}
static struct clock_event_device clockevent_sysctr = {
.name = "i.MX system counter timer",
.features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_DYNIRQ,
.set_state_oneshot = sysctr_set_state_oneshot,
.set_next_event = sysctr_set_next_event,
.set_state_shutdown = sysctr_set_state_shutdown,
.rating = 200,
};
static struct irqaction sysctr_timer_irq = {
.name = "iMX system counter timer",
.flags = IRQF_TIMER | IRQF_IRQPOLL,
.handler = sysctr_timer_interrupt,
.dev_id = &clockevent_sysctr,
};
static int __init sysctr_clockevent_init(unsigned long rate, int irq)
{
setup_irq(irq, &sysctr_timer_irq);
clockevent_sysctr.cpumask = cpumask_of(0);
clockevent_sysctr.irq = irq;
clockevents_config_and_register(&clockevent_sysctr,
rate, 0xff, 0x7fffffff);
return 0;
}
static int __init sysctr_timer_init(struct device_node *np)
{
u32 rate;
int irq;
pr_info("system counter timer init\n");
sys_ctr_rd_base = of_iomap(np, 0);
BUG_ON(!sys_ctr_rd_base);
sys_ctr_cmp_base = of_iomap(np, 1);
BUG_ON(!sys_ctr_cmp_base);
/*
* the purpose of this driver is to provide a global timer,
* So only use one compare frame, request frame0's irq only.
*/
irq = irq_of_parse_and_map(np, 0);
if (of_property_read_u32(np, "clock-frequency", &rate))
return -EINVAL;
sysctr_clocksource_init(rate);
sysctr_clockevent_init(rate, irq);
return 0;
}
CLOCKSOURCE_OF_DECLARE(imx8m, "nxp,sysctr-timer", sysctr_timer_init);