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// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/sched_clock.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/io.h>
#include <asm/mach/time.h>
#include "soc.h"
#include "platform.h"
/*************************************************************************
* Timer handling for EP93xx
*************************************************************************
* The ep93xx has four internal timers. Timers 1, 2 (both 16 bit) and
* 3 (32 bit) count down at 508 kHz, are self-reloading, and can generate
* an interrupt on underflow. Timer 4 (40 bit) counts down at 983.04 kHz,
* is free-running, and can't generate interrupts.
*
* The 508 kHz timers are ideal for use for the timer interrupt, as the
* most common values of HZ divide 508 kHz nicely. We pick the 32 bit
* timer (timer 3) to get as long sleep intervals as possible when using
* CONFIG_NO_HZ.
*
* The higher clock rate of timer 4 makes it a better choice than the
* other timers for use as clock source and for sched_clock(), providing
* a stable 40 bit time base.
*************************************************************************
*/
#define EP93XX_TIMER_REG(x) (EP93XX_TIMER_BASE + (x))
#define EP93XX_TIMER1_LOAD EP93XX_TIMER_REG(0x00)
#define EP93XX_TIMER1_VALUE EP93XX_TIMER_REG(0x04)
#define EP93XX_TIMER1_CONTROL EP93XX_TIMER_REG(0x08)
#define EP93XX_TIMER123_CONTROL_ENABLE (1 << 7)
#define EP93XX_TIMER123_CONTROL_MODE (1 << 6)
#define EP93XX_TIMER123_CONTROL_CLKSEL (1 << 3)
#define EP93XX_TIMER1_CLEAR EP93XX_TIMER_REG(0x0c)
#define EP93XX_TIMER2_LOAD EP93XX_TIMER_REG(0x20)
#define EP93XX_TIMER2_VALUE EP93XX_TIMER_REG(0x24)
#define EP93XX_TIMER2_CONTROL EP93XX_TIMER_REG(0x28)
#define EP93XX_TIMER2_CLEAR EP93XX_TIMER_REG(0x2c)
#define EP93XX_TIMER4_VALUE_LOW EP93XX_TIMER_REG(0x60)
#define EP93XX_TIMER4_VALUE_HIGH EP93XX_TIMER_REG(0x64)
#define EP93XX_TIMER4_VALUE_HIGH_ENABLE (1 << 8)
#define EP93XX_TIMER3_LOAD EP93XX_TIMER_REG(0x80)
#define EP93XX_TIMER3_VALUE EP93XX_TIMER_REG(0x84)
#define EP93XX_TIMER3_CONTROL EP93XX_TIMER_REG(0x88)
#define EP93XX_TIMER3_CLEAR EP93XX_TIMER_REG(0x8c)
#define EP93XX_TIMER123_RATE 508469
#define EP93XX_TIMER4_RATE 983040
static u64 notrace ep93xx_read_sched_clock(void)
{
u64 ret;
ret = readl(EP93XX_TIMER4_VALUE_LOW);
ret |= ((u64) (readl(EP93XX_TIMER4_VALUE_HIGH) & 0xff) << 32);
return ret;
}
static u64 ep93xx_clocksource_read(struct clocksource *c)
{
u64 ret;
ret = readl(EP93XX_TIMER4_VALUE_LOW);
ret |= ((u64) (readl(EP93XX_TIMER4_VALUE_HIGH) & 0xff) << 32);
return (u64) ret;
}
static int ep93xx_clkevt_set_next_event(unsigned long next,
struct clock_event_device *evt)
{
/* Default mode: periodic, off, 508 kHz */
u32 tmode = EP93XX_TIMER123_CONTROL_MODE |
EP93XX_TIMER123_CONTROL_CLKSEL;
/* Clear timer */
writel(tmode, EP93XX_TIMER3_CONTROL);
/* Set next event */
writel(next, EP93XX_TIMER3_LOAD);
writel(tmode | EP93XX_TIMER123_CONTROL_ENABLE,
EP93XX_TIMER3_CONTROL);
return 0;
}
static int ep93xx_clkevt_shutdown(struct clock_event_device *evt)
{
/* Disable timer */
writel(0, EP93XX_TIMER3_CONTROL);
return 0;
}
static struct clock_event_device ep93xx_clockevent = {
.name = "timer1",
.features = CLOCK_EVT_FEAT_ONESHOT,
.set_state_shutdown = ep93xx_clkevt_shutdown,
.set_state_oneshot = ep93xx_clkevt_shutdown,
.tick_resume = ep93xx_clkevt_shutdown,
.set_next_event = ep93xx_clkevt_set_next_event,
.rating = 300,
};
static irqreturn_t ep93xx_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = dev_id;
/* Writing any value clears the timer interrupt */
writel(1, EP93XX_TIMER3_CLEAR);
evt->event_handler(evt);
return IRQ_HANDLED;
}
void __init ep93xx_timer_init(void)
{
int irq = IRQ_EP93XX_TIMER3;
unsigned long flags = IRQF_TIMER | IRQF_IRQPOLL;
/* Enable and register clocksource and sched_clock on timer 4 */
writel(EP93XX_TIMER4_VALUE_HIGH_ENABLE,
EP93XX_TIMER4_VALUE_HIGH);
clocksource_mmio_init(NULL, "timer4",
EP93XX_TIMER4_RATE, 200, 40,
ep93xx_clocksource_read);
sched_clock_register(ep93xx_read_sched_clock, 40,
EP93XX_TIMER4_RATE);
/* Set up clockevent on timer 3 */
if (request_irq(irq, ep93xx_timer_interrupt, flags, "ep93xx timer",
&ep93xx_clockevent))
pr_err("Failed to request irq %d (ep93xx timer)\n", irq);
clockevents_config_and_register(&ep93xx_clockevent,
EP93XX_TIMER123_RATE,
1,
0xffffffffU);
}
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