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// SPDX-License-Identifier: GPL-2.0
/*
* Renesas Timer Support - OSTM
*
* Copyright (C) 2017 Renesas Electronics America, Inc.
* Copyright (C) 2017 Chris Brandt
*/
#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/sched_clock.h>
#include <linux/slab.h>
#include "timer-of.h"
/*
* The OSTM contains independent channels.
* The first OSTM channel probed will be set up as a free running
* clocksource. Additionally we will use this clocksource for the system
* schedule timer sched_clock().
*
* The second (or more) channel probed will be set up as an interrupt
* driven clock event.
*/
static void __iomem *system_clock; /* For sched_clock() */
/* OSTM REGISTERS */
#define OSTM_CMP 0x000 /* RW,32 */
#define OSTM_CNT 0x004 /* R,32 */
#define OSTM_TE 0x010 /* R,8 */
#define OSTM_TS 0x014 /* W,8 */
#define OSTM_TT 0x018 /* W,8 */
#define OSTM_CTL 0x020 /* RW,8 */
#define TE 0x01
#define TS 0x01
#define TT 0x01
#define CTL_PERIODIC 0x00
#define CTL_ONESHOT 0x02
#define CTL_FREERUN 0x02
static void ostm_timer_stop(struct timer_of *to)
{
if (readb(timer_of_base(to) + OSTM_TE) & TE) {
writeb(TT, timer_of_base(to) + OSTM_TT);
/*
* Read back the register simply to confirm the write operation
* has completed since I/O writes can sometimes get queued by
* the bus architecture.
*/
while (readb(timer_of_base(to) + OSTM_TE) & TE)
;
}
}
static int __init ostm_init_clksrc(struct timer_of *to)
{
ostm_timer_stop(to);
writel(0, timer_of_base(to) + OSTM_CMP);
writeb(CTL_FREERUN, timer_of_base(to) + OSTM_CTL);
writeb(TS, timer_of_base(to) + OSTM_TS);
return clocksource_mmio_init(timer_of_base(to) + OSTM_CNT,
to->np->full_name, timer_of_rate(to), 300,
32, clocksource_mmio_readl_up);
}
static u64 notrace ostm_read_sched_clock(void)
{
return readl(system_clock);
}
static void __init ostm_init_sched_clock(struct timer_of *to)
{
system_clock = timer_of_base(to) + OSTM_CNT;
sched_clock_register(ostm_read_sched_clock, 32, timer_of_rate(to));
}
static int ostm_clock_event_next(unsigned long delta,
struct clock_event_device *ced)
{
struct timer_of *to = to_timer_of(ced);
ostm_timer_stop(to);
writel(delta, timer_of_base(to) + OSTM_CMP);
writeb(CTL_ONESHOT, timer_of_base(to) + OSTM_CTL);
writeb(TS, timer_of_base(to) + OSTM_TS);
return 0;
}
static int ostm_shutdown(struct clock_event_device *ced)
{
struct timer_of *to = to_timer_of(ced);
ostm_timer_stop(to);
return 0;
}
static int ostm_set_periodic(struct clock_event_device *ced)
{
struct timer_of *to = to_timer_of(ced);
if (clockevent_state_oneshot(ced) || clockevent_state_periodic(ced))
ostm_timer_stop(to);
writel(timer_of_period(to) - 1, timer_of_base(to) + OSTM_CMP);
writeb(CTL_PERIODIC, timer_of_base(to) + OSTM_CTL);
writeb(TS, timer_of_base(to) + OSTM_TS);
return 0;
}
static int ostm_set_oneshot(struct clock_event_device *ced)
{
struct timer_of *to = to_timer_of(ced);
ostm_timer_stop(to);
return 0;
}
static irqreturn_t ostm_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *ced = dev_id;
if (clockevent_state_oneshot(ced))
ostm_timer_stop(to_timer_of(ced));
/* notify clockevent layer */
if (ced->event_handler)
ced->event_handler(ced);
return IRQ_HANDLED;
}
static int __init ostm_init_clkevt(struct timer_of *to)
{
struct clock_event_device *ced = &to->clkevt;
ced->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC;
ced->set_state_shutdown = ostm_shutdown;
ced->set_state_periodic = ostm_set_periodic;
ced->set_state_oneshot = ostm_set_oneshot;
ced->set_next_event = ostm_clock_event_next;
ced->shift = 32;
ced->rating = 300;
ced->cpumask = cpumask_of(0);
clockevents_config_and_register(ced, timer_of_rate(to), 0xf,
0xffffffff);
return 0;
}
static int __init ostm_init(struct device_node *np)
{
struct timer_of *to;
int ret;
to = kzalloc(sizeof(*to), GFP_KERNEL);
if (!to)
return -ENOMEM;
to->flags = TIMER_OF_BASE | TIMER_OF_CLOCK;
if (system_clock) {
/*
* clock sources don't use interrupts, clock events do
*/
to->flags |= TIMER_OF_IRQ;
to->of_irq.flags = IRQF_TIMER | IRQF_IRQPOLL;
to->of_irq.handler = ostm_timer_interrupt;
}
ret = timer_of_init(np, to);
if (ret)
goto err_free;
/*
* First probed device will be used as system clocksource. Any
* additional devices will be used as clock events.
*/
if (!system_clock) {
ret = ostm_init_clksrc(to);
if (ret)
goto err_cleanup;
ostm_init_sched_clock(to);
pr_info("%pOF: used for clocksource\n", np);
} else {
ret = ostm_init_clkevt(to);
if (ret)
goto err_cleanup;
pr_info("%pOF: used for clock events\n", np);
}
return 0;
err_cleanup:
timer_of_cleanup(to);
err_free:
kfree(to);
return ret;
}
TIMER_OF_DECLARE(ostm, "renesas,ostm", ostm_init);
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