/*
* Renesas Timer Support - OSTM
*
* Copyright (C) 2017 Renesas Electronics America, Inc.
* Copyright (C) 2017 Chris Brandt
*
* 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
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/sched_clock.h>
#include <linux/slab.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.
*/
struct ostm_device {
void __iomem *base;
unsigned long ticks_per_jiffy;
struct clock_event_device ced;
};
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 struct ostm_device *ced_to_ostm(struct clock_event_device *ced)
{
return container_of(ced, struct ostm_device, ced);
}
static void ostm_timer_stop(struct ostm_device *ostm)
{
if (readb(ostm->base + OSTM_TE) & TE) {
writeb(TT, ostm->base + 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(ostm->base + OSTM_TE) & TE)
;
}
}
static int __init ostm_init_clksrc(struct ostm_device *ostm, unsigned long rate)
{
/*
* irq not used (clock sources don't use interrupts)
*/
ostm_timer_stop(ostm);
writel(0, ostm->base + OSTM_CMP);
writeb(CTL_FREERUN, ostm->base + OSTM_CTL);
writeb(TS, ostm->base + OSTM_TS);
return clocksource_mmio_init(ostm->base + OSTM_CNT,
"ostm", rate,
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 ostm_device *ostm,
unsigned long rate)
{
system_clock = ostm->base + OSTM_CNT;
sched_clock_register(ostm_read_sched_clock, 32, rate);
}
static int ostm_clock_event_next(unsigned long delta,
struct clock_event_device *ced)
{
struct ostm_device *ostm = ced_to_ostm(ced);
ostm_timer_stop(ostm);
writel(delta, ostm->base + OSTM_CMP);
writeb(CTL_ONESHOT, ostm->base + OSTM_CTL);
writeb(TS, ostm->base + OSTM_TS);
return 0;
}
static int ostm_shutdown(struct clock_event_device *ced)
{
struct ostm_device *ostm = ced_to_ostm(ced);
ostm_timer_stop(ostm);
return 0;
}
static int ostm_set_periodic(struct clock_event_device *ced)
{
struct ostm_device *ostm = ced_to_ostm(ced);
if (clockevent_state_oneshot(ced) || clockevent_state_periodic(ced))
ostm_timer_stop(ostm);
writel(ostm->ticks_per_jiffy - 1, ostm->base + OSTM_CMP);
writeb(CTL_PERIODIC, ostm->base + OSTM_CTL);
writeb(TS, ostm->base + OSTM_TS);
return 0;
}
static int ostm_set_oneshot(struct clock_event_device *ced)
{
struct ostm_device *ostm = ced_to_ostm(ced);
ostm_timer_stop(ostm);
return 0;
}
static irqreturn_t ostm_timer_interrupt(int irq, void *dev_id)
{
struct ostm_device *ostm = dev_id;
if (clockevent_state_oneshot(&ostm->ced))
ostm_timer_stop(ostm);
/* notify clockevent layer */
if (ostm->ced.event_handler)
ostm->ced.event_handler(&ostm->ced);
return IRQ_HANDLED;
}
static int __init ostm_init_clkevt(struct ostm_device *ostm, int irq,
unsigned long rate)
{
struct clock_event_device *ced = &ostm->ced;
int ret = -ENXIO;
ret = request_irq(irq, ostm_timer_interrupt,
IRQF_TIMER | IRQF_IRQPOLL,
"ostm", ostm);
if (ret) {
pr_err("ostm: failed to request irq\n");
return ret;
}
ced->name = "ostm";
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, rate, 0xf, 0xffffffff);
return 0;
}
static int __init ostm_init(struct device_node *np)
{
struct ostm_device *ostm;
int ret = -EFAULT;
struct clk *ostm_clk = NULL;
int irq;
unsigned long rate;
ostm = kzalloc(sizeof(*ostm), GFP_KERNEL);
if (!ostm)
return -ENOMEM;
ostm->base = of_iomap(np, 0);
if (!ostm->base) {
pr_err("ostm: failed to remap I/O memory\n");
goto err;
}
irq = irq_of_parse_and_map(np, 0);
if (irq < 0) {
pr_err("ostm: Failed to get irq\n");
goto err;
}
ostm_clk = of_clk_get(np, 0);
if (IS_ERR(ostm_clk)) {
pr_err("ostm: Failed to get clock\n");
ostm_clk = NULL;
goto err;
}
ret = clk_prepare_enable(ostm_clk);
if (ret) {
pr_err("ostm: Failed to enable clock\n");
goto err;
}
rate = clk_get_rate(ostm_clk);
ostm->ticks_per_jiffy = (rate + HZ / 2) / HZ;
/*
* 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(ostm, rate);
if (!ret) {
ostm_init_sched_clock(ostm, rate);
pr_info("ostm: used for clocksource\n");
}
} else {
ret = ostm_init_clkevt(ostm, irq, rate);
if (!ret)
pr_info("ostm: used for clock events\n");
}
err:
if (ret) {
clk_disable_unprepare(ostm_clk);
iounmap(ostm->base);
kfree(ostm);
return ret;
}
return 0;
}
CLOCKSOURCE_OF_DECLARE(ostm, "renesas,ostm", ostm_init);
