/*
* Copyright (C) 2015 ARM Limited
*
* Author: Vladimir Murzin <vladimir.murzin@arm.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/clocksource.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/of_address.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/sched_clock.h>
#include <linux/slab.h>
#define TIMER_CTRL 0x0
#define TIMER_CTRL_ENABLE BIT(0)
#define TIMER_CTRL_IE BIT(3)
#define TIMER_VALUE 0x4
#define TIMER_RELOAD 0x8
#define TIMER_INT 0xc
struct clockevent_mps2 {
void __iomem *reg;
u32 clock_count_per_tick;
struct clock_event_device clkevt;
};
static void __iomem *sched_clock_base;
static u64 notrace mps2_sched_read(void)
{
return ~readl_relaxed(sched_clock_base + TIMER_VALUE);
}
static inline struct clockevent_mps2 *to_mps2_clkevt(struct clock_event_device *c)
{
return container_of(c, struct clockevent_mps2, clkevt);
}
static void clockevent_mps2_writel(u32 val, struct clock_event_device *c, u32 offset)
{
writel_relaxed(val, to_mps2_clkevt(c)->reg + offset);
}
static int mps2_timer_shutdown(struct clock_event_device *ce)
{
clockevent_mps2_writel(0, ce, TIMER_RELOAD);
clockevent_mps2_writel(0, ce, TIMER_CTRL);
return 0;
}
static int mps2_timer_set_next_event(unsigned long next, struct clock_event_device *ce)
{
clockevent_mps2_writel(next, ce, TIMER_VALUE);
clockevent_mps2_writel(TIMER_CTRL_IE | TIMER_CTRL_ENABLE, ce, TIMER_CTRL);
return 0;
}
static int mps2_timer_set_periodic(struct clock_event_device *ce)
{
u32 clock_count_per_tick = to_mps2_clkevt(ce)->clock_count_per_tick;
clockevent_mps2_writel(clock_count_per_tick, ce, TIMER_RELOAD);
clockevent_mps2_writel(clock_count_per_tick, ce, TIMER_VALUE);
clockevent_mps2_writel(TIMER_CTRL_IE | TIMER_CTRL_ENABLE, ce, TIMER_CTRL);
return 0;
}
static irqreturn_t mps2_timer_interrupt(int irq, void *dev_id)
{
struct clockevent_mps2 *ce = dev_id;
u32 status = readl_relaxed(ce->reg + TIMER_INT);
if (!status) {
pr_warn("spurious interrupt\n");
return IRQ_NONE;
}
writel_relaxed(1, ce->reg + TIMER_INT);
ce->clkevt.event_handler(&ce->clkevt);
return IRQ_HANDLED;
}
static int __init mps2_clockevent_init(struct device_node *np)
{
void __iomem *base;
struct clk *clk = NULL;
struct clockevent_mps2 *ce;
u32 rate;
int irq, ret;
const char *name = "mps2-clkevt";
ret = of_property_read_u32(np, "clock-frequency", &rate);
if (ret) {
clk = of_clk_get(np, 0);
if (IS_ERR(clk)) {
ret = PTR_ERR(clk);
pr_err("failed to get clock for clockevent: %d\n", ret);
goto out;
}
ret = clk_prepare_enable(clk);
if (ret) {
pr_err("failed to enable clock for clockevent: %d\n", ret);
goto out_clk_put;
}
rate = clk_get_rate(clk);
}
base = of_iomap(np, 0);
if (!base) {
ret = -EADDRNOTAVAIL;
pr_err("failed to map register for clockevent: %d\n", ret);
goto out_clk_disable;
}
irq = irq_of_parse_and_map(np, 0);
if (!irq) {
ret = -ENOENT;
pr_err("failed to get irq for clockevent: %d\n", ret);
goto out_iounmap;
}
ce = kzalloc(sizeof(*ce), GFP_KERNEL);
if (!ce) {
ret = -ENOMEM;
goto out_iounmap;
}
ce->reg = base;
ce->clock_count_per_tick = DIV_ROUND_CLOSEST(rate, HZ);
ce->clkevt.irq = irq;
ce->clkevt.name = name;
ce->clkevt.rating = 200;
ce->clkevt.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
ce->clkevt.cpumask = cpu_possible_mask;
ce->clkevt.set_state_shutdown = mps2_timer_shutdown,
ce->clkevt.set_state_periodic = mps2_timer_set_periodic,
ce->clkevt.set_state_oneshot = mps2_timer_shutdown,
ce->clkevt.set_next_event = mps2_timer_set_next_event;
/* Ensure timer is disabled */
writel_relaxed(0, base + TIMER_CTRL);
ret = request_irq(irq, mps2_timer_interrupt, IRQF_TIMER, name, ce);
if (ret) {
pr_err("failed to request irq for clockevent: %d\n", ret);
goto out_kfree;
}
clockevents_config_and_register(&ce->clkevt, rate, 0xf, 0xffffffff);
return 0;
out_kfree:
kfree(ce);
out_iounmap:
iounmap(base);
out_clk_disable:
/* clk_{disable, unprepare, put}() can handle NULL as a parameter */
clk_disable_unprepare(clk);
out_clk_put:
clk_put(clk);
out:
return ret;
}
static int __init mps2_clocksource_init(struct device_node *np)
{
void __iomem *base;
struct clk *clk = NULL;
u32 rate;
int ret;
const char *name = "mps2-clksrc";
ret = of_property_read_u32(np, "clock-frequency", &rate);
if (ret) {
clk = of_clk_get(np, 0);
if (IS_ERR(clk)) {
ret = PTR_ERR(clk);
pr_err("failed to get clock for clocksource: %d\n", ret);
goto out;
}
ret = clk_prepare_enable(clk);
if (ret) {
pr_err("failed to enable clock for clocksource: %d\n", ret);
goto out_clk_put;
}
rate = clk_get_rate(clk);
}
base = of_iomap(np, 0);
if (!base) {
ret = -EADDRNOTAVAIL;
pr_err("failed to map register for clocksource: %d\n", ret);
goto out_clk_disable;
}
/* Ensure timer is disabled */
writel_relaxed(0, base + TIMER_CTRL);
/* ... and set it up as free-running clocksource */
writel_relaxed(0xffffffff, base + TIMER_VALUE);
writel_relaxed(0xffffffff, base + TIMER_RELOAD);
writel_relaxed(TIMER_CTRL_ENABLE, base + TIMER_CTRL);
ret = clocksource_mmio_init(base + TIMER_VALUE, name,
rate, 200, 32,
clocksource_mmio_readl_down);
if (ret) {
pr_err("failed to init clocksource: %d\n", ret);
goto out_iounmap;
}
sched_clock_base = base;
sched_clock_register(mps2_sched_read, 32, rate);
return 0;
out_iounmap:
iounmap(base);
out_clk_disable:
/* clk_{disable, unprepare, put}() can handle NULL as a parameter */
clk_disable_unprepare(clk);
out_clk_put:
clk_put(clk);
out:
return ret;
}
static int __init mps2_timer_init(struct device_node *np)
{
static int has_clocksource, has_clockevent;
int ret;
if (!has_clocksource) {
ret = mps2_clocksource_init(np);
if (!ret) {
has_clocksource = 1;
return 0;
}
}
if (!has_clockevent) {
ret = mps2_clockevent_init(np);
if (!ret) {
has_clockevent = 1;
return 0;
}
}
return 0;
}
TIMER_OF_DECLARE(mps2_timer, "arm,mps2-timer", mps2_timer_init);
