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/*
* MOXA ART SoCs timer handling.
*
* Copyright (C) 2013 Jonas Jensen
*
* Jonas Jensen <jonas.jensen@gmail.com>
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqreturn.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/io.h>
#include <linux/clocksource.h>
#include <linux/bitops.h>
#define TIMER1_BASE 0x00
#define TIMER2_BASE 0x10
#define TIMER3_BASE 0x20
#define REG_COUNT 0x0 /* writable */
#define REG_LOAD 0x4
#define REG_MATCH1 0x8
#define REG_MATCH2 0xC
#define TIMER_CR 0x30
#define TIMER_INTR_STATE 0x34
#define TIMER_INTR_MASK 0x38
/*
* TIMER_CR flags:
*
* TIMEREG_CR_*_CLOCK 0: PCLK, 1: EXT1CLK
* TIMEREG_CR_*_INT overflow interrupt enable bit
*/
#define TIMEREG_CR_1_ENABLE BIT(0)
#define TIMEREG_CR_1_CLOCK BIT(1)
#define TIMEREG_CR_1_INT BIT(2)
#define TIMEREG_CR_2_ENABLE BIT(3)
#define TIMEREG_CR_2_CLOCK BIT(4)
#define TIMEREG_CR_2_INT BIT(5)
#define TIMEREG_CR_3_ENABLE BIT(6)
#define TIMEREG_CR_3_CLOCK BIT(7)
#define TIMEREG_CR_3_INT BIT(8)
#define TIMEREG_CR_COUNT_UP BIT(9)
#define TIMER1_ENABLE (TIMEREG_CR_2_ENABLE | TIMEREG_CR_1_ENABLE)
#define TIMER1_DISABLE (TIMEREG_CR_2_ENABLE)
static void __iomem *base;
static unsigned int clock_count_per_tick;
static inline void moxart_disable(struct clock_event_device *evt)
{
writel(TIMER1_DISABLE, base + TIMER_CR);
}
static inline void moxart_enable(struct clock_event_device *evt)
{
writel(TIMER1_ENABLE, base + TIMER_CR);
}
static int moxart_shutdown(struct clock_event_device *evt)
{
moxart_disable(evt);
return 0;
}
static int moxart_set_oneshot(struct clock_event_device *evt)
{
moxart_disable(evt);
writel(~0, base + TIMER1_BASE + REG_LOAD);
return 0;
}
static int moxart_set_periodic(struct clock_event_device *evt)
{
writel(clock_count_per_tick, base + TIMER1_BASE + REG_LOAD);
moxart_enable(evt);
return 0;
}
static int moxart_clkevt_next_event(unsigned long cycles,
struct clock_event_device *evt)
{
u32 u;
moxart_disable(evt);
u = readl(base + TIMER1_BASE + REG_COUNT) - cycles;
writel(u, base + TIMER1_BASE + REG_MATCH1);
moxart_enable(evt);
return 0;
}
static struct clock_event_device moxart_clockevent = {
.name = "moxart_timer",
.rating = 200,
.features = CLOCK_EVT_FEAT_PERIODIC |
CLOCK_EVT_FEAT_ONESHOT,
.set_state_shutdown = moxart_shutdown,
.set_state_periodic = moxart_set_periodic,
.set_state_oneshot = moxart_set_oneshot,
.tick_resume = moxart_set_oneshot,
.set_next_event = moxart_clkevt_next_event,
};
static irqreturn_t moxart_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = dev_id;
evt->event_handler(evt);
return IRQ_HANDLED;
}
static struct irqaction moxart_timer_irq = {
.name = "moxart-timer",
.flags = IRQF_TIMER,
.handler = moxart_timer_interrupt,
.dev_id = &moxart_clockevent,
};
static int __init moxart_timer_init(struct device_node *node)
{
int ret, irq;
unsigned long pclk;
struct clk *clk;
base = of_iomap(node, 0);
if (!base) {
pr_err("%s: of_iomap failed\n", node->full_name);
return -ENXIO;
}
irq = irq_of_parse_and_map(node, 0);
if (irq <= 0) {
pr_err("%s: irq_of_parse_and_map failed\n", node->full_name);
return -EINVAL;
}
ret = setup_irq(irq, &moxart_timer_irq);
if (ret) {
pr_err("%s: setup_irq failed\n", node->full_name);
return ret;
}
clk = of_clk_get(node, 0);
if (IS_ERR(clk)) {
pr_err("%s: of_clk_get failed\n", node->full_name);
return PTR_ERR(clk);
}
pclk = clk_get_rate(clk);
ret = clocksource_mmio_init(base + TIMER2_BASE + REG_COUNT,
"moxart_timer", pclk, 200, 32,
clocksource_mmio_readl_down);
if (ret) {
pr_err("%s: clocksource_mmio_init failed\n", node->full_name);
return ret;
}
clock_count_per_tick = DIV_ROUND_CLOSEST(pclk, HZ);
writel(~0, base + TIMER2_BASE + REG_LOAD);
writel(TIMEREG_CR_2_ENABLE, base + TIMER_CR);
moxart_clockevent.cpumask = cpumask_of(0);
moxart_clockevent.irq = irq;
/*
* documentation is not publicly available:
* min_delta / max_delta obtained by trial-and-error,
* max_delta 0xfffffffe should be ok because count
* register size is u32
*/
clockevents_config_and_register(&moxart_clockevent, pclk,
0x4, 0xfffffffe);
return 0;
}
CLOCKSOURCE_OF_DECLARE(moxart, "moxa,moxart-timer", moxart_timer_init);
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