blob: 7f4547418ee1c8cb5ae5a2fa8398a39da068f406 [file] [log] [blame]
/*
* Copyright (C) 2013-2014 Altera Corporation
* Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
* Copyright (C) 2004 Microtronix Datacom Ltd.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#include <linux/interrupt.h>
#include <linux/clockchips.h>
#include <linux/clocksource.h>
#include <linux/delay.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/io.h>
#include <linux/slab.h>
#define ALTERA_TIMER_STATUS_REG 0
#define ALTERA_TIMER_CONTROL_REG 4
#define ALTERA_TIMER_PERIODL_REG 8
#define ALTERA_TIMER_PERIODH_REG 12
#define ALTERA_TIMER_SNAPL_REG 16
#define ALTERA_TIMER_SNAPH_REG 20
#define ALTERA_TIMER_CONTROL_ITO_MSK (0x1)
#define ALTERA_TIMER_CONTROL_CONT_MSK (0x2)
#define ALTERA_TIMER_CONTROL_START_MSK (0x4)
#define ALTERA_TIMER_CONTROL_STOP_MSK (0x8)
struct nios2_timer {
void __iomem *base;
unsigned long freq;
};
struct nios2_clockevent_dev {
struct nios2_timer timer;
struct clock_event_device ced;
};
struct nios2_clocksource {
struct nios2_timer timer;
struct clocksource cs;
};
static inline struct nios2_clockevent_dev *
to_nios2_clkevent(struct clock_event_device *evt)
{
return container_of(evt, struct nios2_clockevent_dev, ced);
}
static inline struct nios2_clocksource *
to_nios2_clksource(struct clocksource *cs)
{
return container_of(cs, struct nios2_clocksource, cs);
}
static u16 timer_readw(struct nios2_timer *timer, u32 offs)
{
return readw(timer->base + offs);
}
static void timer_writew(struct nios2_timer *timer, u16 val, u32 offs)
{
writew(val, timer->base + offs);
}
static inline unsigned long read_timersnapshot(struct nios2_timer *timer)
{
unsigned long count;
timer_writew(timer, 0, ALTERA_TIMER_SNAPL_REG);
count = timer_readw(timer, ALTERA_TIMER_SNAPH_REG) << 16 |
timer_readw(timer, ALTERA_TIMER_SNAPL_REG);
return count;
}
static cycle_t nios2_timer_read(struct clocksource *cs)
{
struct nios2_clocksource *nios2_cs = to_nios2_clksource(cs);
unsigned long flags;
u32 count;
local_irq_save(flags);
count = read_timersnapshot(&nios2_cs->timer);
local_irq_restore(flags);
/* Counter is counting down */
return ~count;
}
static struct nios2_clocksource nios2_cs = {
.cs = {
.name = "nios2-clksrc",
.rating = 250,
.read = nios2_timer_read,
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
},
};
cycles_t get_cycles(void)
{
return nios2_timer_read(&nios2_cs.cs);
}
static void nios2_timer_start(struct nios2_timer *timer)
{
u16 ctrl;
ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
ctrl |= ALTERA_TIMER_CONTROL_START_MSK;
timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
}
static void nios2_timer_stop(struct nios2_timer *timer)
{
u16 ctrl;
ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
ctrl |= ALTERA_TIMER_CONTROL_STOP_MSK;
timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
}
static void nios2_timer_config(struct nios2_timer *timer, unsigned long period,
enum clock_event_mode mode)
{
u16 ctrl;
/* The timer's actual period is one cycle greater than the value
* stored in the period register. */
period--;
ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
/* stop counter */
timer_writew(timer, ctrl | ALTERA_TIMER_CONTROL_STOP_MSK,
ALTERA_TIMER_CONTROL_REG);
/* write new count */
timer_writew(timer, period, ALTERA_TIMER_PERIODL_REG);
timer_writew(timer, period >> 16, ALTERA_TIMER_PERIODH_REG);
ctrl |= ALTERA_TIMER_CONTROL_START_MSK | ALTERA_TIMER_CONTROL_ITO_MSK;
if (mode == CLOCK_EVT_MODE_PERIODIC)
ctrl |= ALTERA_TIMER_CONTROL_CONT_MSK;
else
ctrl &= ~ALTERA_TIMER_CONTROL_CONT_MSK;
timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
}
static int nios2_timer_set_next_event(unsigned long delta,
struct clock_event_device *evt)
{
struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
nios2_timer_config(&nios2_ced->timer, delta, evt->mode);
return 0;
}
static void nios2_timer_set_mode(enum clock_event_mode mode,
struct clock_event_device *evt)
{
unsigned long period;
struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
struct nios2_timer *timer = &nios2_ced->timer;
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
period = DIV_ROUND_UP(timer->freq, HZ);
nios2_timer_config(timer, period, CLOCK_EVT_MODE_PERIODIC);
break;
case CLOCK_EVT_MODE_ONESHOT:
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_SHUTDOWN:
nios2_timer_stop(timer);
break;
case CLOCK_EVT_MODE_RESUME:
nios2_timer_start(timer);
break;
}
}
irqreturn_t timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = (struct clock_event_device *) dev_id;
struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
/* Clear the interrupt condition */
timer_writew(&nios2_ced->timer, 0, ALTERA_TIMER_STATUS_REG);
evt->event_handler(evt);
return IRQ_HANDLED;
}
static void __init nios2_timer_get_base_and_freq(struct device_node *np,
void __iomem **base, u32 *freq)
{
*base = of_iomap(np, 0);
if (!*base)
panic("Unable to map reg for %s\n", np->name);
if (of_property_read_u32(np, "clock-frequency", freq))
panic("Unable to get %s clock frequency\n", np->name);
}
static struct nios2_clockevent_dev nios2_ce = {
.ced = {
.name = "nios2-clkevent",
.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
.rating = 250,
.shift = 32,
.set_next_event = nios2_timer_set_next_event,
.set_mode = nios2_timer_set_mode,
},
};
static __init void nios2_clockevent_init(struct device_node *timer)
{
void __iomem *iobase;
u32 freq;
int irq;
nios2_timer_get_base_and_freq(timer, &iobase, &freq);
irq = irq_of_parse_and_map(timer, 0);
if (!irq)
panic("Unable to parse timer irq\n");
nios2_ce.timer.base = iobase;
nios2_ce.timer.freq = freq;
nios2_ce.ced.cpumask = cpumask_of(0);
nios2_ce.ced.irq = irq;
nios2_timer_stop(&nios2_ce.timer);
/* clear pending interrupt */
timer_writew(&nios2_ce.timer, 0, ALTERA_TIMER_STATUS_REG);
if (request_irq(irq, timer_interrupt, IRQF_TIMER, timer->name,
&nios2_ce.ced))
panic("Unable to setup timer irq\n");
clockevents_config_and_register(&nios2_ce.ced, freq, 1, ULONG_MAX);
}
static __init void nios2_clocksource_init(struct device_node *timer)
{
unsigned int ctrl;
void __iomem *iobase;
u32 freq;
nios2_timer_get_base_and_freq(timer, &iobase, &freq);
nios2_cs.timer.base = iobase;
nios2_cs.timer.freq = freq;
clocksource_register_hz(&nios2_cs.cs, freq);
timer_writew(&nios2_cs.timer, USHRT_MAX, ALTERA_TIMER_PERIODL_REG);
timer_writew(&nios2_cs.timer, USHRT_MAX, ALTERA_TIMER_PERIODH_REG);
/* interrupt disable + continuous + start */
ctrl = ALTERA_TIMER_CONTROL_CONT_MSK | ALTERA_TIMER_CONTROL_START_MSK;
timer_writew(&nios2_cs.timer, ctrl, ALTERA_TIMER_CONTROL_REG);
/* Calibrate the delay loop directly */
lpj_fine = freq / HZ;
}
/*
* The first timer instance will use as a clockevent. If there are two or
* more instances, the second one gets used as clocksource and all
* others are unused.
*/
static void __init nios2_time_init(struct device_node *timer)
{
static int num_called;
switch (num_called) {
case 0:
nios2_clockevent_init(timer);
break;
case 1:
nios2_clocksource_init(timer);
break;
default:
break;
}
num_called++;
}
void read_persistent_clock(struct timespec *ts)
{
ts->tv_sec = mktime(2007, 1, 1, 0, 0, 0);
ts->tv_nsec = 0;
}
void __init time_init(void)
{
clocksource_of_init();
}
CLOCKSOURCE_OF_DECLARE(nios2_timer, "altr,timer-1.0", nios2_time_init);