360 lines
8.4 KiB
C
360 lines
8.4 KiB
C
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/*
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* Copyright (C) 2013-2014 Altera Corporation
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* Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
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* Copyright (C) 2004 Microtronix Datacom Ltd.
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*/
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#include <linux/export.h>
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#include <linux/interrupt.h>
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#include <linux/clockchips.h>
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#include <linux/clocksource.h>
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#include <linux/delay.h>
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#include <linux/of.h>
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#include <linux/of_address.h>
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#include <linux/of_irq.h>
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#include <linux/io.h>
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#include <linux/slab.h>
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#define ALTR_TIMER_COMPATIBLE "altr,timer-1.0"
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#define ALTERA_TIMER_STATUS_REG 0
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#define ALTERA_TIMER_CONTROL_REG 4
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#define ALTERA_TIMER_PERIODL_REG 8
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#define ALTERA_TIMER_PERIODH_REG 12
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#define ALTERA_TIMER_SNAPL_REG 16
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#define ALTERA_TIMER_SNAPH_REG 20
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#define ALTERA_TIMER_CONTROL_ITO_MSK (0x1)
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#define ALTERA_TIMER_CONTROL_CONT_MSK (0x2)
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#define ALTERA_TIMER_CONTROL_START_MSK (0x4)
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#define ALTERA_TIMER_CONTROL_STOP_MSK (0x8)
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struct nios2_timer {
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void __iomem *base;
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unsigned long freq;
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};
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struct nios2_clockevent_dev {
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struct nios2_timer timer;
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struct clock_event_device ced;
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};
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struct nios2_clocksource {
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struct nios2_timer timer;
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struct clocksource cs;
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};
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static inline struct nios2_clockevent_dev *
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to_nios2_clkevent(struct clock_event_device *evt)
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{
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return container_of(evt, struct nios2_clockevent_dev, ced);
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}
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static inline struct nios2_clocksource *
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to_nios2_clksource(struct clocksource *cs)
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{
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return container_of(cs, struct nios2_clocksource, cs);
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}
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static u16 timer_readw(struct nios2_timer *timer, u32 offs)
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{
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return readw(timer->base + offs);
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}
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static void timer_writew(struct nios2_timer *timer, u16 val, u32 offs)
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{
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writew(val, timer->base + offs);
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}
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static inline unsigned long read_timersnapshot(struct nios2_timer *timer)
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{
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unsigned long count;
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timer_writew(timer, 0, ALTERA_TIMER_SNAPL_REG);
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count = timer_readw(timer, ALTERA_TIMER_SNAPH_REG) << 16 |
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timer_readw(timer, ALTERA_TIMER_SNAPL_REG);
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return count;
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}
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static u64 nios2_timer_read(struct clocksource *cs)
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{
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struct nios2_clocksource *nios2_cs = to_nios2_clksource(cs);
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unsigned long flags;
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u32 count;
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local_irq_save(flags);
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count = read_timersnapshot(&nios2_cs->timer);
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local_irq_restore(flags);
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/* Counter is counting down */
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return ~count;
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}
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static struct nios2_clocksource nios2_cs = {
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.cs = {
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.name = "nios2-clksrc",
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.rating = 250,
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.read = nios2_timer_read,
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.mask = CLOCKSOURCE_MASK(32),
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.flags = CLOCK_SOURCE_IS_CONTINUOUS,
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},
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};
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cycles_t get_cycles(void)
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{
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/* Only read timer if it has been initialized */
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if (nios2_cs.timer.base)
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return nios2_timer_read(&nios2_cs.cs);
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return 0;
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}
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EXPORT_SYMBOL(get_cycles);
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static void nios2_timer_start(struct nios2_timer *timer)
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{
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u16 ctrl;
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ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
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ctrl |= ALTERA_TIMER_CONTROL_START_MSK;
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timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
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}
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static void nios2_timer_stop(struct nios2_timer *timer)
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{
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u16 ctrl;
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ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
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ctrl |= ALTERA_TIMER_CONTROL_STOP_MSK;
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timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
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}
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static void nios2_timer_config(struct nios2_timer *timer, unsigned long period,
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bool periodic)
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{
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u16 ctrl;
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/* The timer's actual period is one cycle greater than the value
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* stored in the period register. */
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period--;
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ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
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/* stop counter */
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timer_writew(timer, ctrl | ALTERA_TIMER_CONTROL_STOP_MSK,
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ALTERA_TIMER_CONTROL_REG);
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/* write new count */
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timer_writew(timer, period, ALTERA_TIMER_PERIODL_REG);
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timer_writew(timer, period >> 16, ALTERA_TIMER_PERIODH_REG);
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ctrl |= ALTERA_TIMER_CONTROL_START_MSK | ALTERA_TIMER_CONTROL_ITO_MSK;
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if (periodic)
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ctrl |= ALTERA_TIMER_CONTROL_CONT_MSK;
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else
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ctrl &= ~ALTERA_TIMER_CONTROL_CONT_MSK;
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timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
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}
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static int nios2_timer_set_next_event(unsigned long delta,
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struct clock_event_device *evt)
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{
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struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
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nios2_timer_config(&nios2_ced->timer, delta, false);
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return 0;
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}
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static int nios2_timer_shutdown(struct clock_event_device *evt)
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{
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struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
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struct nios2_timer *timer = &nios2_ced->timer;
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nios2_timer_stop(timer);
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return 0;
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}
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static int nios2_timer_set_periodic(struct clock_event_device *evt)
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{
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unsigned long period;
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struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
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struct nios2_timer *timer = &nios2_ced->timer;
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period = DIV_ROUND_UP(timer->freq, HZ);
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nios2_timer_config(timer, period, true);
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return 0;
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}
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static int nios2_timer_resume(struct clock_event_device *evt)
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{
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struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
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struct nios2_timer *timer = &nios2_ced->timer;
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nios2_timer_start(timer);
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return 0;
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}
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irqreturn_t timer_interrupt(int irq, void *dev_id)
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{
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struct clock_event_device *evt = (struct clock_event_device *) dev_id;
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struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
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/* Clear the interrupt condition */
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timer_writew(&nios2_ced->timer, 0, ALTERA_TIMER_STATUS_REG);
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evt->event_handler(evt);
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return IRQ_HANDLED;
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}
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static int __init nios2_timer_get_base_and_freq(struct device_node *np,
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void __iomem **base, u32 *freq)
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{
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*base = of_iomap(np, 0);
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if (!*base) {
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pr_crit("Unable to map reg for %s\n", np->name);
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return -ENXIO;
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}
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if (of_property_read_u32(np, "clock-frequency", freq)) {
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pr_crit("Unable to get %s clock frequency\n", np->name);
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return -EINVAL;
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}
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return 0;
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}
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static struct nios2_clockevent_dev nios2_ce = {
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.ced = {
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.name = "nios2-clkevent",
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.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
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.rating = 250,
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.shift = 32,
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.set_next_event = nios2_timer_set_next_event,
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.set_state_shutdown = nios2_timer_shutdown,
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.set_state_periodic = nios2_timer_set_periodic,
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.set_state_oneshot = nios2_timer_shutdown,
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.tick_resume = nios2_timer_resume,
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},
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};
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static __init int nios2_clockevent_init(struct device_node *timer)
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{
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void __iomem *iobase;
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u32 freq;
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int irq, ret;
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ret = nios2_timer_get_base_and_freq(timer, &iobase, &freq);
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if (ret)
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return ret;
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irq = irq_of_parse_and_map(timer, 0);
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if (!irq) {
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pr_crit("Unable to parse timer irq\n");
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return -EINVAL;
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}
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nios2_ce.timer.base = iobase;
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nios2_ce.timer.freq = freq;
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nios2_ce.ced.cpumask = cpumask_of(0);
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nios2_ce.ced.irq = irq;
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nios2_timer_stop(&nios2_ce.timer);
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/* clear pending interrupt */
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timer_writew(&nios2_ce.timer, 0, ALTERA_TIMER_STATUS_REG);
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ret = request_irq(irq, timer_interrupt, IRQF_TIMER, timer->name,
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&nios2_ce.ced);
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if (ret) {
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pr_crit("Unable to setup timer irq\n");
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return ret;
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}
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clockevents_config_and_register(&nios2_ce.ced, freq, 1, ULONG_MAX);
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return 0;
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}
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static __init int nios2_clocksource_init(struct device_node *timer)
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{
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unsigned int ctrl;
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void __iomem *iobase;
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u32 freq;
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int ret;
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ret = nios2_timer_get_base_and_freq(timer, &iobase, &freq);
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if (ret)
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return ret;
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nios2_cs.timer.base = iobase;
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nios2_cs.timer.freq = freq;
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ret = clocksource_register_hz(&nios2_cs.cs, freq);
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if (ret)
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return ret;
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timer_writew(&nios2_cs.timer, USHRT_MAX, ALTERA_TIMER_PERIODL_REG);
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timer_writew(&nios2_cs.timer, USHRT_MAX, ALTERA_TIMER_PERIODH_REG);
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/* interrupt disable + continuous + start */
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ctrl = ALTERA_TIMER_CONTROL_CONT_MSK | ALTERA_TIMER_CONTROL_START_MSK;
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timer_writew(&nios2_cs.timer, ctrl, ALTERA_TIMER_CONTROL_REG);
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/* Calibrate the delay loop directly */
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lpj_fine = freq / HZ;
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return 0;
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}
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/*
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* The first timer instance will use as a clockevent. If there are two or
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* more instances, the second one gets used as clocksource and all
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* others are unused.
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*/
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static int __init nios2_time_init(struct device_node *timer)
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{
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static int num_called;
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int ret;
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switch (num_called) {
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case 0:
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ret = nios2_clockevent_init(timer);
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break;
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case 1:
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ret = nios2_clocksource_init(timer);
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break;
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default:
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ret = 0;
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break;
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}
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num_called++;
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return ret;
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}
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void read_persistent_clock64(struct timespec64 *ts)
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{
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ts->tv_sec = mktime64(2007, 1, 1, 0, 0, 0);
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ts->tv_nsec = 0;
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}
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void __init time_init(void)
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{
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struct device_node *np;
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int count = 0;
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for_each_compatible_node(np, NULL, ALTR_TIMER_COMPATIBLE)
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count++;
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if (count < 2)
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panic("%d timer is found, it needs 2 timers in system\n", count);
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timer_probe();
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}
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TIMER_OF_DECLARE(nios2_timer, ALTR_TIMER_COMPATIBLE, nios2_time_init);
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