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![Daniel Lezcano](/assets/img/avatar_default.png)
The CLOCKSOURCE_OF_DECLARE macro is used widely for the timers to declare the clocksource at early stage. However, this macro is also used to initialize the clockevent if any, or the clockevent only. It was originally suggested to declare another macro to initialize a clockevent, so in order to separate the two entities even they belong to the same IP. This was not accepted because of the impact on the DT where splitting a clocksource/clockevent definition does not make sense as it is a Linux concept not a hardware description. On the other side, the clocksource has not interrupt declared while the clockevent has, so it is easy from the driver to know if the description is for a clockevent or a clocksource, IOW it could be implemented at the driver level. So instead of dealing with a named clocksource macro, let's use a more generic one: TIMER_OF_DECLARE. The patch has not functional changes. Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Acked-by: Heiko Stuebner <heiko@sntech.de> Acked-by: Neil Armstrong <narmstrong@baylibre.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Matthias Brugger <matthias.bgg@gmail.com> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
230 lines
5.4 KiB
C
230 lines
5.4 KiB
C
/*
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* Keystone broadcast clock-event
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*
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* Copyright 2013 Texas Instruments, Inc.
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*
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* Author: Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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*/
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#include <linux/clk.h>
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#include <linux/clockchips.h>
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#include <linux/clocksource.h>
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#include <linux/interrupt.h>
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#include <linux/of_address.h>
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#include <linux/of_irq.h>
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#define TIMER_NAME "timer-keystone"
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/* Timer register offsets */
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#define TIM12 0x10
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#define TIM34 0x14
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#define PRD12 0x18
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#define PRD34 0x1c
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#define TCR 0x20
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#define TGCR 0x24
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#define INTCTLSTAT 0x44
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/* Timer register bitfields */
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#define TCR_ENAMODE_MASK 0xC0
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#define TCR_ENAMODE_ONESHOT_MASK 0x40
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#define TCR_ENAMODE_PERIODIC_MASK 0x80
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#define TGCR_TIM_UNRESET_MASK 0x03
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#define INTCTLSTAT_ENINT_MASK 0x01
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/**
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* struct keystone_timer: holds timer's data
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* @base: timer memory base address
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* @hz_period: cycles per HZ period
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* @event_dev: event device based on timer
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*/
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static struct keystone_timer {
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void __iomem *base;
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unsigned long hz_period;
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struct clock_event_device event_dev;
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} timer;
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static inline u32 keystone_timer_readl(unsigned long rg)
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{
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return readl_relaxed(timer.base + rg);
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}
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static inline void keystone_timer_writel(u32 val, unsigned long rg)
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{
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writel_relaxed(val, timer.base + rg);
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}
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/**
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* keystone_timer_barrier: write memory barrier
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* use explicit barrier to avoid using readl/writel non relaxed function
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* variants, because in our case non relaxed variants hide the true places
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* where barrier is needed.
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*/
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static inline void keystone_timer_barrier(void)
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{
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__iowmb();
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}
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/**
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* keystone_timer_config: configures timer to work in oneshot/periodic modes.
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* @ mask: mask of the mode to configure
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* @ period: cycles number to configure for
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*/
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static int keystone_timer_config(u64 period, int mask)
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{
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u32 tcr;
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u32 off;
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tcr = keystone_timer_readl(TCR);
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off = tcr & ~(TCR_ENAMODE_MASK);
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/* set enable mode */
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tcr |= mask;
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/* disable timer */
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keystone_timer_writel(off, TCR);
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/* here we have to be sure the timer has been disabled */
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keystone_timer_barrier();
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/* reset counter to zero, set new period */
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keystone_timer_writel(0, TIM12);
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keystone_timer_writel(0, TIM34);
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keystone_timer_writel(period & 0xffffffff, PRD12);
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keystone_timer_writel(period >> 32, PRD34);
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/*
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* enable timer
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* here we have to be sure that CNTLO, CNTHI, PRDLO, PRDHI registers
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* have been written.
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*/
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keystone_timer_barrier();
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keystone_timer_writel(tcr, TCR);
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return 0;
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}
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static void keystone_timer_disable(void)
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{
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u32 tcr;
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tcr = keystone_timer_readl(TCR);
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/* disable timer */
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tcr &= ~(TCR_ENAMODE_MASK);
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keystone_timer_writel(tcr, TCR);
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}
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static irqreturn_t keystone_timer_interrupt(int irq, void *dev_id)
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{
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struct clock_event_device *evt = dev_id;
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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 keystone_set_next_event(unsigned long cycles,
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struct clock_event_device *evt)
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{
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return keystone_timer_config(cycles, TCR_ENAMODE_ONESHOT_MASK);
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}
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static int keystone_shutdown(struct clock_event_device *evt)
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{
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keystone_timer_disable();
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return 0;
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}
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static int keystone_set_periodic(struct clock_event_device *evt)
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{
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keystone_timer_config(timer.hz_period, TCR_ENAMODE_PERIODIC_MASK);
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return 0;
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}
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static int __init keystone_timer_init(struct device_node *np)
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{
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struct clock_event_device *event_dev = &timer.event_dev;
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unsigned long rate;
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struct clk *clk;
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int irq, error;
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irq = irq_of_parse_and_map(np, 0);
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if (!irq) {
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pr_err("%s: failed to map interrupts\n", __func__);
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return -EINVAL;
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}
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timer.base = of_iomap(np, 0);
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if (!timer.base) {
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pr_err("%s: failed to map registers\n", __func__);
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return -ENXIO;
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}
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clk = of_clk_get(np, 0);
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if (IS_ERR(clk)) {
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pr_err("%s: failed to get clock\n", __func__);
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iounmap(timer.base);
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return PTR_ERR(clk);
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}
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error = clk_prepare_enable(clk);
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if (error) {
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pr_err("%s: failed to enable clock\n", __func__);
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goto err;
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}
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rate = clk_get_rate(clk);
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/* disable, use internal clock source */
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keystone_timer_writel(0, TCR);
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/* here we have to be sure the timer has been disabled */
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keystone_timer_barrier();
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/* reset timer as 64-bit, no pre-scaler, plus features are disabled */
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keystone_timer_writel(0, TGCR);
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/* unreset timer */
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keystone_timer_writel(TGCR_TIM_UNRESET_MASK, TGCR);
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/* init counter to zero */
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keystone_timer_writel(0, TIM12);
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keystone_timer_writel(0, TIM34);
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timer.hz_period = DIV_ROUND_UP(rate, HZ);
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/* enable timer interrupts */
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keystone_timer_writel(INTCTLSTAT_ENINT_MASK, INTCTLSTAT);
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error = request_irq(irq, keystone_timer_interrupt, IRQF_TIMER,
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TIMER_NAME, event_dev);
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if (error) {
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pr_err("%s: failed to setup irq\n", __func__);
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goto err;
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}
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/* setup clockevent */
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event_dev->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
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event_dev->set_next_event = keystone_set_next_event;
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event_dev->set_state_shutdown = keystone_shutdown;
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event_dev->set_state_periodic = keystone_set_periodic;
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event_dev->set_state_oneshot = keystone_shutdown;
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event_dev->cpumask = cpu_all_mask;
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event_dev->owner = THIS_MODULE;
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event_dev->name = TIMER_NAME;
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event_dev->irq = irq;
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clockevents_config_and_register(event_dev, rate, 1, ULONG_MAX);
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pr_info("keystone timer clock @%lu Hz\n", rate);
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return 0;
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err:
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clk_put(clk);
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iounmap(timer.base);
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return error;
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}
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TIMER_OF_DECLARE(keystone_timer, "ti,keystone-timer",
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keystone_timer_init);
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