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MIPS: Loongson1B: Add a clockevent/clocksource using PWM Timer
This patch add a clockevent/clocksource using PWM Timer for Loongson1B, which is based on earlier work by Tang, Haifeng. Signed-off-by: Kelvin Cheung <keguang.zhang@gmail.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/8025/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Kelvin Cheung
Ralf Baechle
parent
f29ad10de6
commit
c5d58e9e79
@ -5,8 +5,8 @@ choice
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config LOONGSON1_LS1B
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bool "Loongson LS1B board"
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select CEVT_R4K
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select CSRC_R4K
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select CEVT_R4K if !MIPS_EXTERNAL_TIMER
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select CSRC_R4K if !MIPS_EXTERNAL_TIMER
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select SYS_HAS_CPU_LOONGSON1B
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select DMA_NONCOHERENT
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select BOOT_ELF32
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@ -21,4 +21,41 @@ config LOONGSON1_LS1B
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endchoice
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menuconfig CEVT_CSRC_LS1X
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bool "Use PWM Timer for clockevent/clocksource"
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select MIPS_EXTERNAL_TIMER
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depends on CPU_LOONGSON1
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help
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This option changes the default clockevent/clocksource to PWM Timer,
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and is required by Loongson1 CPUFreq support.
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If unsure, say N.
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choice
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prompt "Select clockevent/clocksource"
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depends on CEVT_CSRC_LS1X
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default TIMER_USE_PWM0
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config TIMER_USE_PWM0
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bool "Use PWM Timer 0"
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help
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Use PWM Timer 0 as the default clockevent/clocksourcer.
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config TIMER_USE_PWM1
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bool "Use PWM Timer 1"
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help
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Use PWM Timer 1 as the default clockevent/clocksourcer.
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config TIMER_USE_PWM2
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bool "Use PWM Timer 2"
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help
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Use PWM Timer 2 as the default clockevent/clocksourcer.
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config TIMER_USE_PWM3
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bool "Use PWM Timer 3"
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help
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Use PWM Timer 3 as the default clockevent/clocksourcer.
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endchoice
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endif # MACH_LOONGSON1
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@ -2,4 +2,4 @@
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# Makefile for common code of loongson1 based machines.
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#
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obj-y += clock.o irq.o platform.o prom.o reset.o setup.o
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obj-y += time.o irq.o platform.o prom.o reset.o setup.o
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@ -1,28 +0,0 @@
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/*
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* Copyright (c) 2011 Zhang, Keguang <keguang.zhang@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*/
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#include <linux/clk.h>
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#include <linux/err.h>
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#include <asm/time.h>
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#include <platform.h>
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void __init plat_time_init(void)
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{
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struct clk *clk;
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/* Initialize LS1X clocks */
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ls1x_clk_init();
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/* setup mips r4k timer */
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clk = clk_get(NULL, "cpu");
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if (IS_ERR(clk))
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panic("unable to get cpu clock, err=%ld", PTR_ERR(clk));
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mips_hpt_frequency = clk_get_rate(clk) / 2;
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}
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226
arch/mips/loongson1/common/time.c
Normal file
226
arch/mips/loongson1/common/time.c
Normal file
@ -0,0 +1,226 @@
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/*
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* Copyright (c) 2014 Zhang, Keguang <keguang.zhang@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*/
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#include <linux/clk.h>
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#include <linux/interrupt.h>
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#include <asm/time.h>
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#include <loongson1.h>
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#include <platform.h>
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#ifdef CONFIG_CEVT_CSRC_LS1X
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#if defined(CONFIG_TIMER_USE_PWM1)
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#define LS1X_TIMER_BASE LS1X_PWM1_BASE
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#define LS1X_TIMER_IRQ LS1X_PWM1_IRQ
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#elif defined(CONFIG_TIMER_USE_PWM2)
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#define LS1X_TIMER_BASE LS1X_PWM2_BASE
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#define LS1X_TIMER_IRQ LS1X_PWM2_IRQ
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#elif defined(CONFIG_TIMER_USE_PWM3)
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#define LS1X_TIMER_BASE LS1X_PWM3_BASE
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#define LS1X_TIMER_IRQ LS1X_PWM3_IRQ
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#else
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#define LS1X_TIMER_BASE LS1X_PWM0_BASE
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#define LS1X_TIMER_IRQ LS1X_PWM0_IRQ
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#endif
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DEFINE_RAW_SPINLOCK(ls1x_timer_lock);
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static void __iomem *timer_base;
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static uint32_t ls1x_jiffies_per_tick;
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static inline void ls1x_pwmtimer_set_period(uint32_t period)
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{
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__raw_writel(period, timer_base + PWM_HRC);
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__raw_writel(period, timer_base + PWM_LRC);
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}
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static inline void ls1x_pwmtimer_restart(void)
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{
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__raw_writel(0x0, timer_base + PWM_CNT);
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__raw_writel(INT_EN | CNT_EN, timer_base + PWM_CTRL);
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}
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void __init ls1x_pwmtimer_init(void)
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{
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timer_base = ioremap(LS1X_TIMER_BASE, 0xf);
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if (!timer_base)
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panic("Failed to remap timer registers");
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ls1x_jiffies_per_tick = DIV_ROUND_CLOSEST(mips_hpt_frequency, HZ);
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ls1x_pwmtimer_set_period(ls1x_jiffies_per_tick);
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ls1x_pwmtimer_restart();
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}
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static cycle_t ls1x_clocksource_read(struct clocksource *cs)
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{
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unsigned long flags;
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int count;
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u32 jifs;
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static int old_count;
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static u32 old_jifs;
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raw_spin_lock_irqsave(&ls1x_timer_lock, flags);
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/*
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* Although our caller may have the read side of xtime_lock,
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* this is now a seqlock, and we are cheating in this routine
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* by having side effects on state that we cannot undo if
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* there is a collision on the seqlock and our caller has to
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* retry. (Namely, old_jifs and old_count.) So we must treat
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* jiffies as volatile despite the lock. We read jiffies
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* before latching the timer count to guarantee that although
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* the jiffies value might be older than the count (that is,
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* the counter may underflow between the last point where
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* jiffies was incremented and the point where we latch the
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* count), it cannot be newer.
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*/
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jifs = jiffies;
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/* read the count */
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count = __raw_readl(timer_base + PWM_CNT);
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/*
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* It's possible for count to appear to go the wrong way for this
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* reason:
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*
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* The timer counter underflows, but we haven't handled the resulting
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* interrupt and incremented jiffies yet.
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*
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* Previous attempts to handle these cases intelligently were buggy, so
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* we just do the simple thing now.
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*/
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if (count < old_count && jifs == old_jifs)
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count = old_count;
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old_count = count;
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old_jifs = jifs;
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raw_spin_unlock_irqrestore(&ls1x_timer_lock, flags);
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return (cycle_t) (jifs * ls1x_jiffies_per_tick) + count;
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}
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static struct clocksource ls1x_clocksource = {
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.name = "ls1x-pwmtimer",
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.read = ls1x_clocksource_read,
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.mask = CLOCKSOURCE_MASK(24),
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.flags = CLOCK_SOURCE_IS_CONTINUOUS,
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};
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static irqreturn_t ls1x_clockevent_isr(int irq, void *devid)
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{
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struct clock_event_device *cd = devid;
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ls1x_pwmtimer_restart();
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cd->event_handler(cd);
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return IRQ_HANDLED;
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}
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static void ls1x_clockevent_set_mode(enum clock_event_mode mode,
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struct clock_event_device *cd)
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{
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raw_spin_lock(&ls1x_timer_lock);
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switch (mode) {
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case CLOCK_EVT_MODE_PERIODIC:
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ls1x_pwmtimer_set_period(ls1x_jiffies_per_tick);
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ls1x_pwmtimer_restart();
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case CLOCK_EVT_MODE_RESUME:
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__raw_writel(INT_EN | CNT_EN, timer_base + PWM_CTRL);
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break;
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case CLOCK_EVT_MODE_ONESHOT:
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case CLOCK_EVT_MODE_SHUTDOWN:
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__raw_writel(__raw_readl(timer_base + PWM_CTRL) & ~CNT_EN,
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timer_base + PWM_CTRL);
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break;
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default:
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break;
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}
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raw_spin_unlock(&ls1x_timer_lock);
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}
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static int ls1x_clockevent_set_next(unsigned long evt,
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struct clock_event_device *cd)
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{
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raw_spin_lock(&ls1x_timer_lock);
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ls1x_pwmtimer_set_period(evt);
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ls1x_pwmtimer_restart();
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raw_spin_unlock(&ls1x_timer_lock);
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return 0;
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}
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static struct clock_event_device ls1x_clockevent = {
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.name = "ls1x-pwmtimer",
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.features = CLOCK_EVT_FEAT_PERIODIC,
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.rating = 300,
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.irq = LS1X_TIMER_IRQ,
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.set_next_event = ls1x_clockevent_set_next,
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.set_mode = ls1x_clockevent_set_mode,
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};
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static struct irqaction ls1x_pwmtimer_irqaction = {
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.name = "ls1x-pwmtimer",
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.handler = ls1x_clockevent_isr,
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.dev_id = &ls1x_clockevent,
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.flags = IRQF_PERCPU | IRQF_TIMER,
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};
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static void __init ls1x_time_init(void)
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{
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struct clock_event_device *cd = &ls1x_clockevent;
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int ret;
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if (!mips_hpt_frequency)
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panic("Invalid timer clock rate");
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ls1x_pwmtimer_init();
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clockevent_set_clock(cd, mips_hpt_frequency);
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cd->max_delta_ns = clockevent_delta2ns(0xffffff, cd);
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cd->min_delta_ns = clockevent_delta2ns(0x000300, cd);
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cd->cpumask = cpumask_of(smp_processor_id());
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clockevents_register_device(cd);
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ls1x_clocksource.rating = 200 + mips_hpt_frequency / 10000000;
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ret = clocksource_register_hz(&ls1x_clocksource, mips_hpt_frequency);
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if (ret)
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panic(KERN_ERR "Failed to register clocksource: %d\n", ret);
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setup_irq(LS1X_TIMER_IRQ, &ls1x_pwmtimer_irqaction);
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}
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#endif /* CONFIG_CEVT_CSRC_LS1X */
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void __init plat_time_init(void)
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{
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struct clk *clk = NULL;
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/* initialize LS1X clocks */
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ls1x_clk_init();
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#ifdef CONFIG_CEVT_CSRC_LS1X
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/* setup LS1X PWM timer */
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clk = clk_get(NULL, "ls1x_pwmtimer");
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if (IS_ERR(clk))
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panic("unable to get timer clock, err=%ld", PTR_ERR(clk));
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mips_hpt_frequency = clk_get_rate(clk);
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ls1x_time_init();
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#else
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/* setup mips r4k timer */
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clk = clk_get(NULL, "cpu_clk");
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if (IS_ERR(clk))
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panic("unable to get cpu clock, err=%ld", PTR_ERR(clk));
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mips_hpt_frequency = clk_get_rate(clk) / 2;
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#endif /* CONFIG_CEVT_CSRC_LS1X */
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}
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