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133 lines
3.2 KiB
C
133 lines
3.2 KiB
C
/*
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* Moschip MCS814x timer routines
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*
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* Copyright (C) 2012, Florian Fainelli <florian@openwrt.org>
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*
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* Licensed under GPLv2
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*/
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#include <linux/kernel.h>
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#include <linux/interrupt.h>
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#include <linux/time.h>
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#include <linux/timex.h>
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#include <linux/irq.h>
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#include <linux/err.h>
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#include <linux/clk.h>
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#include <linux/io.h>
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#include <linux/of.h>
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#include <linux/of_address.h>
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#include <asm/mach/time.h>
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#include <mach/mcs814x.h>
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/* Timer block registers */
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#define TIMER_VAL 0x00
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#define TIMER_CTL 0x04
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#define TIMER_CTL_EN 0x01
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#define TIMER_CTL_DBG 0x02
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static u32 last_reload;
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static u32 timer_correct;
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static u32 clock_rate;
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static u32 timer_reload_value;
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static void __iomem *mcs814x_timer_base;
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static inline u32 ticks2usecs(u32 x)
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{
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return x / (clock_rate / 1000000);
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}
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/*
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* Returns number of ms since last clock interrupt. Note that interrupts
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* will have been disabled by do_gettimeoffset()
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*/
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static u32 mcs814x_gettimeoffset(void)
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{
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u32 ticks = readl_relaxed(mcs814x_timer_base + TIMER_VAL);
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if (ticks < last_reload)
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return ticks2usecs(ticks + (u32)(0xffffffff - last_reload));
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else
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return ticks2usecs(ticks - last_reload);
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}
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static irqreturn_t mcs814x_timer_interrupt(int irq, void *dev_id)
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{
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u32 count = readl_relaxed(mcs814x_timer_base + TIMER_VAL);
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/* take into account delay up to this moment */
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last_reload = count + timer_correct + timer_reload_value;
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if (last_reload < timer_reload_value) {
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last_reload = timer_reload_value;
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} else {
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if (timer_correct == 0)
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timer_correct = readl_relaxed(mcs814x_timer_base + TIMER_VAL) - count;
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}
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writel_relaxed(last_reload, mcs814x_timer_base + TIMER_VAL);
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timer_tick();
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return IRQ_HANDLED;
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}
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static struct irqaction mcs814x_timer_irq = {
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.name = "mcs814x-timer",
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.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
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.handler = mcs814x_timer_interrupt,
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};
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static struct of_device_id mcs814x_timer_ids[] = {
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{ .compatible = "moschip,mcs814x-timer" },
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{ /* sentinel */ },
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};
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static void __init mcs814x_of_timer_init(void)
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{
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struct device_node *np;
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const unsigned int *intspec;
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np = of_find_matching_node(NULL, mcs814x_timer_ids);
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if (!np)
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panic("unable to find compatible timer node in dtb");
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mcs814x_timer_base = of_iomap(np, 0);
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if (!mcs814x_timer_base)
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panic("unable to remap timer cpu registers");
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intspec = of_get_property(np, "interrupts", NULL);
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if (!intspec)
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panic("no interrupts property for timer");
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mcs814x_timer_irq.irq = be32_to_cpup(intspec);
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}
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void __init mcs814x_timer_init(void)
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{
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struct clk *clk;
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arch_gettimeoffset = mcs814x_gettimeoffset;
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clk = clk_get_sys("timer0", NULL);
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if (IS_ERR_OR_NULL(clk))
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panic("unable to get timer0 clock");
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clock_rate = clk_get_rate(clk);
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mcs814x_of_timer_init();
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pr_info("Timer frequency: %d (kHz)\n", clock_rate / 1000);
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timer_reload_value = 0xffffffff - (clock_rate / HZ);
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/* disable timer */
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writel_relaxed(~TIMER_CTL_EN, mcs814x_timer_base + TIMER_CTL);
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writel_relaxed(timer_reload_value, mcs814x_timer_base + TIMER_VAL);
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last_reload = timer_reload_value;
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setup_irq(mcs814x_timer_irq.irq, &mcs814x_timer_irq);
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/* enable timer, stop timer in debug mode */
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writel_relaxed(TIMER_CTL_EN | TIMER_CTL_DBG,
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mcs814x_timer_base + TIMER_CTL);
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}
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