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/*
* arch/arm/mach-lpc32xx/timer.c
*
* Author: Kevin Wells <kevin.wells@nxp.com>
*
* Copyright (C) 2009 - 2010 NXP Semiconductors
* Copyright (C) 2009 Fontys University of Applied Sciences, Eindhoven
* Ed Schouten <e.schouten@fontys.nl>
* Laurens Timmermans <l.timmermans@fontys.nl>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/time.h>
#include <linux/err.h>
#include <linux/clockchips.h>
#include <asm/mach/time.h>
#include <mach/hardware.h>
#include <mach/platform.h>
#include "common.h"
static int lpc32xx_clkevt_next_event(unsigned long delta,
struct clock_event_device *dev)
{
__raw_writel(LPC32XX_TIMER_CNTR_TCR_RESET,
LPC32XX_TIMER_TCR(LPC32XX_TIMER0_BASE));
__raw_writel(delta, LPC32XX_TIMER_PR(LPC32XX_TIMER0_BASE));
__raw_writel(LPC32XX_TIMER_CNTR_TCR_EN,
LPC32XX_TIMER_TCR(LPC32XX_TIMER0_BASE));
return 0;
}
static void lpc32xx_clkevt_mode(enum clock_event_mode mode,
struct clock_event_device *dev)
{
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
WARN_ON(1);
break;
case CLOCK_EVT_MODE_ONESHOT:
case CLOCK_EVT_MODE_SHUTDOWN:
/*
* Disable the timer. When using oneshot, we must also
* disable the timer to wait for the first call to
* set_next_event().
*/
__raw_writel(0, LPC32XX_TIMER_TCR(LPC32XX_TIMER0_BASE));
break;
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_RESUME:
break;
}
}
static struct clock_event_device lpc32xx_clkevt = {
.name = "lpc32xx_clkevt",
.features = CLOCK_EVT_FEAT_ONESHOT,
.shift = 32,
.rating = 300,
.set_next_event = lpc32xx_clkevt_next_event,
.set_mode = lpc32xx_clkevt_mode,
};
static irqreturn_t lpc32xx_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = &lpc32xx_clkevt;
/* Clear match */
__raw_writel(LPC32XX_TIMER_CNTR_MTCH_BIT(0),
LPC32XX_TIMER_IR(LPC32XX_TIMER0_BASE));
evt->event_handler(evt);
return IRQ_HANDLED;
}
static struct irqaction lpc32xx_timer_irq = {
.name = "LPC32XX Timer Tick",
.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
.handler = lpc32xx_timer_interrupt,
};
/*
* The clock management driver isn't initialized at this point, so the
* clocks need to be enabled here manually and then tagged as used in
* the clock driver initialization
*/
static void __init lpc32xx_timer_init(void)
{
u32 clkrate, pllreg;
/* Enable timer clock */
__raw_writel(LPC32XX_CLKPWR_TMRPWMCLK_TIMER0_EN |
LPC32XX_CLKPWR_TMRPWMCLK_TIMER1_EN,
LPC32XX_CLKPWR_TIMERS_PWMS_CLK_CTRL_1);
/*
* The clock driver isn't initialized at this point. So determine if
* the SYSCLK is driven from the PLL397 or main oscillator and then use
* it to compute the PLL frequency and the PCLK divider to get the base
* timer rates. This rate is needed to compute the tick rate.
*/
if (clk_is_sysclk_mainosc() != 0)
clkrate = LPC32XX_MAIN_OSC_FREQ;
else
clkrate = 397 * LPC32XX_CLOCK_OSC_FREQ;
/* Get ARM HCLKPLL register and convert it into a frequency */
pllreg = __raw_readl(LPC32XX_CLKPWR_HCLKPLL_CTRL) & 0x1FFFF;
clkrate = clk_get_pllrate_from_reg(clkrate, pllreg);
/* Get PCLK divider and divide ARM PLL clock by it to get timer rate */
clkrate = clkrate / clk_get_pclk_div();
/* Initial timer setup */
__raw_writel(0, LPC32XX_TIMER_TCR(LPC32XX_TIMER0_BASE));
__raw_writel(LPC32XX_TIMER_CNTR_MTCH_BIT(0),
LPC32XX_TIMER_IR(LPC32XX_TIMER0_BASE));
__raw_writel(1, LPC32XX_TIMER_MR0(LPC32XX_TIMER0_BASE));
__raw_writel(LPC32XX_TIMER_CNTR_MCR_MTCH(0) |
LPC32XX_TIMER_CNTR_MCR_STOP(0) |
LPC32XX_TIMER_CNTR_MCR_RESET(0),
LPC32XX_TIMER_MCR(LPC32XX_TIMER0_BASE));
/* Setup tick interrupt */
setup_irq(IRQ_LPC32XX_TIMER0, &lpc32xx_timer_irq);
/* Setup the clockevent structure. */
lpc32xx_clkevt.mult = div_sc(clkrate, NSEC_PER_SEC,
lpc32xx_clkevt.shift);
lpc32xx_clkevt.max_delta_ns = clockevent_delta2ns(-1,
&lpc32xx_clkevt);
lpc32xx_clkevt.min_delta_ns = clockevent_delta2ns(1,
&lpc32xx_clkevt) + 1;
lpc32xx_clkevt.cpumask = cpumask_of(0);
clockevents_register_device(&lpc32xx_clkevt);
/* Use timer1 as clock source. */
__raw_writel(LPC32XX_TIMER_CNTR_TCR_RESET,
LPC32XX_TIMER_TCR(LPC32XX_TIMER1_BASE));
__raw_writel(0, LPC32XX_TIMER_PR(LPC32XX_TIMER1_BASE));
__raw_writel(0, LPC32XX_TIMER_MCR(LPC32XX_TIMER1_BASE));
__raw_writel(LPC32XX_TIMER_CNTR_TCR_EN,
LPC32XX_TIMER_TCR(LPC32XX_TIMER1_BASE));
clocksource_mmio_init(LPC32XX_TIMER_TC(LPC32XX_TIMER1_BASE),
"lpc32xx_clksrc", clkrate, 300, 32, clocksource_mmio_readl_up);
}
struct sys_timer lpc32xx_timer = {
.init = &lpc32xx_timer_init,
};
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