linux-imx

/*

 * Copyright 2012-2013 Freescale Semiconductor, Inc.

 *

 * 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.

 */

​

#include <linux/interrupt.h>

#include <linux/clockchips.h>

#include <linux/clk.h>

#include <linux/of_address.h>

#include <linux/of_irq.h>

#include <linux/sched_clock.h>

​

/*

 * Each pit takes 0x10 Bytes register space

 */

#define PITMCR      0x00

#define PIT0_OFFSET 0x100

#define PITn_OFFSET(n)  (PIT0_OFFSET + 0x10 * (n))

#define PITLDVAL    0x00

#define PITCVAL     0x04

#define PITTCTRL    0x08

#define PITTFLG     0x0c

​

#define PITMCR_MDIS (0x1 << 1)

​

#define PITTCTRL_TEN    (0x1 << 0)

#define PITTCTRL_TIE    (0x1 << 1)

#define PITCTRL_CHN (0x1 << 2)

​

#define PITTFLG_TIF 0x1

​

static void __iomem *clksrc_base;

static void __iomem *clkevt_base;

static unsigned long cycle_per_jiffy;

​

static inline void pit_timer_enable(void)

{

    __raw_writel(PITTCTRL_TEN | PITTCTRL_TIE, clkevt_base + PITTCTRL);

}

​

static inline void pit_timer_disable(void)

{

    __raw_writel(0, clkevt_base + PITTCTRL);

}

​

static inline void pit_irq_acknowledge(void)

{

    __raw_writel(PITTFLG_TIF, clkevt_base + PITTFLG);

}

​

static u64 notrace pit_read_sched_clock(void)

{

    return ~__raw_readl(clksrc_base + PITCVAL);

}

​

static int __init pit_clocksource_init(unsigned long rate)

{

    /* set the max load value and start the clock source counter */

    __raw_writel(0, clksrc_base + PITTCTRL);

    __raw_writel(~0UL, clksrc_base + PITLDVAL);

    __raw_writel(PITTCTRL_TEN, clksrc_base + PITTCTRL);

​

    sched_clock_register(pit_read_sched_clock, 32, rate);

    return clocksource_mmio_init(clksrc_base + PITCVAL, "vf-pit", rate,

            300, 32, clocksource_mmio_readl_down);

}

​

static int pit_set_next_event(unsigned long delta,

                struct clock_event_device *unused)

{

    /*

     * set a new value to PITLDVAL register will not restart the timer,

     * to abort the current cycle and start a timer period with the new

     * value, the timer must be disabled and enabled again.

     * and the PITLAVAL should be set to delta minus one according to pit

     * hardware requirement.

     */

    pit_timer_disable();

    __raw_writel(delta - 1, clkevt_base + PITLDVAL);

    pit_timer_enable();

​

    return 0;

}

​

static int pit_shutdown(struct clock_event_device *evt)

{

    pit_timer_disable();

    return 0;