linux-imx

/*

 * Copyright (C) ST-Ericsson SA 2011

 *

 * License Terms: GNU General Public License v2

 * Author: Mattias Wallin <mattias.wallin@stericsson.com> for ST-Ericsson

 * Author: Sundar Iyer for ST-Ericsson

 * sched_clock implementation is based on:

 * plat-nomadik/timer.c Linus Walleij <linus.walleij@stericsson.com>

 *

 * DBx500-PRCMU Timer

 * The PRCMU has 5 timers which are available in a always-on

 * power domain.  We use the Timer 4 for our always-on clock

 * source on DB8500.

 */

#include <linux/of.h>

#include <linux/of_address.h>

#include <linux/clockchips.h>

​

#define RATE_32K        32768

​

#define TIMER_MODE_CONTINOUS    0x1

#define TIMER_DOWNCOUNT_VAL 0xffffffff

​

#define PRCMU_TIMER_REF     0

#define PRCMU_TIMER_DOWNCOUNT   0x4

#define PRCMU_TIMER_MODE    0x8

​

static void __iomem *clksrc_dbx500_timer_base;

​

static u64 notrace clksrc_dbx500_prcmu_read(struct clocksource *cs)

{

    void __iomem *base = clksrc_dbx500_timer_base;

    u32 count, count2;

​

    do {

        count = readl_relaxed(base + PRCMU_TIMER_DOWNCOUNT);

        count2 = readl_relaxed(base + PRCMU_TIMER_DOWNCOUNT);

    } while (count2 != count);

​

    /* Negate because the timer is a decrementing counter */

    return ~count;

}

​

static struct clocksource clocksource_dbx500_prcmu = {

    .name       = "dbx500-prcmu-timer",

    .rating     = 100,

    .read       = clksrc_dbx500_prcmu_read,

    .mask       = CLOCKSOURCE_MASK(32),

    .flags      = CLOCK_SOURCE_IS_CONTINUOUS | CLOCK_SOURCE_SUSPEND_NONSTOP,

};

​

static int __init clksrc_dbx500_prcmu_init(struct device_node *node)

{

    clksrc_dbx500_timer_base = of_iomap(node, 0);

​

    /*

     * The A9 sub system expects the timer to be configured as

     * a continous looping timer.

     * The PRCMU should configure it but if it for some reason

     * don't we do it here.

     */

    if (readl(clksrc_dbx500_timer_base + PRCMU_TIMER_MODE) !=

        TIMER_MODE_CONTINOUS) {