linux-imx

/*

 * Clocksource using the Low Power Timer found in the Low Power Controller (LPC)

 *

 * Copyright (C) 2015 STMicroelectronics – All Rights Reserved

 *

 * Author(s): Francesco Virlinzi <francesco.virlinzi@st.com>

 *        Ajit Pal Singh <ajitpal.singh@st.com>

 *

 * 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/clk.h>

#include <linux/clocksource.h>

#include <linux/init.h>

#include <linux/of_address.h>

#include <linux/sched_clock.h>

#include <linux/slab.h>

​

#include <dt-bindings/mfd/st-lpc.h>

​

/* Low Power Timer */

#define LPC_LPT_LSB_OFF     0x400

#define LPC_LPT_MSB_OFF     0x404

#define LPC_LPT_START_OFF   0x408

​

static struct st_clksrc_ddata {

    struct clk      *clk;

    void __iomem        *base;

} ddata;

​

static void __init st_clksrc_reset(void)

{

    writel_relaxed(0, ddata.base + LPC_LPT_START_OFF);

    writel_relaxed(0, ddata.base + LPC_LPT_MSB_OFF);

    writel_relaxed(0, ddata.base + LPC_LPT_LSB_OFF);

    writel_relaxed(1, ddata.base + LPC_LPT_START_OFF);

}

​

static u64 notrace st_clksrc_sched_clock_read(void)

{

    return (u64)readl_relaxed(ddata.base + LPC_LPT_LSB_OFF);

}

​

static int __init st_clksrc_init(void)

{

    unsigned long rate;

    int ret;

​

    st_clksrc_reset();

​

    rate = clk_get_rate(ddata.clk);

​

    sched_clock_register(st_clksrc_sched_clock_read, 32, rate);

​

    ret = clocksource_mmio_init(ddata.base + LPC_LPT_LSB_OFF,

                    "clksrc-st-lpc", rate, 300, 32,

                    clocksource_mmio_readl_up);

    if (ret) {

        pr_err("clksrc-st-lpc: Failed to register clocksource\n");

        return ret;