linux-imx

// SPDX-License-Identifier: GPL-2.0

/*

 * Renesas Timer Support - OSTM

 *

 * Copyright (C) 2017 Renesas Electronics America, Inc.

 * Copyright (C) 2017 Chris Brandt

 */

​

#include <linux/of_address.h>

#include <linux/of_irq.h>

#include <linux/clk.h>

#include <linux/clockchips.h>

#include <linux/interrupt.h>

#include <linux/sched_clock.h>

#include <linux/slab.h>

​

/*

 * The OSTM contains independent channels.

 * The first OSTM channel probed will be set up as a free running

 * clocksource. Additionally we will use this clocksource for the system

 * schedule timer sched_clock().

 *

 * The second (or more) channel probed will be set up as an interrupt

 * driven clock event.

 */

​

struct ostm_device {

    void __iomem *base;

    unsigned long ticks_per_jiffy;

    struct clock_event_device ced;

};

​

static void __iomem *system_clock;  /* For sched_clock() */

​

/* OSTM REGISTERS */

#define OSTM_CMP        0x000   /* RW,32 */

#define OSTM_CNT        0x004   /* R,32 */

#define OSTM_TE         0x010   /* R,8 */

#define OSTM_TS         0x014   /* W,8 */

#define OSTM_TT         0x018   /* W,8 */

#define OSTM_CTL        0x020   /* RW,8 */

​

#define TE          0x01

#define TS          0x01

#define TT          0x01

#define CTL_PERIODIC        0x00

#define CTL_ONESHOT     0x02

#define CTL_FREERUN     0x02

​

static struct ostm_device *ced_to_ostm(struct clock_event_device *ced)

{

    return container_of(ced, struct ostm_device, ced);

}

​

static void ostm_timer_stop(struct ostm_device *ostm)

{

    if (readb(ostm->base + OSTM_TE) & TE) {

        writeb(TT, ostm->base + OSTM_TT);

​

        /*

         * Read back the register simply to confirm the write operation

         * has completed since I/O writes can sometimes get queued by

         * the bus architecture.