sh_mtu2.c

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/*
 * SuperH Timer Support - MTU2
 *
 *  Copyright (C) 2009 Magnus Damm
 *
 * 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
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/clk.h>
#include <linux/irq.h>
#include <linux/err.h>
#include <linux/clockchips.h>
#include <linux/sh_timer.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/pm_domain.h>
#include <linux/pm_runtime.h>

struct sh_mtu2_priv {
    void __iomem *mapbase;
    struct clk *clk;
    struct irqaction irqaction;
    struct platform_device *pdev;
    unsigned long rate;
    unsigned long periodic;
    struct clock_event_device ced;
};

static DEFINE_RAW_SPINLOCK(sh_mtu2_lock);

#define TSTR -1 /* shared register */
#define TCR  0 /* channel register */
#define TMDR 1 /* channel register */
#define TIOR 2 /* channel register */
#define TIER 3 /* channel register */
#define TSR  4 /* channel register */
#define TCNT 5 /* channel register */
#define TGR  6 /* channel register */

static unsigned long mtu2_reg_offs[] = {
    [TCR] = 0,
    [TMDR] = 1,
    [TIOR] = 2,
    [TIER] = 4,
    [TSR] = 5,
    [TCNT] = 6,
    [TGR] = 8,
};

static inline unsigned long sh_mtu2_read(struct sh_mtu2_priv *p, int reg_nr)
{
    struct sh_timer_config *cfg = p->pdev->dev.platform_data;
    void __iomem *base = p->mapbase;
    unsigned long offs;

    if (reg_nr == TSTR)
        return ioread8(base + cfg->channel_offset);

    offs = mtu2_reg_offs[reg_nr];

    if ((reg_nr == TCNT) || (reg_nr == TGR))
        return ioread16(base + offs);
    else
        return ioread8(base + offs);
}

static inline void sh_mtu2_write(struct sh_mtu2_priv *p, int reg_nr,
                unsigned long value)
{
    struct sh_timer_config *cfg = p->pdev->dev.platform_data;
    void __iomem *base = p->mapbase;
    unsigned long offs;

    if (reg_nr == TSTR) {
        iowrite8(value, base + cfg->channel_offset);
        return;
    }

    offs = mtu2_reg_offs[reg_nr];

    if ((reg_nr == TCNT) || (reg_nr == TGR))
        iowrite16(value, base + offs);
    else
        iowrite8(value, base + offs);
}

static void sh_mtu2_start_stop_ch(struct sh_mtu2_priv *p, int start)
{
    struct sh_timer_config *cfg = p->pdev->dev.platform_data;
    unsigned long flags, value;

    /* start stop register shared by multiple timer channels */
    raw_spin_lock_irqsave(&sh_mtu2_lock, flags);
    value = sh_mtu2_read(p, TSTR);

    if (start)
        value |= 1 << cfg->timer_bit;
    else
        value &= ~(1 << cfg->timer_bit);

    sh_mtu2_write(p, TSTR, value);
    raw_spin_unlock_irqrestore(&sh_mtu2_lock, flags);
}

static int sh_mtu2_enable(struct sh_mtu2_priv *p)
{
    int ret;

    pm_runtime_get_sync(&p->pdev->dev);
    dev_pm_syscore_device(&p->pdev->dev, true);

    /* enable clock */
    ret = clk_enable(p->clk);
    if (ret) {
        dev_err(&p->pdev->dev, "cannot enable clock\n");
        return ret;
    }

    /* make sure channel is disabled */
    sh_mtu2_start_stop_ch(p, 0);

    p->rate = clk_get_rate(p->clk) / 64;
    p->periodic = (p->rate + HZ/2) / HZ;

    /* "Periodic Counter Operation" */
    sh_mtu2_write(p, TCR, 0x23); /* TGRA clear, divide clock by 64 */
    sh_mtu2_write(p, TIOR, 0);
    sh_mtu2_write(p, TGR, p->periodic);
    sh_mtu2_write(p, TCNT, 0);
    sh_mtu2_write(p, TMDR, 0);
    sh_mtu2_write(p, TIER, 0x01);

    /* enable channel */
    sh_mtu2_start_stop_ch(p, 1);

    return 0;
}

static void sh_mtu2_disable(struct sh_mtu2_priv *p)
{
    /* disable channel */
    sh_mtu2_start_stop_ch(p, 0);

    /* stop clock */
    clk_disable(p->clk);

    dev_pm_syscore_device(&p->pdev->dev, false);
    pm_runtime_put(&p->pdev->dev);
}

static irqreturn_t sh_mtu2_interrupt(int irq, void *dev_id)
{
    struct sh_mtu2_priv *p = dev_id;

    /* acknowledge interrupt */
    sh_mtu2_read(p, TSR);
    sh_mtu2_write(p, TSR, 0xfe);

    /* notify clockevent layer */
    p->ced.event_handler(&p->ced);
    return IRQ_HANDLED;
}

static struct sh_mtu2_priv *ced_to_sh_mtu2(struct clock_event_device *ced)
{
    return container_of(ced, struct sh_mtu2_priv, ced);
}

static void sh_mtu2_clock_event_mode(enum clock_event_mode mode,
                    struct clock_event_device *ced)
{
    struct sh_mtu2_priv *p = ced_to_sh_mtu2(ced);
    int disabled = 0;

    /* deal with old setting first */
    switch (ced->mode) {
    case CLOCK_EVT_MODE_PERIODIC:
        sh_mtu2_disable(p);
        disabled = 1;
        break;
    default:
        break;
    }

    switch (mode) {
    case CLOCK_EVT_MODE_PERIODIC:
        dev_info(&p->pdev->dev, "used for periodic clock events\n");
        sh_mtu2_enable(p);
        break;
    case CLOCK_EVT_MODE_UNUSED:
        if (!disabled)
            sh_mtu2_disable(p);
        break;
    case CLOCK_EVT_MODE_SHUTDOWN:
    default:
        break;
    }
}

static void sh_mtu2_clock_event_suspend(struct clock_event_device *ced)
{
    pm_genpd_syscore_poweroff(&ced_to_sh_mtu2(ced)->pdev->dev);
}

static void sh_mtu2_clock_event_resume(struct clock_event_device *ced)
{
    pm_genpd_syscore_poweron(&ced_to_sh_mtu2(ced)->pdev->dev);
}

static void sh_mtu2_register_clockevent(struct sh_mtu2_priv *p,
                       char *name, unsigned long rating)
{
    struct clock_event_device *ced = &p->ced;
    int ret;

    memset(ced, 0, sizeof(*ced));

    ced->name = name;
    ced->features = CLOCK_EVT_FEAT_PERIODIC;
    ced->rating = rating;
    ced->cpumask = cpumask_of(0);
    ced->set_mode = sh_mtu2_clock_event_mode;
    ced->suspend = sh_mtu2_clock_event_suspend;
    ced->resume = sh_mtu2_clock_event_resume;

    dev_info(&p->pdev->dev, "used for clock events\n");
    clockevents_register_device(ced);

    ret = setup_irq(p->irqaction.irq, &p->irqaction);
    if (ret) {
        dev_err(&p->pdev->dev, "failed to request irq %d\n",
            p->irqaction.irq);
        return;
    }
}

static int sh_mtu2_register(struct sh_mtu2_priv *p, char *name,
                unsigned long clockevent_rating)
{
    if (clockevent_rating)
        sh_mtu2_register_clockevent(p, name, clockevent_rating);

    return 0;
}

static int sh_mtu2_setup(struct sh_mtu2_priv *p, struct platform_device *pdev)
{
    struct sh_timer_config *cfg = pdev->dev.platform_data;
    struct resource *res;
    int irq, ret;
    ret = -ENXIO;

    memset(p, 0, sizeof(*p));
    p->pdev = pdev;

    if (!cfg) {
        dev_err(&p->pdev->dev, "missing platform data\n");
        goto err0;
    }

    platform_set_drvdata(pdev, p);

    res = platform_get_resource(p->pdev, IORESOURCE_MEM, 0);
    if (!res) {
        dev_err(&p->pdev->dev, "failed to get I/O memory\n");
        goto err0;
    }

    irq = platform_get_irq(p->pdev, 0);
    if (irq < 0) {
        dev_err(&p->pdev->dev, "failed to get irq\n");
        goto err0;
    }

    /* map memory, let mapbase point to our channel */
    p->mapbase = ioremap_nocache(res->start, resource_size(res));
    if (p->mapbase == NULL) {
        dev_err(&p->pdev->dev, "failed to remap I/O memory\n");
        goto err0;
    }

    /* setup data for setup_irq() (too early for request_irq()) */
    p->irqaction.name = dev_name(&p->pdev->dev);
    p->irqaction.handler = sh_mtu2_interrupt;
    p->irqaction.dev_id = p;
    p->irqaction.irq = irq;
    p->irqaction.flags = IRQF_DISABLED | IRQF_TIMER | \
                 IRQF_IRQPOLL  | IRQF_NOBALANCING;

    /* get hold of clock */
    p->clk = clk_get(&p->pdev->dev, "mtu2_fck");
    if (IS_ERR(p->clk)) {
        dev_err(&p->pdev->dev, "cannot get clock\n");
        ret = PTR_ERR(p->clk);
        goto err1;
    }

    return sh_mtu2_register(p, (char *)dev_name(&p->pdev->dev),
                cfg->clockevent_rating);
 err1:
    iounmap(p->mapbase);
 err0:
    return ret;
}

static int __devinit sh_mtu2_probe(struct platform_device *pdev)
{
    struct sh_mtu2_priv *p = platform_get_drvdata(pdev);
    struct sh_timer_config *cfg = pdev->dev.platform_data;
    int ret;

    if (!is_early_platform_device(pdev)) {
        pm_runtime_set_active(&pdev->dev);
        pm_runtime_enable(&pdev->dev);
    }

    if (p) {
        dev_info(&pdev->dev, "kept as earlytimer\n");
        goto out;
    }

    p = kmalloc(sizeof(*p), GFP_KERNEL);
    if (p == NULL) {
        dev_err(&pdev->dev, "failed to allocate driver data\n");
        return -ENOMEM;
    }

    ret = sh_mtu2_setup(p, pdev);
    if (ret) {
        kfree(p);
        platform_set_drvdata(pdev, NULL);
        pm_runtime_idle(&pdev->dev);
        return ret;
    }
    if (is_early_platform_device(pdev))
        return 0;

 out:
    if (cfg->clockevent_rating)
        pm_runtime_irq_safe(&pdev->dev);
    else
        pm_runtime_idle(&pdev->dev);

    return 0;
}

static int __devexit sh_mtu2_remove(struct platform_device *pdev)
{
    return -EBUSY; /* cannot unregister clockevent */
}

static struct platform_driver sh_mtu2_device_driver = {
    .probe      = sh_mtu2_probe,
    .remove     = __devexit_p(sh_mtu2_remove),
    .driver     = {
        .name   = "sh_mtu2",
    }
};

static int __init sh_mtu2_init(void)
{
    return platform_driver_register(&sh_mtu2_device_driver);
}

static void __exit sh_mtu2_exit(void)
{
    platform_driver_unregister(&sh_mtu2_device_driver);
}

early_platform_init("earlytimer", &sh_mtu2_device_driver);
module_init(sh_mtu2_init);
module_exit(sh_mtu2_exit);

MODULE_AUTHOR("Magnus Damm");
MODULE_DESCRIPTION("SuperH MTU2 Timer Driver");
MODULE_LICENSE("GPL v2");