timer.c

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/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2008 Maxime Bizon <[email protected]>
 */

#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/clk.h>
#include <bcm63xx_cpu.h>
#include <bcm63xx_io.h>
#include <bcm63xx_timer.h>
#include <bcm63xx_regs.h>

static DEFINE_RAW_SPINLOCK(timer_reg_lock);
static DEFINE_RAW_SPINLOCK(timer_data_lock);
static struct clk *periph_clk;

static struct timer_data {
    void    (*cb)(void *);
    void    *data;
} timer_data[BCM63XX_TIMER_COUNT];

static irqreturn_t timer_interrupt(int irq, void *dev_id)
{
    u32 stat;
    int i;

    raw_spin_lock(&timer_reg_lock);
    stat = bcm_timer_readl(TIMER_IRQSTAT_REG);
    bcm_timer_writel(stat, TIMER_IRQSTAT_REG);
    raw_spin_unlock(&timer_reg_lock);

    for (i = 0; i < BCM63XX_TIMER_COUNT; i++) {
        if (!(stat & TIMER_IRQSTAT_TIMER_CAUSE(i)))
            continue;

        raw_spin_lock(&timer_data_lock);
        if (!timer_data[i].cb) {
            raw_spin_unlock(&timer_data_lock);
            continue;
        }

        timer_data[i].cb(timer_data[i].data);
        raw_spin_unlock(&timer_data_lock);
    }

    return IRQ_HANDLED;
}

int bcm63xx_timer_enable(int id)
{
    u32 reg;
    unsigned long flags;

    if (id >= BCM63XX_TIMER_COUNT)
        return -EINVAL;

    raw_spin_lock_irqsave(&timer_reg_lock, flags);

    reg = bcm_timer_readl(TIMER_CTLx_REG(id));
    reg |= TIMER_CTL_ENABLE_MASK;
    bcm_timer_writel(reg, TIMER_CTLx_REG(id));

    reg = bcm_timer_readl(TIMER_IRQSTAT_REG);
    reg |= TIMER_IRQSTAT_TIMER_IR_EN(id);
    bcm_timer_writel(reg, TIMER_IRQSTAT_REG);

    raw_spin_unlock_irqrestore(&timer_reg_lock, flags);
    return 0;
}

EXPORT_SYMBOL(bcm63xx_timer_enable);

int bcm63xx_timer_disable(int id)
{
    u32 reg;
    unsigned long flags;

    if (id >= BCM63XX_TIMER_COUNT)
        return -EINVAL;

    raw_spin_lock_irqsave(&timer_reg_lock, flags);

    reg = bcm_timer_readl(TIMER_CTLx_REG(id));
    reg &= ~TIMER_CTL_ENABLE_MASK;
    bcm_timer_writel(reg, TIMER_CTLx_REG(id));

    reg = bcm_timer_readl(TIMER_IRQSTAT_REG);
    reg &= ~TIMER_IRQSTAT_TIMER_IR_EN(id);
    bcm_timer_writel(reg, TIMER_IRQSTAT_REG);

    raw_spin_unlock_irqrestore(&timer_reg_lock, flags);
    return 0;
}

EXPORT_SYMBOL(bcm63xx_timer_disable);

int bcm63xx_timer_register(int id, void (*callback)(void *data), void *data)
{
    unsigned long flags;
    int ret;

    if (id >= BCM63XX_TIMER_COUNT || !callback)
        return -EINVAL;

    ret = 0;
    raw_spin_lock_irqsave(&timer_data_lock, flags);
    if (timer_data[id].cb) {
        ret = -EBUSY;
        goto out;
    }

    timer_data[id].cb = callback;
    timer_data[id].data = data;

out:
    raw_spin_unlock_irqrestore(&timer_data_lock, flags);
    return ret;
}

EXPORT_SYMBOL(bcm63xx_timer_register);

void bcm63xx_timer_unregister(int id)
{
    unsigned long flags;

    if (id >= BCM63XX_TIMER_COUNT)
        return;

    raw_spin_lock_irqsave(&timer_data_lock, flags);
    timer_data[id].cb = NULL;
    raw_spin_unlock_irqrestore(&timer_data_lock, flags);
}

EXPORT_SYMBOL(bcm63xx_timer_unregister);

unsigned int bcm63xx_timer_countdown(unsigned int countdown_us)
{
    return (clk_get_rate(periph_clk) / (1000 * 1000)) * countdown_us;
}

EXPORT_SYMBOL(bcm63xx_timer_countdown);

int bcm63xx_timer_set(int id, int monotonic, unsigned int countdown_us)
{
    u32 reg, countdown;
    unsigned long flags;

    if (id >= BCM63XX_TIMER_COUNT)
        return -EINVAL;

    countdown = bcm63xx_timer_countdown(countdown_us);
    if (countdown & ~TIMER_CTL_COUNTDOWN_MASK)
        return -EINVAL;

    raw_spin_lock_irqsave(&timer_reg_lock, flags);
    reg = bcm_timer_readl(TIMER_CTLx_REG(id));

    if (monotonic)
        reg &= ~TIMER_CTL_MONOTONIC_MASK;
    else
        reg |= TIMER_CTL_MONOTONIC_MASK;

    reg &= ~TIMER_CTL_COUNTDOWN_MASK;
    reg |= countdown;
    bcm_timer_writel(reg, TIMER_CTLx_REG(id));

    raw_spin_unlock_irqrestore(&timer_reg_lock, flags);
    return 0;
}

EXPORT_SYMBOL(bcm63xx_timer_set);

int bcm63xx_timer_init(void)
{
    int ret, irq;
    u32 reg;

    reg = bcm_timer_readl(TIMER_IRQSTAT_REG);
    reg &= ~TIMER_IRQSTAT_TIMER0_IR_EN;
    reg &= ~TIMER_IRQSTAT_TIMER1_IR_EN;
    reg &= ~TIMER_IRQSTAT_TIMER2_IR_EN;
    bcm_timer_writel(reg, TIMER_IRQSTAT_REG);

    periph_clk = clk_get(NULL, "periph");
    if (IS_ERR(periph_clk))
        return -ENODEV;

    irq = bcm63xx_get_irq_number(IRQ_TIMER);
    ret = request_irq(irq, timer_interrupt, 0, "bcm63xx_timer", NULL);
    if (ret) {
        printk(KERN_ERR "bcm63xx_timer: failed to register irq\n");
        return ret;
    }

    return 0;
}

arch_initcall(bcm63xx_timer_init);