/*
 * 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 <mbizon@freebox.fr>
 */

#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/export.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);

static 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) {
                pr_err("%s: failed to register irq\n", __func__);
                return ret;
        }

        return 0;
}

arch_initcall(bcm63xx_timer_init);