pl080.c

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/*
 * arch/arm/plat-spear/pl080.c
 *
 * DMAC pl080 definitions for SPEAr platform
 *
 * Copyright (C) 2012 ST Microelectronics
 * Viresh Kumar <[email protected]>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/amba/pl08x.h>
#include <linux/amba/bus.h>
#include <linux/bug.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/spinlock_types.h>
#include <mach/spear.h>
#include <mach/misc_regs.h>

static spinlock_t lock = __SPIN_LOCK_UNLOCKED(x);

struct {
    unsigned char busy;
    unsigned char val;
} signals[16] = {{0, 0}, };

int pl080_get_signal(const struct pl08x_channel_data *cd)
{
    unsigned int signal = cd->min_signal, val;
    unsigned long flags;

    spin_lock_irqsave(&lock, flags);

    /* Return if signal is already acquired by somebody else */
    if (signals[signal].busy &&
            (signals[signal].val != cd->muxval)) {
        spin_unlock_irqrestore(&lock, flags);
        return -EBUSY;
    }

    /* If acquiring for the first time, configure it */
    if (!signals[signal].busy) {
        val = readl(DMA_CHN_CFG);

        /*
         * Each request line has two bits in DMA_CHN_CFG register. To
         * goto the bits of current request line, do left shift of
         * value by 2 * signal number.
         */
        val &= ~(0x3 << (signal * 2));
        val |= cd->muxval << (signal * 2);
        writel(val, DMA_CHN_CFG);
    }

    signals[signal].busy++;
    signals[signal].val = cd->muxval;
    spin_unlock_irqrestore(&lock, flags);

    return signal;
}

void pl080_put_signal(const struct pl08x_channel_data *cd, int signal)
{
    unsigned long flags;

    spin_lock_irqsave(&lock, flags);

    /* if signal is not used */
    if (!signals[signal].busy)
        BUG();

    signals[signal].busy--;

    spin_unlock_irqrestore(&lock, flags);
}