// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  ISA DMA support functions
 *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
 */

/*
 * Defining following add some delay. Maybe this helps for some broken
 * ISA DMA controllers.
 */

#undef HAVE_REALLY_SLOW_DMA_CONTROLLER

#include <linux/export.h>
#include <linux/isa-dma.h>
#include <sound/core.h>

/**
 * snd_dma_program - program an ISA DMA transfer
 * @dma: the dma number
 * @addr: the physical address of the buffer
 * @size: the DMA transfer size
 * @mode: the DMA transfer mode, DMA_MODE_XXX
 *
 * Programs an ISA DMA transfer for the given buffer.
 */
void snd_dma_program(unsigned long dma,
                     unsigned long addr, unsigned int size,
                     unsigned short mode)
{
        unsigned long flags;

        flags = claim_dma_lock();
        disable_dma(dma);
        clear_dma_ff(dma);
        set_dma_mode(dma, mode);
        set_dma_addr(dma, addr);
        set_dma_count(dma, size);
        if (!(mode & DMA_MODE_NO_ENABLE))
                enable_dma(dma);
        release_dma_lock(flags);
}
EXPORT_SYMBOL(snd_dma_program);

/**
 * snd_dma_disable - stop the ISA DMA transfer
 * @dma: the dma number
 *
 * Stops the ISA DMA transfer.
 */
void snd_dma_disable(unsigned long dma)
{
        unsigned long flags;

        flags = claim_dma_lock();
        clear_dma_ff(dma);
        disable_dma(dma);
        release_dma_lock(flags);
}
EXPORT_SYMBOL(snd_dma_disable);

/**
 * snd_dma_pointer - return the current pointer to DMA transfer buffer in bytes
 * @dma: the dma number
 * @size: the dma transfer size
 *
 * Return: The current pointer in DMA transfer buffer in bytes.
 */
unsigned int snd_dma_pointer(unsigned long dma, unsigned int size)
{
        unsigned long flags;
        unsigned int result, result1;

        flags = claim_dma_lock();
        clear_dma_ff(dma);
        if (!isa_dma_bridge_buggy)
                disable_dma(dma);
        result = get_dma_residue(dma);
        /*
         * HACK - read the counter again and choose higher value in order to
         * avoid reading during counter lower byte roll over if the
         * isa_dma_bridge_buggy is set.
         */
        result1 = get_dma_residue(dma);
        if (!isa_dma_bridge_buggy)
                enable_dma(dma);
        release_dma_lock(flags);
        if (unlikely(result < result1))
                result = result1;
#ifdef CONFIG_SND_DEBUG
        if (result > size)
                pr_err("ALSA: pointer (0x%x) for DMA #%ld is greater than transfer size (0x%x)\n", result, dma, size);
#endif
        if (result >= size || result == 0)
                return 0;
        else
                return size - result;
}
EXPORT_SYMBOL(snd_dma_pointer);

struct snd_dma_data {
        int dma;
};

static void __snd_release_dma(struct device *dev, void *data)
{
        struct snd_dma_data *p = data;

        snd_dma_disable(p->dma);
        free_dma(p->dma);
}

/**
 * snd_devm_request_dma - the managed version of request_dma()
 * @dev: the device pointer
 * @dma: the dma number
 * @name: the name string of the requester
 *
 * The requested DMA will be automatically released at unbinding via devres.
 *
 * Return: zero on success, or a negative error code
 */
int snd_devm_request_dma(struct device *dev, int dma, const char *name)
{
        struct snd_dma_data *p;

        if (request_dma(dma, name))
                return -EBUSY;
        p = devres_alloc(__snd_release_dma, sizeof(*p), GFP_KERNEL);
        if (!p) {
                free_dma(dma);
                return -ENOMEM;
        }
        p->dma = dma;
        devres_add(dev, p);
        return 0;
}
EXPORT_SYMBOL_GPL(snd_devm_request_dma);