// SPDX-License-Identifier: GPL-2.0
/*
 * arch/sh/drivers/dma/dma-api.c
 *
 * SuperH-specific DMA management API
 *
 * Copyright (C) 2003, 2004, 2005  Paul Mundt
 */
#include <linux/init.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/list.h>
#include <linux/platform_device.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <asm/dma.h>

DEFINE_SPINLOCK(dma_spin_lock);
static LIST_HEAD(registered_dmac_list);

struct dma_info *get_dma_info(unsigned int chan)
{
        struct dma_info *info;

        /*
         * Look for each DMAC's range to determine who the owner of
         * the channel is.
         */
        list_for_each_entry(info, &registered_dmac_list, list) {
                if ((chan <  info->first_vchannel_nr) ||
                    (chan >= info->first_vchannel_nr + info->nr_channels))
                        continue;

                return info;
        }

        return NULL;
}
EXPORT_SYMBOL(get_dma_info);

static unsigned int get_nr_channels(void)
{
        struct dma_info *info;
        unsigned int nr = 0;

        if (unlikely(list_empty(&registered_dmac_list)))
                return nr;

        list_for_each_entry(info, &registered_dmac_list, list)
                nr += info->nr_channels;

        return nr;
}

struct dma_channel *get_dma_channel(unsigned int chan)
{
        struct dma_info *info = get_dma_info(chan);
        struct dma_channel *channel;
        int i;

        if (unlikely(!info))
                return ERR_PTR(-EINVAL);

        for (i = 0; i < info->nr_channels; i++) {
                channel = &info->channels[i];
                if (channel->vchan == chan)
                        return channel;
        }

        return NULL;
}
EXPORT_SYMBOL(get_dma_channel);

int get_dma_residue(unsigned int chan)
{
        struct dma_info *info = get_dma_info(chan);
        struct dma_channel *channel = get_dma_channel(chan);

        if (info->ops->get_residue)
                return info->ops->get_residue(channel);

        return 0;
}
EXPORT_SYMBOL(get_dma_residue);

int request_dma(unsigned int chan, const char *dev_id)
{
        struct dma_channel *channel = { 0 };
        struct dma_info *info = get_dma_info(chan);
        int result;

        channel = get_dma_channel(chan);
        if (atomic_xchg(&channel->busy, 1))
                return -EBUSY;

        strscpy(channel->dev_id, dev_id, sizeof(channel->dev_id));

        if (info->ops->request) {
                result = info->ops->request(channel);
                if (result)
                        atomic_set(&channel->busy, 0);

                return result;
        }

        return 0;
}
EXPORT_SYMBOL(request_dma);

void free_dma(unsigned int chan)
{
        struct dma_info *info = get_dma_info(chan);
        struct dma_channel *channel = get_dma_channel(chan);

        if (info->ops->free)
                info->ops->free(channel);

        atomic_set(&channel->busy, 0);
}
EXPORT_SYMBOL(free_dma);

void dma_wait_for_completion(unsigned int chan)
{
        struct dma_info *info = get_dma_info(chan);
        struct dma_channel *channel = get_dma_channel(chan);

        if (channel->flags & DMA_TEI_CAPABLE) {
                wait_event(channel->wait_queue,
                           (info->ops->get_residue(channel) == 0));
                return;
        }

        while (info->ops->get_residue(channel))
                cpu_relax();
}
EXPORT_SYMBOL(dma_wait_for_completion);

void dma_configure_channel(unsigned int chan, unsigned long flags)
{
        struct dma_info *info = get_dma_info(chan);
        struct dma_channel *channel = get_dma_channel(chan);

        if (info->ops->configure)
                info->ops->configure(channel, flags);
}
EXPORT_SYMBOL(dma_configure_channel);

int dma_xfer(unsigned int chan, unsigned long from,
             unsigned long to, size_t size, unsigned int mode)
{
        struct dma_info *info = get_dma_info(chan);
        struct dma_channel *channel = get_dma_channel(chan);

        channel->sar    = from;
        channel->dar    = to;
        channel->count  = size;
        channel->mode   = mode;

        return info->ops->xfer(channel);
}
EXPORT_SYMBOL(dma_xfer);

static int dma_proc_show(struct seq_file *m, void *v)
{
        struct dma_info *info = v;

        if (list_empty(&registered_dmac_list))
                return 0;

        /*
         * Iterate over each registered DMAC
         */
        list_for_each_entry(info, &registered_dmac_list, list) {
                int i;

                /*
                 * Iterate over each channel
                 */
                for (i = 0; i < info->nr_channels; i++) {
                        struct dma_channel *channel = info->channels + i;

                        if (!(channel->flags & DMA_CONFIGURED))
                                continue;

                        seq_printf(m, "%2d: %14s    %s\n", i,
                                   info->name, channel->dev_id);
                }
        }

        return 0;
}

int register_dmac(struct dma_info *info)
{
        unsigned int total_channels, i;

        INIT_LIST_HEAD(&info->list);

        printk(KERN_INFO "DMA: Registering %s handler (%d channel%s).\n",
               info->name, info->nr_channels, info->nr_channels > 1 ? "s" : "");

        BUG_ON((info->flags & DMAC_CHANNELS_CONFIGURED) && !info->channels);

        info->pdev = platform_device_register_simple(info->name, -1,
                                                     NULL, 0);
        if (IS_ERR(info->pdev))
                return PTR_ERR(info->pdev);

        /*
         * Don't touch pre-configured channels
         */
        if (!(info->flags & DMAC_CHANNELS_CONFIGURED)) {
                unsigned int size;

                size = sizeof(struct dma_channel) * info->nr_channels;

                info->channels = kzalloc(size, GFP_KERNEL);
                if (!info->channels)
                        return -ENOMEM;
        }

        total_channels = get_nr_channels();
        info->first_vchannel_nr = total_channels;
        for (i = 0; i < info->nr_channels; i++) {
                struct dma_channel *chan = &info->channels[i];

                atomic_set(&chan->busy, 0);

                chan->chan  = info->first_channel_nr + i;
                chan->vchan = info->first_channel_nr + i + total_channels;

                memcpy(chan->dev_id, "Unused", 7);

                if (info->flags & DMAC_CHANNELS_TEI_CAPABLE)
                        chan->flags |= DMA_TEI_CAPABLE;

                init_waitqueue_head(&chan->wait_queue);
                dma_create_sysfs_files(chan, info);
        }

        list_add(&info->list, &registered_dmac_list);

        return 0;
}
EXPORT_SYMBOL(register_dmac);

void unregister_dmac(struct dma_info *info)
{
        unsigned int i;

        for (i = 0; i < info->nr_channels; i++)
                dma_remove_sysfs_files(info->channels + i, info);

        if (!(info->flags & DMAC_CHANNELS_CONFIGURED))
                kfree(info->channels);

        list_del(&info->list);
        platform_device_unregister(info->pdev);
}
EXPORT_SYMBOL(unregister_dmac);

static int __init dma_api_init(void)
{
        printk(KERN_NOTICE "DMA: Registering DMA API.\n");
        return proc_create_single("dma", 0, NULL, dma_proc_show) ? 0 : -ENOMEM;
}
subsys_initcall(dma_api_init);

MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
MODULE_DESCRIPTION("DMA API for SuperH");
MODULE_LICENSE("GPL v2");