/*
 * Freescale i.MX28 APBH DMA driver
 *
 * Copyright (C) 2011 Marek Vasut <marek.vasut@gmail.com>
 * on behalf of DENX Software Engineering GmbH
 *
 * Based on code from LTIB:
 * Copyright (C) 2010 Freescale Semiconductor, Inc. All Rights Reserved.
 *
 * SPDX-License-Identifier:     GPL-2.0+
 */

#include <linux/list.h>

#include <common.h>
#include <malloc.h>
#include <asm/errno.h>
#include <asm/io.h>
#include <asm/arch/clock.h>
#include <asm/arch/imx-regs.h>
#include <asm/arch/sys_proto.h>
#include <asm/imx-common/dma.h>
#include <asm/imx-common/regs-apbh.h>

static struct mxs_dma_chan mxs_dma_channels[MXS_MAX_DMA_CHANNELS];

/*
 * Test is the DMA channel is valid channel
 */
int mxs_dma_validate_chan(int channel)
{
        struct mxs_dma_chan *pchan;

        if ((channel < 0) || (channel >= MXS_MAX_DMA_CHANNELS))
                return -EINVAL;

        pchan = mxs_dma_channels + channel;
        if (!(pchan->flags & MXS_DMA_FLAGS_ALLOCATED))
                return -EINVAL;

        return 0;
}

/*
 * Return the address of the command within a descriptor.
 */
static unsigned int mxs_dma_cmd_address(struct mxs_dma_desc *desc)
{
        return desc->address + offsetof(struct mxs_dma_desc, cmd);
}

/*
 * Read a DMA channel's hardware semaphore.
 *
 * As used by the MXS platform's DMA software, the DMA channel's hardware
 * semaphore reflects the number of DMA commands the hardware will process, but
 * has not yet finished. This is a volatile value read directly from hardware,
 * so it must be be viewed as immediately stale.
 *
 * If the channel is not marked busy, or has finished processing all its
 * commands, this value should be zero.
 *
 * See mxs_dma_append() for details on how DMA command blocks must be configured
 * to maintain the expected behavior of the semaphore's value.
 */
static int mxs_dma_read_semaphore(int channel)
{
        struct mxs_apbh_regs *apbh_regs =
                (struct mxs_apbh_regs *)MXS_APBH_BASE;
        uint32_t tmp;
        int ret;

        ret = mxs_dma_validate_chan(channel);
        if (ret)
                return ret;

        tmp = readl(&apbh_regs->ch[channel].hw_apbh_ch_sema);

        tmp &= APBH_CHn_SEMA_PHORE_MASK;
        tmp >>= APBH_CHn_SEMA_PHORE_OFFSET;

        return tmp;
}

#ifndef CONFIG_SYS_DCACHE_OFF
void mxs_dma_flush_desc(struct mxs_dma_desc *desc)
{
        uint32_t addr;
        uint32_t size;

        addr = (uint32_t)desc;
        size = roundup(sizeof(struct mxs_dma_desc), MXS_DMA_ALIGNMENT);

        flush_dcache_range(addr, addr + size);
}
#else
inline void mxs_dma_flush_desc(struct mxs_dma_desc *desc) {}
#endif

/*
 * Enable a DMA channel.
 *
 * If the given channel has any DMA descriptors on its active list, this
 * function causes the DMA hardware to begin processing them.
 *
 * This function marks the DMA channel as "busy," whether or not there are any
 * descriptors to process.
 */
static int mxs_dma_enable(int channel)
{
        struct mxs_apbh_regs *apbh_regs =
                (struct mxs_apbh_regs *)MXS_APBH_BASE;
        unsigned int sem;
        struct mxs_dma_chan *pchan;
        struct mxs_dma_desc *pdesc;
        int ret;

        ret = mxs_dma_validate_chan(channel);
        if (ret)
                return ret;

        pchan = mxs_dma_channels + channel;

        if (pchan->pending_num == 0) {
                pchan->flags |= MXS_DMA_FLAGS_BUSY;
                return 0;
        }

        pdesc = list_first_entry(&pchan->active, struct mxs_dma_desc, node);
        if (pdesc == NULL)
                return -EFAULT;

        if (pchan->flags & MXS_DMA_FLAGS_BUSY) {
                if (!(pdesc->cmd.data & MXS_DMA_DESC_CHAIN))
                        return 0;

                sem = mxs_dma_read_semaphore(channel);
                if (sem == 0)
                        return 0;

                if (sem == 1) {
                        pdesc = list_entry(pdesc->node.next,
                                           struct mxs_dma_desc, node);
                        writel(mxs_dma_cmd_address(pdesc),
                                &apbh_regs->ch[channel].hw_apbh_ch_nxtcmdar);
                }
                writel(pchan->pending_num,
                        &apbh_regs->ch[channel].hw_apbh_ch_sema);
                pchan->active_num += pchan->pending_num;
                pchan->pending_num = 0;
        } else {
                pchan->active_num += pchan->pending_num;
                pchan->pending_num = 0;
                writel(mxs_dma_cmd_address(pdesc),
                        &apbh_regs->ch[channel].hw_apbh_ch_nxtcmdar);
                writel(pchan->active_num,
                        &apbh_regs->ch[channel].hw_apbh_ch_sema);
                writel(1 << (channel + APBH_CTRL0_CLKGATE_CHANNEL_OFFSET),
                        &apbh_regs->hw_apbh_ctrl0_clr);
        }

        pchan->flags |= MXS_DMA_FLAGS_BUSY;
        return 0;
}

/*
 * Disable a DMA channel.
 *
 * This function shuts down a DMA channel and marks it as "not busy." Any
 * descriptors on the active list are immediately moved to the head of the
 * "done" list, whether or not they have actually been processed by the
 * hardware. The "ready" flags of these descriptors are NOT cleared, so they
 * still appear to be active.
 *
 * This function immediately shuts down a DMA channel's hardware, aborting any
 * I/O that may be in progress, potentially leaving I/O hardware in an undefined
 * state. It is unwise to call this function if there is ANY chance the hardware
 * is still processing a command.
 */
static int mxs_dma_disable(int channel)
{
        struct mxs_dma_chan *pchan;
        struct mxs_apbh_regs *apbh_regs =
                (struct mxs_apbh_regs *)MXS_APBH_BASE;
        int ret;

        ret = mxs_dma_validate_chan(channel);
        if (ret)
                return ret;

        pchan = mxs_dma_channels + channel;

        if (!(pchan->flags & MXS_DMA_FLAGS_BUSY))
                return -EINVAL;

        writel(1 << (channel + APBH_CTRL0_CLKGATE_CHANNEL_OFFSET),
                &apbh_regs->hw_apbh_ctrl0_set);

        pchan->flags &= ~MXS_DMA_FLAGS_BUSY;
        pchan->active_num = 0;
        pchan->pending_num = 0;
        list_splice_init(&pchan->active, &pchan->done);

        return 0;
}

/*
 * Resets the DMA channel hardware.
 */
static int mxs_dma_reset(int channel)
{
        struct mxs_apbh_regs *apbh_regs =
                (struct mxs_apbh_regs *)MXS_APBH_BASE;
        int ret;
#if defined(CONFIG_MX23)
        uint32_t setreg = (uint32_t)(&apbh_regs->hw_apbh_ctrl0_set);
        uint32_t offset = APBH_CTRL0_RESET_CHANNEL_OFFSET;
#elif (defined(CONFIG_MX28) || defined(CONFIG_MX6))
        uint32_t setreg = (uint32_t)(&apbh_regs->hw_apbh_channel_ctrl_set);
        uint32_t offset = APBH_CHANNEL_CTRL_RESET_CHANNEL_OFFSET;
#endif

        ret = mxs_dma_validate_chan(channel);
        if (ret)
                return ret;

        writel(1 << (channel + offset), setreg);

        return 0;
}

/*
 * Enable or disable DMA interrupt.
 *
 * This function enables the given DMA channel to interrupt the CPU.
 */
static int mxs_dma_enable_irq(int channel, int enable)
{
        struct mxs_apbh_regs *apbh_regs =
                (struct mxs_apbh_regs *)MXS_APBH_BASE;
        int ret;

        ret = mxs_dma_validate_chan(channel);
        if (ret)
                return ret;

        if (enable)
                writel(1 << (channel + APBH_CTRL1_CH_CMDCMPLT_IRQ_EN_OFFSET),
                        &apbh_regs->hw_apbh_ctrl1_set);
        else
                writel(1 << (channel + APBH_CTRL1_CH_CMDCMPLT_IRQ_EN_OFFSET),
                        &apbh_regs->hw_apbh_ctrl1_clr);

        return 0;
}

/*
 * Clear DMA interrupt.
 *
 * The software that is using the DMA channel must register to receive its
 * interrupts and, when they arrive, must call this function to clear them.
 */
static int mxs_dma_ack_irq(int channel)
{
        struct mxs_apbh_regs *apbh_regs =
                (struct mxs_apbh_regs *)MXS_APBH_BASE;
        int ret;

        ret = mxs_dma_validate_chan(channel);
        if (ret)
                return ret;

        writel(1 << channel, &apbh_regs->hw_apbh_ctrl1_clr);
        writel(1 << channel, &apbh_regs->hw_apbh_ctrl2_clr);

        return 0;
}

/*
 * Request to reserve a DMA channel
 */
static int mxs_dma_request(int channel)
{
        struct mxs_dma_chan *pchan;

        if ((channel < 0) || (channel >= MXS_MAX_DMA_CHANNELS))
                return -EINVAL;

        pchan = mxs_dma_channels + channel;
        if ((pchan->flags & MXS_DMA_FLAGS_VALID) != MXS_DMA_FLAGS_VALID)
                return -ENODEV;

        if (pchan->flags & MXS_DMA_FLAGS_ALLOCATED)
                return -EBUSY;

        pchan->flags |= MXS_DMA_FLAGS_ALLOCATED;
        pchan->active_num = 0;
        pchan->pending_num = 0;

        INIT_LIST_HEAD(&pchan->active);
        INIT_LIST_HEAD(&pchan->done);

        return 0;
}

/*
 * Release a DMA channel.
 *
 * This function releases a DMA channel from its current owner.
 *
 * The channel will NOT be released if it's marked "busy" (see
 * mxs_dma_enable()).
 */
int mxs_dma_release(int channel)
{
        struct mxs_dma_chan *pchan;
        int ret;

        ret = mxs_dma_validate_chan(channel);
        if (ret)
                return ret;

        pchan = mxs_dma_channels + channel;

        if (pchan->flags & MXS_DMA_FLAGS_BUSY)
                return -EBUSY;

        pchan->dev = 0;
        pchan->active_num = 0;
        pchan->pending_num = 0;
        pchan->flags &= ~MXS_DMA_FLAGS_ALLOCATED;

        return 0;
}

/*
 * Allocate DMA descriptor
 */
struct mxs_dma_desc *mxs_dma_desc_alloc(void)
{
        struct mxs_dma_desc *pdesc;
        uint32_t size;

        size = roundup(sizeof(struct mxs_dma_desc), MXS_DMA_ALIGNMENT);
        pdesc = memalign(MXS_DMA_ALIGNMENT, size);

        if (pdesc == NULL)
                return NULL;

        memset(pdesc, 0, sizeof(*pdesc));
        pdesc->address = (dma_addr_t)pdesc;

        return pdesc;
};

/*
 * Free DMA descriptor
 */
void mxs_dma_desc_free(struct mxs_dma_desc *pdesc)
{
        if (pdesc == NULL)
                return;

        free(pdesc);
}

/*
 * Add a DMA descriptor to a channel.
 *
 * If the descriptor list for this channel is not empty, this function sets the
 * CHAIN bit and the NEXTCMD_ADDR fields in the last descriptor's DMA command so
 * it will chain to the new descriptor's command.
 *
 * Then, this function marks the new descriptor as "ready," adds it to the end
 * of the active descriptor list, and increments the count of pending
 * descriptors.
 *
 * The MXS platform DMA software imposes some rules on DMA commands to maintain
 * important invariants. These rules are NOT checked, but they must be carefully
 * applied by software that uses MXS DMA channels.
 *
 * Invariant:
 *     The DMA channel's hardware semaphore must reflect the number of DMA
 *     commands the hardware will process, but has not yet finished.
 *
 * Explanation:
 *     A DMA channel begins processing commands when its hardware semaphore is
 *     written with a value greater than zero, and it stops processing commands
 *     when the semaphore returns to zero.
 *
 *     When a channel finishes a DMA command, it will decrement its semaphore if
 *     the DECREMENT_SEMAPHORE bit is set in that command's flags bits.
 *
 *     In principle, it's not necessary for the DECREMENT_SEMAPHORE to be set,
 *     unless it suits the purposes of the software. For example, one could
 *     construct a series of five DMA commands, with the DECREMENT_SEMAPHORE
 *     bit set only in the last one. Then, setting the DMA channel's hardware
 *     semaphore to one would cause the entire series of five commands to be
 *     processed. However, this example would violate the invariant given above.
 *
 * Rule:
 *    ALL DMA commands MUST have the DECREMENT_SEMAPHORE bit set so that the DMA
 *    channel's hardware semaphore will be decremented EVERY time a command is
 *    processed.
 */
int mxs_dma_desc_append(int channel, struct mxs_dma_desc *pdesc)
{
        struct mxs_dma_chan *pchan;
        struct mxs_dma_desc *last;
        int ret;

        ret = mxs_dma_validate_chan(channel);
        if (ret)
                return ret;

        pchan = mxs_dma_channels + channel;

        pdesc->cmd.next = mxs_dma_cmd_address(pdesc);
        pdesc->flags |= MXS_DMA_DESC_FIRST | MXS_DMA_DESC_LAST;

        if (!list_empty(&pchan->active)) {
                last = list_entry(pchan->active.prev, struct mxs_dma_desc,
                                        node);

                pdesc->flags &= ~MXS_DMA_DESC_FIRST;
                last->flags &= ~MXS_DMA_DESC_LAST;

                last->cmd.next = mxs_dma_cmd_address(pdesc);
                last->cmd.data |= MXS_DMA_DESC_CHAIN;

                mxs_dma_flush_desc(last);
        }
        pdesc->flags |= MXS_DMA_DESC_READY;
        if (pdesc->flags & MXS_DMA_DESC_FIRST)
                pchan->pending_num++;
        list_add_tail(&pdesc->node, &pchan->active);

        mxs_dma_flush_desc(pdesc);

        return ret;
}

/*
 * Clean up processed DMA descriptors.
 *
 * This function removes processed DMA descriptors from the "active" list. Pass
 * in a non-NULL list head to get the descriptors moved to your list. Pass NULL
 * to get the descriptors moved to the channel's "done" list. Descriptors on
 * the "done" list can be retrieved with mxs_dma_get_finished().
 *
 * This function marks the DMA channel as "not busy" if no unprocessed
 * descriptors remain on the "active" list.
 */
static int mxs_dma_finish(int channel, struct list_head *head)
{
        int sem;
        struct mxs_dma_chan *pchan;
        struct list_head *p, *q;
        struct mxs_dma_desc *pdesc;
        int ret;

        ret = mxs_dma_validate_chan(channel);
        if (ret)
                return ret;

        pchan = mxs_dma_channels + channel;

        sem = mxs_dma_read_semaphore(channel);
        if (sem < 0)
                return sem;

        if (sem == pchan->active_num)
                return 0;

        list_for_each_safe(p, q, &pchan->active) {
                if ((pchan->active_num) <= sem)
                        break;

                pdesc = list_entry(p, struct mxs_dma_desc, node);
                pdesc->flags &= ~MXS_DMA_DESC_READY;

                if (head)
                        list_move_tail(p, head);
                else
                        list_move_tail(p, &pchan->done);

                if (pdesc->flags & MXS_DMA_DESC_LAST)
                        pchan->active_num--;
        }

        if (sem == 0)
                pchan->flags &= ~MXS_DMA_FLAGS_BUSY;

        return 0;
}

/*
 * Wait for DMA channel to complete
 */
static int mxs_dma_wait_complete(uint32_t timeout, unsigned int chan)
{
        struct mxs_apbh_regs *apbh_regs =
                (struct mxs_apbh_regs *)MXS_APBH_BASE;
        int ret;

        ret = mxs_dma_validate_chan(chan);
        if (ret)
                return ret;

        if (mxs_wait_mask_set(&apbh_regs->hw_apbh_ctrl1_reg,
                                1 << chan, timeout)) {
                ret = -ETIMEDOUT;
                mxs_dma_reset(chan);
        }

        return ret;
}

/*
 * Execute the DMA channel
 */
int mxs_dma_go(int chan)
{
        uint32_t timeout = 10000000;
        int ret;

        LIST_HEAD(tmp_desc_list);

        mxs_dma_enable_irq(chan, 1);
        mxs_dma_enable(chan);

        /* Wait for DMA to finish. */
        ret = mxs_dma_wait_complete(timeout, chan);

        /* Clear out the descriptors we just ran. */
        mxs_dma_finish(chan, &tmp_desc_list);

        /* Shut the DMA channel down. */
        mxs_dma_ack_irq(chan);
        mxs_dma_reset(chan);
        mxs_dma_enable_irq(chan, 0);
        mxs_dma_disable(chan);

        return ret;
}

/*
 * Execute a continuously running circular DMA descriptor.
 * NOTE: This is not intended for general use, but rather
 *       for the LCD driver in Smart-LCD mode. It allows
 *       continuous triggering of the RUN bit there.
 */
void mxs_dma_circ_start(int chan, struct mxs_dma_desc *pdesc)
{
        struct mxs_apbh_regs *apbh_regs =
                (struct mxs_apbh_regs *)MXS_APBH_BASE;

        mxs_dma_flush_desc(pdesc);

        mxs_dma_enable_irq(chan, 1);

        writel(mxs_dma_cmd_address(pdesc),
                &apbh_regs->ch[chan].hw_apbh_ch_nxtcmdar);
        writel(1, &apbh_regs->ch[chan].hw_apbh_ch_sema);
        writel(1 << (chan + APBH_CTRL0_CLKGATE_CHANNEL_OFFSET),
                &apbh_regs->hw_apbh_ctrl0_clr);
}

/*
 * Initialize the DMA hardware
 */
void mxs_dma_init(void)
{
        struct mxs_apbh_regs *apbh_regs =
                (struct mxs_apbh_regs *)MXS_APBH_BASE;

        mxs_reset_block(&apbh_regs->hw_apbh_ctrl0_reg);

#ifdef CONFIG_APBH_DMA_BURST8
        writel(APBH_CTRL0_AHB_BURST8_EN,
                &apbh_regs->hw_apbh_ctrl0_set);
#else
        writel(APBH_CTRL0_AHB_BURST8_EN,
                &apbh_regs->hw_apbh_ctrl0_clr);
#endif

#ifdef CONFIG_APBH_DMA_BURST
        writel(APBH_CTRL0_APB_BURST_EN,
                &apbh_regs->hw_apbh_ctrl0_set);
#else
        writel(APBH_CTRL0_APB_BURST_EN,
                &apbh_regs->hw_apbh_ctrl0_clr);
#endif
}

int mxs_dma_init_channel(int channel)
{
        struct mxs_dma_chan *pchan;
        int ret;

        pchan = mxs_dma_channels + channel;
        pchan->flags = MXS_DMA_FLAGS_VALID;

        ret = mxs_dma_request(channel);

        if (ret) {
                printf("MXS DMA: Can't acquire DMA channel %i\n",
                        channel);
                return ret;
        }

        mxs_dma_reset(channel);
        mxs_dma_ack_irq(channel);

        return 0;
}