// SPDX-License-Identifier: GPL-2.0
//
// Loongson ALSA SoC Platform (DMA) driver
//
// Copyright (C) 2023 Loongson Technology Corporation Limited
// Author: Yingkun Meng <mengyingkun@loongson.cn>
//

#include <linux/module.h>
#include <linux/io-64-nonatomic-lo-hi.h>
#include <linux/delay.h>
#include <linux/pm_runtime.h>
#include <linux/dma-mapping.h>
#include <sound/soc.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include "loongson_i2s.h"

/* DMA dma_order Register */
#define DMA_ORDER_STOP          BIT(4) /* DMA stop */
#define DMA_ORDER_START         BIT(3) /* DMA start */
#define DMA_ORDER_ASK_VALID     BIT(2) /* DMA ask valid flag */
#define DMA_ORDER_AXI_UNCO      BIT(1) /* Uncache access */
#define DMA_ORDER_ADDR_64       BIT(0) /* 64bits address support */

#define DMA_ORDER_ASK_MASK      (~0x1fUL) /* Ask addr mask */
#define DMA_ORDER_CTRL_MASK     (0x0fUL)  /* Control mask  */

/*
 * DMA registers descriptor.
 */
struct loongson_dma_desc {
        u32 order;              /* Next descriptor address register */
        u32 saddr;              /* Source address register */
        u32 daddr;              /* Device address register */
        u32 length;             /* Total length register */
        u32 step_length;        /* Memory stride register */
        u32 step_times;         /* Repeat time register */
        u32 cmd;                /* Command register */
        u32 stats;              /* Status register */
        u32 order_hi;           /* Next descriptor high address register */
        u32 saddr_hi;           /* High source address register */
        u32 res[6];             /* Reserved */
} __packed;

struct loongson_runtime_data {
        struct loongson_dma_data *dma_data;

        struct loongson_dma_desc *dma_desc_arr;
        dma_addr_t dma_desc_arr_phy;
        int dma_desc_arr_size;

        struct loongson_dma_desc *dma_pos_desc;
        dma_addr_t dma_pos_desc_phy;
};

static const struct snd_pcm_hardware ls_pcm_hardware = {
        .info = SNDRV_PCM_INFO_MMAP |
                SNDRV_PCM_INFO_INTERLEAVED |
                SNDRV_PCM_INFO_MMAP_VALID |
                SNDRV_PCM_INFO_RESUME |
                SNDRV_PCM_INFO_PAUSE,
        .formats = (SNDRV_PCM_FMTBIT_S8 |
                SNDRV_PCM_FMTBIT_S16_LE |
                SNDRV_PCM_FMTBIT_S20_3LE |
                SNDRV_PCM_FMTBIT_S24_LE),
        .period_bytes_min = 128,
        .period_bytes_max = 128 * 1024,
        .periods_min = 1,
        .periods_max = PAGE_SIZE / sizeof(struct loongson_dma_desc),
        .buffer_bytes_max = 1024 * 1024,
};

static struct
loongson_dma_desc *dma_desc_save(struct loongson_runtime_data *prtd)
{
        void __iomem *order_reg = prtd->dma_data->order_addr;
        u64 val;

        val = (u64)prtd->dma_pos_desc_phy & DMA_ORDER_ASK_MASK;
        val |= (readq(order_reg) & DMA_ORDER_CTRL_MASK);
        val |= DMA_ORDER_ASK_VALID;
        writeq(val, order_reg);

        while (readl(order_reg) & DMA_ORDER_ASK_VALID)
                udelay(2);

        return prtd->dma_pos_desc;
}

static int loongson_pcm_trigger(struct snd_soc_component *component,
                                struct snd_pcm_substream *substream, int cmd)
{
        struct loongson_runtime_data *prtd = substream->runtime->private_data;
        struct device *dev = substream->pcm->card->dev;
        void __iomem *order_reg = prtd->dma_data->order_addr;
        u64 val;

        switch (cmd) {
        case SNDRV_PCM_TRIGGER_START:
        case SNDRV_PCM_TRIGGER_RESUME:
        case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
                val = prtd->dma_pos_desc_phy & DMA_ORDER_ASK_MASK;
                if (dev->coherent_dma_mask == DMA_BIT_MASK(64))
                        val |= DMA_ORDER_ADDR_64;
                else
                        val &= ~DMA_ORDER_ADDR_64;
                val |= (readq(order_reg) & DMA_ORDER_CTRL_MASK);
                val |= DMA_ORDER_START;
                writeq(val, order_reg);

                while ((readl(order_reg) & DMA_ORDER_START))
                        udelay(2);
                break;
        case SNDRV_PCM_TRIGGER_STOP:
        case SNDRV_PCM_TRIGGER_SUSPEND:
        case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
                dma_desc_save(prtd);

                /* dma stop */
                val = readq(order_reg) | DMA_ORDER_STOP;
                writeq(val, order_reg);
                udelay(1000);

                break;
        default:
                dev_err(dev, "Invalid pcm trigger operation\n");
                return -EINVAL;
        }

        return 0;
}

static int loongson_pcm_hw_params(struct snd_soc_component *component,
                                  struct snd_pcm_substream *substream,
                                  struct snd_pcm_hw_params *params)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct device *dev = substream->pcm->card->dev;
        struct loongson_runtime_data *prtd = runtime->private_data;
        size_t buf_len = params_buffer_bytes(params);
        size_t period_len = params_period_bytes(params);
        dma_addr_t order_addr, mem_addr;
        struct loongson_dma_desc *desc;
        u32 num_periods;
        int i;

        if (buf_len % period_len) {
                dev_err(dev, "buf len not multiply of period len\n");
                return -EINVAL;
        }

        num_periods = buf_len / period_len;
        if (!num_periods || num_periods > prtd->dma_desc_arr_size) {
                dev_err(dev, "dma data too small or too big\n");
                return -EINVAL;
        }

        snd_pcm_set_runtime_buffer(substream, &substream->dma_buffer);
        runtime->dma_bytes = buf_len;

        /* initialize dma descriptor array */
        mem_addr = runtime->dma_addr;
        order_addr = prtd->dma_desc_arr_phy;
        for (i = 0; i < num_periods; i++) {
                desc = &prtd->dma_desc_arr[i];

                /* next descriptor physical address */
                order_addr += sizeof(*desc);
                desc->order = lower_32_bits(order_addr | BIT(0));
                desc->order_hi = upper_32_bits(order_addr);

                desc->saddr = lower_32_bits(mem_addr);
                desc->saddr_hi = upper_32_bits(mem_addr);
                desc->daddr = prtd->dma_data->dev_addr;

                desc->cmd = BIT(0);
                if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
                        desc->cmd |= BIT(12);

                desc->length = period_len >> 2;
                desc->step_length = 0;
                desc->step_times = 1;

                mem_addr += period_len;
        }
        desc = &prtd->dma_desc_arr[num_periods - 1];
        desc->order = lower_32_bits(prtd->dma_desc_arr_phy | BIT(0));
        desc->order_hi = upper_32_bits(prtd->dma_desc_arr_phy);

        /* init position descriptor */
        *prtd->dma_pos_desc = *prtd->dma_desc_arr;

        return 0;
}

static snd_pcm_uframes_t
loongson_pcm_pointer(struct snd_soc_component *component,
                     struct snd_pcm_substream *substream)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct loongson_runtime_data *prtd = runtime->private_data;
        struct loongson_dma_desc *desc;
        snd_pcm_uframes_t x;
        u64 addr;

        desc = dma_desc_save(prtd);
        addr = ((u64)desc->saddr_hi << 32) | desc->saddr;

        x = bytes_to_frames(runtime, addr - runtime->dma_addr);
        if (x == runtime->buffer_size)
                x = 0;
        return x;
}

static irqreturn_t loongson_pcm_dma_irq(int irq, void *devid)
{
        struct snd_pcm_substream *substream = devid;

        snd_pcm_period_elapsed(substream);
        return IRQ_HANDLED;
}

static int loongson_pcm_open(struct snd_soc_component *component,
                             struct snd_pcm_substream *substream)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct snd_soc_pcm_runtime *rtd = snd_soc_substream_to_rtd(substream);
        struct snd_card *card = substream->pcm->card;
        struct loongson_runtime_data *prtd;
        struct loongson_dma_data *dma_data;

        /*
         * For mysterious reasons (and despite what the manual says)
         * playback samples are lost if the DMA count is not a multiple
         * of the DMA burst size.  Let's add a rule to enforce that.
         */
        snd_pcm_hw_constraint_step(runtime, 0,
                                   SNDRV_PCM_HW_PARAM_PERIOD_BYTES, 128);
        snd_pcm_hw_constraint_step(runtime, 0,
                                   SNDRV_PCM_HW_PARAM_BUFFER_BYTES, 128);
        snd_pcm_hw_constraint_integer(substream->runtime,
                                      SNDRV_PCM_HW_PARAM_PERIODS);
        snd_soc_set_runtime_hwparams(substream, &ls_pcm_hardware);

        prtd = kzalloc_obj(*prtd);
        if (!prtd)
                return -ENOMEM;

        prtd->dma_desc_arr = dma_alloc_coherent(card->dev, PAGE_SIZE,
                                                &prtd->dma_desc_arr_phy,
                                                GFP_KERNEL);
        if (!prtd->dma_desc_arr)
                goto desc_err;

        prtd->dma_desc_arr_size = PAGE_SIZE / sizeof(*prtd->dma_desc_arr);

        prtd->dma_pos_desc = dma_alloc_coherent(card->dev,
                                                sizeof(*prtd->dma_pos_desc),
                                                &prtd->dma_pos_desc_phy,
                                                GFP_KERNEL);
        if (!prtd->dma_pos_desc)
                goto pos_err;

        dma_data = snd_soc_dai_get_dma_data(snd_soc_rtd_to_cpu(rtd, 0), substream);
        prtd->dma_data = dma_data;

        substream->runtime->private_data = prtd;

        return 0;
pos_err:
        dma_free_coherent(card->dev, PAGE_SIZE, prtd->dma_desc_arr,
                          prtd->dma_desc_arr_phy);
desc_err:
        kfree(prtd);

        return -ENOMEM;
}

static int loongson_pcm_close(struct snd_soc_component *component,
                              struct snd_pcm_substream *substream)
{
        struct snd_card *card = substream->pcm->card;
        struct loongson_runtime_data *prtd = substream->runtime->private_data;

        dma_free_coherent(card->dev, PAGE_SIZE, prtd->dma_desc_arr,
                          prtd->dma_desc_arr_phy);

        dma_free_coherent(card->dev, sizeof(*prtd->dma_pos_desc),
                          prtd->dma_pos_desc, prtd->dma_pos_desc_phy);

        kfree(prtd);
        return 0;
}

static int loongson_pcm_mmap(struct snd_soc_component *component,
                             struct snd_pcm_substream *substream,
                             struct vm_area_struct *vma)
{
        return remap_pfn_range(vma, vma->vm_start,
                        substream->dma_buffer.addr >> PAGE_SHIFT,
                        vma->vm_end - vma->vm_start, vma->vm_page_prot);
}

static int loongson_pcm_new(struct snd_soc_component *component,
                            struct snd_soc_pcm_runtime *rtd)
{
        struct snd_card *card = rtd->card->snd_card;
        struct snd_pcm_substream *substream;
        struct loongson_dma_data *dma_data;
        unsigned int i;
        int ret;

        for_each_pcm_streams(i) {
                substream = rtd->pcm->streams[i].substream;
                if (!substream)
                        continue;

                dma_data = snd_soc_dai_get_dma_data(snd_soc_rtd_to_cpu(rtd, 0),
                                                    substream);
                ret = devm_request_irq(card->dev, dma_data->irq,
                                       loongson_pcm_dma_irq,
                                       IRQF_TRIGGER_HIGH, LS_I2S_DRVNAME,
                                       substream);
                if (ret < 0) {
                        dev_err(card->dev, "request irq for DMA failed\n");
                        return ret;
                }
        }

        return snd_pcm_set_fixed_buffer_all(rtd->pcm, SNDRV_DMA_TYPE_DEV,
                                            card->dev,
                                            ls_pcm_hardware.buffer_bytes_max);
}

const struct snd_soc_component_driver loongson_i2s_component = {
        .name           = LS_I2S_DRVNAME,
        .open           = loongson_pcm_open,
        .close          = loongson_pcm_close,
        .hw_params      = loongson_pcm_hw_params,
        .trigger        = loongson_pcm_trigger,
        .pointer        = loongson_pcm_pointer,
        .mmap           = loongson_pcm_mmap,
        .pcm_construct  = loongson_pcm_new,
};