// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *   ALSA driver for ATI IXP 150/200/250 AC97 modem controllers
 *
 *      Copyright (c) 2004 Takashi Iwai <tiwai@suse.de>
 */

#include <linux/io.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include <sound/info.h>
#include <sound/ac97_codec.h>
#include <sound/initval.h>

MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
MODULE_DESCRIPTION("ATI IXP MC97 controller");
MODULE_LICENSE("GPL");

static int index = -2; /* Exclude the first card */
static char *id = SNDRV_DEFAULT_STR1;   /* ID for this card */
static int ac97_clock = 48000;

module_param(index, int, 0444);
MODULE_PARM_DESC(index, "Index value for ATI IXP controller.");
module_param(id, charp, 0444);
MODULE_PARM_DESC(id, "ID string for ATI IXP controller.");
module_param(ac97_clock, int, 0444);
MODULE_PARM_DESC(ac97_clock, "AC'97 codec clock (default 48000Hz).");

/* just for backward compatibility */
static bool enable;
module_param(enable, bool, 0444);


/*
 */

#define ATI_REG_ISR                     0x00    /* interrupt source */
#define  ATI_REG_ISR_MODEM_IN_XRUN      (1U<<0)
#define  ATI_REG_ISR_MODEM_IN_STATUS    (1U<<1)
#define  ATI_REG_ISR_MODEM_OUT1_XRUN    (1U<<2)
#define  ATI_REG_ISR_MODEM_OUT1_STATUS  (1U<<3)
#define  ATI_REG_ISR_MODEM_OUT2_XRUN    (1U<<4)
#define  ATI_REG_ISR_MODEM_OUT2_STATUS  (1U<<5)
#define  ATI_REG_ISR_MODEM_OUT3_XRUN    (1U<<6)
#define  ATI_REG_ISR_MODEM_OUT3_STATUS  (1U<<7)
#define  ATI_REG_ISR_PHYS_INTR          (1U<<8)
#define  ATI_REG_ISR_PHYS_MISMATCH      (1U<<9)
#define  ATI_REG_ISR_CODEC0_NOT_READY   (1U<<10)
#define  ATI_REG_ISR_CODEC1_NOT_READY   (1U<<11)
#define  ATI_REG_ISR_CODEC2_NOT_READY   (1U<<12)
#define  ATI_REG_ISR_NEW_FRAME          (1U<<13)
#define  ATI_REG_ISR_MODEM_GPIO_DATA    (1U<<14)

#define ATI_REG_IER                     0x04    /* interrupt enable */
#define  ATI_REG_IER_MODEM_IN_XRUN_EN   (1U<<0)
#define  ATI_REG_IER_MODEM_STATUS_EN    (1U<<1)
#define  ATI_REG_IER_MODEM_OUT1_XRUN_EN (1U<<2)
#define  ATI_REG_IER_MODEM_OUT2_XRUN_EN (1U<<4)
#define  ATI_REG_IER_MODEM_OUT3_XRUN_EN (1U<<6)
#define  ATI_REG_IER_PHYS_INTR_EN       (1U<<8)
#define  ATI_REG_IER_PHYS_MISMATCH_EN   (1U<<9)
#define  ATI_REG_IER_CODEC0_INTR_EN     (1U<<10)
#define  ATI_REG_IER_CODEC1_INTR_EN     (1U<<11)
#define  ATI_REG_IER_CODEC2_INTR_EN     (1U<<12)
#define  ATI_REG_IER_NEW_FRAME_EN       (1U<<13)        /* (RO */
#define  ATI_REG_IER_MODEM_GPIO_DATA_EN (1U<<14)        /* (WO) modem is running */
#define  ATI_REG_IER_MODEM_SET_BUS_BUSY (1U<<15)

#define ATI_REG_CMD                     0x08    /* command */
#define  ATI_REG_CMD_POWERDOWN  (1U<<0)
#define  ATI_REG_CMD_MODEM_RECEIVE_EN   (1U<<1) /* modem only */
#define  ATI_REG_CMD_MODEM_SEND1_EN     (1U<<2) /* modem only */
#define  ATI_REG_CMD_MODEM_SEND2_EN     (1U<<3) /* modem only */
#define  ATI_REG_CMD_MODEM_SEND3_EN     (1U<<4) /* modem only */
#define  ATI_REG_CMD_MODEM_STATUS_MEM   (1U<<5) /* modem only */
#define  ATI_REG_CMD_MODEM_IN_DMA_EN    (1U<<8) /* modem only */
#define  ATI_REG_CMD_MODEM_OUT_DMA1_EN  (1U<<9) /* modem only */
#define  ATI_REG_CMD_MODEM_OUT_DMA2_EN  (1U<<10)        /* modem only */
#define  ATI_REG_CMD_MODEM_OUT_DMA3_EN  (1U<<11)        /* modem only */
#define  ATI_REG_CMD_AUDIO_PRESENT      (1U<<20)
#define  ATI_REG_CMD_MODEM_GPIO_THRU_DMA        (1U<<22)        /* modem only */
#define  ATI_REG_CMD_LOOPBACK_EN        (1U<<23)
#define  ATI_REG_CMD_PACKED_DIS         (1U<<24)
#define  ATI_REG_CMD_BURST_EN           (1U<<25)
#define  ATI_REG_CMD_PANIC_EN           (1U<<26)
#define  ATI_REG_CMD_MODEM_PRESENT      (1U<<27)
#define  ATI_REG_CMD_ACLINK_ACTIVE      (1U<<28)
#define  ATI_REG_CMD_AC_SOFT_RESET      (1U<<29)
#define  ATI_REG_CMD_AC_SYNC            (1U<<30)
#define  ATI_REG_CMD_AC_RESET           (1U<<31)

#define ATI_REG_PHYS_OUT_ADDR           0x0c
#define  ATI_REG_PHYS_OUT_CODEC_MASK    (3U<<0)
#define  ATI_REG_PHYS_OUT_RW            (1U<<2)
#define  ATI_REG_PHYS_OUT_ADDR_EN       (1U<<8)
#define  ATI_REG_PHYS_OUT_ADDR_SHIFT    9
#define  ATI_REG_PHYS_OUT_DATA_SHIFT    16

#define ATI_REG_PHYS_IN_ADDR            0x10
#define  ATI_REG_PHYS_IN_READ_FLAG      (1U<<8)
#define  ATI_REG_PHYS_IN_ADDR_SHIFT     9
#define  ATI_REG_PHYS_IN_DATA_SHIFT     16

#define ATI_REG_SLOTREQ                 0x14

#define ATI_REG_COUNTER                 0x18
#define  ATI_REG_COUNTER_SLOT           (3U<<0) /* slot # */
#define  ATI_REG_COUNTER_BITCLOCK       (31U<<8)

#define ATI_REG_IN_FIFO_THRESHOLD       0x1c

#define ATI_REG_MODEM_IN_DMA_LINKPTR    0x20
#define ATI_REG_MODEM_IN_DMA_DT_START   0x24    /* RO */
#define ATI_REG_MODEM_IN_DMA_DT_NEXT    0x28    /* RO */
#define ATI_REG_MODEM_IN_DMA_DT_CUR     0x2c    /* RO */
#define ATI_REG_MODEM_IN_DMA_DT_SIZE    0x30
#define ATI_REG_MODEM_OUT_FIFO          0x34    /* output threshold */
#define  ATI_REG_MODEM_OUT1_DMA_THRESHOLD_MASK  (0xf<<16)
#define  ATI_REG_MODEM_OUT1_DMA_THRESHOLD_SHIFT 16
#define ATI_REG_MODEM_OUT_DMA1_LINKPTR  0x38
#define ATI_REG_MODEM_OUT_DMA2_LINKPTR  0x3c
#define ATI_REG_MODEM_OUT_DMA3_LINKPTR  0x40
#define ATI_REG_MODEM_OUT_DMA1_DT_START 0x44
#define ATI_REG_MODEM_OUT_DMA1_DT_NEXT  0x48
#define ATI_REG_MODEM_OUT_DMA1_DT_CUR   0x4c
#define ATI_REG_MODEM_OUT_DMA2_DT_START 0x50
#define ATI_REG_MODEM_OUT_DMA2_DT_NEXT  0x54
#define ATI_REG_MODEM_OUT_DMA2_DT_CUR   0x58
#define ATI_REG_MODEM_OUT_DMA3_DT_START 0x5c
#define ATI_REG_MODEM_OUT_DMA3_DT_NEXT  0x60
#define ATI_REG_MODEM_OUT_DMA3_DT_CUR   0x64
#define ATI_REG_MODEM_OUT_DMA12_DT_SIZE 0x68
#define ATI_REG_MODEM_OUT_DMA3_DT_SIZE  0x6c
#define ATI_REG_MODEM_OUT_FIFO_USED     0x70
#define ATI_REG_MODEM_OUT_GPIO          0x74
#define  ATI_REG_MODEM_OUT_GPIO_EN         1
#define  ATI_REG_MODEM_OUT_GPIO_DATA_SHIFT 5
#define ATI_REG_MODEM_IN_GPIO           0x78

#define ATI_REG_MODEM_MIRROR            0x7c
#define ATI_REG_AUDIO_MIRROR            0x80

#define ATI_REG_MODEM_FIFO_FLUSH        0x88
#define  ATI_REG_MODEM_FIFO_OUT1_FLUSH  (1U<<0)
#define  ATI_REG_MODEM_FIFO_OUT2_FLUSH  (1U<<1)
#define  ATI_REG_MODEM_FIFO_OUT3_FLUSH  (1U<<2)
#define  ATI_REG_MODEM_FIFO_IN_FLUSH    (1U<<3)

/* LINKPTR */
#define  ATI_REG_LINKPTR_EN             (1U<<0)

#define ATI_MAX_DESCRIPTORS     256     /* max number of descriptor packets */


struct atiixp_modem;

/*
 * DMA packate descriptor
 */

struct atiixp_dma_desc {
        __le32 addr;    /* DMA buffer address */
        u16 status;     /* status bits */
        u16 size;       /* size of the packet in dwords */
        __le32 next;    /* address of the next packet descriptor */
};

/*
 * stream enum
 */
enum { ATI_DMA_PLAYBACK, ATI_DMA_CAPTURE, NUM_ATI_DMAS }; /* DMAs */
enum { ATI_PCM_OUT, ATI_PCM_IN, NUM_ATI_PCMS }; /* AC97 pcm slots */
enum { ATI_PCMDEV_ANALOG, NUM_ATI_PCMDEVS }; /* pcm devices */

#define NUM_ATI_CODECS  3


/*
 * constants and callbacks for each DMA type
 */
struct atiixp_dma_ops {
        int type;                       /* ATI_DMA_XXX */
        unsigned int llp_offset;        /* LINKPTR offset */
        unsigned int dt_cur;            /* DT_CUR offset */
        /* called from open callback */
        void (*enable_dma)(struct atiixp_modem *chip, int on);
        /* called from trigger (START/STOP) */
        void (*enable_transfer)(struct atiixp_modem *chip, int on);
        /* called from trigger (STOP only) */
        void (*flush_dma)(struct atiixp_modem *chip);
};

/*
 * DMA stream
 */
struct atiixp_dma {
        const struct atiixp_dma_ops *ops;
        struct snd_dma_buffer desc_buf;
        struct snd_pcm_substream *substream;    /* assigned PCM substream */
        unsigned int buf_addr, buf_bytes;       /* DMA buffer address, bytes */
        unsigned int period_bytes, periods;
        int opened;
        int running;
        int pcm_open_flag;
        int ac97_pcm_type;      /* index # of ac97_pcm to access, -1 = not used */
};

/*
 * ATI IXP chip
 */
struct atiixp_modem {
        struct snd_card *card;
        struct pci_dev *pci;

        struct resource *res;           /* memory i/o */
        unsigned long addr;
        void __iomem *remap_addr;
        int irq;
        
        struct snd_ac97_bus *ac97_bus;
        struct snd_ac97 *ac97[NUM_ATI_CODECS];

        spinlock_t reg_lock;

        struct atiixp_dma dmas[NUM_ATI_DMAS];
        struct ac97_pcm *pcms[NUM_ATI_PCMS];
        struct snd_pcm *pcmdevs[NUM_ATI_PCMDEVS];

        int max_channels;               /* max. channels for PCM out */

        unsigned int codec_not_ready_bits;      /* for codec detection */

        int spdif_over_aclink;          /* passed from the module option */
        struct mutex open_mutex;        /* playback open mutex */
};


/*
 */
static const struct pci_device_id snd_atiixp_ids[] = {
        { PCI_VDEVICE(ATI, 0x434d), 0 }, /* SB200 */
        { PCI_VDEVICE(ATI, 0x4378), 0 }, /* SB400 */
        { 0, }
};

MODULE_DEVICE_TABLE(pci, snd_atiixp_ids);


/*
 * lowlevel functions
 */

/*
 * update the bits of the given register.
 * return 1 if the bits changed.
 */
static int snd_atiixp_update_bits(struct atiixp_modem *chip, unsigned int reg,
                                  unsigned int mask, unsigned int value)
{
        void __iomem *addr = chip->remap_addr + reg;
        unsigned int data, old_data;
        old_data = data = readl(addr);
        data &= ~mask;
        data |= value;
        if (old_data == data)
                return 0;
        writel(data, addr);
        return 1;
}

/*
 * macros for easy use
 */
#define atiixp_write(chip,reg,value) \
        writel(value, chip->remap_addr + ATI_REG_##reg)
#define atiixp_read(chip,reg) \
        readl(chip->remap_addr + ATI_REG_##reg)
#define atiixp_update(chip,reg,mask,val) \
        snd_atiixp_update_bits(chip, ATI_REG_##reg, mask, val)

/*
 * handling DMA packets
 *
 * we allocate a linear buffer for the DMA, and split it to  each packet.
 * in a future version, a scatter-gather buffer should be implemented.
 */

#define ATI_DESC_LIST_SIZE \
        PAGE_ALIGN(ATI_MAX_DESCRIPTORS * sizeof(struct atiixp_dma_desc))

/*
 * build packets ring for the given buffer size.
 *
 * IXP handles the buffer descriptors, which are connected as a linked
 * list.  although we can change the list dynamically, in this version,
 * a static RING of buffer descriptors is used.
 *
 * the ring is built in this function, and is set up to the hardware. 
 */
static int atiixp_build_dma_packets(struct atiixp_modem *chip,
                                    struct atiixp_dma *dma,
                                    struct snd_pcm_substream *substream,
                                    unsigned int periods,
                                    unsigned int period_bytes)
{
        unsigned int i;
        u32 addr, desc_addr;
        unsigned long flags;

        if (periods > ATI_MAX_DESCRIPTORS)
                return -ENOMEM;

        if (dma->desc_buf.area == NULL) {
                if (snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV, &chip->pci->dev,
                                        ATI_DESC_LIST_SIZE, &dma->desc_buf) < 0)
                        return -ENOMEM;
                dma->period_bytes = dma->periods = 0; /* clear */
        }

        if (dma->periods == periods && dma->period_bytes == period_bytes)
                return 0;

        /* reset DMA before changing the descriptor table */
        spin_lock_irqsave(&chip->reg_lock, flags);
        writel(0, chip->remap_addr + dma->ops->llp_offset);
        dma->ops->enable_dma(chip, 0);
        dma->ops->enable_dma(chip, 1);
        spin_unlock_irqrestore(&chip->reg_lock, flags);

        /* fill the entries */
        addr = (u32)substream->runtime->dma_addr;
        desc_addr = (u32)dma->desc_buf.addr;
        for (i = 0; i < periods; i++) {
                struct atiixp_dma_desc *desc;
                desc = &((struct atiixp_dma_desc *)dma->desc_buf.area)[i];
                desc->addr = cpu_to_le32(addr);
                desc->status = 0;
                desc->size = period_bytes >> 2; /* in dwords */
                desc_addr += sizeof(struct atiixp_dma_desc);
                if (i == periods - 1)
                        desc->next = cpu_to_le32((u32)dma->desc_buf.addr);
                else
                        desc->next = cpu_to_le32(desc_addr);
                addr += period_bytes;
        }

        writel((u32)dma->desc_buf.addr | ATI_REG_LINKPTR_EN,
               chip->remap_addr + dma->ops->llp_offset);

        dma->period_bytes = period_bytes;
        dma->periods = periods;

        return 0;
}

/*
 * remove the ring buffer and release it if assigned
 */
static void atiixp_clear_dma_packets(struct atiixp_modem *chip,
                                     struct atiixp_dma *dma,
                                     struct snd_pcm_substream *substream)
{
        if (dma->desc_buf.area) {
                writel(0, chip->remap_addr + dma->ops->llp_offset);
                snd_dma_free_pages(&dma->desc_buf);
                dma->desc_buf.area = NULL;
        }
}

/*
 * AC97 interface
 */
static int snd_atiixp_acquire_codec(struct atiixp_modem *chip)
{
        int timeout = 1000;

        while (atiixp_read(chip, PHYS_OUT_ADDR) & ATI_REG_PHYS_OUT_ADDR_EN) {
                if (! timeout--) {
                        dev_warn(chip->card->dev, "codec acquire timeout\n");
                        return -EBUSY;
                }
                udelay(1);
        }
        return 0;
}

static unsigned short snd_atiixp_codec_read(struct atiixp_modem *chip,
                                            unsigned short codec,
                                            unsigned short reg)
{
        unsigned int data;
        int timeout;

        if (snd_atiixp_acquire_codec(chip) < 0)
                return 0xffff;
        data = (reg << ATI_REG_PHYS_OUT_ADDR_SHIFT) |
                ATI_REG_PHYS_OUT_ADDR_EN |
                ATI_REG_PHYS_OUT_RW |
                codec;
        atiixp_write(chip, PHYS_OUT_ADDR, data);
        if (snd_atiixp_acquire_codec(chip) < 0)
                return 0xffff;
        timeout = 1000;
        do {
                data = atiixp_read(chip, PHYS_IN_ADDR);
                if (data & ATI_REG_PHYS_IN_READ_FLAG)
                        return data >> ATI_REG_PHYS_IN_DATA_SHIFT;
                udelay(1);
        } while (--timeout);
        /* time out may happen during reset */
        if (reg < 0x7c)
                dev_warn(chip->card->dev, "codec read timeout (reg %x)\n", reg);
        return 0xffff;
}


static void snd_atiixp_codec_write(struct atiixp_modem *chip,
                                   unsigned short codec,
                                   unsigned short reg, unsigned short val)
{
        unsigned int data;
    
        if (snd_atiixp_acquire_codec(chip) < 0)
                return;
        data = ((unsigned int)val << ATI_REG_PHYS_OUT_DATA_SHIFT) |
                ((unsigned int)reg << ATI_REG_PHYS_OUT_ADDR_SHIFT) |
                ATI_REG_PHYS_OUT_ADDR_EN | codec;
        atiixp_write(chip, PHYS_OUT_ADDR, data);
}


static unsigned short snd_atiixp_ac97_read(struct snd_ac97 *ac97,
                                           unsigned short reg)
{
        struct atiixp_modem *chip = ac97->private_data;
        return snd_atiixp_codec_read(chip, ac97->num, reg);
    
}

static void snd_atiixp_ac97_write(struct snd_ac97 *ac97, unsigned short reg,
                                  unsigned short val)
{
        struct atiixp_modem *chip = ac97->private_data;
        if (reg == AC97_GPIO_STATUS) {
                atiixp_write(chip, MODEM_OUT_GPIO,
                        (val << ATI_REG_MODEM_OUT_GPIO_DATA_SHIFT) | ATI_REG_MODEM_OUT_GPIO_EN);
                return;
        }
        snd_atiixp_codec_write(chip, ac97->num, reg, val);
}

/*
 * reset AC link
 */
static int snd_atiixp_aclink_reset(struct atiixp_modem *chip)
{
        int timeout;

        /* reset powerdoewn */
        if (atiixp_update(chip, CMD, ATI_REG_CMD_POWERDOWN, 0))
                udelay(10);

        /* perform a software reset */
        atiixp_update(chip, CMD, ATI_REG_CMD_AC_SOFT_RESET, ATI_REG_CMD_AC_SOFT_RESET);
        atiixp_read(chip, CMD);
        udelay(10);
        atiixp_update(chip, CMD, ATI_REG_CMD_AC_SOFT_RESET, 0);
    
        timeout = 10;
        while (! (atiixp_read(chip, CMD) & ATI_REG_CMD_ACLINK_ACTIVE)) {
                /* do a hard reset */
                atiixp_update(chip, CMD, ATI_REG_CMD_AC_SYNC|ATI_REG_CMD_AC_RESET,
                              ATI_REG_CMD_AC_SYNC);
                atiixp_read(chip, CMD);
                msleep(1);
                atiixp_update(chip, CMD, ATI_REG_CMD_AC_RESET, ATI_REG_CMD_AC_RESET);
                if (!--timeout) {
                        dev_err(chip->card->dev, "codec reset timeout\n");
                        break;
                }
        }

        /* deassert RESET and assert SYNC to make sure */
        atiixp_update(chip, CMD, ATI_REG_CMD_AC_SYNC|ATI_REG_CMD_AC_RESET,
                      ATI_REG_CMD_AC_SYNC|ATI_REG_CMD_AC_RESET);

        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int snd_atiixp_aclink_down(struct atiixp_modem *chip)
{
        // if (atiixp_read(chip, MODEM_MIRROR) & 0x1) /* modem running, too? */
        //      return -EBUSY;
        atiixp_update(chip, CMD,
                     ATI_REG_CMD_POWERDOWN | ATI_REG_CMD_AC_RESET,
                     ATI_REG_CMD_POWERDOWN);
        return 0;
}
#endif

/*
 * auto-detection of codecs
 *
 * the IXP chip can generate interrupts for the non-existing codecs.
 * NEW_FRAME interrupt is used to make sure that the interrupt is generated
 * even if all three codecs are connected.
 */

#define ALL_CODEC_NOT_READY \
            (ATI_REG_ISR_CODEC0_NOT_READY |\
             ATI_REG_ISR_CODEC1_NOT_READY |\
             ATI_REG_ISR_CODEC2_NOT_READY)
#define CODEC_CHECK_BITS (ALL_CODEC_NOT_READY|ATI_REG_ISR_NEW_FRAME)

static int snd_atiixp_codec_detect(struct atiixp_modem *chip)
{
        int timeout;

        chip->codec_not_ready_bits = 0;
        atiixp_write(chip, IER, CODEC_CHECK_BITS);
        /* wait for the interrupts */
        timeout = 50;
        while (timeout-- > 0) {
                msleep(1);
                if (chip->codec_not_ready_bits)
                        break;
        }
        atiixp_write(chip, IER, 0); /* disable irqs */

        if ((chip->codec_not_ready_bits & ALL_CODEC_NOT_READY) == ALL_CODEC_NOT_READY) {
                dev_err(chip->card->dev, "no codec detected!\n");
                return -ENXIO;
        }
        return 0;
}


/*
 * enable DMA and irqs
 */
static int snd_atiixp_chip_start(struct atiixp_modem *chip)
{
        unsigned int reg;

        /* set up spdif, enable burst mode */
        reg = atiixp_read(chip, CMD);
        reg |= ATI_REG_CMD_BURST_EN;
        if(!(reg & ATI_REG_CMD_MODEM_PRESENT))
                reg |= ATI_REG_CMD_MODEM_PRESENT;
        atiixp_write(chip, CMD, reg);

        /* clear all interrupt source */
        atiixp_write(chip, ISR, 0xffffffff);
        /* enable irqs */
        atiixp_write(chip, IER,
                     ATI_REG_IER_MODEM_STATUS_EN |
                     ATI_REG_IER_MODEM_IN_XRUN_EN |
                     ATI_REG_IER_MODEM_OUT1_XRUN_EN);
        return 0;
}


/*
 * disable DMA and IRQs
 */
static int snd_atiixp_chip_stop(struct atiixp_modem *chip)
{
        /* clear interrupt source */
        atiixp_write(chip, ISR, atiixp_read(chip, ISR));
        /* disable irqs */
        atiixp_write(chip, IER, 0);
        return 0;
}


/*
 * PCM section
 */

/*
 * pointer callback simplly reads XXX_DMA_DT_CUR register as the current
 * position.  when SG-buffer is implemented, the offset must be calculated
 * correctly...
 */
static snd_pcm_uframes_t snd_atiixp_pcm_pointer(struct snd_pcm_substream *substream)
{
        struct atiixp_modem *chip = snd_pcm_substream_chip(substream);
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct atiixp_dma *dma = runtime->private_data;
        unsigned int curptr;
        int timeout = 1000;

        while (timeout--) {
                curptr = readl(chip->remap_addr + dma->ops->dt_cur);
                if (curptr < dma->buf_addr)
                        continue;
                curptr -= dma->buf_addr;
                if (curptr >= dma->buf_bytes)
                        continue;
                return bytes_to_frames(runtime, curptr);
        }
        dev_dbg(chip->card->dev, "invalid DMA pointer read 0x%x (buf=%x)\n",
                   readl(chip->remap_addr + dma->ops->dt_cur), dma->buf_addr);
        return 0;
}

/*
 * XRUN detected, and stop the PCM substream
 */
static void snd_atiixp_xrun_dma(struct atiixp_modem *chip,
                                struct atiixp_dma *dma)
{
        if (! dma->substream || ! dma->running)
                return;
        dev_dbg(chip->card->dev, "XRUN detected (DMA %d)\n", dma->ops->type);
        snd_pcm_stop_xrun(dma->substream);
}

/*
 * the period ack.  update the substream.
 */
static void snd_atiixp_update_dma(struct atiixp_modem *chip,
                                  struct atiixp_dma *dma)
{
        if (! dma->substream || ! dma->running)
                return;
        snd_pcm_period_elapsed(dma->substream);
}

/* set BUS_BUSY interrupt bit if any DMA is running */
/* call with spinlock held */
static void snd_atiixp_check_bus_busy(struct atiixp_modem *chip)
{
        unsigned int bus_busy;
        if (atiixp_read(chip, CMD) & (ATI_REG_CMD_MODEM_SEND1_EN |
                                      ATI_REG_CMD_MODEM_RECEIVE_EN))
                bus_busy = ATI_REG_IER_MODEM_SET_BUS_BUSY;
        else
                bus_busy = 0;
        atiixp_update(chip, IER, ATI_REG_IER_MODEM_SET_BUS_BUSY, bus_busy);
}

/* common trigger callback
 * calling the lowlevel callbacks in it
 */
static int snd_atiixp_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
{
        struct atiixp_modem *chip = snd_pcm_substream_chip(substream);
        struct atiixp_dma *dma = substream->runtime->private_data;
        int err = 0;

        if (snd_BUG_ON(!dma->ops->enable_transfer ||
                       !dma->ops->flush_dma))
                return -EINVAL;

        spin_lock(&chip->reg_lock);
        switch(cmd) {
        case SNDRV_PCM_TRIGGER_START:
                dma->ops->enable_transfer(chip, 1);
                dma->running = 1;
                break;
        case SNDRV_PCM_TRIGGER_STOP:
                dma->ops->enable_transfer(chip, 0);
                dma->running = 0;
                break;
        default:
                err = -EINVAL;
                break;
        }
        if (! err) {
        snd_atiixp_check_bus_busy(chip);
        if (cmd == SNDRV_PCM_TRIGGER_STOP) {
                dma->ops->flush_dma(chip);
                snd_atiixp_check_bus_busy(chip);
        }
        }
        spin_unlock(&chip->reg_lock);
        return err;
}


/*
 * lowlevel callbacks for each DMA type
 *
 * every callback is supposed to be called in chip->reg_lock spinlock
 */

/* flush FIFO of analog OUT DMA */
static void atiixp_out_flush_dma(struct atiixp_modem *chip)
{
        atiixp_write(chip, MODEM_FIFO_FLUSH, ATI_REG_MODEM_FIFO_OUT1_FLUSH);
}

/* enable/disable analog OUT DMA */
static void atiixp_out_enable_dma(struct atiixp_modem *chip, int on)
{
        unsigned int data;
        data = atiixp_read(chip, CMD);
        if (on) {
                if (data & ATI_REG_CMD_MODEM_OUT_DMA1_EN)
                        return;
                atiixp_out_flush_dma(chip);
                data |= ATI_REG_CMD_MODEM_OUT_DMA1_EN;
        } else
                data &= ~ATI_REG_CMD_MODEM_OUT_DMA1_EN;
        atiixp_write(chip, CMD, data);
}

/* start/stop transfer over OUT DMA */
static void atiixp_out_enable_transfer(struct atiixp_modem *chip, int on)
{
        atiixp_update(chip, CMD, ATI_REG_CMD_MODEM_SEND1_EN,
                      on ? ATI_REG_CMD_MODEM_SEND1_EN : 0);
}

/* enable/disable analog IN DMA */
static void atiixp_in_enable_dma(struct atiixp_modem *chip, int on)
{
        atiixp_update(chip, CMD, ATI_REG_CMD_MODEM_IN_DMA_EN,
                      on ? ATI_REG_CMD_MODEM_IN_DMA_EN : 0);
}

/* start/stop analog IN DMA */
static void atiixp_in_enable_transfer(struct atiixp_modem *chip, int on)
{
        if (on) {
                unsigned int data = atiixp_read(chip, CMD);
                if (! (data & ATI_REG_CMD_MODEM_RECEIVE_EN)) {
                        data |= ATI_REG_CMD_MODEM_RECEIVE_EN;
                        atiixp_write(chip, CMD, data);
                }
        } else
                atiixp_update(chip, CMD, ATI_REG_CMD_MODEM_RECEIVE_EN, 0);
}

/* flush FIFO of analog IN DMA */
static void atiixp_in_flush_dma(struct atiixp_modem *chip)
{
        atiixp_write(chip, MODEM_FIFO_FLUSH, ATI_REG_MODEM_FIFO_IN_FLUSH);
}

/* set up slots and formats for analog OUT */
static int snd_atiixp_playback_prepare(struct snd_pcm_substream *substream)
{
        struct atiixp_modem *chip = snd_pcm_substream_chip(substream);
        unsigned int data;

        spin_lock_irq(&chip->reg_lock);
        /* set output threshold */
        data = atiixp_read(chip, MODEM_OUT_FIFO);
        data &= ~ATI_REG_MODEM_OUT1_DMA_THRESHOLD_MASK;
        data |= 0x04 << ATI_REG_MODEM_OUT1_DMA_THRESHOLD_SHIFT;
        atiixp_write(chip, MODEM_OUT_FIFO, data);
        spin_unlock_irq(&chip->reg_lock);
        return 0;
}

/* set up slots and formats for analog IN */
static int snd_atiixp_capture_prepare(struct snd_pcm_substream *substream)
{
        return 0;
}

/*
 * hw_params - allocate the buffer and set up buffer descriptors
 */
static int snd_atiixp_pcm_hw_params(struct snd_pcm_substream *substream,
                                   struct snd_pcm_hw_params *hw_params)
{
        struct atiixp_modem *chip = snd_pcm_substream_chip(substream);
        struct atiixp_dma *dma = substream->runtime->private_data;
        int err;
        int i;

        dma->buf_addr = substream->runtime->dma_addr;
        dma->buf_bytes = params_buffer_bytes(hw_params);

        err = atiixp_build_dma_packets(chip, dma, substream,
                                       params_periods(hw_params),
                                       params_period_bytes(hw_params));
        if (err < 0)
                return err;

        /* set up modem rate */
        for (i = 0; i < NUM_ATI_CODECS; i++) {
                if (! chip->ac97[i])
                        continue;
                snd_ac97_write(chip->ac97[i], AC97_LINE1_RATE, params_rate(hw_params));
                snd_ac97_write(chip->ac97[i], AC97_LINE1_LEVEL, 0);
        }

        return err;
}

static int snd_atiixp_pcm_hw_free(struct snd_pcm_substream *substream)
{
        struct atiixp_modem *chip = snd_pcm_substream_chip(substream);
        struct atiixp_dma *dma = substream->runtime->private_data;

        atiixp_clear_dma_packets(chip, dma, substream);
        return 0;
}


/*
 * pcm hardware definition, identical for all DMA types
 */
static const struct snd_pcm_hardware snd_atiixp_pcm_hw =
{
        .info =                 (SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_INTERLEAVED |
                                 SNDRV_PCM_INFO_BLOCK_TRANSFER |
                                 SNDRV_PCM_INFO_MMAP_VALID),
        .formats =              SNDRV_PCM_FMTBIT_S16_LE,
        .rates =                (SNDRV_PCM_RATE_8000 |
                                 SNDRV_PCM_RATE_16000 |
                                 SNDRV_PCM_RATE_KNOT),
        .rate_min =             8000,
        .rate_max =             16000,
        .channels_min =         2,
        .channels_max =         2,
        .buffer_bytes_max =     256 * 1024,
        .period_bytes_min =     32,
        .period_bytes_max =     128 * 1024,
        .periods_min =          2,
        .periods_max =          ATI_MAX_DESCRIPTORS,
};

static int snd_atiixp_pcm_open(struct snd_pcm_substream *substream,
                               struct atiixp_dma *dma, int pcm_type)
{
        struct atiixp_modem *chip = snd_pcm_substream_chip(substream);
        struct snd_pcm_runtime *runtime = substream->runtime;
        int err;
        static const unsigned int rates[] = { 8000,  9600, 12000, 16000 };
        static const struct snd_pcm_hw_constraint_list hw_constraints_rates = {
                .count = ARRAY_SIZE(rates),
                .list = rates,
                .mask = 0,
        };

        if (snd_BUG_ON(!dma->ops || !dma->ops->enable_dma))
                return -EINVAL;

        if (dma->opened)
                return -EBUSY;
        dma->substream = substream;
        runtime->hw = snd_atiixp_pcm_hw;
        dma->ac97_pcm_type = pcm_type;
        err = snd_pcm_hw_constraint_list(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
                                         &hw_constraints_rates);
        if (err < 0)
                return err;
        err = snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);
        if (err < 0)
                return err;
        runtime->private_data = dma;

        /* enable DMA bits */
        spin_lock_irq(&chip->reg_lock);
        dma->ops->enable_dma(chip, 1);
        spin_unlock_irq(&chip->reg_lock);
        dma->opened = 1;

        return 0;
}

static int snd_atiixp_pcm_close(struct snd_pcm_substream *substream,
                                struct atiixp_dma *dma)
{
        struct atiixp_modem *chip = snd_pcm_substream_chip(substream);
        /* disable DMA bits */
        if (snd_BUG_ON(!dma->ops || !dma->ops->enable_dma))
                return -EINVAL;
        spin_lock_irq(&chip->reg_lock);
        dma->ops->enable_dma(chip, 0);
        spin_unlock_irq(&chip->reg_lock);
        dma->substream = NULL;
        dma->opened = 0;
        return 0;
}

/*
 */
static int snd_atiixp_playback_open(struct snd_pcm_substream *substream)
{
        struct atiixp_modem *chip = snd_pcm_substream_chip(substream);
        int err;

        mutex_lock(&chip->open_mutex);
        err = snd_atiixp_pcm_open(substream, &chip->dmas[ATI_DMA_PLAYBACK], 0);
        mutex_unlock(&chip->open_mutex);
        if (err < 0)
                return err;
        return 0;
}

static int snd_atiixp_playback_close(struct snd_pcm_substream *substream)
{
        struct atiixp_modem *chip = snd_pcm_substream_chip(substream);
        int err;
        mutex_lock(&chip->open_mutex);
        err = snd_atiixp_pcm_close(substream, &chip->dmas[ATI_DMA_PLAYBACK]);
        mutex_unlock(&chip->open_mutex);
        return err;
}

static int snd_atiixp_capture_open(struct snd_pcm_substream *substream)
{
        struct atiixp_modem *chip = snd_pcm_substream_chip(substream);
        return snd_atiixp_pcm_open(substream, &chip->dmas[ATI_DMA_CAPTURE], 1);
}

static int snd_atiixp_capture_close(struct snd_pcm_substream *substream)
{
        struct atiixp_modem *chip = snd_pcm_substream_chip(substream);
        return snd_atiixp_pcm_close(substream, &chip->dmas[ATI_DMA_CAPTURE]);
}


/* AC97 playback */
static const struct snd_pcm_ops snd_atiixp_playback_ops = {
        .open =         snd_atiixp_playback_open,
        .close =        snd_atiixp_playback_close,
        .hw_params =    snd_atiixp_pcm_hw_params,
        .hw_free =      snd_atiixp_pcm_hw_free,
        .prepare =      snd_atiixp_playback_prepare,
        .trigger =      snd_atiixp_pcm_trigger,
        .pointer =      snd_atiixp_pcm_pointer,
};

/* AC97 capture */
static const struct snd_pcm_ops snd_atiixp_capture_ops = {
        .open =         snd_atiixp_capture_open,
        .close =        snd_atiixp_capture_close,
        .hw_params =    snd_atiixp_pcm_hw_params,
        .hw_free =      snd_atiixp_pcm_hw_free,
        .prepare =      snd_atiixp_capture_prepare,
        .trigger =      snd_atiixp_pcm_trigger,
        .pointer =      snd_atiixp_pcm_pointer,
};

static const struct atiixp_dma_ops snd_atiixp_playback_dma_ops = {
        .type = ATI_DMA_PLAYBACK,
        .llp_offset = ATI_REG_MODEM_OUT_DMA1_LINKPTR,
        .dt_cur = ATI_REG_MODEM_OUT_DMA1_DT_CUR,
        .enable_dma = atiixp_out_enable_dma,
        .enable_transfer = atiixp_out_enable_transfer,
        .flush_dma = atiixp_out_flush_dma,
};
        
static const struct atiixp_dma_ops snd_atiixp_capture_dma_ops = {
        .type = ATI_DMA_CAPTURE,
        .llp_offset = ATI_REG_MODEM_IN_DMA_LINKPTR,
        .dt_cur = ATI_REG_MODEM_IN_DMA_DT_CUR,
        .enable_dma = atiixp_in_enable_dma,
        .enable_transfer = atiixp_in_enable_transfer,
        .flush_dma = atiixp_in_flush_dma,
};

static int snd_atiixp_pcm_new(struct atiixp_modem *chip)
{
        struct snd_pcm *pcm;
        int err;

        /* initialize constants */
        chip->dmas[ATI_DMA_PLAYBACK].ops = &snd_atiixp_playback_dma_ops;
        chip->dmas[ATI_DMA_CAPTURE].ops = &snd_atiixp_capture_dma_ops;

        /* PCM #0: analog I/O */
        err = snd_pcm_new(chip->card, "ATI IXP MC97", ATI_PCMDEV_ANALOG, 1, 1, &pcm);
        if (err < 0)
                return err;
        snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &snd_atiixp_playback_ops);
        snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_atiixp_capture_ops);
        pcm->dev_class = SNDRV_PCM_CLASS_MODEM;
        pcm->private_data = chip;
        strcpy(pcm->name, "ATI IXP MC97");
        chip->pcmdevs[ATI_PCMDEV_ANALOG] = pcm;

        snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_DEV,
                                       &chip->pci->dev, 64*1024, 128*1024);

        return 0;
}



/*
 * interrupt handler
 */

static irqreturn_t snd_atiixp_interrupt(int irq, void *dev_id)
{
        struct atiixp_modem *chip = dev_id;
        unsigned int status;

        status = atiixp_read(chip, ISR);

        if (! status)
                return IRQ_NONE;

        /* process audio DMA */
        if (status & ATI_REG_ISR_MODEM_OUT1_XRUN)
                snd_atiixp_xrun_dma(chip,  &chip->dmas[ATI_DMA_PLAYBACK]);
        else if (status & ATI_REG_ISR_MODEM_OUT1_STATUS)
                snd_atiixp_update_dma(chip, &chip->dmas[ATI_DMA_PLAYBACK]);
        if (status & ATI_REG_ISR_MODEM_IN_XRUN)
                snd_atiixp_xrun_dma(chip,  &chip->dmas[ATI_DMA_CAPTURE]);
        else if (status & ATI_REG_ISR_MODEM_IN_STATUS)
                snd_atiixp_update_dma(chip, &chip->dmas[ATI_DMA_CAPTURE]);

        /* for codec detection */
        if (status & CODEC_CHECK_BITS) {
                unsigned int detected;
                detected = status & CODEC_CHECK_BITS;
                spin_lock(&chip->reg_lock);
                chip->codec_not_ready_bits |= detected;
                atiixp_update(chip, IER, detected, 0); /* disable the detected irqs */
                spin_unlock(&chip->reg_lock);
        }

        /* ack */
        atiixp_write(chip, ISR, status);

        return IRQ_HANDLED;
}


/*
 * ac97 mixer section
 */

static int snd_atiixp_mixer_new(struct atiixp_modem *chip, int clock)
{
        struct snd_ac97_bus *pbus;
        struct snd_ac97_template ac97;
        int i, err;
        int codec_count;
        static const struct snd_ac97_bus_ops ops = {
                .write = snd_atiixp_ac97_write,
                .read = snd_atiixp_ac97_read,
        };
        static const unsigned int codec_skip[NUM_ATI_CODECS] = {
                ATI_REG_ISR_CODEC0_NOT_READY,
                ATI_REG_ISR_CODEC1_NOT_READY,
                ATI_REG_ISR_CODEC2_NOT_READY,
        };

        if (snd_atiixp_codec_detect(chip) < 0)
                return -ENXIO;

        err = snd_ac97_bus(chip->card, 0, &ops, chip, &pbus);
        if (err < 0)
                return err;
        pbus->clock = clock;
        chip->ac97_bus = pbus;

        codec_count = 0;
        for (i = 0; i < NUM_ATI_CODECS; i++) {
                if (chip->codec_not_ready_bits & codec_skip[i])
                        continue;
                memset(&ac97, 0, sizeof(ac97));
                ac97.private_data = chip;
                ac97.pci = chip->pci;
                ac97.num = i;
                ac97.scaps = AC97_SCAP_SKIP_AUDIO | AC97_SCAP_POWER_SAVE;
                err = snd_ac97_mixer(pbus, &ac97, &chip->ac97[i]);
                if (err < 0) {
                        chip->ac97[i] = NULL; /* to be sure */
                        dev_dbg(chip->card->dev,
                                "codec %d not available for modem\n", i);
                        continue;
                }
                codec_count++;
        }

        if (! codec_count) {
                dev_err(chip->card->dev, "no codec available\n");
                return -ENODEV;
        }

        /* snd_ac97_tune_hardware(chip->ac97, ac97_quirks); */

        return 0;
}


#ifdef CONFIG_PM_SLEEP
/*
 * power management
 */
static int snd_atiixp_suspend(struct device *dev)
{
        struct snd_card *card = dev_get_drvdata(dev);
        struct atiixp_modem *chip = card->private_data;
        int i;

        snd_power_change_state(card, SNDRV_CTL_POWER_D3hot);
        for (i = 0; i < NUM_ATI_CODECS; i++)
                snd_ac97_suspend(chip->ac97[i]);
        snd_atiixp_aclink_down(chip);
        snd_atiixp_chip_stop(chip);
        return 0;
}

static int snd_atiixp_resume(struct device *dev)
{
        struct snd_card *card = dev_get_drvdata(dev);
        struct atiixp_modem *chip = card->private_data;
        int i;

        snd_atiixp_aclink_reset(chip);
        snd_atiixp_chip_start(chip);

        for (i = 0; i < NUM_ATI_CODECS; i++)
                snd_ac97_resume(chip->ac97[i]);

        snd_power_change_state(card, SNDRV_CTL_POWER_D0);
        return 0;
}

static SIMPLE_DEV_PM_OPS(snd_atiixp_pm, snd_atiixp_suspend, snd_atiixp_resume);
#define SND_ATIIXP_PM_OPS       &snd_atiixp_pm
#else
#define SND_ATIIXP_PM_OPS       NULL
#endif /* CONFIG_PM_SLEEP */

/*
 * proc interface for register dump
 */

static void snd_atiixp_proc_read(struct snd_info_entry *entry,
                                 struct snd_info_buffer *buffer)
{
        struct atiixp_modem *chip = entry->private_data;
        int i;

        for (i = 0; i < 256; i += 4)
                snd_iprintf(buffer, "%02x: %08x\n", i, readl(chip->remap_addr + i));
}

static void snd_atiixp_proc_init(struct atiixp_modem *chip)
{
        snd_card_ro_proc_new(chip->card, "atiixp-modem", chip,
                             snd_atiixp_proc_read);
}


/*
 * destructor
 */

static void snd_atiixp_free(struct snd_card *card)
{
        snd_atiixp_chip_stop(card->private_data);
}

/*
 * constructor for chip instance
 */
static int snd_atiixp_init(struct snd_card *card, struct pci_dev *pci)
{
        struct atiixp_modem *chip = card->private_data;
        int err;

        err = pcim_enable_device(pci);
        if (err < 0)
                return err;

        spin_lock_init(&chip->reg_lock);
        mutex_init(&chip->open_mutex);
        chip->card = card;
        chip->pci = pci;
        chip->irq = -1;
        err = pcim_iomap_regions(pci, 1 << 0, "ATI IXP MC97");
        if (err < 0)
                return err;
        chip->addr = pci_resource_start(pci, 0);
        chip->remap_addr = pcim_iomap_table(pci)[0];

        if (devm_request_irq(&pci->dev, pci->irq, snd_atiixp_interrupt,
                             IRQF_SHARED, KBUILD_MODNAME, chip)) {
                dev_err(card->dev, "unable to grab IRQ %d\n", pci->irq);
                return -EBUSY;
        }
        chip->irq = pci->irq;
        card->sync_irq = chip->irq;
        card->private_free = snd_atiixp_free;
        pci_set_master(pci);

        return 0;
}


static int snd_atiixp_probe(struct pci_dev *pci,
                            const struct pci_device_id *pci_id)
{
        struct snd_card *card;
        struct atiixp_modem *chip;
        int err;

        err = snd_devm_card_new(&pci->dev, index, id, THIS_MODULE,
                                sizeof(*chip), &card);
        if (err < 0)
                return err;
        chip = card->private_data;

        strcpy(card->driver, "ATIIXP-MODEM");
        strcpy(card->shortname, "ATI IXP Modem");
        err = snd_atiixp_init(card, pci);
        if (err < 0)
                return err;

        err = snd_atiixp_aclink_reset(chip);
        if (err < 0)
                return err;

        err = snd_atiixp_mixer_new(chip, ac97_clock);
        if (err < 0)
                return err;

        err = snd_atiixp_pcm_new(chip);
        if (err < 0)
                return err;
        
        snd_atiixp_proc_init(chip);

        snd_atiixp_chip_start(chip);

        sprintf(card->longname, "%s rev %x at 0x%lx, irq %i",
                card->shortname, pci->revision, chip->addr, chip->irq);

        err = snd_card_register(card);
        if (err < 0)
                return err;

        pci_set_drvdata(pci, card);
        return 0;
}

static struct pci_driver atiixp_modem_driver = {
        .name = KBUILD_MODNAME,
        .id_table = snd_atiixp_ids,
        .probe = snd_atiixp_probe,
        .driver = {
                .pm = SND_ATIIXP_PM_OPS,
        },
};

module_pci_driver(atiixp_modem_driver);