/*
 * Load Analog Devices SigmaStudio firmware files
 *
 * Copyright 2009-2014 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later.
 */

#include <linux/crc32.h>
#include <linux/firmware.h>
#include <linux/kernel.h>
#include <linux/i2c.h>
#include <linux/regmap.h>
#include <linux/module.h>
#include <linux/slab.h>

#include <sound/control.h>
#include <sound/soc.h>

#include "sigmadsp.h"

#define SIGMA_MAGIC "ADISIGM"

#define SIGMA_FW_CHUNK_TYPE_DATA 0
#define SIGMA_FW_CHUNK_TYPE_CONTROL 1
#define SIGMA_FW_CHUNK_TYPE_SAMPLERATES 2

struct sigmadsp_control {
        struct list_head head;
        uint32_t samplerates;
        unsigned int addr;
        unsigned int num_bytes;
        const char *name;
        struct snd_kcontrol *kcontrol;
        bool cached;
        uint8_t cache[];
};

struct sigmadsp_data {
        struct list_head head;
        uint32_t samplerates;
        unsigned int addr;
        unsigned int length;
        uint8_t data[];
};

struct sigma_fw_chunk {
        __le32 length;
        __le32 tag;
        __le32 samplerates;
} __packed;

struct sigma_fw_chunk_data {
        struct sigma_fw_chunk chunk;
        __le16 addr;
        uint8_t data[];
} __packed;

struct sigma_fw_chunk_control {
        struct sigma_fw_chunk chunk;
        __le16 type;
        __le16 addr;
        __le16 num_bytes;
        const char name[];
} __packed;

struct sigma_fw_chunk_samplerate {
        struct sigma_fw_chunk chunk;
        __le32 samplerates[];
} __packed;

struct sigma_firmware_header {
        unsigned char magic[7];
        u8 version;
        __le32 crc;
} __packed;

enum {
        SIGMA_ACTION_WRITEXBYTES = 0,
        SIGMA_ACTION_WRITESINGLE,
        SIGMA_ACTION_WRITESAFELOAD,
        SIGMA_ACTION_END,
};

struct sigma_action {
        u8 instr;
        u8 len_hi;
        __le16 len;
        __be16 addr;
        unsigned char payload[];
} __packed;

static int sigmadsp_write(struct sigmadsp *sigmadsp, unsigned int addr,
        const uint8_t data[], size_t len)
{
        return sigmadsp->write(sigmadsp->control_data, addr, data, len);
}

static int sigmadsp_read(struct sigmadsp *sigmadsp, unsigned int addr,
        uint8_t data[], size_t len)
{
        return sigmadsp->read(sigmadsp->control_data, addr, data, len);
}

static int sigmadsp_ctrl_info(struct snd_kcontrol *kcontrol,
        struct snd_ctl_elem_info *info)
{
        struct sigmadsp_control *ctrl = (void *)kcontrol->private_value;

        info->type = SNDRV_CTL_ELEM_TYPE_BYTES;
        info->count = ctrl->num_bytes;

        return 0;
}

static int sigmadsp_ctrl_write(struct sigmadsp *sigmadsp,
        struct sigmadsp_control *ctrl, void *data)
{
        /* safeload loads up to 20 bytes in a atomic operation */
        if (ctrl->num_bytes <= 20 && sigmadsp->ops && sigmadsp->ops->safeload)
                return sigmadsp->ops->safeload(sigmadsp, ctrl->addr, data,
                        ctrl->num_bytes);
        else
                return sigmadsp_write(sigmadsp, ctrl->addr, data,
                        ctrl->num_bytes);
}

static int sigmadsp_ctrl_put(struct snd_kcontrol *kcontrol,
        struct snd_ctl_elem_value *ucontrol)
{
        struct sigmadsp_control *ctrl = (void *)kcontrol->private_value;
        struct sigmadsp *sigmadsp = snd_kcontrol_chip(kcontrol);
        uint8_t *data;
        int ret = 0;

        mutex_lock(&sigmadsp->lock);

        data = ucontrol->value.bytes.data;

        if (!(kcontrol->vd[0].access & SNDRV_CTL_ELEM_ACCESS_INACTIVE))
                ret = sigmadsp_ctrl_write(sigmadsp, ctrl, data);

        if (ret == 0) {
                memcpy(ctrl->cache, data, ctrl->num_bytes);
                ctrl->cached = true;
        }

        mutex_unlock(&sigmadsp->lock);

        return ret;
}

static int sigmadsp_ctrl_get(struct snd_kcontrol *kcontrol,
        struct snd_ctl_elem_value *ucontrol)
{
        struct sigmadsp_control *ctrl = (void *)kcontrol->private_value;
        struct sigmadsp *sigmadsp = snd_kcontrol_chip(kcontrol);
        int ret = 0;

        mutex_lock(&sigmadsp->lock);

        if (!ctrl->cached) {
                ret = sigmadsp_read(sigmadsp, ctrl->addr, ctrl->cache,
                        ctrl->num_bytes);
        }

        if (ret == 0) {
                ctrl->cached = true;
                memcpy(ucontrol->value.bytes.data, ctrl->cache,
                        ctrl->num_bytes);
        }

        mutex_unlock(&sigmadsp->lock);

        return ret;
}

static void sigmadsp_control_free(struct snd_kcontrol *kcontrol)
{
        struct sigmadsp_control *ctrl = (void *)kcontrol->private_value;

        ctrl->kcontrol = NULL;
}

static bool sigma_fw_validate_control_name(const char *name, unsigned int len)
{
        unsigned int i;

        for (i = 0; i < len; i++) {
                /* Normal ASCII characters are valid */
                if (name[i] < ' ' || name[i] > '~')
                        return false;
        }

        return true;
}

static int sigma_fw_load_control(struct sigmadsp *sigmadsp,
        const struct sigma_fw_chunk *chunk, unsigned int length)
{
        const struct sigma_fw_chunk_control *ctrl_chunk;
        struct sigmadsp_control *ctrl;
        unsigned int num_bytes;
        size_t name_len;
        char *name;
        int ret;

        if (length <= sizeof(*ctrl_chunk))
                return -EINVAL;

        ctrl_chunk = (const struct sigma_fw_chunk_control *)chunk;

        name_len = length - sizeof(*ctrl_chunk);
        if (name_len >= SNDRV_CTL_ELEM_ID_NAME_MAXLEN)
                name_len = SNDRV_CTL_ELEM_ID_NAME_MAXLEN - 1;

        /* Make sure there are no non-displayable characaters in the string */
        if (!sigma_fw_validate_control_name(ctrl_chunk->name, name_len))
                return -EINVAL;

        num_bytes = le16_to_cpu(ctrl_chunk->num_bytes);
        ctrl = kzalloc(sizeof(*ctrl) + num_bytes, GFP_KERNEL);
        if (!ctrl)
                return -ENOMEM;

        name = kzalloc(name_len + 1, GFP_KERNEL);
        if (!name) {
                ret = -ENOMEM;
                goto err_free_ctrl;
        }
        memcpy(name, ctrl_chunk->name, name_len);
        name[name_len] = '\0';
        ctrl->name = name;

        ctrl->addr = le16_to_cpu(ctrl_chunk->addr);
        ctrl->num_bytes = num_bytes;
        ctrl->samplerates = le32_to_cpu(chunk->samplerates);

        list_add_tail(&ctrl->head, &sigmadsp->ctrl_list);

        return 0;

err_free_ctrl:
        kfree(ctrl);

        return ret;
}

static int sigma_fw_load_data(struct sigmadsp *sigmadsp,
        const struct sigma_fw_chunk *chunk, unsigned int length)
{
        const struct sigma_fw_chunk_data *data_chunk;
        struct sigmadsp_data *data;

        if (length <= sizeof(*data_chunk))
                return -EINVAL;

        data_chunk = (struct sigma_fw_chunk_data *)chunk;

        length -= sizeof(*data_chunk);

        data = kzalloc(sizeof(*data) + length, GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        data->addr = le16_to_cpu(data_chunk->addr);
        data->length = length;
        data->samplerates = le32_to_cpu(chunk->samplerates);
        memcpy(data->data, data_chunk->data, length);
        list_add_tail(&data->head, &sigmadsp->data_list);

        return 0;
}

static int sigma_fw_load_samplerates(struct sigmadsp *sigmadsp,
        const struct sigma_fw_chunk *chunk, unsigned int length)
{
        const struct sigma_fw_chunk_samplerate *rate_chunk;
        unsigned int num_rates;
        unsigned int *rates;
        unsigned int i;

        rate_chunk = (const struct sigma_fw_chunk_samplerate *)chunk;

        num_rates = (length - sizeof(*rate_chunk)) / sizeof(__le32);

        if (num_rates > 32 || num_rates == 0)
                return -EINVAL;

        /* We only allow one samplerates block per file */
        if (sigmadsp->rate_constraints.count)
                return -EINVAL;

        rates = kcalloc(num_rates, sizeof(*rates), GFP_KERNEL);
        if (!rates)
                return -ENOMEM;

        for (i = 0; i < num_rates; i++)
                rates[i] = le32_to_cpu(rate_chunk->samplerates[i]);

        sigmadsp->rate_constraints.count = num_rates;
        sigmadsp->rate_constraints.list = rates;

        return 0;
}

static int sigmadsp_fw_load_v2(struct sigmadsp *sigmadsp,
        const struct firmware *fw)
{
        struct sigma_fw_chunk *chunk;
        unsigned int length, pos;
        int ret;

        /*
         * Make sure that there is at least one chunk to avoid integer
         * underflows later on. Empty firmware is still valid though.
         */
        if (fw->size < sizeof(*chunk) + sizeof(struct sigma_firmware_header))
                return 0;

        pos = sizeof(struct sigma_firmware_header);

        while (pos < fw->size - sizeof(*chunk)) {
                chunk = (struct sigma_fw_chunk *)(fw->data + pos);

                length = le32_to_cpu(chunk->length);

                if (length > fw->size - pos || length < sizeof(*chunk))
                        return -EINVAL;

                switch (le32_to_cpu(chunk->tag)) {
                case SIGMA_FW_CHUNK_TYPE_DATA:
                        ret = sigma_fw_load_data(sigmadsp, chunk, length);
                        break;
                case SIGMA_FW_CHUNK_TYPE_CONTROL:
                        ret = sigma_fw_load_control(sigmadsp, chunk, length);
                        break;
                case SIGMA_FW_CHUNK_TYPE_SAMPLERATES:
                        ret = sigma_fw_load_samplerates(sigmadsp, chunk, length);
                        break;
                default:
                        dev_warn(sigmadsp->dev, "Unknown chunk type: %d\n",
                                chunk->tag);
                        ret = 0;
                        break;
                }

                if (ret)
                        return ret;

                /*
                 * This can not overflow since if length is larger than the
                 * maximum firmware size (0x4000000) we'll error out earilier.
                 */
                pos += ALIGN(length, sizeof(__le32));
        }

        return 0;
}

static inline u32 sigma_action_len(struct sigma_action *sa)
{
        return (sa->len_hi << 16) | le16_to_cpu(sa->len);
}

static size_t sigma_action_size(struct sigma_action *sa)
{
        size_t payload = 0;

        switch (sa->instr) {
        case SIGMA_ACTION_WRITEXBYTES:
        case SIGMA_ACTION_WRITESINGLE:
        case SIGMA_ACTION_WRITESAFELOAD:
                payload = sigma_action_len(sa);
                break;
        default:
                break;
        }

        payload = ALIGN(payload, 2);

        return payload + sizeof(struct sigma_action);
}

/*
 * Returns a negative error value in case of an error, 0 if processing of
 * the firmware should be stopped after this action, 1 otherwise.
 */
static int process_sigma_action(struct sigmadsp *sigmadsp,
        struct sigma_action *sa)
{
        size_t len = sigma_action_len(sa);
        struct sigmadsp_data *data;

        pr_debug("%s: instr:%i addr:%#x len:%zu\n", __func__,
                sa->instr, sa->addr, len);

        switch (sa->instr) {
        case SIGMA_ACTION_WRITEXBYTES:
        case SIGMA_ACTION_WRITESINGLE:
        case SIGMA_ACTION_WRITESAFELOAD:
                if (len < 3)
                        return -EINVAL;

                data = kzalloc(sizeof(*data) + len - 2, GFP_KERNEL);
                if (!data)
                        return -ENOMEM;

                data->addr = be16_to_cpu(sa->addr);
                data->length = len - 2;
                memcpy(data->data, sa->payload, data->length);
                list_add_tail(&data->head, &sigmadsp->data_list);
                break;
        case SIGMA_ACTION_END:
                return 0;
        default:
                return -EINVAL;
        }

        return 1;
}

static int sigmadsp_fw_load_v1(struct sigmadsp *sigmadsp,
        const struct firmware *fw)
{
        struct sigma_action *sa;
        size_t size, pos;
        int ret;

        pos = sizeof(struct sigma_firmware_header);

        while (pos + sizeof(*sa) <= fw->size) {
                sa = (struct sigma_action *)(fw->data + pos);

                size = sigma_action_size(sa);
                pos += size;
                if (pos > fw->size || size == 0)
                        break;

                ret = process_sigma_action(sigmadsp, sa);

                pr_debug("%s: action returned %i\n", __func__, ret);

                if (ret <= 0)
                        return ret;
        }

        if (pos != fw->size)
                return -EINVAL;

        return 0;
}

static void sigmadsp_firmware_release(struct sigmadsp *sigmadsp)
{
        struct sigmadsp_control *ctrl, *_ctrl;
        struct sigmadsp_data *data, *_data;

        list_for_each_entry_safe(ctrl, _ctrl, &sigmadsp->ctrl_list, head) {
                kfree(ctrl->name);
                kfree(ctrl);
        }

        list_for_each_entry_safe(data, _data, &sigmadsp->data_list, head)
                kfree(data);

        INIT_LIST_HEAD(&sigmadsp->ctrl_list);
        INIT_LIST_HEAD(&sigmadsp->data_list);
}

static void devm_sigmadsp_release(struct device *dev, void *res)
{
        sigmadsp_firmware_release((struct sigmadsp *)res);
}

static int sigmadsp_firmware_load(struct sigmadsp *sigmadsp, const char *name)
{
        const struct sigma_firmware_header *ssfw_head;
        const struct firmware *fw;
        int ret;
        u32 crc;

        /* first load the blob */
        ret = request_firmware(&fw, name, sigmadsp->dev);
        if (ret) {
                pr_debug("%s: request_firmware() failed with %i\n", __func__, ret);
                goto done;
        }

        /* then verify the header */
        ret = -EINVAL;

        /*
         * Reject too small or unreasonable large files. The upper limit has been
         * chosen a bit arbitrarily, but it should be enough for all practical
         * purposes and having the limit makes it easier to avoid integer
         * overflows later in the loading process.
         */
        if (fw->size < sizeof(*ssfw_head) || fw->size >= 0x4000000) {
                dev_err(sigmadsp->dev, "Failed to load firmware: Invalid size\n");
                goto done;
        }

        ssfw_head = (void *)fw->data;
        if (memcmp(ssfw_head->magic, SIGMA_MAGIC, ARRAY_SIZE(ssfw_head->magic))) {
                dev_err(sigmadsp->dev, "Failed to load firmware: Invalid magic\n");
                goto done;
        }

        crc = crc32(0, fw->data + sizeof(*ssfw_head),
                        fw->size - sizeof(*ssfw_head));
        pr_debug("%s: crc=%x\n", __func__, crc);
        if (crc != le32_to_cpu(ssfw_head->crc)) {
                dev_err(sigmadsp->dev, "Failed to load firmware: Wrong crc checksum: expected %x got %x\n",
                        le32_to_cpu(ssfw_head->crc), crc);
                goto done;
        }

        switch (ssfw_head->version) {
        case 1:
                ret = sigmadsp_fw_load_v1(sigmadsp, fw);
                break;
        case 2:
                ret = sigmadsp_fw_load_v2(sigmadsp, fw);
                break;
        default:
                dev_err(sigmadsp->dev,
                        "Failed to load firmware: Invalid version %d. Supported firmware versions: 1, 2\n",
                        ssfw_head->version);
                ret = -EINVAL;
                break;
        }

        if (ret)
                sigmadsp_firmware_release(sigmadsp);

done:
        release_firmware(fw);

        return ret;
}

static int sigmadsp_init(struct sigmadsp *sigmadsp, struct device *dev,
        const struct sigmadsp_ops *ops, const char *firmware_name)
{
        sigmadsp->ops = ops;
        sigmadsp->dev = dev;

        INIT_LIST_HEAD(&sigmadsp->ctrl_list);
        INIT_LIST_HEAD(&sigmadsp->data_list);
        mutex_init(&sigmadsp->lock);

        return sigmadsp_firmware_load(sigmadsp, firmware_name);
}

/**
 * devm_sigmadsp_init() - Initialize SigmaDSP instance
 * @dev: The parent device
 * @ops: The sigmadsp_ops to use for this instance
 * @firmware_name: Name of the firmware file to load
 *
 * Allocates a SigmaDSP instance and loads the specified firmware file.
 *
 * Returns a pointer to a struct sigmadsp on success, or a PTR_ERR() on error.
 */
struct sigmadsp *devm_sigmadsp_init(struct device *dev,
        const struct sigmadsp_ops *ops, const char *firmware_name)
{
        struct sigmadsp *sigmadsp;
        int ret;

        sigmadsp = devres_alloc(devm_sigmadsp_release, sizeof(*sigmadsp),
                GFP_KERNEL);
        if (!sigmadsp)
                return ERR_PTR(-ENOMEM);

        ret = sigmadsp_init(sigmadsp, dev, ops, firmware_name);
        if (ret) {
                devres_free(sigmadsp);
                return ERR_PTR(ret);
        }

        devres_add(dev, sigmadsp);

        return sigmadsp;
}
EXPORT_SYMBOL_GPL(devm_sigmadsp_init);

static int sigmadsp_rate_to_index(struct sigmadsp *sigmadsp, unsigned int rate)
{
        unsigned int i;

        for (i = 0; i < sigmadsp->rate_constraints.count; i++) {
                if (sigmadsp->rate_constraints.list[i] == rate)
                        return i;
        }

        return -EINVAL;
}

static unsigned int sigmadsp_get_samplerate_mask(struct sigmadsp *sigmadsp,
        unsigned int samplerate)
{
        int samplerate_index;

        if (samplerate == 0)
                return 0;

        if (sigmadsp->rate_constraints.count) {
                samplerate_index = sigmadsp_rate_to_index(sigmadsp, samplerate);
                if (samplerate_index < 0)
                        return 0;

                return BIT(samplerate_index);
        } else {
                return ~0;
        }
}

static bool sigmadsp_samplerate_valid(unsigned int supported,
        unsigned int requested)
{
        /* All samplerates are supported */
        if (!supported)
                return true;

        return supported & requested;
}

static int sigmadsp_alloc_control(struct sigmadsp *sigmadsp,
        struct sigmadsp_control *ctrl, unsigned int samplerate_mask)
{
        struct snd_kcontrol_new template;
        struct snd_kcontrol *kcontrol;

        memset(&template, 0, sizeof(template));
        template.iface = SNDRV_CTL_ELEM_IFACE_MIXER;
        template.name = ctrl->name;
        template.info = sigmadsp_ctrl_info;
        template.get = sigmadsp_ctrl_get;
        template.put = sigmadsp_ctrl_put;
        template.private_value = (unsigned long)ctrl;
        template.access = SNDRV_CTL_ELEM_ACCESS_READWRITE;
        if (!sigmadsp_samplerate_valid(ctrl->samplerates, samplerate_mask))
                template.access |= SNDRV_CTL_ELEM_ACCESS_INACTIVE;

        kcontrol = snd_ctl_new1(&template, sigmadsp);
        if (!kcontrol)
                return -ENOMEM;

        kcontrol->private_free = sigmadsp_control_free;
        ctrl->kcontrol = kcontrol;

        return snd_ctl_add(sigmadsp->component->card->snd_card, kcontrol);
}

static void sigmadsp_activate_ctrl(struct sigmadsp *sigmadsp,
        struct sigmadsp_control *ctrl, unsigned int samplerate_mask)
{
        struct snd_card *card = sigmadsp->component->card->snd_card;
        struct snd_kcontrol_volatile *vd;
        struct snd_ctl_elem_id id;
        bool active;
        bool changed = false;

        active = sigmadsp_samplerate_valid(ctrl->samplerates, samplerate_mask);

        down_write(&card->controls_rwsem);
        if (!ctrl->kcontrol) {
                up_write(&card->controls_rwsem);
                return;
        }

        id = ctrl->kcontrol->id;
        vd = &ctrl->kcontrol->vd[0];
        if (active == (bool)(vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE)) {
                vd->access ^= SNDRV_CTL_ELEM_ACCESS_INACTIVE;
                changed = true;
        }
        up_write(&card->controls_rwsem);

        if (active && changed) {
                mutex_lock(&sigmadsp->lock);
                if (ctrl->cached)
                        sigmadsp_ctrl_write(sigmadsp, ctrl, ctrl->cache);
                mutex_unlock(&sigmadsp->lock);
        }

        if (changed)
                snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_INFO, &id);
}

/**
 * sigmadsp_attach() - Attach a sigmadsp instance to a ASoC component
 * @sigmadsp: The sigmadsp instance to attach
 * @component: The component to attach to
 *
 * Typically called in the components probe callback.
 *
 * Note, once this function has been called the firmware must not be released
 * until after the ALSA snd_card that the component belongs to has been
 * disconnected, even if sigmadsp_attach() returns an error.
 */
int sigmadsp_attach(struct sigmadsp *sigmadsp,
        struct snd_soc_component *component)
{
        struct sigmadsp_control *ctrl;
        unsigned int samplerate_mask;
        int ret;

        sigmadsp->component = component;

        samplerate_mask = sigmadsp_get_samplerate_mask(sigmadsp,
                sigmadsp->current_samplerate);

        list_for_each_entry(ctrl, &sigmadsp->ctrl_list, head) {
                ret = sigmadsp_alloc_control(sigmadsp, ctrl, samplerate_mask);
                if (ret)
                        return ret;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(sigmadsp_attach);

/**
 * sigmadsp_setup() - Setup the DSP for the specified samplerate
 * @sigmadsp: The sigmadsp instance to configure
 * @samplerate: The samplerate the DSP should be configured for
 *
 * Loads the appropriate firmware program and parameter memory (if not already
 * loaded) and enables the controls for the specified samplerate. Any control
 * parameter changes that have been made previously will be restored.
 *
 * Returns 0 on success, a negative error code otherwise.
 */
int sigmadsp_setup(struct sigmadsp *sigmadsp, unsigned int samplerate)
{
        struct sigmadsp_control *ctrl;
        unsigned int samplerate_mask;
        struct sigmadsp_data *data;
        int ret;

        if (sigmadsp->current_samplerate == samplerate)
                return 0;

        samplerate_mask = sigmadsp_get_samplerate_mask(sigmadsp, samplerate);
        if (samplerate_mask == 0)
                return -EINVAL;

        list_for_each_entry(data, &sigmadsp->data_list, head) {
                if (!sigmadsp_samplerate_valid(data->samplerates,
                    samplerate_mask))
                        continue;
                ret = sigmadsp_write(sigmadsp, data->addr, data->data,
                        data->length);
                if (ret)
                        goto err;
        }

        list_for_each_entry(ctrl, &sigmadsp->ctrl_list, head)
                sigmadsp_activate_ctrl(sigmadsp, ctrl, samplerate_mask);

        sigmadsp->current_samplerate = samplerate;

        return 0;
err:
        sigmadsp_reset(sigmadsp);

        return ret;
}
EXPORT_SYMBOL_GPL(sigmadsp_setup);

/**
 * sigmadsp_reset() - Notify the sigmadsp instance that the DSP has been reset
 * @sigmadsp: The sigmadsp instance to reset
 *
 * Should be called whenever the DSP has been reset and parameter and program
 * memory need to be re-loaded.
 */
void sigmadsp_reset(struct sigmadsp *sigmadsp)
{
        struct sigmadsp_control *ctrl;

        list_for_each_entry(ctrl, &sigmadsp->ctrl_list, head)
                sigmadsp_activate_ctrl(sigmadsp, ctrl, false);

        sigmadsp->current_samplerate = 0;
}
EXPORT_SYMBOL_GPL(sigmadsp_reset);

/**
 * sigmadsp_restrict_params() - Applies DSP firmware specific constraints
 * @sigmadsp: The sigmadsp instance
 * @substream: The substream to restrict
 *
 * Applies samplerate constraints that may be required by the firmware Should
 * typically be called from the CODEC/component drivers startup callback.
 *
 * Returns 0 on success, a negative error code otherwise.
 */
int sigmadsp_restrict_params(struct sigmadsp *sigmadsp,
        struct snd_pcm_substream *substream)
{
        if (sigmadsp->rate_constraints.count == 0)
                return 0;

        return snd_pcm_hw_constraint_list(substream->runtime, 0,
                SNDRV_PCM_HW_PARAM_RATE, &sigmadsp->rate_constraints);
}
EXPORT_SYMBOL_GPL(sigmadsp_restrict_params);

MODULE_LICENSE("GPL");