// SPDX-License-Identifier: GPL-2.0-only
/*
 * fireworks_transaction.c - a part of driver for Fireworks based devices
 *
 * Copyright (c) 2013-2014 Takashi Sakamoto
 */

/*
 * Fireworks have its own transaction. The transaction can be delivered by AV/C
 * Vendor Specific command frame or usual asynchronous transaction. At least,
 * Windows driver and firmware version 5.5 or later don't use AV/C command.
 *
 * Transaction substance:
 *  At first, 6 data exist. Following to the data, parameters for each command
 *  exist. All of the parameters are 32 bit aligned to big endian.
 *   data[0]:   Length of transaction substance
 *   data[1]:   Transaction version
 *   data[2]:   Sequence number. This is incremented by the device
 *   data[3]:   Transaction category
 *   data[4]:   Transaction command
 *   data[5]:   Return value in response.
 *   data[6-]:  Parameters
 *
 * Transaction address:
 *  command:    0xecc000000000
 *  response:   0xecc080000000 (default)
 *
 * I note that the address for response can be changed by command. But this
 * module uses the default address.
 */
#include "./fireworks.h"

#define MEMORY_SPACE_EFW_COMMAND        0xecc000000000ULL
#define MEMORY_SPACE_EFW_RESPONSE       0xecc080000000ULL

#define ERROR_RETRIES 3
#define ERROR_DELAY_MS 5
#define EFC_TIMEOUT_MS 125

static DEFINE_SPINLOCK(instances_lock);
static struct snd_efw *instances[SNDRV_CARDS] = SNDRV_DEFAULT_PTR;

static DEFINE_SPINLOCK(transaction_queues_lock);
static LIST_HEAD(transaction_queues);

enum transaction_queue_state {
        STATE_PENDING,
        STATE_BUS_RESET,
        STATE_COMPLETE
};

struct transaction_queue {
        struct list_head list;
        struct fw_unit *unit;
        void *buf;
        unsigned int size;
        u32 seqnum;
        enum transaction_queue_state state;
        wait_queue_head_t wait;
};

int snd_efw_transaction_cmd(struct fw_unit *unit,
                            const void *cmd, unsigned int size)
{
        return snd_fw_transaction(unit, TCODE_WRITE_BLOCK_REQUEST,
                                  MEMORY_SPACE_EFW_COMMAND,
                                  (void *)cmd, size, 0);
}

int snd_efw_transaction_run(struct fw_unit *unit,
                            const void *cmd, unsigned int cmd_size,
                            void *resp, unsigned int resp_size)
{
        struct transaction_queue t;
        unsigned int tries;
        int ret;

        t.unit = unit;
        t.buf = resp;
        t.size = resp_size;
        t.seqnum = be32_to_cpu(((struct snd_efw_transaction *)cmd)->seqnum) + 1;
        t.state = STATE_PENDING;
        init_waitqueue_head(&t.wait);

        scoped_guard(spinlock_irq, &transaction_queues_lock) {
                list_add_tail(&t.list, &transaction_queues);
        }

        tries = 0;
        do {
                ret = snd_efw_transaction_cmd(t.unit, (void *)cmd, cmd_size);
                if (ret < 0)
                        break;

                wait_event_timeout(t.wait, t.state != STATE_PENDING,
                                   msecs_to_jiffies(EFC_TIMEOUT_MS));

                if (t.state == STATE_COMPLETE) {
                        ret = t.size;
                        break;
                } else if (t.state == STATE_BUS_RESET) {
                        msleep(ERROR_DELAY_MS);
                } else if (++tries >= ERROR_RETRIES) {
                        dev_err(&t.unit->device, "EFW transaction timed out\n");
                        ret = -EIO;
                        break;
                }
        } while (1);

        scoped_guard(spinlock_irq, &transaction_queues_lock) {
                list_del(&t.list);
        }

        return ret;
}

static void
copy_resp_to_buf(struct snd_efw *efw, void *data, size_t length, int *rcode)
{
        size_t capacity, till_end;
        struct snd_efw_transaction *t;

        t = (struct snd_efw_transaction *)data;
        length = min_t(size_t, be32_to_cpu(t->length) * sizeof(u32), length);

        guard(spinlock)(&efw->lock);

        if (efw->push_ptr < efw->pull_ptr)
                capacity = (unsigned int)(efw->pull_ptr - efw->push_ptr);
        else
                capacity = snd_efw_resp_buf_size -
                           (unsigned int)(efw->push_ptr - efw->pull_ptr);

        /* confirm enough space for this response */
        if (capacity < length) {
                *rcode = RCODE_CONFLICT_ERROR;
                return;
        }

        /* copy to ring buffer */
        while (length > 0) {
                till_end = snd_efw_resp_buf_size -
                           (unsigned int)(efw->push_ptr - efw->resp_buf);
                till_end = min_t(unsigned int, length, till_end);

                memcpy(efw->push_ptr, data, till_end);

                efw->push_ptr += till_end;
                if (efw->push_ptr >= efw->resp_buf + snd_efw_resp_buf_size)
                        efw->push_ptr -= snd_efw_resp_buf_size;

                length -= till_end;
                data += till_end;
        }

        /* for hwdep */
        wake_up(&efw->hwdep_wait);

        *rcode = RCODE_COMPLETE;
}

static void
handle_resp_for_user(struct fw_card *card, int generation, int source,
                     void *data, size_t length, int *rcode)
{
        struct fw_device *device;
        struct snd_efw *efw;
        unsigned int i;

        guard(spinlock_irq)(&instances_lock);

        for (i = 0; i < SNDRV_CARDS; i++) {
                efw = instances[i];
                if (efw == NULL)
                        continue;
                device = fw_parent_device(efw->unit);
                if ((device->card != card) ||
                    (device->generation != generation))
                        continue;
                smp_rmb();      /* node id vs. generation */
                if (device->node_id != source)
                        continue;

                break;
        }
        if (i == SNDRV_CARDS)
                return;

        copy_resp_to_buf(efw, data, length, rcode);
}

static void
handle_resp_for_kernel(struct fw_card *card, int generation, int source,
                       void *data, size_t length, int *rcode, u32 seqnum)
{
        struct fw_device *device;
        struct transaction_queue *t;

        guard(spinlock_irqsave)(&transaction_queues_lock);
        list_for_each_entry(t, &transaction_queues, list) {
                device = fw_parent_device(t->unit);
                if ((device->card != card) ||
                    (device->generation != generation))
                        continue;
                smp_rmb();      /* node_id vs. generation */
                if (device->node_id != source)
                        continue;

                if ((t->state == STATE_PENDING) && (t->seqnum == seqnum)) {
                        t->state = STATE_COMPLETE;
                        t->size = min_t(unsigned int, length, t->size);
                        memcpy(t->buf, data, t->size);
                        wake_up(&t->wait);
                        *rcode = RCODE_COMPLETE;
                }
        }
}

static void
efw_response(struct fw_card *card, struct fw_request *request,
             int tcode, int destination, int source,
             int generation, unsigned long long offset,
             void *data, size_t length, void *callback_data)
{
        int rcode, dummy;
        u32 seqnum;

        rcode = RCODE_TYPE_ERROR;
        if (length < sizeof(struct snd_efw_transaction)) {
                rcode = RCODE_DATA_ERROR;
                goto end;
        } else if (offset != MEMORY_SPACE_EFW_RESPONSE) {
                rcode = RCODE_ADDRESS_ERROR;
                goto end;
        }

        seqnum = be32_to_cpu(((struct snd_efw_transaction *)data)->seqnum);
        if (seqnum > SND_EFW_TRANSACTION_USER_SEQNUM_MAX + 1) {
                handle_resp_for_kernel(card, generation, source,
                                       data, length, &rcode, seqnum);
                if (snd_efw_resp_buf_debug)
                        handle_resp_for_user(card, generation, source,
                                             data, length, &dummy);
        } else {
                handle_resp_for_user(card, generation, source,
                                     data, length, &rcode);
        }
end:
        fw_send_response(card, request, rcode);
}

void snd_efw_transaction_add_instance(struct snd_efw *efw)
{
        unsigned int i;

        guard(spinlock_irq)(&instances_lock);

        for (i = 0; i < SNDRV_CARDS; i++) {
                if (instances[i] != NULL)
                        continue;
                instances[i] = efw;
                break;
        }
}

void snd_efw_transaction_remove_instance(struct snd_efw *efw)
{
        unsigned int i;

        guard(spinlock_irq)(&instances_lock);

        for (i = 0; i < SNDRV_CARDS; i++) {
                if (instances[i] != efw)
                        continue;
                instances[i] = NULL;
        }
}

void snd_efw_transaction_bus_reset(struct fw_unit *unit)
{
        struct transaction_queue *t;

        guard(spinlock_irq)(&transaction_queues_lock);
        list_for_each_entry(t, &transaction_queues, list) {
                if ((t->unit == unit) &&
                    (t->state == STATE_PENDING)) {
                        t->state = STATE_BUS_RESET;
                        wake_up(&t->wait);
                }
        }
}

static struct fw_address_handler resp_register_handler = {
        .length = SND_EFW_RESPONSE_MAXIMUM_BYTES,
        .address_callback = efw_response
};

int snd_efw_transaction_register(void)
{
        static const struct fw_address_region resp_register_region = {
                .start  = MEMORY_SPACE_EFW_RESPONSE,
                .end    = MEMORY_SPACE_EFW_RESPONSE +
                          SND_EFW_RESPONSE_MAXIMUM_BYTES
        };
        return fw_core_add_address_handler(&resp_register_handler,
                                           &resp_register_region);
}

void snd_efw_transaction_unregister(void)
{
        WARN_ON(!list_empty(&transaction_queues));
        fw_core_remove_address_handler(&resp_register_handler);
}