Merge tag 'trace-printf-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace...

[drm/drm-misc.git] / drivers / firewire / core-card.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2005-2007  Kristian Hoegsberg <krh@bitplanet.net>
 */

#include <linux/bug.h>
#include <linux/completion.h>
#include <linux/crc-itu-t.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/firewire.h>
#include <linux/firewire-constants.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>

#include <linux/atomic.h>
#include <asm/byteorder.h>

#include "core.h"
#include <trace/events/firewire.h>

#define define_fw_printk_level(func, kern_level)                \
void func(const struct fw_card *card, const char *fmt, ...)     \
{                                                               \
        struct va_format vaf;                                   \
        va_list args;                                           \
                                                                \
        va_start(args, fmt);                                    \
        vaf.fmt = fmt;                                          \
        vaf.va = &args;                                         \
        printk(kern_level KBUILD_MODNAME " %s: %pV",            \
               dev_name(card->device), &vaf);                   \
        va_end(args);                                           \
}
define_fw_printk_level(fw_err, KERN_ERR);
define_fw_printk_level(fw_notice, KERN_NOTICE);

int fw_compute_block_crc(__be32 *block)
{
        int length;
        u16 crc;

        length = (be32_to_cpu(block[0]) >> 16) & 0xff;
        crc = crc_itu_t(0, (u8 *)&block[1], length * 4);
        *block |= cpu_to_be32(crc);

        return length;
}

static DEFINE_MUTEX(card_mutex);
static LIST_HEAD(card_list);

static LIST_HEAD(descriptor_list);
static int descriptor_count;

static __be32 tmp_config_rom[256];
/* ROM header, bus info block, root dir header, capabilities = 7 quadlets */
static size_t config_rom_length = 1 + 4 + 1 + 1;

#define BIB_CRC(v)              ((v) <<  0)
#define BIB_CRC_LENGTH(v)       ((v) << 16)
#define BIB_INFO_LENGTH(v)      ((v) << 24)
#define BIB_BUS_NAME            0x31333934 /* "1394" */
#define BIB_LINK_SPEED(v)       ((v) <<  0)
#define BIB_GENERATION(v)       ((v) <<  4)
#define BIB_MAX_ROM(v)          ((v) <<  8)
#define BIB_MAX_RECEIVE(v)      ((v) << 12)
#define BIB_CYC_CLK_ACC(v)      ((v) << 16)
#define BIB_PMC                 ((1) << 27)
#define BIB_BMC                 ((1) << 28)
#define BIB_ISC                 ((1) << 29)
#define BIB_CMC                 ((1) << 30)
#define BIB_IRMC                ((1) << 31)
#define NODE_CAPABILITIES       0x0c0083c0 /* per IEEE 1394 clause 8.3.2.6.5.2 */

/*
 * IEEE-1394 specifies a default SPLIT_TIMEOUT value of 800 cycles (100 ms),
 * but we have to make it longer because there are many devices whose firmware
 * is just too slow for that.
 */
#define DEFAULT_SPLIT_TIMEOUT   (2 * 8000)

#define CANON_OUI               0x000085

static void generate_config_rom(struct fw_card *card, __be32 *config_rom)
{
        struct fw_descriptor *desc;
        int i, j, k, length;

        /*
         * Initialize contents of config rom buffer.  On the OHCI
         * controller, block reads to the config rom accesses the host
         * memory, but quadlet read access the hardware bus info block
         * registers.  That's just crack, but it means we should make
         * sure the contents of bus info block in host memory matches
         * the version stored in the OHCI registers.
         */

        config_rom[0] = cpu_to_be32(
                BIB_CRC_LENGTH(4) | BIB_INFO_LENGTH(4) | BIB_CRC(0));
        config_rom[1] = cpu_to_be32(BIB_BUS_NAME);
        config_rom[2] = cpu_to_be32(
                BIB_LINK_SPEED(card->link_speed) |
                BIB_GENERATION(card->config_rom_generation++ % 14 + 2) |
                BIB_MAX_ROM(2) |
                BIB_MAX_RECEIVE(card->max_receive) |
                BIB_BMC | BIB_ISC | BIB_CMC | BIB_IRMC);
        config_rom[3] = cpu_to_be32(card->guid >> 32);
        config_rom[4] = cpu_to_be32(card->guid);

        /* Generate root directory. */
        config_rom[6] = cpu_to_be32(NODE_CAPABILITIES);
        i = 7;
        j = 7 + descriptor_count;

        /* Generate root directory entries for descriptors. */
        list_for_each_entry (desc, &descriptor_list, link) {
                if (desc->immediate > 0)
                        config_rom[i++] = cpu_to_be32(desc->immediate);
                config_rom[i] = cpu_to_be32(desc->key | (j - i));
                i++;
                j += desc->length;
        }

        /* Update root directory length. */
        config_rom[5] = cpu_to_be32((i - 5 - 1) << 16);

        /* End of root directory, now copy in descriptors. */
        list_for_each_entry (desc, &descriptor_list, link) {
                for (k = 0; k < desc->length; k++)
                        config_rom[i + k] = cpu_to_be32(desc->data[k]);
                i += desc->length;
        }

        /* Calculate CRCs for all blocks in the config rom.  This
         * assumes that CRC length and info length are identical for
         * the bus info block, which is always the case for this
         * implementation. */
        for (i = 0; i < j; i += length + 1)
                length = fw_compute_block_crc(config_rom + i);

        WARN_ON(j != config_rom_length);
}

static void update_config_roms(void)
{
        struct fw_card *card;

        list_for_each_entry (card, &card_list, link) {
                generate_config_rom(card, tmp_config_rom);
                card->driver->set_config_rom(card, tmp_config_rom,
                                             config_rom_length);
        }
}

static size_t required_space(struct fw_descriptor *desc)
{
        /* descriptor + entry into root dir + optional immediate entry */
        return desc->length + 1 + (desc->immediate > 0 ? 1 : 0);
}

int fw_core_add_descriptor(struct fw_descriptor *desc)
{
        size_t i;

        /*
         * Check descriptor is valid; the length of all blocks in the
         * descriptor has to add up to exactly the length of the
         * block.
         */
        i = 0;
        while (i < desc->length)
                i += (desc->data[i] >> 16) + 1;

        if (i != desc->length)
                return -EINVAL;

        guard(mutex)(&card_mutex);

        if (config_rom_length + required_space(desc) > 256)
                return -EBUSY;

        list_add_tail(&desc->link, &descriptor_list);
        config_rom_length += required_space(desc);
        descriptor_count++;
        if (desc->immediate > 0)
                descriptor_count++;
        update_config_roms();

        return 0;
}
EXPORT_SYMBOL(fw_core_add_descriptor);

void fw_core_remove_descriptor(struct fw_descriptor *desc)
{
        guard(mutex)(&card_mutex);

        list_del(&desc->link);
        config_rom_length -= required_space(desc);
        descriptor_count--;
        if (desc->immediate > 0)
                descriptor_count--;
        update_config_roms();
}
EXPORT_SYMBOL(fw_core_remove_descriptor);

static int reset_bus(struct fw_card *card, bool short_reset)
{
        int reg = short_reset ? 5 : 1;
        int bit = short_reset ? PHY_BUS_SHORT_RESET : PHY_BUS_RESET;

        trace_bus_reset_initiate(card->index, card->generation, short_reset);

        return card->driver->update_phy_reg(card, reg, 0, bit);
}

void fw_schedule_bus_reset(struct fw_card *card, bool delayed, bool short_reset)
{
        trace_bus_reset_schedule(card->index, card->generation, short_reset);

        /* We don't try hard to sort out requests of long vs. short resets. */
        card->br_short = short_reset;

        /* Use an arbitrary short delay to combine multiple reset requests. */
        fw_card_get(card);
        if (!queue_delayed_work(fw_workqueue, &card->br_work,
                                delayed ? DIV_ROUND_UP(HZ, 100) : 0))
                fw_card_put(card);
}
EXPORT_SYMBOL(fw_schedule_bus_reset);

static void br_work(struct work_struct *work)
{
        struct fw_card *card = container_of(work, struct fw_card, br_work.work);

        /* Delay for 2s after last reset per IEEE 1394 clause 8.2.1. */
        if (card->reset_jiffies != 0 &&
            time_before64(get_jiffies_64(), card->reset_jiffies + 2 * HZ)) {
                trace_bus_reset_postpone(card->index, card->generation, card->br_short);

                if (!queue_delayed_work(fw_workqueue, &card->br_work, 2 * HZ))
                        fw_card_put(card);
                return;
        }

        fw_send_phy_config(card, FW_PHY_CONFIG_NO_NODE_ID, card->generation,
                           FW_PHY_CONFIG_CURRENT_GAP_COUNT);
        reset_bus(card, card->br_short);
        fw_card_put(card);
}

static void allocate_broadcast_channel(struct fw_card *card, int generation)
{
        int channel, bandwidth = 0;

        if (!card->broadcast_channel_allocated) {
                fw_iso_resource_manage(card, generation, 1ULL << 31,
                                       &channel, &bandwidth, true);
                if (channel != 31) {
                        fw_notice(card, "failed to allocate broadcast channel\n");
                        return;
                }
                card->broadcast_channel_allocated = true;
        }

        device_for_each_child(card->device, (void *)(long)generation,
                              fw_device_set_broadcast_channel);
}

static const char gap_count_table[] = {
        63, 5, 7, 8, 10, 13, 16, 18, 21, 24, 26, 29, 32, 35, 37, 40
};

void fw_schedule_bm_work(struct fw_card *card, unsigned long delay)
{
        fw_card_get(card);
        if (!schedule_delayed_work(&card->bm_work, delay))
                fw_card_put(card);
}

static void bm_work(struct work_struct *work)
{
        struct fw_card *card = container_of(work, struct fw_card, bm_work.work);
        struct fw_device *root_device, *irm_device;
        struct fw_node *root_node;
        int root_id, new_root_id, irm_id, bm_id, local_id;
        int gap_count, generation, grace, rcode;
        bool do_reset = false;
        bool root_device_is_running;
        bool root_device_is_cmc;
        bool irm_is_1394_1995_only;
        bool keep_this_irm;
        __be32 transaction_data[2];

        spin_lock_irq(&card->lock);

        if (card->local_node == NULL) {
                spin_unlock_irq(&card->lock);
                goto out_put_card;
        }

        generation = card->generation;

        root_node = card->root_node;
        fw_node_get(root_node);
        root_device = root_node->data;
        root_device_is_running = root_device &&
                        atomic_read(&root_device->state) == FW_DEVICE_RUNNING;
        root_device_is_cmc = root_device && root_device->cmc;

        irm_device = card->irm_node->data;
        irm_is_1394_1995_only = irm_device && irm_device->config_rom &&
                        (irm_device->config_rom[2] & 0x000000f0) == 0;

        /* Canon MV5i works unreliably if it is not root node. */
        keep_this_irm = irm_device && irm_device->config_rom &&
                        irm_device->config_rom[3] >> 8 == CANON_OUI;

        root_id  = root_node->node_id;
        irm_id   = card->irm_node->node_id;
        local_id = card->local_node->node_id;

        grace = time_after64(get_jiffies_64(),
                             card->reset_jiffies + DIV_ROUND_UP(HZ, 8));

        if ((is_next_generation(generation, card->bm_generation) &&
             !card->bm_abdicate) ||
            (card->bm_generation != generation && grace)) {
                /*
                 * This first step is to figure out who is IRM and
                 * then try to become bus manager.  If the IRM is not
                 * well defined (e.g. does not have an active link
                 * layer or does not responds to our lock request, we
                 * will have to do a little vigilante bus management.
                 * In that case, we do a goto into the gap count logic
                 * so that when we do the reset, we still optimize the
                 * gap count.  That could well save a reset in the
                 * next generation.
                 */

                if (!card->irm_node->link_on) {
                        new_root_id = local_id;
                        fw_notice(card, "%s, making local node (%02x) root\n",
                                  "IRM has link off", new_root_id);
                        goto pick_me;
                }

                if (irm_is_1394_1995_only && !keep_this_irm) {
                        new_root_id = local_id;
                        fw_notice(card, "%s, making local node (%02x) root\n",
                                  "IRM is not 1394a compliant", new_root_id);
                        goto pick_me;
                }

                transaction_data[0] = cpu_to_be32(0x3f);
                transaction_data[1] = cpu_to_be32(local_id);

                spin_unlock_irq(&card->lock);

                rcode = fw_run_transaction(card, TCODE_LOCK_COMPARE_SWAP,
                                irm_id, generation, SCODE_100,
                                CSR_REGISTER_BASE + CSR_BUS_MANAGER_ID,
                                transaction_data, 8);

                if (rcode == RCODE_GENERATION)
                        /* Another bus reset, BM work has been rescheduled. */
                        goto out;

                bm_id = be32_to_cpu(transaction_data[0]);

                scoped_guard(spinlock_irq, &card->lock) {
                        if (rcode == RCODE_COMPLETE && generation == card->generation)
                                card->bm_node_id =
                                    bm_id == 0x3f ? local_id : 0xffc0 | bm_id;
                }

                if (rcode == RCODE_COMPLETE && bm_id != 0x3f) {
                        /* Somebody else is BM.  Only act as IRM. */
                        if (local_id == irm_id)
                                allocate_broadcast_channel(card, generation);

                        goto out;
                }

                if (rcode == RCODE_SEND_ERROR) {
                        /*
                         * We have been unable to send the lock request due to
                         * some local problem.  Let's try again later and hope
                         * that the problem has gone away by then.
                         */
                        fw_schedule_bm_work(card, DIV_ROUND_UP(HZ, 8));
                        goto out;
                }

                spin_lock_irq(&card->lock);

                if (rcode != RCODE_COMPLETE && !keep_this_irm) {
                        /*
                         * The lock request failed, maybe the IRM
                         * isn't really IRM capable after all. Let's
                         * do a bus reset and pick the local node as
                         * root, and thus, IRM.
                         */
                        new_root_id = local_id;
                        fw_notice(card, "BM lock failed (%s), making local node (%02x) root\n",
                                  fw_rcode_string(rcode), new_root_id);
                        goto pick_me;
                }
        } else if (card->bm_generation != generation) {
                /*
                 * We weren't BM in the last generation, and the last
                 * bus reset is less than 125ms ago.  Reschedule this job.
                 */
                spin_unlock_irq(&card->lock);
                fw_schedule_bm_work(card, DIV_ROUND_UP(HZ, 8));
                goto out;
        }

        /*
         * We're bus manager for this generation, so next step is to
         * make sure we have an active cycle master and do gap count
         * optimization.
         */
        card->bm_generation = generation;

        if (card->gap_count == 0) {
                /*
                 * If self IDs have inconsistent gap counts, do a
                 * bus reset ASAP. The config rom read might never
                 * complete, so don't wait for it. However, still
                 * send a PHY configuration packet prior to the
                 * bus reset. The PHY configuration packet might
                 * fail, but 1394-2008 8.4.5.2 explicitly permits
                 * it in this case, so it should be safe to try.
                 */
                new_root_id = local_id;
                /*
                 * We must always send a bus reset if the gap count
                 * is inconsistent, so bypass the 5-reset limit.
                 */
                card->bm_retries = 0;
        } else if (root_device == NULL) {
                /*
                 * Either link_on is false, or we failed to read the
                 * config rom.  In either case, pick another root.
                 */
                new_root_id = local_id;
        } else if (!root_device_is_running) {
                /*
                 * If we haven't probed this device yet, bail out now
                 * and let's try again once that's done.
                 */
                spin_unlock_irq(&card->lock);
                goto out;
        } else if (root_device_is_cmc) {
                /*
                 * We will send out a force root packet for this
                 * node as part of the gap count optimization.
                 */
                new_root_id = root_id;
        } else {
                /*
                 * Current root has an active link layer and we
                 * successfully read the config rom, but it's not
                 * cycle master capable.
                 */
                new_root_id = local_id;
        }

 pick_me:
        /*
         * Pick a gap count from 1394a table E-1.  The table doesn't cover
         * the typically much larger 1394b beta repeater delays though.
         */
        if (!card->beta_repeaters_present &&
            root_node->max_hops < ARRAY_SIZE(gap_count_table))
                gap_count = gap_count_table[root_node->max_hops];
        else
                gap_count = 63;

        /*
         * Finally, figure out if we should do a reset or not.  If we have
         * done less than 5 resets with the same physical topology and we
         * have either a new root or a new gap count setting, let's do it.
         */

        if (card->bm_retries++ < 5 &&
            (card->gap_count != gap_count || new_root_id != root_id))
                do_reset = true;

        spin_unlock_irq(&card->lock);

        if (do_reset) {
                fw_notice(card, "phy config: new root=%x, gap_count=%d\n",
                          new_root_id, gap_count);
                fw_send_phy_config(card, new_root_id, generation, gap_count);
                /*
                 * Where possible, use a short bus reset to minimize
                 * disruption to isochronous transfers. But in the event
                 * of a gap count inconsistency, use a long bus reset.
                 *
                 * As noted in 1394a 8.4.6.2, nodes on a mixed 1394/1394a bus
                 * may set different gap counts after a bus reset. On a mixed
                 * 1394/1394a bus, a short bus reset can get doubled. Some
                 * nodes may treat the double reset as one bus reset and others
                 * may treat it as two, causing a gap count inconsistency
                 * again. Using a long bus reset prevents this.
                 */
                reset_bus(card, card->gap_count != 0);
                /* Will allocate broadcast channel after the reset. */
                goto out;
        }

        if (root_device_is_cmc) {
                /*
                 * Make sure that the cycle master sends cycle start packets.
                 */
                transaction_data[0] = cpu_to_be32(CSR_STATE_BIT_CMSTR);
                rcode = fw_run_transaction(card, TCODE_WRITE_QUADLET_REQUEST,
                                root_id, generation, SCODE_100,
                                CSR_REGISTER_BASE + CSR_STATE_SET,
                                transaction_data, 4);
                if (rcode == RCODE_GENERATION)
                        goto out;
        }

        if (local_id == irm_id)
                allocate_broadcast_channel(card, generation);

 out:
        fw_node_put(root_node);
 out_put_card:
        fw_card_put(card);
}

void fw_card_initialize(struct fw_card *card,
                        const struct fw_card_driver *driver,
                        struct device *device)
{
        static atomic_t index = ATOMIC_INIT(-1);

        card->index = atomic_inc_return(&index);
        card->driver = driver;
        card->device = device;
        card->current_tlabel = 0;
        card->tlabel_mask = 0;
        card->split_timeout_hi = DEFAULT_SPLIT_TIMEOUT / 8000;
        card->split_timeout_lo = (DEFAULT_SPLIT_TIMEOUT % 8000) << 19;
        card->split_timeout_cycles = DEFAULT_SPLIT_TIMEOUT;
        card->split_timeout_jiffies =
                        DIV_ROUND_UP(DEFAULT_SPLIT_TIMEOUT * HZ, 8000);
        card->color = 0;
        card->broadcast_channel = BROADCAST_CHANNEL_INITIAL;

        kref_init(&card->kref);
        init_completion(&card->done);
        INIT_LIST_HEAD(&card->transaction_list);
        INIT_LIST_HEAD(&card->phy_receiver_list);
        spin_lock_init(&card->lock);

        card->local_node = NULL;

        INIT_DELAYED_WORK(&card->br_work, br_work);
        INIT_DELAYED_WORK(&card->bm_work, bm_work);
}
EXPORT_SYMBOL(fw_card_initialize);

int fw_card_add(struct fw_card *card, u32 max_receive, u32 link_speed, u64 guid,
                unsigned int supported_isoc_contexts)
{
        struct workqueue_struct *isoc_wq;
        int ret;

        // This workqueue should be:
        //  * != WQ_BH                  Sleepable.
        //  * == WQ_UNBOUND             Any core can process data for isoc context. The
        //                              implementation of unit protocol could consumes the core
        //                              longer somehow.
        //  * != WQ_MEM_RECLAIM         Not used for any backend of block device.
        //  * == WQ_FREEZABLE           Isochronous communication is at regular interval in real
        //                              time, thus should be drained if possible at freeze phase.
        //  * == WQ_HIGHPRI             High priority to process semi-realtime timestamped data.
        //  * == WQ_SYSFS               Parameters are available via sysfs.
        //  * max_active == n_it + n_ir A hardIRQ could notify events for multiple isochronous
        //                              contexts if they are scheduled to the same cycle.
        isoc_wq = alloc_workqueue("firewire-isoc-card%u",
                                  WQ_UNBOUND | WQ_FREEZABLE | WQ_HIGHPRI | WQ_SYSFS,
                                  supported_isoc_contexts, card->index);
        if (!isoc_wq)
                return -ENOMEM;

        card->max_receive = max_receive;
        card->link_speed = link_speed;
        card->guid = guid;

        guard(mutex)(&card_mutex);

        generate_config_rom(card, tmp_config_rom);
        ret = card->driver->enable(card, tmp_config_rom, config_rom_length);
        if (ret < 0) {
                destroy_workqueue(isoc_wq);
                return ret;
        }

        card->isoc_wq = isoc_wq;
        list_add_tail(&card->link, &card_list);

        return 0;
}
EXPORT_SYMBOL(fw_card_add);

/*
 * The next few functions implement a dummy driver that is used once a card
 * driver shuts down an fw_card.  This allows the driver to cleanly unload,
 * as all IO to the card will be handled (and failed) by the dummy driver
 * instead of calling into the module.  Only functions for iso context
 * shutdown still need to be provided by the card driver.
 *
 * .read/write_csr() should never be called anymore after the dummy driver
 * was bound since they are only used within request handler context.
 * .set_config_rom() is never called since the card is taken out of card_list
 * before switching to the dummy driver.
 */

static int dummy_read_phy_reg(struct fw_card *card, int address)
{
        return -ENODEV;
}

static int dummy_update_phy_reg(struct fw_card *card, int address,
                                int clear_bits, int set_bits)
{
        return -ENODEV;
}

static void dummy_send_request(struct fw_card *card, struct fw_packet *packet)
{
        packet->callback(packet, card, RCODE_CANCELLED);
}

static void dummy_send_response(struct fw_card *card, struct fw_packet *packet)
{
        packet->callback(packet, card, RCODE_CANCELLED);
}

static int dummy_cancel_packet(struct fw_card *card, struct fw_packet *packet)
{
        return -ENOENT;
}

static int dummy_enable_phys_dma(struct fw_card *card,
                                 int node_id, int generation)
{
        return -ENODEV;
}

static struct fw_iso_context *dummy_allocate_iso_context(struct fw_card *card,
                                int type, int channel, size_t header_size)
{
        return ERR_PTR(-ENODEV);
}

static u32 dummy_read_csr(struct fw_card *card, int csr_offset)
{
        return 0;
}

static void dummy_write_csr(struct fw_card *card, int csr_offset, u32 value)
{
}

static int dummy_start_iso(struct fw_iso_context *ctx,
                           s32 cycle, u32 sync, u32 tags)
{
        return -ENODEV;
}

static int dummy_set_iso_channels(struct fw_iso_context *ctx, u64 *channels)
{
        return -ENODEV;
}

static int dummy_queue_iso(struct fw_iso_context *ctx, struct fw_iso_packet *p,
                           struct fw_iso_buffer *buffer, unsigned long payload)
{
        return -ENODEV;
}

static void dummy_flush_queue_iso(struct fw_iso_context *ctx)
{
}

static int dummy_flush_iso_completions(struct fw_iso_context *ctx)
{
        return -ENODEV;
}

static const struct fw_card_driver dummy_driver_template = {
        .read_phy_reg           = dummy_read_phy_reg,
        .update_phy_reg         = dummy_update_phy_reg,
        .send_request           = dummy_send_request,
        .send_response          = dummy_send_response,
        .cancel_packet          = dummy_cancel_packet,
        .enable_phys_dma        = dummy_enable_phys_dma,
        .read_csr               = dummy_read_csr,
        .write_csr              = dummy_write_csr,
        .allocate_iso_context   = dummy_allocate_iso_context,
        .start_iso              = dummy_start_iso,
        .set_iso_channels       = dummy_set_iso_channels,
        .queue_iso              = dummy_queue_iso,
        .flush_queue_iso        = dummy_flush_queue_iso,
        .flush_iso_completions  = dummy_flush_iso_completions,
};

void fw_card_release(struct kref *kref)
{
        struct fw_card *card = container_of(kref, struct fw_card, kref);

        complete(&card->done);
}
EXPORT_SYMBOL_GPL(fw_card_release);

void fw_core_remove_card(struct fw_card *card)
{
        struct fw_card_driver dummy_driver = dummy_driver_template;

        might_sleep();

        card->driver->update_phy_reg(card, 4,
                                     PHY_LINK_ACTIVE | PHY_CONTENDER, 0);
        fw_schedule_bus_reset(card, false, true);

        scoped_guard(mutex, &card_mutex)
                list_del_init(&card->link);

        /* Switch off most of the card driver interface. */
        dummy_driver.free_iso_context   = card->driver->free_iso_context;
        dummy_driver.stop_iso           = card->driver->stop_iso;
        card->driver = &dummy_driver;
        drain_workqueue(card->isoc_wq);

        scoped_guard(spinlock_irqsave, &card->lock)
                fw_destroy_nodes(card);

        /* Wait for all users, especially device workqueue jobs, to finish. */
        fw_card_put(card);
        wait_for_completion(&card->done);

        destroy_workqueue(card->isoc_wq);

        WARN_ON(!list_empty(&card->transaction_list));
}
EXPORT_SYMBOL(fw_core_remove_card);

/**
 * fw_card_read_cycle_time: read from Isochronous Cycle Timer Register of 1394 OHCI in MMIO region
 *                          for controller card.
 * @card: The instance of card for 1394 OHCI controller.
 * @cycle_time: The mutual reference to value of cycle time for the read operation.
 *
 * Read value from Isochronous Cycle Timer Register of 1394 OHCI in MMIO region for the given
 * controller card. This function accesses the region without any lock primitives or IRQ mask.
 * When returning successfully, the content of @value argument has value aligned to host endianness,
 * formetted by CYCLE_TIME CSR Register of IEEE 1394 std.
 *
 * Context: Any context.
 * Return:
 * * 0 - Read successfully.
 * * -ENODEV - The controller is unavailable due to being removed or unbound.
 */
int fw_card_read_cycle_time(struct fw_card *card, u32 *cycle_time)
{
        if (card->driver->read_csr == dummy_read_csr)
                return -ENODEV;

        // It's possible to switch to dummy driver between the above and the below. This is the best
        // effort to return -ENODEV.
        *cycle_time = card->driver->read_csr(card, CSR_CYCLE_TIME);
        return 0;
}
EXPORT_SYMBOL_GPL(fw_card_read_cycle_time);