firewire: core: retry on local errors in bus manager election

[linux/fpc-iii.git] / drivers / firewire / core-card.c

/*
 * Copyright (C) 2005-2007  Kristian Hoegsberg <krh@bitplanet.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

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

#include "core.h"

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 */

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;
        int ret;

        /*
         * 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;

        mutex_lock(&card_mutex);

        if (config_rom_length + required_space(desc) > 256) {
                ret = -EBUSY;
        } else {
                list_add_tail(&desc->link, &descriptor_list);
                config_rom_length += required_space(desc);
                descriptor_count++;
                if (desc->immediate > 0)
                        descriptor_count++;
                update_config_roms();
                ret = 0;
        }

        mutex_unlock(&card_mutex);

        return ret;
}
EXPORT_SYMBOL(fw_core_add_descriptor);

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

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

        mutex_unlock(&card_mutex);
}
EXPORT_SYMBOL(fw_core_remove_descriptor);

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

        fw_iso_resource_manage(card, generation, 1ULL << 31, &channel,
                               &bandwidth, true, card->bm_transaction_data);
        if (channel == 31) {
                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->work, delay))
                fw_card_put(card);
}

static void fw_card_bm_work(struct work_struct *work)
{
        struct fw_card *card = container_of(work, struct fw_card, work.work);
        struct fw_device *root_device;
        struct fw_node *root_node;
        unsigned long flags;
        int root_id, new_root_id, irm_id, local_id;
        int gap_count, generation, grace, rcode;
        bool do_reset = false;
        bool root_device_is_running;
        bool root_device_is_cmc;

        spin_lock_irqsave(&card->lock, flags);

        if (card->local_node == NULL) {
                spin_unlock_irqrestore(&card->lock, flags);
                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;
        root_id  = root_node->node_id;
        irm_id   = card->irm_node->node_id;
        local_id = card->local_node->node_id;

        grace = time_after(jiffies, card->reset_jiffies + DIV_ROUND_UP(HZ, 8));

        if (is_next_generation(generation, card->bm_generation) ||
            (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_notify("IRM has link off, making local node (%02x) root.\n",
                                  new_root_id);
                        goto pick_me;
                }

                card->bm_transaction_data[0] = cpu_to_be32(0x3f);
                card->bm_transaction_data[1] = cpu_to_be32(local_id);

                spin_unlock_irqrestore(&card->lock, flags);

                rcode = fw_run_transaction(card, TCODE_LOCK_COMPARE_SWAP,
                                irm_id, generation, SCODE_100,
                                CSR_REGISTER_BASE + CSR_BUS_MANAGER_ID,
                                card->bm_transaction_data,
                                sizeof(card->bm_transaction_data));

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

                if (rcode == RCODE_COMPLETE &&
                    card->bm_transaction_data[0] != cpu_to_be32(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_irqsave(&card->lock, flags);

                if (rcode != RCODE_COMPLETE) {
                        /*
                         * 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_notify("BM lock failed, making local node (%02x) root.\n",
                                  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_irqrestore(&card->lock, flags);
                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 (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_irqrestore(&card->lock, flags);
                goto out;
        } else if (root_device_is_cmc) {
                /*
                 * FIXME: I suppose we should set the cmstr bit in the
                 * STATE_CLEAR register of this node, as described in
                 * 1394-1995, 8.4.2.6.  Also, send out a force root
                 * packet for this node.
                 */
                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_irqrestore(&card->lock, flags);

        if (do_reset) {
                fw_notify("phy config: card %d, new root=%x, gap_count=%d\n",
                          card->index, new_root_id, gap_count);
                fw_send_phy_config(card, new_root_id, generation, gap_count);
                fw_core_initiate_bus_reset(card, 1);
                /* Will allocate broadcast channel after the reset. */
        } else {
                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->color = 0;
        card->broadcast_channel = BROADCAST_CHANNEL_INITIAL;

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

        card->local_node = NULL;

        INIT_DELAYED_WORK(&card->work, fw_card_bm_work);
}
EXPORT_SYMBOL(fw_card_initialize);

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

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

        mutex_lock(&card_mutex);

        generate_config_rom(card, tmp_config_rom);
        ret = card->driver->enable(card, tmp_config_rom, config_rom_length);
        if (ret == 0)
                list_add_tail(&card->link, &card_list);

        mutex_unlock(&card_mutex);

        return ret;
}
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.
 */

static int dummy_enable(struct fw_card *card,
                        const __be32 *config_rom, size_t length)
{
        BUG();
        return -1;
}

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

static int dummy_set_config_rom(struct fw_card *card,
                                const __be32 *config_rom, size_t length)
{
        /*
         * We take the card out of card_list before setting the dummy
         * driver, so this should never get called.
         */
        BUG();
        return -1;
}

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

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

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 const struct fw_card_driver dummy_driver_template = {
        .enable          = dummy_enable,
        .update_phy_reg  = dummy_update_phy_reg,
        .set_config_rom  = dummy_set_config_rom,
        .send_request    = dummy_send_request,
        .cancel_packet   = dummy_cancel_packet,
        .send_response   = dummy_send_response,
        .enable_phys_dma = dummy_enable_phys_dma,
};

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

        complete(&card->done);
}

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

        card->driver->update_phy_reg(card, 4,
                                     PHY_LINK_ACTIVE | PHY_CONTENDER, 0);
        fw_core_initiate_bus_reset(card, 1);

        mutex_lock(&card_mutex);
        list_del_init(&card->link);
        mutex_unlock(&card_mutex);

        /* 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;

        fw_destroy_nodes(card);

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

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

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

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