/*
 * Connection Management Procedures (IEC 61883-1) helper functions
 *
 * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
 * Licensed under the terms of the GNU General Public License, version 2.
 */

#include <linux/device.h>
#include <linux/firewire.h>
#include <linux/firewire-constants.h>
#include <linux/module.h>
#include <linux/sched.h>
#include "lib.h"
#include "iso-resources.h"
#include "cmp.h"

/* MPR common fields */
#define MPR_SPEED_MASK          0xc0000000
#define MPR_SPEED_SHIFT         30
#define MPR_XSPEED_MASK         0x00000060
#define MPR_XSPEED_SHIFT        5
#define MPR_PLUGS_MASK          0x0000001f

/* PCR common fields */
#define PCR_ONLINE              0x80000000
#define PCR_BCAST_CONN          0x40000000
#define PCR_P2P_CONN_MASK       0x3f000000
#define PCR_P2P_CONN_SHIFT      24
#define PCR_CHANNEL_MASK        0x003f0000
#define PCR_CHANNEL_SHIFT       16

/* oPCR specific fields */
#define OPCR_XSPEED_MASK        0x00C00000
#define OPCR_XSPEED_SHIFT       22
#define OPCR_SPEED_MASK         0x0000C000
#define OPCR_SPEED_SHIFT        14
#define OPCR_OVERHEAD_ID_MASK   0x00003C00
#define OPCR_OVERHEAD_ID_SHIFT  10

enum bus_reset_handling {
        ABORT_ON_BUS_RESET,
        SUCCEED_ON_BUS_RESET,
};

static __printf(2, 3)
void cmp_error(struct cmp_connection *c, const char *fmt, ...)
{
        va_list va;

        va_start(va, fmt);
        dev_err(&c->resources.unit->device, "%cPCR%u: %pV",
                (c->direction == CMP_INPUT) ? 'i' : 'o',
                c->pcr_index, &(struct va_format){ fmt, &va });
        va_end(va);
}

static u64 mpr_address(struct cmp_connection *c)
{
        if (c->direction == CMP_INPUT)
                return CSR_REGISTER_BASE + CSR_IMPR;
        else
                return CSR_REGISTER_BASE + CSR_OMPR;
}

static u64 pcr_address(struct cmp_connection *c)
{
        if (c->direction == CMP_INPUT)
                return CSR_REGISTER_BASE + CSR_IPCR(c->pcr_index);
        else
                return CSR_REGISTER_BASE + CSR_OPCR(c->pcr_index);
}

static int pcr_modify(struct cmp_connection *c,
                      __be32 (*modify)(struct cmp_connection *c, __be32 old),
                      int (*check)(struct cmp_connection *c, __be32 pcr),
                      enum bus_reset_handling bus_reset_handling)
{
        __be32 old_arg, buffer[2];
        int err;

        buffer[0] = c->last_pcr_value;
        for (;;) {
                old_arg = buffer[0];
                buffer[1] = modify(c, buffer[0]);

                err = snd_fw_transaction(
                                c->resources.unit, TCODE_LOCK_COMPARE_SWAP,
                                pcr_address(c), buffer, 8,
                                FW_FIXED_GENERATION | c->resources.generation);

                if (err < 0) {
                        if (err == -EAGAIN &&
                            bus_reset_handling == SUCCEED_ON_BUS_RESET)
                                err = 0;
                        return err;
                }

                if (buffer[0] == old_arg) /* success? */
                        break;

                if (check) {
                        err = check(c, buffer[0]);
                        if (err < 0)
                                return err;
                }
        }
        c->last_pcr_value = buffer[1];

        return 0;
}


/**
 * cmp_connection_init - initializes a connection manager
 * @c: the connection manager to initialize
 * @unit: a unit of the target device
 * @direction: input or output
 * @pcr_index: the index of the iPCR/oPCR on the target device
 */
int cmp_connection_init(struct cmp_connection *c,
                        struct fw_unit *unit,
                        enum cmp_direction direction,
                        unsigned int pcr_index)
{
        __be32 mpr_be;
        u32 mpr;
        int err;

        c->direction = direction;
        err = snd_fw_transaction(unit, TCODE_READ_QUADLET_REQUEST,
                                 mpr_address(c), &mpr_be, 4, 0);
        if (err < 0)
                return err;
        mpr = be32_to_cpu(mpr_be);

        if (pcr_index >= (mpr & MPR_PLUGS_MASK))
                return -EINVAL;

        err = fw_iso_resources_init(&c->resources, unit);
        if (err < 0)
                return err;

        c->connected = false;
        mutex_init(&c->mutex);
        c->last_pcr_value = cpu_to_be32(0x80000000);
        c->pcr_index = pcr_index;
        c->max_speed = (mpr & MPR_SPEED_MASK) >> MPR_SPEED_SHIFT;
        if (c->max_speed == SCODE_BETA)
                c->max_speed += (mpr & MPR_XSPEED_MASK) >> MPR_XSPEED_SHIFT;

        return 0;
}
EXPORT_SYMBOL(cmp_connection_init);

/**
 * cmp_connection_check_used - check connection is already esablished or not
 * @c: the connection manager to be checked
 * @used: the pointer to store the result of checking the connection
 */
int cmp_connection_check_used(struct cmp_connection *c, bool *used)
{
        __be32 pcr;
        int err;

        err = snd_fw_transaction(
                        c->resources.unit, TCODE_READ_QUADLET_REQUEST,
                        pcr_address(c), &pcr, 4, 0);
        if (err >= 0)
                *used = !!(pcr & cpu_to_be32(PCR_BCAST_CONN |
                                             PCR_P2P_CONN_MASK));

        return err;
}
EXPORT_SYMBOL(cmp_connection_check_used);

/**
 * cmp_connection_destroy - free connection manager resources
 * @c: the connection manager
 */
void cmp_connection_destroy(struct cmp_connection *c)
{
        WARN_ON(c->connected);
        mutex_destroy(&c->mutex);
        fw_iso_resources_destroy(&c->resources);
}
EXPORT_SYMBOL(cmp_connection_destroy);


static __be32 ipcr_set_modify(struct cmp_connection *c, __be32 ipcr)
{
        ipcr &= ~cpu_to_be32(PCR_BCAST_CONN |
                             PCR_P2P_CONN_MASK |
                             PCR_CHANNEL_MASK);
        ipcr |= cpu_to_be32(1 << PCR_P2P_CONN_SHIFT);
        ipcr |= cpu_to_be32(c->resources.channel << PCR_CHANNEL_SHIFT);

        return ipcr;
}

static int get_overhead_id(struct cmp_connection *c)
{
        int id;

        /*
         * apply "oPCR overhead ID encoding"
         * the encoding table can convert up to 512.
         * here the value over 512 is converted as the same way as 512.
         */
        for (id = 1; id < 16; id++) {
                if (c->resources.bandwidth_overhead < (id << 5))
                        break;
        }
        if (id == 16)
                id = 0;

        return id;
}

static __be32 opcr_set_modify(struct cmp_connection *c, __be32 opcr)
{
        unsigned int spd, xspd;

        /* generate speed and extended speed field value */
        if (c->speed > SCODE_400) {
                spd  = SCODE_800;
                xspd = c->speed - SCODE_800;
        } else {
                spd = c->speed;
                xspd = 0;
        }

        opcr &= ~cpu_to_be32(PCR_BCAST_CONN |
                             PCR_P2P_CONN_MASK |
                             OPCR_XSPEED_MASK |
                             PCR_CHANNEL_MASK |
                             OPCR_SPEED_MASK |
                             OPCR_OVERHEAD_ID_MASK);
        opcr |= cpu_to_be32(1 << PCR_P2P_CONN_SHIFT);
        opcr |= cpu_to_be32(xspd << OPCR_XSPEED_SHIFT);
        opcr |= cpu_to_be32(c->resources.channel << PCR_CHANNEL_SHIFT);
        opcr |= cpu_to_be32(spd << OPCR_SPEED_SHIFT);
        opcr |= cpu_to_be32(get_overhead_id(c) << OPCR_OVERHEAD_ID_SHIFT);

        return opcr;
}

static int pcr_set_check(struct cmp_connection *c, __be32 pcr)
{
        if (pcr & cpu_to_be32(PCR_BCAST_CONN |
                              PCR_P2P_CONN_MASK)) {
                cmp_error(c, "plug is already in use\n");
                return -EBUSY;
        }
        if (!(pcr & cpu_to_be32(PCR_ONLINE))) {
                cmp_error(c, "plug is not on-line\n");
                return -ECONNREFUSED;
        }

        return 0;
}

/**
 * cmp_connection_establish - establish a connection to the target
 * @c: the connection manager
 * @max_payload_bytes: the amount of data (including CIP headers) per packet
 *
 * This function establishes a point-to-point connection from the local
 * computer to the target by allocating isochronous resources (channel and
 * bandwidth) and setting the target's input/output plug control register.
 * When this function succeeds, the caller is responsible for starting
 * transmitting packets.
 */
int cmp_connection_establish(struct cmp_connection *c,
                             unsigned int max_payload_bytes)
{
        int err;

        if (WARN_ON(c->connected))
                return -EISCONN;

        c->speed = min(c->max_speed,
                       fw_parent_device(c->resources.unit)->max_speed);

        mutex_lock(&c->mutex);

retry_after_bus_reset:
        err = fw_iso_resources_allocate(&c->resources,
                                        max_payload_bytes, c->speed);
        if (err < 0)
                goto err_mutex;

        if (c->direction == CMP_OUTPUT)
                err = pcr_modify(c, opcr_set_modify, pcr_set_check,
                                 ABORT_ON_BUS_RESET);
        else
                err = pcr_modify(c, ipcr_set_modify, pcr_set_check,
                                 ABORT_ON_BUS_RESET);

        if (err == -EAGAIN) {
                fw_iso_resources_free(&c->resources);
                goto retry_after_bus_reset;
        }
        if (err < 0)
                goto err_resources;

        c->connected = true;

        mutex_unlock(&c->mutex);

        return 0;

err_resources:
        fw_iso_resources_free(&c->resources);
err_mutex:
        mutex_unlock(&c->mutex);

        return err;
}
EXPORT_SYMBOL(cmp_connection_establish);

/**
 * cmp_connection_update - update the connection after a bus reset
 * @c: the connection manager
 *
 * This function must be called from the driver's .update handler to
 * reestablish any connection that might have been active.
 *
 * Returns zero on success, or a negative error code.  On an error, the
 * connection is broken and the caller must stop transmitting iso packets.
 */
int cmp_connection_update(struct cmp_connection *c)
{
        int err;

        mutex_lock(&c->mutex);

        if (!c->connected) {
                mutex_unlock(&c->mutex);
                return 0;
        }

        err = fw_iso_resources_update(&c->resources);
        if (err < 0)
                goto err_unconnect;

        if (c->direction == CMP_OUTPUT)
                err = pcr_modify(c, opcr_set_modify, pcr_set_check,
                                 SUCCEED_ON_BUS_RESET);
        else
                err = pcr_modify(c, ipcr_set_modify, pcr_set_check,
                                 SUCCEED_ON_BUS_RESET);

        if (err < 0)
                goto err_resources;

        mutex_unlock(&c->mutex);

        return 0;

err_resources:
        fw_iso_resources_free(&c->resources);
err_unconnect:
        c->connected = false;
        mutex_unlock(&c->mutex);

        return err;
}
EXPORT_SYMBOL(cmp_connection_update);

static __be32 pcr_break_modify(struct cmp_connection *c, __be32 pcr)
{
        return pcr & ~cpu_to_be32(PCR_BCAST_CONN | PCR_P2P_CONN_MASK);
}

/**
 * cmp_connection_break - break the connection to the target
 * @c: the connection manager
 *
 * This function deactives the connection in the target's input/output plug
 * control register, and frees the isochronous resources of the connection.
 * Before calling this function, the caller should cease transmitting packets.
 */
void cmp_connection_break(struct cmp_connection *c)
{
        int err;

        mutex_lock(&c->mutex);

        if (!c->connected) {
                mutex_unlock(&c->mutex);
                return;
        }

        err = pcr_modify(c, pcr_break_modify, NULL, SUCCEED_ON_BUS_RESET);
        if (err < 0)
                cmp_error(c, "plug is still connected\n");

        fw_iso_resources_free(&c->resources);

        c->connected = false;

        mutex_unlock(&c->mutex);
}
EXPORT_SYMBOL(cmp_connection_break);