/*
 * Thunderbolt Cactus Ridge driver - switch/port utility functions
 *
 * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
 */

#include <linux/delay.h>
#include <linux/slab.h>

#include "tb.h"

/* port utility functions */

static const char *tb_port_type(struct tb_regs_port_header *port)
{
        switch (port->type >> 16) {
        case 0:
                switch ((u8) port->type) {
                case 0:
                        return "Inactive";
                case 1:
                        return "Port";
                case 2:
                        return "NHI";
                default:
                        return "unknown";
                }
        case 0x2:
                return "Ethernet";
        case 0x8:
                return "SATA";
        case 0xe:
                return "DP/HDMI";
        case 0x10:
                return "PCIe";
        case 0x20:
                return "USB";
        default:
                return "unknown";
        }
}

static void tb_dump_port(struct tb *tb, struct tb_regs_port_header *port)
{
        tb_info(tb,
                " Port %d: %x:%x (Revision: %d, TB Version: %d, Type: %s (%#x))\n",
                port->port_number, port->vendor_id, port->device_id,
                port->revision, port->thunderbolt_version, tb_port_type(port),
                port->type);
        tb_info(tb, "  Max hop id (in/out): %d/%d\n",
                port->max_in_hop_id, port->max_out_hop_id);
        tb_info(tb, "  Max counters: %d\n", port->max_counters);
        tb_info(tb, "  NFC Credits: %#x\n", port->nfc_credits);
}

/**
 * tb_port_state() - get connectedness state of a port
 *
 * The port must have a TB_CAP_PHY (i.e. it should be a real port).
 *
 * Return: Returns an enum tb_port_state on success or an error code on failure.
 */
static int tb_port_state(struct tb_port *port)
{
        struct tb_cap_phy phy;
        int res;
        if (port->cap_phy == 0) {
                tb_port_WARN(port, "does not have a PHY\n");
                return -EINVAL;
        }
        res = tb_port_read(port, &phy, TB_CFG_PORT, port->cap_phy, 2);
        if (res)
                return res;
        return phy.state;
}

/**
 * tb_wait_for_port() - wait for a port to become ready
 *
 * Wait up to 1 second for a port to reach state TB_PORT_UP. If
 * wait_if_unplugged is set then we also wait if the port is in state
 * TB_PORT_UNPLUGGED (it takes a while for the device to be registered after
 * switch resume). Otherwise we only wait if a device is registered but the link
 * has not yet been established.
 *
 * Return: Returns an error code on failure. Returns 0 if the port is not
 * connected or failed to reach state TB_PORT_UP within one second. Returns 1
 * if the port is connected and in state TB_PORT_UP.
 */
int tb_wait_for_port(struct tb_port *port, bool wait_if_unplugged)
{
        int retries = 10;
        int state;
        if (!port->cap_phy) {
                tb_port_WARN(port, "does not have PHY\n");
                return -EINVAL;
        }
        if (tb_is_upstream_port(port)) {
                tb_port_WARN(port, "is the upstream port\n");
                return -EINVAL;
        }

        while (retries--) {
                state = tb_port_state(port);
                if (state < 0)
                        return state;
                if (state == TB_PORT_DISABLED) {
                        tb_port_info(port, "is disabled (state: 0)\n");
                        return 0;
                }
                if (state == TB_PORT_UNPLUGGED) {
                        if (wait_if_unplugged) {
                                /* used during resume */
                                tb_port_info(port,
                                             "is unplugged (state: 7), retrying...\n");
                                msleep(100);
                                continue;
                        }
                        tb_port_info(port, "is unplugged (state: 7)\n");
                        return 0;
                }
                if (state == TB_PORT_UP) {
                        tb_port_info(port,
                                     "is connected, link is up (state: 2)\n");
                        return 1;
                }

                /*
                 * After plug-in the state is TB_PORT_CONNECTING. Give it some
                 * time.
                 */
                tb_port_info(port,
                             "is connected, link is not up (state: %d), retrying...\n",
                             state);
                msleep(100);
        }
        tb_port_warn(port,
                     "failed to reach state TB_PORT_UP. Ignoring port...\n");
        return 0;
}

/**
 * tb_port_add_nfc_credits() - add/remove non flow controlled credits to port
 *
 * Change the number of NFC credits allocated to @port by @credits. To remove
 * NFC credits pass a negative amount of credits.
 *
 * Return: Returns 0 on success or an error code on failure.
 */
int tb_port_add_nfc_credits(struct tb_port *port, int credits)
{
        if (credits == 0)
                return 0;
        tb_port_info(port,
                     "adding %#x NFC credits (%#x -> %#x)",
                     credits,
                     port->config.nfc_credits,
                     port->config.nfc_credits + credits);
        port->config.nfc_credits += credits;
        return tb_port_write(port, &port->config.nfc_credits,
                             TB_CFG_PORT, 4, 1);
}

/**
 * tb_port_clear_counter() - clear a counter in TB_CFG_COUNTER
 *
 * Return: Returns 0 on success or an error code on failure.
 */
int tb_port_clear_counter(struct tb_port *port, int counter)
{
        u32 zero[3] = { 0, 0, 0 };
        tb_port_info(port, "clearing counter %d\n", counter);
        return tb_port_write(port, zero, TB_CFG_COUNTERS, 3 * counter, 3);
}

/**
 * tb_init_port() - initialize a port
 *
 * This is a helper method for tb_switch_alloc. Does not check or initialize
 * any downstream switches.
 *
 * Return: Returns 0 on success or an error code on failure.
 */
static int tb_init_port(struct tb_port *port)
{
        int res;
        int cap;

        res = tb_port_read(port, &port->config, TB_CFG_PORT, 0, 8);
        if (res)
                return res;

        /* Port 0 is the switch itself and has no PHY. */
        if (port->config.type == TB_TYPE_PORT && port->port != 0) {
                cap = tb_find_cap(port, TB_CFG_PORT, TB_CAP_PHY);

                if (cap > 0)
                        port->cap_phy = cap;
                else
                        tb_port_WARN(port, "non switch port without a PHY\n");
        }

        tb_dump_port(port->sw->tb, &port->config);

        /* TODO: Read dual link port, DP port and more from EEPROM. */
        return 0;

}

/* switch utility functions */

static void tb_dump_switch(struct tb *tb, struct tb_regs_switch_header *sw)
{
        tb_info(tb,
                " Switch: %x:%x (Revision: %d, TB Version: %d)\n",
                sw->vendor_id, sw->device_id, sw->revision,
                sw->thunderbolt_version);
        tb_info(tb, "  Max Port Number: %d\n", sw->max_port_number);
        tb_info(tb, "  Config:\n");
        tb_info(tb,
                "   Upstream Port Number: %d Depth: %d Route String: %#llx Enabled: %d, PlugEventsDelay: %dms\n",
                sw->upstream_port_number, sw->depth,
                (((u64) sw->route_hi) << 32) | sw->route_lo,
                sw->enabled, sw->plug_events_delay);
        tb_info(tb,
                "   unknown1: %#x unknown4: %#x\n",
                sw->__unknown1, sw->__unknown4);
}

/**
 * reset_switch() - reconfigure route, enable and send TB_CFG_PKG_RESET
 *
 * Return: Returns 0 on success or an error code on failure.
 */
int tb_switch_reset(struct tb *tb, u64 route)
{
        struct tb_cfg_result res;
        struct tb_regs_switch_header header = {
                header.route_hi = route >> 32,
                header.route_lo = route,
                header.enabled = true,
        };
        tb_info(tb, "resetting switch at %llx\n", route);
        res.err = tb_cfg_write(tb->ctl, ((u32 *) &header) + 2, route,
                        0, 2, 2, 2);
        if (res.err)
                return res.err;
        res = tb_cfg_reset(tb->ctl, route, TB_CFG_DEFAULT_TIMEOUT);
        if (res.err > 0)
                return -EIO;
        return res.err;
}

struct tb_switch *get_switch_at_route(struct tb_switch *sw, u64 route)
{
        u8 next_port = route; /*
                               * Routes use a stride of 8 bits,
                               * eventhough a port index has 6 bits at most.
                               * */
        if (route == 0)
                return sw;
        if (next_port > sw->config.max_port_number)
                return NULL;
        if (tb_is_upstream_port(&sw->ports[next_port]))
                return NULL;
        if (!sw->ports[next_port].remote)
                return NULL;
        return get_switch_at_route(sw->ports[next_port].remote->sw,
                                   route >> TB_ROUTE_SHIFT);
}

/**
 * tb_plug_events_active() - enable/disable plug events on a switch
 *
 * Also configures a sane plug_events_delay of 255ms.
 *
 * Return: Returns 0 on success or an error code on failure.
 */
static int tb_plug_events_active(struct tb_switch *sw, bool active)
{
        u32 data;
        int res;

        sw->config.plug_events_delay = 0xff;
        res = tb_sw_write(sw, ((u32 *) &sw->config) + 4, TB_CFG_SWITCH, 4, 1);
        if (res)
                return res;

        res = tb_sw_read(sw, &data, TB_CFG_SWITCH, sw->cap_plug_events + 1, 1);
        if (res)
                return res;

        if (active) {
                data = data & 0xFFFFFF83;
                switch (sw->config.device_id) {
                case 0x1513:
                case 0x151a:
                case 0x1549:
                        break;
                default:
                        data |= 4;
                }
        } else {
                data = data | 0x7c;
        }
        return tb_sw_write(sw, &data, TB_CFG_SWITCH,
                           sw->cap_plug_events + 1, 1);
}


/**
 * tb_switch_free() - free a tb_switch and all downstream switches
 */
void tb_switch_free(struct tb_switch *sw)
{
        int i;
        /* port 0 is the switch itself and never has a remote */
        for (i = 1; i <= sw->config.max_port_number; i++) {
                if (tb_is_upstream_port(&sw->ports[i]))
                        continue;
                if (sw->ports[i].remote)
                        tb_switch_free(sw->ports[i].remote->sw);
                sw->ports[i].remote = NULL;
        }

        if (!sw->is_unplugged)
                tb_plug_events_active(sw, false);

        kfree(sw->ports);
        kfree(sw->drom);
        kfree(sw);
}

/**
 * tb_switch_alloc() - allocate and initialize a switch
 *
 * Return: Returns a NULL on failure.
 */
struct tb_switch *tb_switch_alloc(struct tb *tb, u64 route)
{
        int i;
        int cap;
        struct tb_switch *sw;
        int upstream_port = tb_cfg_get_upstream_port(tb->ctl, route);
        if (upstream_port < 0)
                return NULL;

        sw = kzalloc(sizeof(*sw), GFP_KERNEL);
        if (!sw)
                return NULL;

        sw->tb = tb;
        if (tb_cfg_read(tb->ctl, &sw->config, route, 0, 2, 0, 5))
                goto err;
        tb_info(tb,
                "initializing Switch at %#llx (depth: %d, up port: %d)\n",
                route, tb_route_length(route), upstream_port);
        tb_info(tb, "old switch config:\n");
        tb_dump_switch(tb, &sw->config);

        /* configure switch */
        sw->config.upstream_port_number = upstream_port;
        sw->config.depth = tb_route_length(route);
        sw->config.route_lo = route;
        sw->config.route_hi = route >> 32;
        sw->config.enabled = 1;
        /* from here on we may use the tb_sw_* functions & macros */

        if (sw->config.vendor_id != 0x8086)
                tb_sw_warn(sw, "unknown switch vendor id %#x\n",
                           sw->config.vendor_id);

        if (sw->config.device_id != 0x1547 && sw->config.device_id != 0x1549)
                tb_sw_warn(sw, "unsupported switch device id %#x\n",
                           sw->config.device_id);

        /* upload configuration */
        if (tb_sw_write(sw, 1 + (u32 *) &sw->config, TB_CFG_SWITCH, 1, 3))
                goto err;

        /* initialize ports */
        sw->ports = kcalloc(sw->config.max_port_number + 1, sizeof(*sw->ports),
                                GFP_KERNEL);
        if (!sw->ports)
                goto err;

        for (i = 0; i <= sw->config.max_port_number; i++) {
                /* minimum setup for tb_find_cap and tb_drom_read to work */
                sw->ports[i].sw = sw;
                sw->ports[i].port = i;
        }

        cap = tb_find_cap(&sw->ports[0], TB_CFG_SWITCH, TB_CAP_PLUG_EVENTS);
        if (cap < 0) {
                tb_sw_warn(sw, "cannot find TB_CAP_PLUG_EVENTS aborting\n");
                goto err;
        }
        sw->cap_plug_events = cap;

        /* read drom */
        if (tb_drom_read(sw))
                tb_sw_warn(sw, "tb_eeprom_read_rom failed, continuing\n");
        tb_sw_info(sw, "uid: %#llx\n", sw->uid);

        for (i = 0; i <= sw->config.max_port_number; i++) {
                if (sw->ports[i].disabled) {
                        tb_port_info(&sw->ports[i], "disabled by eeprom\n");
                        continue;
                }
                if (tb_init_port(&sw->ports[i]))
                        goto err;
        }

        /* TODO: I2C, IECS, link controller */

        if (tb_plug_events_active(sw, true))
                goto err;

        return sw;
err:
        kfree(sw->ports);
        kfree(sw->drom);
        kfree(sw);
        return NULL;
}

/**
 * tb_sw_set_unpplugged() - set is_unplugged on switch and downstream switches
 */
void tb_sw_set_unpplugged(struct tb_switch *sw)
{
        int i;
        if (sw == sw->tb->root_switch) {
                tb_sw_WARN(sw, "cannot unplug root switch\n");
                return;
        }
        if (sw->is_unplugged) {
                tb_sw_WARN(sw, "is_unplugged already set\n");
                return;
        }
        sw->is_unplugged = true;
        for (i = 0; i <= sw->config.max_port_number; i++) {
                if (!tb_is_upstream_port(&sw->ports[i]) && sw->ports[i].remote)
                        tb_sw_set_unpplugged(sw->ports[i].remote->sw);
        }
}

int tb_switch_resume(struct tb_switch *sw)
{
        int i, err;
        u64 uid;
        tb_sw_info(sw, "resuming switch\n");

        err = tb_drom_read_uid_only(sw, &uid);
        if (err) {
                tb_sw_warn(sw, "uid read failed\n");
                return err;
        }
        if (sw->uid != uid) {
                tb_sw_info(sw,
                        "changed while suspended (uid %#llx -> %#llx)\n",
                        sw->uid, uid);
                return -ENODEV;
        }

        /* upload configuration */
        err = tb_sw_write(sw, 1 + (u32 *) &sw->config, TB_CFG_SWITCH, 1, 3);
        if (err)
                return err;

        err = tb_plug_events_active(sw, true);
        if (err)
                return err;

        /* check for surviving downstream switches */
        for (i = 1; i <= sw->config.max_port_number; i++) {
                struct tb_port *port = &sw->ports[i];
                if (tb_is_upstream_port(port))
                        continue;
                if (!port->remote)
                        continue;
                if (tb_wait_for_port(port, true) <= 0
                        || tb_switch_resume(port->remote->sw)) {
                        tb_port_warn(port,
                                     "lost during suspend, disconnecting\n");
                        tb_sw_set_unpplugged(port->remote->sw);
                }
        }
        return 0;
}

void tb_switch_suspend(struct tb_switch *sw)
{
        int i, err;
        err = tb_plug_events_active(sw, false);
        if (err)
                return;

        for (i = 1; i <= sw->config.max_port_number; i++) {
                if (!tb_is_upstream_port(&sw->ports[i]) && sw->ports[i].remote)
                        tb_switch_suspend(sw->ports[i].remote->sw);
        }
        /*
         * TODO: invoke tb_cfg_prepare_to_sleep here? does not seem to have any
         * effect?
         */
}