// SPDX-License-Identifier: GPL-2.0
/*
 * Thunderbolt/USB4 retimer support.
 *
 * Copyright (C) 2020, Intel Corporation
 * Authors: Kranthi Kuntala <kranthi.kuntala@intel.com>
 *          Mika Westerberg <mika.westerberg@linux.intel.com>
 */

#include <linux/delay.h>
#include <linux/pm_runtime.h>
#include <linux/sched/signal.h>

#include "sb_regs.h"
#include "tb.h"

#if IS_ENABLED(CONFIG_USB4_DEBUGFS_MARGINING)
#define TB_MAX_RETIMER_INDEX    6
#else
#define TB_MAX_RETIMER_INDEX    2
#endif

/**
 * tb_retimer_nvm_read() - Read contents of retimer NVM
 * @rt: Retimer device
 * @address: NVM address (in bytes) to start reading
 * @buf: Data read from NVM is stored here
 * @size: Number of bytes to read
 *
 * Reads retimer NVM and copies the contents to @buf.
 *
 * Return: %0 if the read was successful, negative errno in case of failure.
 */
int tb_retimer_nvm_read(struct tb_retimer *rt, unsigned int address, void *buf,
                        size_t size)
{
        return usb4_port_retimer_nvm_read(rt->port, rt->index, address, buf, size);
}

static int nvm_read(void *priv, unsigned int offset, void *val, size_t bytes)
{
        struct tb_nvm *nvm = priv;
        struct tb_retimer *rt = tb_to_retimer(nvm->dev);
        int ret;

        pm_runtime_get_sync(&rt->dev);

        if (!mutex_trylock(&rt->tb->lock)) {
                ret = restart_syscall();
                goto out;
        }

        ret = tb_retimer_nvm_read(rt, offset, val, bytes);
        mutex_unlock(&rt->tb->lock);

out:
        pm_runtime_mark_last_busy(&rt->dev);
        pm_runtime_put_autosuspend(&rt->dev);

        return ret;
}

static int nvm_write(void *priv, unsigned int offset, void *val, size_t bytes)
{
        struct tb_nvm *nvm = priv;
        struct tb_retimer *rt = tb_to_retimer(nvm->dev);
        int ret = 0;

        if (!mutex_trylock(&rt->tb->lock))
                return restart_syscall();

        ret = tb_nvm_write_buf(nvm, offset, val, bytes);
        mutex_unlock(&rt->tb->lock);

        return ret;
}

static int tb_retimer_nvm_add(struct tb_retimer *rt)
{
        struct tb_nvm *nvm;
        int ret;

        nvm = tb_nvm_alloc(&rt->dev);
        if (IS_ERR(nvm)) {
                ret = PTR_ERR(nvm) == -EOPNOTSUPP ? 0 : PTR_ERR(nvm);
                goto err_nvm;
        }

        ret = tb_nvm_read_version(nvm);
        if (ret)
                goto err_nvm;

        ret = tb_nvm_add_active(nvm, nvm_read);
        if (ret)
                goto err_nvm;

        if (!rt->no_nvm_upgrade) {
                ret = tb_nvm_add_non_active(nvm, nvm_write);
                if (ret)
                        goto err_nvm;
        }

        rt->nvm = nvm;
        dev_dbg(&rt->dev, "NVM version %x.%x\n", nvm->major, nvm->minor);
        return 0;

err_nvm:
        dev_dbg(&rt->dev, "NVM upgrade disabled\n");
        rt->no_nvm_upgrade = true;
        if (!IS_ERR(nvm))
                tb_nvm_free(nvm);

        return ret;
}

static int tb_retimer_nvm_validate_and_write(struct tb_retimer *rt)
{
        unsigned int image_size;
        const u8 *buf;
        int ret;

        ret = tb_nvm_validate(rt->nvm);
        if (ret)
                return ret;

        buf = rt->nvm->buf_data_start;
        image_size = rt->nvm->buf_data_size;

        ret = usb4_port_retimer_nvm_write(rt->port, rt->index, 0, buf,
                                         image_size);
        if (ret)
                return ret;

        rt->nvm->flushed = true;
        return 0;
}

static int tb_retimer_nvm_authenticate(struct tb_retimer *rt, bool auth_only)
{
        u32 status;
        int ret;

        if (auth_only) {
                ret = usb4_port_retimer_nvm_set_offset(rt->port, rt->index, 0);
                if (ret)
                        return ret;
        }

        ret = usb4_port_retimer_nvm_authenticate(rt->port, rt->index);
        if (ret)
                return ret;

        usleep_range(100, 150);

        /*
         * Check the status now if we still can access the retimer. It
         * is expected that the below fails.
         */
        ret = usb4_port_retimer_nvm_authenticate_status(rt->port, rt->index,
                                                        &status);
        if (!ret) {
                rt->auth_status = status;
                return status ? -EINVAL : 0;
        }

        return 0;
}

static ssize_t device_show(struct device *dev, struct device_attribute *attr,
                           char *buf)
{
        struct tb_retimer *rt = tb_to_retimer(dev);

        return sysfs_emit(buf, "%#x\n", rt->device);
}
static DEVICE_ATTR_RO(device);

static ssize_t nvm_authenticate_show(struct device *dev,
        struct device_attribute *attr, char *buf)
{
        struct tb_retimer *rt = tb_to_retimer(dev);
        int ret;

        if (!mutex_trylock(&rt->tb->lock))
                return restart_syscall();

        if (!rt->nvm)
                ret = -EAGAIN;
        else
                ret = sysfs_emit(buf, "%#x\n", rt->auth_status);

        mutex_unlock(&rt->tb->lock);

        return ret;
}

static void tb_retimer_nvm_authenticate_status(struct tb_port *port, u32 *status)
{
        int i;

        tb_port_dbg(port, "reading NVM authentication status of retimers\n");

        /*
         * Before doing anything else, read the authentication status.
         * If the retimer has it set, store it for the new retimer
         * device instance.
         */
        for (i = 1; i <= TB_MAX_RETIMER_INDEX; i++) {
                if (usb4_port_retimer_nvm_authenticate_status(port, i, &status[i]))
                        break;
        }
}

static void tb_retimer_set_inbound_sbtx(struct tb_port *port)
{
        int i;

        /*
         * When USB4 port is online sideband communications are
         * already up.
         */
        if (!usb4_port_device_is_offline(port->usb4))
                return;

        tb_port_dbg(port, "enabling sideband transactions\n");

        for (i = 1; i <= TB_MAX_RETIMER_INDEX; i++)
                usb4_port_retimer_set_inbound_sbtx(port, i);
}

static void tb_retimer_unset_inbound_sbtx(struct tb_port *port)
{
        int i;

        /*
         * When USB4 port is offline we need to keep the sideband
         * communications up to make it possible to communicate with
         * the connected retimers.
         */
        if (usb4_port_device_is_offline(port->usb4))
                return;

        tb_port_dbg(port, "disabling sideband transactions\n");

        for (i = TB_MAX_RETIMER_INDEX; i >= 1; i--) {
                if (usb4_port_retimer_unset_inbound_sbtx(port, i))
                        break;
        }
}

static ssize_t nvm_authenticate_store(struct device *dev,
        struct device_attribute *attr, const char *buf, size_t count)
{
        struct tb_retimer *rt = tb_to_retimer(dev);
        int val, ret;

        pm_runtime_get_sync(&rt->dev);

        if (!mutex_trylock(&rt->tb->lock)) {
                ret = restart_syscall();
                goto exit_rpm;
        }

        if (!rt->nvm) {
                ret = -EAGAIN;
                goto exit_unlock;
        }

        ret = kstrtoint(buf, 10, &val);
        if (ret)
                goto exit_unlock;

        /* Always clear status */
        rt->auth_status = 0;

        if (val) {
                /*
                 * When NVM authentication starts the retimer is not
                 * accessible so calling tb_retimer_unset_inbound_sbtx()
                 * will fail and therefore we do not call it. Exception
                 * is when the validation fails or we only write the new
                 * NVM image without authentication.
                 */
                tb_retimer_set_inbound_sbtx(rt->port);
                if (val == AUTHENTICATE_ONLY) {
                        ret = tb_retimer_nvm_authenticate(rt, true);
                } else {
                        if (!rt->nvm->flushed) {
                                if (!rt->nvm->buf) {
                                        ret = -EINVAL;
                                        goto exit_unlock;
                                }

                                ret = tb_retimer_nvm_validate_and_write(rt);
                                if (ret || val == WRITE_ONLY)
                                        goto exit_unlock;
                        }
                        if (val == WRITE_AND_AUTHENTICATE)
                                ret = tb_retimer_nvm_authenticate(rt, false);
                }
        }

exit_unlock:
        if (ret || val == WRITE_ONLY)
                tb_retimer_unset_inbound_sbtx(rt->port);
        mutex_unlock(&rt->tb->lock);
exit_rpm:
        pm_runtime_mark_last_busy(&rt->dev);
        pm_runtime_put_autosuspend(&rt->dev);

        if (ret)
                return ret;
        return count;
}
static DEVICE_ATTR_RW(nvm_authenticate);

static ssize_t nvm_version_show(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        struct tb_retimer *rt = tb_to_retimer(dev);
        int ret;

        if (!mutex_trylock(&rt->tb->lock))
                return restart_syscall();

        if (!rt->nvm)
                ret = -EAGAIN;
        else
                ret = sysfs_emit(buf, "%x.%x\n", rt->nvm->major, rt->nvm->minor);

        mutex_unlock(&rt->tb->lock);
        return ret;
}
static DEVICE_ATTR_RO(nvm_version);

static ssize_t vendor_show(struct device *dev, struct device_attribute *attr,
                           char *buf)
{
        struct tb_retimer *rt = tb_to_retimer(dev);

        return sysfs_emit(buf, "%#x\n", rt->vendor);
}
static DEVICE_ATTR_RO(vendor);

static umode_t retimer_is_visible(struct kobject *kobj, struct attribute *attr,
                                  int n)
{
        struct device *dev = kobj_to_dev(kobj);
        struct tb_retimer *rt = tb_to_retimer(dev);

        if (attr == &dev_attr_nvm_authenticate.attr ||
            attr == &dev_attr_nvm_version.attr)
                return rt->no_nvm_upgrade ? 0 : attr->mode;

        return attr->mode;
}

static struct attribute *retimer_attrs[] = {
        &dev_attr_device.attr,
        &dev_attr_nvm_authenticate.attr,
        &dev_attr_nvm_version.attr,
        &dev_attr_vendor.attr,
        NULL
};

static const struct attribute_group retimer_group = {
        .is_visible = retimer_is_visible,
        .attrs = retimer_attrs,
};

static const struct attribute_group *retimer_groups[] = {
        &retimer_group,
        NULL
};

static void tb_retimer_release(struct device *dev)
{
        struct tb_retimer *rt = tb_to_retimer(dev);

        kfree(rt);
}

const struct device_type tb_retimer_type = {
        .name = "thunderbolt_retimer",
        .groups = retimer_groups,
        .release = tb_retimer_release,
};

static int tb_retimer_add(struct tb_port *port, u8 index, u32 auth_status,
                          bool on_board)
{
        struct tb_retimer *rt;
        u32 vendor, device;
        int ret;

        ret = usb4_port_sb_read(port, USB4_SB_TARGET_RETIMER, index,
                                USB4_SB_VENDOR_ID, &vendor, sizeof(vendor));
        if (ret) {
                if (ret != -ENODEV)
                        tb_port_warn(port, "failed read retimer VendorId: %d\n", ret);
                return ret;
        }

        ret = usb4_port_sb_read(port, USB4_SB_TARGET_RETIMER, index,
                                USB4_SB_PRODUCT_ID, &device, sizeof(device));
        if (ret) {
                if (ret != -ENODEV)
                        tb_port_warn(port, "failed read retimer ProductId: %d\n", ret);
                return ret;
        }


        rt = kzalloc_obj(*rt);
        if (!rt)
                return -ENOMEM;

        rt->index = index;
        rt->vendor = vendor;
        rt->device = device;
        rt->auth_status = auth_status;
        rt->port = port;
        rt->tb = port->sw->tb;

        /*
         * Only support NVM upgrade for on-board retimers. The retimers
         * on the other side of the connection.
         */
        if (!on_board || usb4_port_retimer_nvm_sector_size(port, index) <= 0)
                rt->no_nvm_upgrade = true;

        rt->dev.parent = &port->usb4->dev;
        rt->dev.bus = &tb_bus_type;
        rt->dev.type = &tb_retimer_type;
        dev_set_name(&rt->dev, "%s:%u.%u", dev_name(&port->sw->dev),
                     port->port, index);

        ret = device_register(&rt->dev);
        if (ret) {
                dev_err(&rt->dev, "failed to register retimer: %d\n", ret);
                put_device(&rt->dev);
                return ret;
        }

        ret = tb_retimer_nvm_add(rt);
        if (ret) {
                dev_err(&rt->dev, "failed to add NVM devices: %d\n", ret);
                device_unregister(&rt->dev);
                return ret;
        }

        dev_info(&rt->dev, "new retimer found, vendor=%#x device=%#x\n",
                 rt->vendor, rt->device);

        pm_runtime_no_callbacks(&rt->dev);
        pm_runtime_set_active(&rt->dev);
        pm_runtime_enable(&rt->dev);
        pm_runtime_set_autosuspend_delay(&rt->dev, TB_AUTOSUSPEND_DELAY);
        pm_runtime_mark_last_busy(&rt->dev);
        pm_runtime_use_autosuspend(&rt->dev);

        tb_retimer_debugfs_init(rt);
        return 0;
}

static void tb_retimer_remove(struct tb_retimer *rt)
{
        dev_info(&rt->dev, "retimer disconnected\n");
        tb_retimer_debugfs_remove(rt);
        tb_nvm_free(rt->nvm);
        device_unregister(&rt->dev);
}

struct tb_retimer_lookup {
        const struct tb_port *port;
        u8 index;
};

static int retimer_match(struct device *dev, const void *data)
{
        const struct tb_retimer_lookup *lookup = data;
        struct tb_retimer *rt = tb_to_retimer(dev);

        return rt && rt->port == lookup->port && rt->index == lookup->index;
}

static struct tb_retimer *tb_port_find_retimer(struct tb_port *port, u8 index)
{
        struct tb_retimer_lookup lookup = { .port = port, .index = index };
        struct device *dev;

        dev = device_find_child(&port->usb4->dev, &lookup, retimer_match);
        if (dev)
                return tb_to_retimer(dev);

        return NULL;
}

/**
 * tb_retimer_scan() - Scan for on-board retimers under port
 * @port: USB4 port to scan
 * @add: If true also registers found retimers
 *
 * Brings the sideband into a state where retimers can be accessed.
 * Then tries to enumerate on-board retimers connected to @port. Found
 * retimers are registered as children of @port if @add is set.  Does
 * not scan for cable retimers for now.
 *
 * Return: %0 on success, negative errno otherwise.
 */
int tb_retimer_scan(struct tb_port *port, bool add)
{
        u32 status[TB_MAX_RETIMER_INDEX + 1] = {};
        int ret, i, max, last_idx = 0;

        /*
         * Send broadcast RT to make sure retimer indices facing this
         * port are set.
         */
        ret = usb4_port_enumerate_retimers(port);
        if (ret)
                return ret;

        /*
         * Immediately after sending enumerate retimers read the
         * authentication status of each retimer.
         */
        tb_retimer_nvm_authenticate_status(port, status);

        /*
         * Enable sideband channel for each retimer. We can do this
         * regardless whether there is device connected or not.
         */
        tb_retimer_set_inbound_sbtx(port);

        for (max = 1, i = 1; i <= TB_MAX_RETIMER_INDEX; i++) {
                /*
                 * Last retimer is true only for the last on-board
                 * retimer (the one connected directly to the Type-C
                 * port).
                 */
                ret = usb4_port_retimer_is_last(port, i);
                if (ret > 0)
                        last_idx = i;
                else if (ret < 0)
                        break;

                max = i;
        }

        ret = 0;
        if (!IS_ENABLED(CONFIG_USB4_DEBUGFS_MARGINING))
                max = min(last_idx, max);

        /* Add retimers if they do not exist already */
        for (i = 1; i <= max; i++) {
                struct tb_retimer *rt;

                /* Skip cable retimers */
                if (usb4_port_retimer_is_cable(port, i))
                        continue;

                rt = tb_port_find_retimer(port, i);
                if (rt) {
                        put_device(&rt->dev);
                } else if (add) {
                        ret = tb_retimer_add(port, i, status[i], i <= last_idx);
                        if (ret && ret != -EOPNOTSUPP)
                                break;
                }
        }

        tb_retimer_unset_inbound_sbtx(port);
        return ret;
}

static int remove_retimer(struct device *dev, void *data)
{
        struct tb_retimer *rt = tb_to_retimer(dev);
        struct tb_port *port = data;

        if (rt && rt->port == port)
                tb_retimer_remove(rt);
        return 0;
}

/**
 * tb_retimer_remove_all() - Remove all retimers under port
 * @port: USB4 port whose retimers to remove
 *
 * This removes all previously added retimers under @port.
 */
void tb_retimer_remove_all(struct tb_port *port)
{
        struct usb4_port *usb4;

        usb4 = port->usb4;
        if (usb4)
                device_for_each_child_reverse(&usb4->dev, port,
                                              remove_retimer);
}