// SPDX-License-Identifier: GPL-2.0-only
/*
 * cec-api.c - HDMI Consumer Electronics Control framework - API
 *
 * Copyright 2016 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
 */

#include <linux/errno.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/kmod.h>
#include <linux/ktime.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/version.h>

#include <media/cec-pin.h>
#include "cec-priv.h"
#include "cec-pin-priv.h"

static inline struct cec_devnode *cec_devnode_data(struct file *filp)
{
        struct cec_fh *fh = filp->private_data;

        return &fh->adap->devnode;
}

/* CEC file operations */

static __poll_t cec_poll(struct file *filp,
                             struct poll_table_struct *poll)
{
        struct cec_fh *fh = filp->private_data;
        struct cec_adapter *adap = fh->adap;
        __poll_t res = 0;

        poll_wait(filp, &fh->wait, poll);
        if (!cec_is_registered(adap))
                return EPOLLERR | EPOLLHUP | EPOLLPRI;
        mutex_lock(&adap->lock);
        if (adap->is_configured &&
            adap->transmit_queue_sz < CEC_MAX_MSG_TX_QUEUE_SZ)
                res |= EPOLLOUT | EPOLLWRNORM;
        if (fh->queued_msgs)
                res |= EPOLLIN | EPOLLRDNORM;
        if (fh->total_queued_events)
                res |= EPOLLPRI;
        mutex_unlock(&adap->lock);
        return res;
}

static bool cec_is_busy(const struct cec_adapter *adap,
                        const struct cec_fh *fh)
{
        bool valid_initiator = adap->cec_initiator && adap->cec_initiator == fh;
        bool valid_follower = adap->cec_follower && adap->cec_follower == fh;

        /*
         * Exclusive initiators and followers can always access the CEC adapter
         */
        if (valid_initiator || valid_follower)
                return false;
        /*
         * All others can only access the CEC adapter if there is no
         * exclusive initiator and they are in INITIATOR mode.
         */
        return adap->cec_initiator ||
               fh->mode_initiator == CEC_MODE_NO_INITIATOR;
}

static long cec_adap_g_caps(struct cec_adapter *adap,
                            struct cec_caps __user *parg)
{
        struct cec_caps caps = {};

        strscpy(caps.driver, adap->devnode.dev.parent->driver->name,
                sizeof(caps.driver));
        strscpy(caps.name, adap->name, sizeof(caps.name));
        caps.available_log_addrs = adap->available_log_addrs;
        caps.capabilities = adap->capabilities;
        caps.version = LINUX_VERSION_CODE;
        if (copy_to_user(parg, &caps, sizeof(caps)))
                return -EFAULT;
        return 0;
}

static long cec_adap_g_phys_addr(struct cec_adapter *adap,
                                 __u16 __user *parg)
{
        u16 phys_addr;

        mutex_lock(&adap->lock);
        phys_addr = adap->phys_addr;
        mutex_unlock(&adap->lock);
        if (copy_to_user(parg, &phys_addr, sizeof(phys_addr)))
                return -EFAULT;
        return 0;
}

static int cec_validate_phys_addr(u16 phys_addr)
{
        int i;

        if (phys_addr == CEC_PHYS_ADDR_INVALID)
                return 0;
        for (i = 0; i < 16; i += 4)
                if (phys_addr & (0xf << i))
                        break;
        if (i == 16)
                return 0;
        for (i += 4; i < 16; i += 4)
                if ((phys_addr & (0xf << i)) == 0)
                        return -EINVAL;
        return 0;
}

static long cec_adap_s_phys_addr(struct cec_adapter *adap, struct cec_fh *fh,
                                 bool block, __u16 __user *parg)
{
        u16 phys_addr;
        long err;

        if (!(adap->capabilities & CEC_CAP_PHYS_ADDR))
                return -ENOTTY;
        if (copy_from_user(&phys_addr, parg, sizeof(phys_addr)))
                return -EFAULT;

        err = cec_validate_phys_addr(phys_addr);
        if (err)
                return err;
        mutex_lock(&adap->lock);
        if (cec_is_busy(adap, fh))
                err = -EBUSY;
        else
                __cec_s_phys_addr(adap, phys_addr, block);
        mutex_unlock(&adap->lock);
        return err;
}

static long cec_adap_g_log_addrs(struct cec_adapter *adap,
                                 struct cec_log_addrs __user *parg)
{
        struct cec_log_addrs log_addrs;

        mutex_lock(&adap->lock);
        /*
         * We use memcpy here instead of assignment since there is a
         * hole at the end of struct cec_log_addrs that an assignment
         * might ignore. So when we do copy_to_user() we could leak
         * one byte of memory.
         */
        memcpy(&log_addrs, &adap->log_addrs, sizeof(log_addrs));
        if (!adap->is_configured)
                memset(log_addrs.log_addr, CEC_LOG_ADDR_INVALID,
                       sizeof(log_addrs.log_addr));
        mutex_unlock(&adap->lock);

        if (copy_to_user(parg, &log_addrs, sizeof(log_addrs)))
                return -EFAULT;
        return 0;
}

static long cec_adap_s_log_addrs(struct cec_adapter *adap, struct cec_fh *fh,
                                 bool block, struct cec_log_addrs __user *parg)
{
        struct cec_log_addrs log_addrs;
        long err = -EBUSY;

        if (!(adap->capabilities & CEC_CAP_LOG_ADDRS))
                return -ENOTTY;
        if (copy_from_user(&log_addrs, parg, sizeof(log_addrs)))
                return -EFAULT;
        log_addrs.flags &= CEC_LOG_ADDRS_FL_ALLOW_UNREG_FALLBACK |
                           CEC_LOG_ADDRS_FL_ALLOW_RC_PASSTHRU |
                           CEC_LOG_ADDRS_FL_CDC_ONLY;
        mutex_lock(&adap->lock);
        if (!adap->is_claiming_log_addrs && !adap->is_configuring &&
            (!log_addrs.num_log_addrs || !adap->is_configured) &&
            !cec_is_busy(adap, fh)) {
                err = __cec_s_log_addrs(adap, &log_addrs, block);
                if (!err)
                        log_addrs = adap->log_addrs;
        }
        mutex_unlock(&adap->lock);
        if (err)
                return err;
        if (copy_to_user(parg, &log_addrs, sizeof(log_addrs)))
                return -EFAULT;
        return 0;
}

static long cec_adap_g_connector_info(struct cec_adapter *adap,
                                      struct cec_log_addrs __user *parg)
{
        int ret = 0;

        if (!(adap->capabilities & CEC_CAP_CONNECTOR_INFO))
                return -ENOTTY;

        mutex_lock(&adap->lock);
        if (copy_to_user(parg, &adap->conn_info, sizeof(adap->conn_info)))
                ret = -EFAULT;
        mutex_unlock(&adap->lock);
        return ret;
}

static long cec_transmit(struct cec_adapter *adap, struct cec_fh *fh,
                         bool block, struct cec_msg __user *parg)
{
        struct cec_msg msg = {};
        long err = 0;

        if (!(adap->capabilities & CEC_CAP_TRANSMIT))
                return -ENOTTY;
        if (copy_from_user(&msg, parg, sizeof(msg)))
                return -EFAULT;

        mutex_lock(&adap->lock);
        if (adap->log_addrs.num_log_addrs == 0)
                err = -EPERM;
        else if (adap->is_configuring && !msg_is_raw(&msg))
                err = -ENONET;
        else if (cec_is_busy(adap, fh))
                err = -EBUSY;
        else
                err = cec_transmit_msg_fh(adap, &msg, fh, block);
        mutex_unlock(&adap->lock);
        if (err)
                return err;
        if (copy_to_user(parg, &msg, sizeof(msg)))
                return -EFAULT;
        return 0;
}

/* Called by CEC_RECEIVE: wait for a message to arrive */
static int cec_receive_msg(struct cec_fh *fh, struct cec_msg *msg, bool block)
{
        u32 timeout = msg->timeout;
        int res;

        do {
                mutex_lock(&fh->lock);
                /* Are there received messages queued up? */
                if (fh->queued_msgs) {
                        /* Yes, return the first one */
                        struct cec_msg_entry *entry =
                                list_first_entry(&fh->msgs,
                                                 struct cec_msg_entry, list);

                        list_del(&entry->list);
                        *msg = entry->msg;
                        kfree(entry);
                        fh->queued_msgs--;
                        mutex_unlock(&fh->lock);
                        /* restore original timeout value */
                        msg->timeout = timeout;
                        return 0;
                }

                /* No, return EAGAIN in non-blocking mode or wait */
                mutex_unlock(&fh->lock);

                /* Return when in non-blocking mode */
                if (!block)
                        return -EAGAIN;

                if (msg->timeout) {
                        /* The user specified a timeout */
                        res = wait_event_interruptible_timeout(fh->wait,
                                                               fh->queued_msgs,
                                msecs_to_jiffies(msg->timeout));
                        if (res == 0)
                                res = -ETIMEDOUT;
                        else if (res > 0)
                                res = 0;
                } else {
                        /* Wait indefinitely */
                        res = wait_event_interruptible(fh->wait,
                                                       fh->queued_msgs);
                }
                /* Exit on error, otherwise loop to get the new message */
        } while (!res);
        return res;
}

static long cec_receive(struct cec_adapter *adap, struct cec_fh *fh,
                        bool block, struct cec_msg __user *parg)
{
        struct cec_msg msg = {};
        long err;

        if (copy_from_user(&msg, parg, sizeof(msg)))
                return -EFAULT;

        err = cec_receive_msg(fh, &msg, block);
        if (err)
                return err;
        msg.flags = 0;
        if (copy_to_user(parg, &msg, sizeof(msg)))
                return -EFAULT;
        return 0;
}

static long cec_dqevent(struct cec_adapter *adap, struct cec_fh *fh,
                        bool block, struct cec_event __user *parg)
{
        struct cec_event_entry *ev = NULL;
        u64 ts = ~0ULL;
        unsigned int i;
        unsigned int ev_idx;
        long err = 0;

        mutex_lock(&fh->lock);
        while (!fh->total_queued_events && block) {
                mutex_unlock(&fh->lock);
                err = wait_event_interruptible(fh->wait,
                                               fh->total_queued_events);
                if (err)
                        return err;
                mutex_lock(&fh->lock);
        }

        /* Find the oldest event */
        for (i = 0; i < CEC_NUM_EVENTS; i++) {
                struct cec_event_entry *entry =
                        list_first_entry_or_null(&fh->events[i],
                                                 struct cec_event_entry, list);

                if (entry && entry->ev.ts <= ts) {
                        ev = entry;
                        ev_idx = i;
                        ts = ev->ev.ts;
                }
        }

        if (!ev) {
                err = -EAGAIN;
                goto unlock;
        }
        list_del(&ev->list);

        if (copy_to_user(parg, &ev->ev, sizeof(ev->ev)))
                err = -EFAULT;
        if (ev_idx >= CEC_NUM_CORE_EVENTS)
                kfree(ev);
        fh->queued_events[ev_idx]--;
        fh->total_queued_events--;

unlock:
        mutex_unlock(&fh->lock);
        return err;
}

static long cec_g_mode(struct cec_adapter *adap, struct cec_fh *fh,
                       u32 __user *parg)
{
        u32 mode = fh->mode_initiator | fh->mode_follower;

        if (copy_to_user(parg, &mode, sizeof(mode)))
                return -EFAULT;
        return 0;
}

static long cec_s_mode(struct cec_adapter *adap, struct cec_fh *fh,
                       u32 __user *parg)
{
        u32 mode;
        u8 mode_initiator;
        u8 mode_follower;
        bool send_pin_event = false;
        long err = 0;

        if (copy_from_user(&mode, parg, sizeof(mode)))
                return -EFAULT;
        if (mode & ~(CEC_MODE_INITIATOR_MSK | CEC_MODE_FOLLOWER_MSK)) {
                dprintk(1, "%s: invalid mode bits set\n", __func__);
                return -EINVAL;
        }

        mode_initiator = mode & CEC_MODE_INITIATOR_MSK;
        mode_follower = mode & CEC_MODE_FOLLOWER_MSK;

        if (mode_initiator > CEC_MODE_EXCL_INITIATOR ||
            mode_follower > CEC_MODE_MONITOR_ALL) {
                dprintk(1, "%s: unknown mode\n", __func__);
                return -EINVAL;
        }

        if (mode_follower == CEC_MODE_MONITOR_ALL &&
            !(adap->capabilities & CEC_CAP_MONITOR_ALL)) {
                dprintk(1, "%s: MONITOR_ALL not supported\n", __func__);
                return -EINVAL;
        }

        if (mode_follower == CEC_MODE_MONITOR_PIN &&
            !(adap->capabilities & CEC_CAP_MONITOR_PIN)) {
                dprintk(1, "%s: MONITOR_PIN not supported\n", __func__);
                return -EINVAL;
        }

        /* Follower modes should always be able to send CEC messages */
        if ((mode_initiator == CEC_MODE_NO_INITIATOR ||
             !(adap->capabilities & CEC_CAP_TRANSMIT)) &&
            mode_follower >= CEC_MODE_FOLLOWER &&
            mode_follower <= CEC_MODE_EXCL_FOLLOWER_PASSTHRU) {
                dprintk(1, "%s: cannot transmit\n", __func__);
                return -EINVAL;
        }

        /* Monitor modes require CEC_MODE_NO_INITIATOR */
        if (mode_initiator && mode_follower >= CEC_MODE_MONITOR_PIN) {
                dprintk(1, "%s: monitor modes require NO_INITIATOR\n",
                        __func__);
                return -EINVAL;
        }

        /* Monitor modes require CAP_NET_ADMIN */
        if (mode_follower >= CEC_MODE_MONITOR_PIN && !capable(CAP_NET_ADMIN))
                return -EPERM;

        mutex_lock(&adap->lock);
        /*
         * You can't become exclusive follower if someone else already
         * has that job.
         */
        if ((mode_follower == CEC_MODE_EXCL_FOLLOWER ||
             mode_follower == CEC_MODE_EXCL_FOLLOWER_PASSTHRU) &&
            adap->cec_follower && adap->cec_follower != fh)
                err = -EBUSY;
        /*
         * You can't become exclusive initiator if someone else already
         * has that job.
         */
        if (mode_initiator == CEC_MODE_EXCL_INITIATOR &&
            adap->cec_initiator && adap->cec_initiator != fh)
                err = -EBUSY;

        if (!err) {
                bool old_mon_all = fh->mode_follower == CEC_MODE_MONITOR_ALL;
                bool new_mon_all = mode_follower == CEC_MODE_MONITOR_ALL;

                if (old_mon_all != new_mon_all) {
                        if (new_mon_all)
                                err = cec_monitor_all_cnt_inc(adap);
                        else
                                cec_monitor_all_cnt_dec(adap);
                }
        }

        if (!err) {
                bool old_mon_pin = fh->mode_follower == CEC_MODE_MONITOR_PIN;
                bool new_mon_pin = mode_follower == CEC_MODE_MONITOR_PIN;

                if (old_mon_pin != new_mon_pin) {
                        send_pin_event = new_mon_pin;
                        if (new_mon_pin)
                                err = cec_monitor_pin_cnt_inc(adap);
                        else
                                cec_monitor_pin_cnt_dec(adap);
                }
        }

        if (err) {
                mutex_unlock(&adap->lock);
                return err;
        }

        if (fh->mode_follower == CEC_MODE_FOLLOWER)
                adap->follower_cnt--;
        if (mode_follower == CEC_MODE_FOLLOWER)
                adap->follower_cnt++;
        if (send_pin_event) {
                struct cec_event ev = {
                        .flags = CEC_EVENT_FL_INITIAL_STATE,
                };

                ev.event = adap->cec_pin_is_high ? CEC_EVENT_PIN_CEC_HIGH :
                                                   CEC_EVENT_PIN_CEC_LOW;
                cec_queue_event_fh(fh, &ev, 0);
        }
        if (mode_follower == CEC_MODE_EXCL_FOLLOWER ||
            mode_follower == CEC_MODE_EXCL_FOLLOWER_PASSTHRU) {
                adap->passthrough =
                        mode_follower == CEC_MODE_EXCL_FOLLOWER_PASSTHRU;
                adap->cec_follower = fh;
        } else if (adap->cec_follower == fh) {
                adap->passthrough = false;
                adap->cec_follower = NULL;
        }
        if (mode_initiator == CEC_MODE_EXCL_INITIATOR)
                adap->cec_initiator = fh;
        else if (adap->cec_initiator == fh)
                adap->cec_initiator = NULL;
        fh->mode_initiator = mode_initiator;
        fh->mode_follower = mode_follower;
        mutex_unlock(&adap->lock);
        return 0;
}

static long cec_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
        struct cec_fh *fh = filp->private_data;
        struct cec_adapter *adap = fh->adap;
        bool block = !(filp->f_flags & O_NONBLOCK);
        void __user *parg = (void __user *)arg;

        if (!cec_is_registered(adap))
                return -ENODEV;

        switch (cmd) {
        case CEC_ADAP_G_CAPS:
                return cec_adap_g_caps(adap, parg);

        case CEC_ADAP_G_PHYS_ADDR:
                return cec_adap_g_phys_addr(adap, parg);

        case CEC_ADAP_S_PHYS_ADDR:
                return cec_adap_s_phys_addr(adap, fh, block, parg);

        case CEC_ADAP_G_LOG_ADDRS:
                return cec_adap_g_log_addrs(adap, parg);

        case CEC_ADAP_S_LOG_ADDRS:
                return cec_adap_s_log_addrs(adap, fh, block, parg);

        case CEC_ADAP_G_CONNECTOR_INFO:
                return cec_adap_g_connector_info(adap, parg);

        case CEC_TRANSMIT:
                return cec_transmit(adap, fh, block, parg);

        case CEC_RECEIVE:
                return cec_receive(adap, fh, block, parg);

        case CEC_DQEVENT:
                return cec_dqevent(adap, fh, block, parg);

        case CEC_G_MODE:
                return cec_g_mode(adap, fh, parg);

        case CEC_S_MODE:
                return cec_s_mode(adap, fh, parg);

        default:
                return -ENOTTY;
        }
}

static int cec_open(struct inode *inode, struct file *filp)
{
        struct cec_devnode *devnode =
                container_of(inode->i_cdev, struct cec_devnode, cdev);
        struct cec_adapter *adap = to_cec_adapter(devnode);
        struct cec_fh *fh = kzalloc_obj(*fh);
        /*
         * Initial events that are automatically sent when the cec device is
         * opened.
         */
        struct cec_event ev = {
                .event = CEC_EVENT_STATE_CHANGE,
                .flags = CEC_EVENT_FL_INITIAL_STATE,
        };
        unsigned int i;
        int err;

        if (!fh)
                return -ENOMEM;

        INIT_LIST_HEAD(&fh->msgs);
        INIT_LIST_HEAD(&fh->xfer_list);
        for (i = 0; i < CEC_NUM_EVENTS; i++)
                INIT_LIST_HEAD(&fh->events[i]);
        mutex_init(&fh->lock);
        init_waitqueue_head(&fh->wait);

        fh->mode_initiator = CEC_MODE_INITIATOR;
        fh->adap = adap;

        err = cec_get_device(adap);
        if (err) {
                kfree(fh);
                return err;
        }

        filp->private_data = fh;

        /* Queue up initial state events */
        ev.state_change.phys_addr = adap->phys_addr;
        ev.state_change.log_addr_mask = adap->log_addrs.log_addr_mask;
        ev.state_change.have_conn_info =
                adap->conn_info.type != CEC_CONNECTOR_TYPE_NO_CONNECTOR;
        cec_queue_event_fh(fh, &ev, 0);
#ifdef CONFIG_CEC_PIN
        if (adap->pin && adap->pin->ops->read_hpd &&
            !adap->devnode.unregistered) {
                err = adap->pin->ops->read_hpd(adap);
                if (err >= 0) {
                        ev.event = err ? CEC_EVENT_PIN_HPD_HIGH :
                                         CEC_EVENT_PIN_HPD_LOW;
                        cec_queue_event_fh(fh, &ev, 0);
                }
        }
        if (adap->pin && adap->pin->ops->read_5v &&
            !adap->devnode.unregistered) {
                err = adap->pin->ops->read_5v(adap);
                if (err >= 0) {
                        ev.event = err ? CEC_EVENT_PIN_5V_HIGH :
                                         CEC_EVENT_PIN_5V_LOW;
                        cec_queue_event_fh(fh, &ev, 0);
                }
        }
#endif

        mutex_lock(&devnode->lock);
        mutex_lock(&devnode->lock_fhs);
        list_add(&fh->list, &devnode->fhs);
        mutex_unlock(&devnode->lock_fhs);
        mutex_unlock(&devnode->lock);

        return 0;
}

/* Override for the release function */
static int cec_release(struct inode *inode, struct file *filp)
{
        struct cec_devnode *devnode = cec_devnode_data(filp);
        struct cec_adapter *adap = to_cec_adapter(devnode);
        struct cec_fh *fh = filp->private_data;
        unsigned int i;

        mutex_lock(&adap->lock);
        if (adap->cec_initiator == fh)
                adap->cec_initiator = NULL;
        if (adap->cec_follower == fh) {
                adap->cec_follower = NULL;
                adap->passthrough = false;
        }
        if (fh->mode_follower == CEC_MODE_FOLLOWER)
                adap->follower_cnt--;
        if (fh->mode_follower == CEC_MODE_MONITOR_PIN)
                cec_monitor_pin_cnt_dec(adap);
        if (fh->mode_follower == CEC_MODE_MONITOR_ALL)
                cec_monitor_all_cnt_dec(adap);
        mutex_unlock(&adap->lock);

        mutex_lock(&devnode->lock);
        mutex_lock(&devnode->lock_fhs);
        list_del(&fh->list);
        mutex_unlock(&devnode->lock_fhs);
        mutex_unlock(&devnode->lock);

        /* Unhook pending transmits from this filehandle. */
        mutex_lock(&adap->lock);
        while (!list_empty(&fh->xfer_list)) {
                struct cec_data *data =
                        list_first_entry(&fh->xfer_list, struct cec_data, xfer_list);

                data->blocking = false;
                data->fh = NULL;
                list_del_init(&data->xfer_list);
        }
        mutex_unlock(&adap->lock);

        mutex_lock(&fh->lock);
        while (!list_empty(&fh->msgs)) {
                struct cec_msg_entry *entry =
                        list_first_entry(&fh->msgs, struct cec_msg_entry, list);

                list_del(&entry->list);
                kfree(entry);
        }
        for (i = CEC_NUM_CORE_EVENTS; i < CEC_NUM_EVENTS; i++) {
                while (!list_empty(&fh->events[i])) {
                        struct cec_event_entry *entry =
                                list_first_entry(&fh->events[i],
                                                 struct cec_event_entry, list);

                        list_del(&entry->list);
                        kfree(entry);
                }
        }
        mutex_unlock(&fh->lock);
        kfree(fh);

        cec_put_device(adap);
        filp->private_data = NULL;
        return 0;
}

const struct file_operations cec_devnode_fops = {
        .owner = THIS_MODULE,
        .open = cec_open,
        .unlocked_ioctl = cec_ioctl,
        .compat_ioctl = cec_ioctl,
        .release = cec_release,
        .poll = cec_poll,
};