// SPDX-License-Identifier: GPL-2.0
#include <linux/errno.h>
#include <linux/miscdevice.h>   /* for misc_register, and MISC_DYNAMIC_MINOR */
#include <linux/types.h>
#include <linux/uaccess.h>

#include "speakup.h"
#include "spk_priv.h"

static int synth_registered, synthu_registered;
static int dev_opened;

/* Latin1 version */
static ssize_t speakup_file_write(struct file *fp, const char __user *buffer,
                                  size_t nbytes, loff_t *ppos)
{
        size_t count = nbytes;
        const char __user *ptr = buffer;
        size_t bytes;
        unsigned long flags;
        u_char buf[256];

        if (!synth)
                return -ENODEV;
        while (count > 0) {
                bytes = min(count, sizeof(buf));
                if (copy_from_user(buf, ptr, bytes))
                        return -EFAULT;
                count -= bytes;
                ptr += bytes;
                spin_lock_irqsave(&speakup_info.spinlock, flags);
                synth_write(buf, bytes);
                spin_unlock_irqrestore(&speakup_info.spinlock, flags);
        }
        return (ssize_t)nbytes;
}

/* UTF-8 version */
static ssize_t speakup_file_writeu(struct file *fp, const char __user *buffer,
                                   size_t nbytes, loff_t *ppos)
{
        size_t count = nbytes, consumed, want;
        const char __user *ptr = buffer;
        size_t bytes;
        unsigned long flags;
        unsigned char buf[256];
        u16 ubuf[256];
        size_t in, out;

        if (!synth)
                return -ENODEV;

        want = 1;
        while (count >= want) {
                /* Copy some UTF-8 piece from userland */
                bytes = min(count, sizeof(buf));
                if (copy_from_user(buf, ptr, bytes))
                        return -EFAULT;

                /* Convert to u16 */
                for (in = 0, out = 0; in < bytes; in += consumed) {
                        s32 value;

                        value = synth_utf8_get(buf + in, bytes - in, &consumed, &want);
                        if (value == -1) {
                                /* Invalid or incomplete */

                                if (want > bytes - in)
                                        /* We don't have it all yet, stop here
                                         * and wait for the rest
                                         */
                                        bytes = in;

                                continue;
                        }

                        if (value < 0x10000)
                                ubuf[out++] = value;
                }

                count -= bytes;
                ptr += bytes;

                /* And speak this up */
                if (out) {
                        spin_lock_irqsave(&speakup_info.spinlock, flags);
                        for (in = 0; in < out; in++)
                                synth_buffer_add(ubuf[in]);
                        synth_start();
                        spin_unlock_irqrestore(&speakup_info.spinlock, flags);
                }
        }

        return (ssize_t)(nbytes - count);
}

static ssize_t speakup_file_read(struct file *fp, char __user *buf,
                                 size_t nbytes, loff_t *ppos)
{
        return 0;
}

static int speakup_file_open(struct inode *ip, struct file *fp)
{
        if (!synth)
                return -ENODEV;
        if (xchg(&dev_opened, 1))
                return -EBUSY;
        return 0;
}

static int speakup_file_release(struct inode *ip, struct file *fp)
{
        dev_opened = 0;
        return 0;
}

static const struct file_operations synth_fops = {
        .read = speakup_file_read,
        .write = speakup_file_write,
        .open = speakup_file_open,
        .release = speakup_file_release,
};

static const struct file_operations synthu_fops = {
        .read = speakup_file_read,
        .write = speakup_file_writeu,
        .open = speakup_file_open,
        .release = speakup_file_release,
};

static struct miscdevice synth_device = {
        .minor = MISC_DYNAMIC_MINOR,
        .name = "synth",
        .fops = &synth_fops,
};

static struct miscdevice synthu_device = {
        .minor = MISC_DYNAMIC_MINOR,
        .name = "synthu",
        .fops = &synthu_fops,
};

void speakup_register_devsynth(void)
{
        if (!synth_registered) {
                if (misc_register(&synth_device)) {
                        pr_warn("Couldn't initialize miscdevice /dev/synth.\n");
                } else {
                        pr_info("initialized device: /dev/synth, node (MAJOR %d, MINOR %d)\n",
                                MISC_MAJOR, synth_device.minor);
                        synth_registered = 1;
                }
        }
        if (!synthu_registered) {
                if (misc_register(&synthu_device)) {
                        pr_warn("Couldn't initialize miscdevice /dev/synthu.\n");
                } else {
                        pr_info("initialized device: /dev/synthu, node (MAJOR %d, MINOR %d)\n",
                                MISC_MAJOR, synthu_device.minor);
                        synthu_registered = 1;
                }
        }
}

void speakup_unregister_devsynth(void)
{
        if (synth_registered) {
                pr_info("speakup: unregistering synth device /dev/synth\n");
                misc_deregister(&synth_device);
                synth_registered = 0;
        }
        if (synthu_registered) {
                pr_info("speakup: unregistering synth device /dev/synthu\n");
                misc_deregister(&synthu_device);
                synthu_registered = 0;
        }
}