// SPDX-FileCopyrightText: 2024 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
// SPDX-License-Identifier: GPL-3.0-only

#include "jfjoch_drv.h"
#include <linux/module.h>
#include <linux/spinlock.h>

static int device_index = 0;

int jfjoch_register_misc_dev(struct pci_dev *pdev) {
    int err;
    struct jfjoch_drvdata *drvdata = pci_get_drvdata(pdev);

    drvdata->file_write_open_count = 0;
    spin_lock_init(&drvdata->file_write_open_count_spinlock);

    snprintf( drvdata->name, 255, "jfjoch%d", device_index++);
    drvdata->miscdev.parent = &pdev->dev;
    drvdata->miscdev.mode  = 0664;
    drvdata->miscdev.minor = MISC_DYNAMIC_MINOR;
    drvdata->miscdev.fops = &jfjoch_cdev_fileops;
    drvdata->miscdev.name = drvdata->name;
    err = misc_register(&drvdata->miscdev);
    if (err)
        pr_notice("Misc device registration failed\n");
    return err;
}


void jfjoch_unregister_misc_dev(struct pci_dev *pdev) {
    struct jfjoch_drvdata *drvdata = pci_get_drvdata(pdev);
    misc_deregister(&drvdata->miscdev);
}

int jfjoch_cdev_open(struct inode *inode, struct file *file) {
    struct jfjoch_drvdata *drvdata = container_of(file->private_data, struct jfjoch_drvdata, miscdev);

    bool ok = true;
    if (file->f_mode & FMODE_WRITE) {
        unsigned long flags;
        spin_lock_irqsave(&drvdata->file_write_open_count_spinlock, flags);
        ok = (drvdata->file_write_open_count == 0);
        drvdata->file_write_open_count = 1;
        spin_unlock_irqrestore(&drvdata->file_write_open_count_spinlock, flags);
    }
    if (!ok)
        return -EBUSY;
    return 0;
}

int jfjoch_cdev_release(struct inode *inode, struct file *file) {
    struct jfjoch_drvdata *drvdata = container_of(file->private_data, struct jfjoch_drvdata, miscdev);
    if (file->f_mode & FMODE_WRITE) {
        unsigned long flags;
        jfjoch_cancel(drvdata);
        spin_lock_irqsave(&drvdata->file_write_open_count_spinlock, flags);
        drvdata->file_write_open_count = 0;
        spin_unlock_irqrestore(&drvdata->file_write_open_count_spinlock, flags);
    }
    return 0;
}