linux-imx

// SPDX-License-Identifier: GPL-2.0

/*

 * GNSS receiver core

 *

 * Copyright (C) 2018 Johan Hovold <johan@kernel.org>

 */

​

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

​

#include <linux/cdev.h>

#include <linux/errno.h>

#include <linux/fs.h>

#include <linux/gnss.h>

#include <linux/idr.h>

#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/poll.h>

#include <linux/slab.h>

#include <linux/uaccess.h>

#include <linux/wait.h>

​

#define GNSS_FLAG_HAS_WRITE_RAW     BIT(0)

​

#define GNSS_MINORS 16

​

static DEFINE_IDA(gnss_minors);

static dev_t gnss_first;

​

/* FIFO size must be a power of two */

#define GNSS_READ_FIFO_SIZE 4096

#define GNSS_WRITE_BUF_SIZE 1024

​

#define to_gnss_device(d) container_of((d), struct gnss_device, dev)

​

static int gnss_open(struct inode *inode, struct file *file)

{

    struct gnss_device *gdev;

    int ret = 0;

​

    gdev = container_of(inode->i_cdev, struct gnss_device, cdev);

​

    get_device(&gdev->dev);

​

    stream_open(inode, file);

    file->private_data = gdev;

​

    down_write(&gdev->rwsem);

    if (gdev->disconnected) {

        ret = -ENODEV;

        goto unlock;

    }

​

    if (gdev->count++ == 0) {

        ret = gdev->ops->open(gdev);

        if (ret)

            gdev->count--;

    }

unlock:

    up_write(&gdev->rwsem);

​

    if (ret)

        put_device(&gdev->dev);