path: root/drivers/net/wwan/wwan_core.c

// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2021, Linaro Ltd <loic.poulain@linaro.org> */

#include <linux/bitmap.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/debugfs.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/idr.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/poll.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/termios.h>
#include <linux/wwan.h>
#include <net/rtnetlink.h>
#include <uapi/linux/wwan.h>

/* Maximum number of minors in use */
#define WWAN_MAX_MINORS		(1 << MINORBITS)

static DEFINE_MUTEX(wwan_register_lock); /* WWAN device create|remove lock */
static DEFINE_IDA(minors); /* minors for WWAN port chardevs */
static DEFINE_IDA(wwan_dev_ids); /* for unique WWAN device IDs */
static struct class *wwan_class;
static int wwan_major;
static struct dentry *wwan_debugfs_dir;

#define to_wwan_dev(d) container_of(d, struct wwan_device, dev)
#define to_wwan_port(d) container_of(d, struct wwan_port, dev)

/* WWAN port flags */
#define WWAN_PORT_TX_OFF	0

/**
 * struct wwan_device - The structure that defines a WWAN device
 *
 * @id: WWAN device unique ID.
 * @dev: Underlying device.
 * @port_id: Current available port ID to pick.
 * @ops: wwan device ops
 * @ops_ctxt: context to pass to ops
 * @debugfs_dir:  WWAN device debugfs dir
 */
struct wwan_device {
	unsigned int id;
	struct device dev;
	atomic_t port_id;
	const struct wwan_ops *ops;
	void *ops_ctxt;
#ifdef CONFIG_WWAN_DEBUGFS
	struct dentry *debugfs_dir;
#endif
};

/**
 * struct wwan_port - The structure that defines a WWAN port
 * @type: Port type
 * @start_count: Port start counter
 * @flags: Store port state and capabilities
 * @ops: Pointer to WWAN port operations
 * @ops_lock: Protect port ops
 * @dev: Underlying device
 * @rxq: Buffer inbound queue
 * @waitqueue: The waitqueue for port fops (read/write/poll)
 * @data_lock: Port specific data access serialization
 * @headroom_len: SKB reserved headroom size
 * @frag_len: Length to fragment packet
 * @at_data: AT port specific data
 */
struct wwan_port {
	enum wwan_port_type type;
	unsigned int start_count;
	unsigned long flags;
	const struct wwan_port_ops *ops;
	struct mutex ops_lock; /* Serialize ops + protect against removal */
	struct device dev;
	struct sk_buff_head rxq;
	wait_queue_head_t waitqueue;
	struct mutex data_lock;	/* Port specific data access serialization */
	size_t headroom_len;
	size_t frag_len;
	union {
		struct {
			struct ktermios termios;
			int mdmbits;
		} at_data;
	};
};

static ssize_t index_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct wwan_device *wwan = to_wwan_dev(dev);

	return sprintf(buf, "%d\n", wwan->id);
}
static DEVICE_ATTR_RO(index);

static struct attribute *wwan_dev_attrs[] = {
	&dev_attr_index.attr,
	NULL,
};
ATTRIBUTE_GROUPS(wwan_dev);

static void wwan_dev_destroy(struct device *dev)
{
	struct wwan_device *wwandev = to_wwan_dev(dev);

	ida_free(&wwan_dev_ids, wwandev->id);
	kfree(wwandev);
}

static const struct device_type wwan_dev_type = {
	.name    = "wwan_dev",
	.release = wwan_dev_destroy,
	.groups = wwan_dev_groups,
};

static int wwan_dev_parent_match(struct device *dev, const void *parent)
{
	return (dev->type == &wwan_dev_type &&
		(dev->parent == parent || dev == parent));
}

static struct wwan_device *wwan_dev_get_by_parent(struct device *parent)
{
	struct device *dev;

	dev = class_find_device(wwan_class, NULL, parent, wwan_dev_parent_match);
	if (!dev)
		return