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// SPDX-License-Identifier: GPL-2.0-only
/*
* WWAN device simulator for WWAN framework testing.
*
* Copyright (c) 2021, Sergey Ryazanov <ryazanov.s.a@gmail.com>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/wwan.h>
#include <linux/debugfs.h>
#include <linux/workqueue.h>
#include <net/arp.h>
static int wwan_hwsim_devsnum = 2;
module_param_named(devices, wwan_hwsim_devsnum, int, 0444);
MODULE_PARM_DESC(devices, "Number of simulated devices");
static const struct class wwan_hwsim_class = {
.name = "wwan_hwsim",
};
static struct dentry *wwan_hwsim_debugfs_topdir;
static struct dentry *wwan_hwsim_debugfs_devcreate;
static DEFINE_SPINLOCK(wwan_hwsim_devs_lock);
static LIST_HEAD(wwan_hwsim_devs);
static unsigned int wwan_hwsim_dev_idx;
static struct workqueue_struct *wwan_wq;
struct wwan_hwsim_dev {
struct list_head list;
unsigned int id;
struct device dev;
struct work_struct del_work;
struct dentry *debugfs_topdir;
struct dentry *debugfs_portcreate;
spinlock_t ports_lock; /* Serialize ports creation/deletion */
unsigned int port_idx;
struct list_head ports;
};
struct wwan_hwsim_port {
struct list_head list;
unsigned int id;
struct wwan_hwsim_dev *dev;
struct wwan_port *wwan;
struct work_struct del_work;
struct dentry *debugfs_topdir;
enum { /* AT command parser state */
AT_PARSER_WAIT_A,
AT_PARSER_WAIT_T,
AT_PARSER_WAIT_TERM,
AT_PARSER_SKIP_LINE,
} pstate;
};
static const struct file_operations wwan_hwsim_debugfs_portdestroy_fops;
static const struct file_operations wwan_hwsim_debugfs_portcreate_fops;
static const struct file_operations wwan_hwsim_debugfs_devdestroy_fops;
static void wwan_hwsim_port_del_work(struct work_struct *work);
static void wwan_hwsim_dev_del_work(struct work_struct *work);
static netdev_tx_t wwan_hwsim_netdev_xmit(struct sk_buff *skb,
struct net_device *ndev)
{
ndev->stats.tx_packets++;
ndev->stats.tx_bytes += skb->len;
consume_skb(skb);
return NETDEV_TX_OK;
}
static const struct net_device_ops wwan_hwsim_netdev_ops = {
.ndo_start_xmit = wwan_hwsim_netdev_xmit,
};
static void wwan_hwsim_netdev_setup(struct net_device *ndev)
{
ndev->netdev_ops = &wwan_hwsim_netdev_ops;
ndev->needs_free_netdev = true;
ndev->mtu = ETH_DATA_LEN;
ndev->min_mtu = ETH_MIN_MTU;
ndev->max_mtu = ETH_MAX_MTU;
ndev->type = ARPHRD_NONE;
ndev->flags = IFF_POINTOPOINT | IFF_NOARP;
}
static const struct wwan_ops wwan_hwsim_wwan_rtnl_ops = {
.priv_size = 0, /* No private data */
.setup = wwan_hwsim_netdev_setup,
};
static int wwan_hwsim_port_start(struct wwan_port *wport)
{
struct wwan_hwsim_port *port = wwan_port_get_drvdata(wport);
port->pstate = AT_PARSER_WAIT_A;
return 0;
}
static void wwan_hwsim_port_stop(struct wwan_port *wport)
{
}
/* Implements a minimalistic AT commands parser that echo input back and
* reply with 'OK' to each input command. See AT command protocol details in the
* ITU-T V.250 recomendations document.
*
* Be aware that this processor is not fully V.250 compliant.
*/
static int wwan_hwsim_port_tx(struct wwan_port *wport, struct sk_buff *in)
{
struct wwan_hwsim_port *port = wwan_port_get_drvdata(wport);
struct sk_buff *out;
int i, n, s;
/* Estimate a max possible number of commands by counting the number of
* termination chars (S3 param, CR by default). And then allocate the
* output buffer that will be enough to fit the echo and result codes of
* all commands.
*/
for (i = 0, n = 0; i < in->len; ++i)
if (in->data[i] == '\r')
n++;
n = in->len + n * (2 + 2 + 2); /* Output buffer size */
out = alloc_skb(n, GFP_KERNEL);
if (!out)
return -ENOMEM;
for (i = 0, s = 0; i < in->len; ++i) {
char c = in->data[i];
if (port->pstate == AT_PARSER_WAIT_A) {
if (c == 'A' || c == 'a')
port->pstate = AT_PARSER_WAIT_T;
else if (c != '\n') /* Ignore formating char */
port->pstate = AT_PARSER_SKIP_LINE;
} else if (port->pstate == AT_PARSER_WAIT_T) {
if (c == 'T' || c == 't')
port->pstate = AT_PARSER_WAIT_TERM;
else
port->pstate = AT_PARSER_SKIP_LINE;
} else if (port->pstate == AT_PARSER_WAIT_TERM) {
if (c != '\r')
continue;
/* Consume the trailing formatting char as well */
if ((i + 1) < in->len && in->data[i + 1] == '\n')
i++;
n = i - s + 1;
skb_put_data(out, &in->data[s], n);/* Echo */
skb_put_data(out, "\r\nOK\r\n", 6);
s = i + 1;
port->pstate = AT_PARSER_WAIT_A;
} else if (port->pstate == AT_PARSER_SKIP_LINE) {
if (c != '\r')
continue;
port->pstate = AT_PARSER_WAIT_A;
}
}
if (i > s) {
/* Echo the processed portion of a not yet completed command */
n = i - s;
skb_put_data(out, &in->data[s], n);
}
consume_skb(in);
wwan_port_rx(wport, out);
return 0;
}
static const struct wwan_port_ops wwan_hwsim_port_ops = {
.start = wwan_hwsim_port_start,
.stop = wwan_hwsim_port_stop,
.tx = wwan_hwsim_port_tx,
};
static struct wwan_hwsim_port *wwan_hwsim_port_new(struct wwan_hwsim_dev *dev)
{
struct wwan_hwsim_port *port;
char name[0x10];
int err;
port = kzalloc(sizeof(*port), GFP_KERNEL);
if (!port)
return ERR_PTR(-ENOMEM);
port->dev = dev;
spin_lock(&dev->ports_lock);
port->id = dev->port_idx++;
spin_unlock(&dev->ports_lock);
port->wwan = wwan_create_port(&dev->dev, WWAN_PORT_AT,
&wwan_hwsim_port_ops,
NULL, port);
if (IS_ERR(port->wwan)) {
err = PTR_ERR(port->wwan);
goto err_free_port;
}
INIT_WORK(&port->del_work, wwan_hwsim_port_del_work);
snprintf(name, sizeof(name), "port%u", port->id);
port->debugfs_topdir = debugfs_create_dir(name, dev->debugfs_topdir);
debugfs_create_file("destroy", 0200, port->debugfs_topdir, port,
&wwan_hwsim_debugfs_portdestroy_fops);
return port;
err_free_port:
kfree(port);
return ERR_PTR(err);
}
static void wwan_hwsim_port_del(struct wwan_hwsim_port *port)
{
debugfs_remove(port->debugfs_topdir);
/* Make sure that there is no pending deletion work */
if (current_work() != &port->del_work)
cancel_work_sync(&port->del_work);
wwan_remove_port(port->wwan);
kfree(port);
}
static void wwan_hwsim_port_del_work(struct work_struct *work)
{
struct wwan_hwsim_port *port =
container_of(work, typeof(*port), del_work);
struct wwan_hwsim_dev *dev = port->dev;
spin_lock(&dev->ports_lock);
if (list_empty(&port->list)) {
/* Someone else deleting port at the moment */
spin_unlock(&dev->ports_lock);
return;
}
list_del_init(&port->list);
spin_unlock(&dev->ports_lock);
wwan_hwsim_port_del(port);
}
static void wwan_hwsim_dev_release(struct device *sysdev)
{
struct wwan_hwsim_dev *dev = container_of(sysdev, typeof(*dev), dev);
kfree(dev);
}
static struct wwan_hwsim_dev *wwan_hwsim_dev_new(void)
{
struct wwan_hwsim_dev *dev;
int err;
dev = kzalloc(sizeof(*dev), GFP_KERNEL);
if (!dev)
return ERR_PTR(-ENOMEM);
spin_lock(&wwan_hwsim_devs_lock);
dev->id = wwan_hwsim_dev_idx++;
spin_unlock(&wwan_hwsim_devs_lock);
dev->dev.release = wwan_hwsim_dev_release;
dev->dev.class = &wwan_hwsim_class;
dev_set_name(&dev->dev, "hwsim%u", dev->id);
spin_lock_init(&dev->ports_lock);
INIT_LIST_HEAD(&dev->ports);
err = device_register(&dev->dev);
if (err)
goto err_free_dev;
INIT_WORK(&dev->del_work, wwan_hwsim_dev_del_work);
err = wwan_register_ops(&dev->dev, &wwan_hwsim_wwan_rtnl_ops, dev, 1);
if (err)
goto err_unreg_dev;
dev->debugfs_topdir = debugfs_create_dir(dev_name(&dev->dev),
wwan_hwsim_debugfs_topdir);
debugfs_create_file("destroy", 0200, dev->debugfs_topdir, dev,
&wwan_hwsim_debugfs_devdestroy_fops);
dev->debugfs_portcreate =
debugfs_create_file("portcreate", 0200,
dev->debugfs_topdir, dev,
&wwan_hwsim_debugfs_portcreate_fops);
return dev;
err_unreg_dev:
device_unregister(&dev->dev);
/* Memory will be freed in the device release callback */
return ERR_PTR(err);
err_free_dev:
put_device(&dev->dev);
return ERR_PTR(err);
}
static void wwan_hwsim_dev_del(struct wwan_hwsim_dev *dev)
{
debugfs_remove(dev->debugfs_portcreate); /* Avoid new ports */
spin_lock(&dev->ports_lock);
while (!list_empty(&dev->ports)) {
struct wwan_hwsim_port *port;
port = list_first_entry(&dev->ports, struct wwan_hwsim_port,
list);
list_del_init(&port->list);
spin_unlock(&dev->ports_lock);
wwan_hwsim_port_del(port);
spin_lock(&dev->ports_lock);
}
spin_unlock(&dev->ports_lock);
debugfs_remove(dev->debugfs_topdir);
/* This will remove all child netdev(s) */
wwan_unregister_ops(&dev->dev);
/* Make sure that there is no pending deletion work */
if (current_work() != &dev->del_work)
cancel_work_sync(&dev->del_work);
device_unregister(&dev->dev);
/* Memory will be freed in the device release callback */
}
static void wwan_hwsim_dev_del_work(struct work_struct *work)
{
struct wwan_hwsim_dev *dev = container_of(work, typeof(*dev), del_work);
spin_lock(&wwan_hwsim_devs_lock);
if (list_empty(&dev->list)) {
/* Someone else deleting device at the moment */
spin_unlock(&wwan_hwsim_devs_lock);
return;
}
list_del_init(&dev->list);
spin_unlock(&wwan_hwsim_devs_lock);
wwan_hwsim_dev_del(dev);
}
static ssize_t wwan_hwsim_debugfs_portdestroy_write(struct file *file,
const char __user *usrbuf,
size_t count, loff_t *ppos)
{
struct wwan_hwsim_port *port = file->private_data;
/* We can not delete port here since it will cause a deadlock due to
* waiting this callback to finish in the debugfs_remove() call. So,
* use workqueue.
*/
queue_work(wwan_wq, &port->del_work);
return count;
}
static const struct file_operations wwan_hwsim_debugfs_portdestroy_fops = {
.write = wwan_hwsim_debugfs_portdestroy_write,
.open = simple_open,
.llseek = noop_llseek,
};
static ssize_t wwan_hwsim_debugfs_portcreate_write(struct file *file,
const char __user *usrbuf,
size_t count, loff_t *ppos)
{
struct wwan_hwsim_dev *dev = file->private_data;
struct wwan_hwsim_port *port;
port = wwan_hwsim_port_new(dev);
if (IS_ERR(port))
return PTR_ERR(port);
spin_lock(&dev->ports_lock);
list_add_tail(&port->list, &dev->ports);
spin_unlock(&dev->ports_lock);
return count;
}
static const struct file_operations wwan_hwsim_debugfs_portcreate_fops = {
.write = wwan_hwsim_debugfs_portcreate_write,
.open = simple_open,
.llseek = noop_llseek,
};
static ssize_t wwan_hwsim_debugfs_devdestroy_write(struct file *file,
const char __user *usrbuf,
size_t count, loff_t *ppos)
{
struct wwan_hwsim_dev *dev = file->private_data;
/* We can not delete device here since it will cause a deadlock due to
* waiting this callback to finish in the debugfs_remove() call. So,
* use workqueue.
*/
queue_work(wwan_wq, &dev->del_work);
return count;
}
static const struct file_operations wwan_hwsim_debugfs_devdestroy_fops = {
.write = wwan_hwsim_debugfs_devdestroy_write,
.open = simple_open,
.llseek = noop_llseek,
};
static ssize_t wwan_hwsim_debugfs_devcreate_write(struct file *file,
const char __user *usrbuf,
size_t count, loff_t *ppos)
{
struct wwan_hwsim_dev *dev;
dev = wwan_hwsim_dev_new();
if (IS_ERR(dev))
return PTR_ERR(dev);
spin_lock(&wwan_hwsim_devs_lock);
list_add_tail(&dev->list, &wwan_hwsim_devs);
spin_unlock(&wwan_hwsim_devs_lock);
return count;
}
static const struct file_operations wwan_hwsim_debugfs_devcreate_fops = {
.write = wwan_hwsim_debugfs_devcreate_write,
.open = simple_open,
.llseek = noop_llseek,
};
static int __init wwan_hwsim_init_devs(void)
{
struct wwan_hwsim_dev *dev;
int i, j;
for (i = 0; i < wwan_hwsim_devsnum; ++i) {
dev = wwan_hwsim_dev_new();
if (IS_ERR(dev))
return PTR_ERR(dev);
spin_lock(&wwan_hwsim_devs_lock);
list_add_tail(&dev->list, &wwan_hwsim_devs);
spin_unlock(&wwan_hwsim_devs_lock);
/* Create a couple of ports per each device to accelerate
* the simulator readiness time.
*/
for (j = 0; j < 2; ++j) {
struct wwan_hwsim_port *port;
port = wwan_hwsim_port_new(dev);
if (IS_ERR(port))
return PTR_ERR(port);
spin_lock(&dev->ports_lock);
list_add_tail(&port->list, &dev->ports);
spin_unlock(&dev->ports_lock);
}
}
return 0;
}
static void wwan_hwsim_free_devs(void)
{
struct wwan_hwsim_dev *dev;
spin_lock(&wwan_hwsim_devs_lock);
while (!list_empty(&wwan_hwsim_devs)) {
dev = list_first_entry(&wwan_hwsim_devs, struct wwan_hwsim_dev,
list);
list_del_init(&dev->list);
spin_unlock(&wwan_hwsim_devs_lock);
wwan_hwsim_dev_del(dev);
spin_lock(&wwan_hwsim_devs_lock);
}
spin_unlock(&wwan_hwsim_devs_lock);
}
static int __init wwan_hwsim_init(void)
{
int err;
if (wwan_hwsim_devsnum < 0 || wwan_hwsim_devsnum > 128)
return -EINVAL;
wwan_wq = alloc_workqueue("wwan_wq", 0, 0);
if (!wwan_wq)
return -ENOMEM;
err = class_register(&wwan_hwsim_class);
if (err)
goto err_wq_destroy;
wwan_hwsim_debugfs_topdir = debugfs_create_dir("wwan_hwsim", NULL);
wwan_hwsim_debugfs_devcreate =
debugfs_create_file("devcreate", 0200,
wwan_hwsim_debugfs_topdir, NULL,
&wwan_hwsim_debugfs_devcreate_fops);
err = wwan_hwsim_init_devs();
if (err)
goto err_clean_devs;
return 0;
err_clean_devs:
debugfs_remove(wwan_hwsim_debugfs_devcreate); /* Avoid new devs */
wwan_hwsim_free_devs();
flush_workqueue(wwan_wq); /* Wait deletion works completion */
debugfs_remove(wwan_hwsim_debugfs_topdir);
class_unregister(&wwan_hwsim_class);
err_wq_destroy:
destroy_workqueue(wwan_wq);
return err;
}
static void __exit wwan_hwsim_exit(void)
{
debugfs_remove(wwan_hwsim_debugfs_devcreate); /* Avoid new devs */
wwan_hwsim_free_devs();
flush_workqueue(wwan_wq); /* Wait deletion works completion */
debugfs_remove(wwan_hwsim_debugfs_topdir);
class_unregister(&wwan_hwsim_class);
destroy_workqueue(wwan_wq);
}
module_init(wwan_hwsim_init);
module_exit(wwan_hwsim_exit);
MODULE_AUTHOR("Sergey Ryazanov");
MODULE_DESCRIPTION("Device simulator for WWAN framework");
MODULE_LICENSE("GPL");