1 files changed, 547 insertions, 0 deletions
diff --git a/drivers/net/wwan/wwan_hwsim.c b/drivers/net/wwan/wwan_hwsim.c
new file mode 100644
index 000000000000..5b62cf3b3c42
--- /dev/null
+++ b/drivers/net/wwan/wwan_hwsim.c
@@ -0,0 +1,547 @@
+// 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 struct class *wwan_hwsim_class;
+
+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;
+
+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;
+			memcpy(skb_put(out, n), &in->data[s], n);/* Echo */
+			memcpy(skb_put(out, 6), "\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;
+		memcpy(skb_put(out, n), &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,
+				      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:
+	kfree(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.
+	 */
+	schedule_work(&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.
+	 */
+	schedule_work(&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_hwsim_class = class_create(THIS_MODULE, "wwan_hwsim");
+	if (IS_ERR(wwan_hwsim_class))
+		return PTR_ERR(wwan_hwsim_class);
+
+	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:
+	wwan_hwsim_free_devs();
+	debugfs_remove(wwan_hwsim_debugfs_topdir);
+	class_destroy(wwan_hwsim_class);
+
+	return err;
+}
+
+static void __exit wwan_hwsim_exit(void)
+{
+	debugfs_remove(wwan_hwsim_debugfs_devcreate);	/* Avoid new devs */
+	wwan_hwsim_free_devs();
+	flush_scheduled_work();		/* Wait deletion works completion */
+	debugfs_remove(wwan_hwsim_debugfs_topdir);
+	class_destroy(wwan_hwsim_class);
+}
+
+module_init(wwan_hwsim_init);
+module_exit(wwan_hwsim_exit);
+
+MODULE_AUTHOR("Sergey Ryazanov");
+MODULE_DESCRIPTION("Device simulator for WWAN framework");
+MODULE_LICENSE("GPL");