--- /dev/null
+// 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/wwan.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 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;
+ 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;
+ enum { /* AT command parser state */
+ AT_PARSER_WAIT_A,
+ AT_PARSER_WAIT_T,
+ AT_PARSER_WAIT_TERM,
+ AT_PARSER_SKIP_LINE,
+ } pstate;
+};
+
+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;
+ 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;
+ }
+
+ return port;
+
+err_free_port:
+ kfree(port);
+
+ return ERR_PTR(err);
+}
+
+static void wwan_hwsim_port_del(struct wwan_hwsim_port *port)
+{
+ wwan_remove_port(port->wwan);
+ kfree(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;
+
+ return dev;
+
+err_free_dev:
+ kfree(dev);
+
+ return ERR_PTR(err);
+}
+
+static void wwan_hwsim_dev_del(struct wwan_hwsim_dev *dev)
+{
+ 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(&port->list);
+ spin_unlock(&dev->ports_lock);
+ wwan_hwsim_port_del(port);
+ spin_lock(&dev->ports_lock);
+ }
+ spin_unlock(&dev->ports_lock);
+
+ device_unregister(&dev->dev);
+ /* Memory will be freed in the device release callback */
+}
+
+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(&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);
+
+ err = wwan_hwsim_init_devs();
+ if (err)
+ goto err_clean_devs;
+
+ return 0;
+
+err_clean_devs:
+ wwan_hwsim_free_devs();
+ class_destroy(wwan_hwsim_class);
+
+ return err;
+}
+
+static void __exit wwan_hwsim_exit(void)
+{
+ wwan_hwsim_free_devs();
+ 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");
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