Merge branch 'wwan-improvements'

Sergey Ryazanov says:

====================
net: WWAN subsystem improvements

While working on WWAN netdev creation support, I notice a few things
that could be done to make the wwan subsystem more developer and user
friendly. This series implements them.

The series begins with a WWAN HW simulator designed simplify testing
and make the WWAN subsystem available for a wider audience. The next two
patches are intended to make the code a bit more clearer. This is
followed by a few patches to make the port device naming more
user-friendly. The series is finishes with a set of changes that allow
the WWAN AT port to be used with terminal emulation software.

All changes were tested with the HW simulator that was introduced in
this series, as well as with a Huawei E3372 LTE modem (a CDC-NCM
device), which I finally found on my desk.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wwan/Kconfig

@@ -20,6 +20,16 @@ config WWAN_CORE
 	  To compile this driver as a module, choose M here: the module will be
 	  called wwan.
 
+config WWAN_HWSIM
+	tristate "Simulated WWAN device"
+	depends on WWAN_CORE
+	help
+	  This driver is a developer testing tool that can be used to test WWAN
+	  framework.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called wwan_hwsim.  If unsure, say N.
+
 config MHI_WWAN_CTRL
 	tristate "MHI WWAN control driver for QCOM-based PCIe modems"
 	select WWAN_CORE

drivers/net/wwan/Makefile

@@ -6,4 +6,6 @@
 obj-$(CONFIG_WWAN_CORE) += wwan.o
 wwan-objs += wwan_core.o
 
+obj-$(CONFIG_WWAN_HWSIM) += wwan_hwsim.o
+
 obj-$(CONFIG_MHI_WWAN_CTRL) += mhi_wwan_ctrl.o

drivers/net/wwan/wwan_core.c

@@ -12,9 +12,11 @@
 #include <linux/skbuff.h>
 #include <linux/slab.h>
 #include <linux/types.h>
+#include <linux/termios.h>
 #include <linux/wwan.h>
 
-#define WWAN_MAX_MINORS 256 /* 256 minors allowed with register_chrdev() */
+/* 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 */
@@ -33,12 +35,10 @@ static int wwan_major;
  *
  * @id: WWAN device unique ID.
  * @dev: Underlying device.
- * @port_id: Current available port ID to pick.
  */
 struct wwan_device {
 	unsigned int id;
 	struct device dev;
-	atomic_t port_id;
 };
 
 /**
@@ -51,6 +51,8 @@ struct wwan_device {
  * @dev: Underlying device
  * @rxq: Buffer inbound queue
  * @waitqueue: The waitqueue for port fops (read/write/poll)
+ * @data_lock: Port specific data access serialization
+ * @at_data: AT port specific data
  */
 struct wwan_port {
 	enum wwan_port_type type;
@@ -61,6 +63,13 @@ struct wwan_port {
 	struct device dev;
 	struct sk_buff_head rxq;
 	wait_queue_head_t waitqueue;
+	struct mutex data_lock;	/* Port specific data access serialization */
+	union {
+		struct {
+			struct ktermios termios;
+			int mdmbits;
+		} at_data;
+	};
 };
 
 static ssize_t index_show(struct device *dev, struct device_attribute *attr, char *buf)
@@ -184,21 +193,38 @@ static void wwan_remove_dev(struct wwan_device *wwandev)
 
 /* ------- WWAN port management ------- */
 
-/* Keep aligned with wwan_port_type enum */
-static const char * const wwan_port_type_str[] = {
-	"AT",
-	"MBIM",
-	"QMI",
-	"QCDM",
-	"FIREHOSE"
+static const struct {
+	const char * const name;	/* Port type name */
+	const char * const devsuf;	/* Port devce name suffix */
+} wwan_port_types[WWAN_PORT_MAX + 1] = {
+	[WWAN_PORT_AT] = {
+		.name = "AT",
+		.devsuf = "at",
+	},
+	[WWAN_PORT_MBIM] = {
+		.name = "MBIM",
+		.devsuf = "mbim",
+	},
+	[WWAN_PORT_QMI] = {
+		.name = "QMI",
+		.devsuf = "qmi",
+	},
+	[WWAN_PORT_QCDM] = {
+		.name = "QCDM",
+		.devsuf = "qcdm",
+	},
+	[WWAN_PORT_FIREHOSE] = {
+		.name = "FIREHOSE",
+		.devsuf = "firehose",
+	},
 };
 
 static ssize_t type_show(struct device *dev, struct device_attribute *attr,
 			 char *buf)
 {
 	struct wwan_port *port = to_wwan_port(dev);
 
-	return sprintf(buf, "%s\n", wwan_port_type_str[port->type]);
+	return sprintf(buf, "%s\n", wwan_port_types[port->type].name);
 }
 static DEVICE_ATTR_RO(type);
 
@@ -213,7 +239,7 @@ static void wwan_port_destroy(struct device *dev)
 	struct wwan_port *port = to_wwan_port(dev);
 
 	ida_free(&minors, MINOR(port->dev.devt));
-	skb_queue_purge(&port->rxq);
+	mutex_destroy(&port->data_lock);
 	mutex_destroy(&port->ops_lock);
 	kfree(port);
 }
@@ -241,6 +267,56 @@ static struct wwan_port *wwan_port_get_by_minor(unsigned int minor)
 	return to_wwan_port(dev);
 }
 
+/* Allocate and set unique name based on passed format
+ *
+ * Name allocation approach is highly inspired by the __dev_alloc_name()
+ * function.
+ *
+ * To avoid names collision, the caller must prevent the new port device
+ * registration as well as concurrent invocation of this function.
+ */
+static int __wwan_port_dev_assign_name(struct wwan_port *port, const char *fmt)
+{
+	struct wwan_device *wwandev = to_wwan_dev(port->dev.parent);
+	const unsigned int max_ports = PAGE_SIZE * 8;
+	struct class_dev_iter iter;
+	unsigned long *idmap;
+	struct device *dev;
+	char buf[0x20];
+	int id;
+
+	idmap = (unsigned long *)get_zeroed_page(GFP_KERNEL);
+	if (!idmap)
+		return -ENOMEM;
+
+	/* Collect ids of same name format ports */
+	class_dev_iter_init(&iter, wwan_class, NULL, &wwan_port_dev_type);
+	while ((dev = class_dev_iter_next(&iter))) {
+		if (dev->parent != &wwandev->dev)
+			continue;
+		if (sscanf(dev_name(dev), fmt, &id) != 1)
+			continue;
+		if (id < 0 || id >= max_ports)
+			continue;
+		set_bit(id, idmap);
+	}
+	class_dev_iter_exit(&iter);
+
+	/* Allocate unique id */
+	id = find_first_zero_bit(idmap, max_ports);
+	free_page((unsigned long)idmap);
+
+	snprintf(buf, sizeof(buf), fmt, id);	/* Name generation */
+
+	dev = device_find_child_by_name(&wwandev->dev, buf);
+	if (dev) {
+		put_device(dev);
+		return -ENFILE;
+	}
+
+	return dev_set_name(&port->dev, buf);
+}
+
 struct wwan_port *wwan_create_port(struct device *parent,
 				   enum wwan_port_type type,
 				   const struct wwan_port_ops *ops,
@@ -249,8 +325,9 @@ struct wwan_port *wwan_create_port(struct device *parent,
 	struct wwan_device *wwandev;
 	struct wwan_port *port;
 	int minor, err = -ENOMEM;
+	char namefmt[0x20];
 
-	if (type >= WWAN_PORT_MAX || !ops)
+	if (type > WWAN_PORT_MAX || !ops)
 		return ERR_PTR(-EINVAL);
 
 	/* A port is always a child of a WWAN device, retrieve (allocate or
@@ -276,19 +353,26 @@ struct wwan_port *wwan_create_port(struct device *parent,
 	mutex_init(&port->ops_lock);
 	skb_queue_head_init(&port->rxq);
 	init_waitqueue_head(&port->waitqueue);
+	mutex_init(&port->data_lock);
 
 	port->dev.parent = &wwandev->dev;
 	port->dev.class = wwan_class;
 	port->dev.type = &wwan_port_dev_type;
 	port->dev.devt = MKDEV(wwan_major, minor);
 	dev_set_drvdata(&port->dev, drvdata);
 
-	/* create unique name based on wwan device id, port index and type */
-	dev_set_name(&port->dev, "wwan%up%u%s", wwandev->id,
-		     atomic_inc_return(&wwandev->port_id),
-		     wwan_port_type_str[port->type]);
+	/* allocate unique name based on wwan device id, port type and number */
+	snprintf(namefmt, sizeof(namefmt), "wwan%u%s%%d", wwandev->id,
+		 wwan_port_types[port->type].devsuf);
 
+	/* Serialize ports registration */
+	mutex_lock(&wwan_register_lock);
+
+	__wwan_port_dev_assign_name(port, namefmt);
 	err = device_register(&port->dev);
+
+	mutex_unlock(&wwan_register_lock);
+
 	if (err)
 		goto error_put_device;
 
@@ -377,8 +461,11 @@ static void wwan_port_op_stop(struct wwan_port *port)
 {
 	mutex_lock(&port->ops_lock);
 	port->start_count--;
-	if (port->ops && !port->start_count)
-		port->ops->stop(port);
+	if (!port->start_count) {
+		if (port->ops)
+			port->ops->stop(port);
+		skb_queue_purge(&port->rxq);
+	}
 	mutex_unlock(&port->ops_lock);
 }
 
@@ -545,13 +632,121 @@ static __poll_t wwan_port_fops_poll(struct file *filp, poll_table *wait)
 	return mask;
 }
 
+/* Implements minimalistic stub terminal IOCTLs support */
+static long wwan_port_fops_at_ioctl(struct wwan_port *port, unsigned int cmd,
+				    unsigned long arg)
+{
+	int ret = 0;
+
+	mutex_lock(&port->data_lock);
+
+	switch (cmd) {
+	case TCFLSH:
+		break;
+
+	case TCGETS:
+		if (copy_to_user((void __user *)arg, &port->at_data.termios,
+				 sizeof(struct termios)))
+			ret = -EFAULT;
+		break;
+
+	case TCSETS:
+	case TCSETSW:
+	case TCSETSF:
+		if (copy_from_user(&port->at_data.termios, (void __user *)arg,
+				   sizeof(struct termios)))
+			ret = -EFAULT;
+		break;
+
+#ifdef TCGETS2
+	case TCGETS2:
+		if (copy_to_user((void __user *)arg, &port->at_data.termios,
+				 sizeof(struct termios2)))
+			ret = -EFAULT;
+		break;
+
+	case TCSETS2:
+	case TCSETSW2:
+	case TCSETSF2:
+		if (copy_from_user(&port->at_data.termios, (void __user *)arg,
+				   sizeof(struct termios2)))
+			ret = -EFAULT;
+		break;
+#endif
+
+	case TIOCMGET:
+		ret = put_user(port->at_data.mdmbits, (int __user *)arg);
+		break;
+
+	case TIOCMSET:
+	case TIOCMBIC:
+	case TIOCMBIS: {
+		int mdmbits;
+
+		if (copy_from_user(&mdmbits, (int __user *)arg, sizeof(int))) {
+			ret = -EFAULT;
+			break;
+		}
+		if (cmd == TIOCMBIC)
+			port->at_data.mdmbits &= ~mdmbits;
+		else if (cmd == TIOCMBIS)
+			port->at_data.mdmbits |= mdmbits;
+		else
+			port->at_data.mdmbits = mdmbits;
+		break;
+	}
+
+	default:
+		ret = -ENOIOCTLCMD;
+	}
+
+	mutex_unlock(&port->data_lock);
+
+	return ret;
+}
+
+static long wwan_port_fops_ioctl(struct file *filp, unsigned int cmd,
+				 unsigned long arg)
+{
+	struct wwan_port *port = filp->private_data;
+	int res;
+
+	if (port->type == WWAN_PORT_AT) {	/* AT port specific IOCTLs */
+		res = wwan_port_fops_at_ioctl(port, cmd, arg);
+		if (res != -ENOIOCTLCMD)
+			return res;
+	}
+
+	switch (cmd) {
+	case TIOCINQ: {	/* aka SIOCINQ aka FIONREAD */
+		unsigned long flags;
+		struct sk_buff *skb;
+		int amount = 0;
+
+		spin_lock_irqsave(&port->rxq.lock, flags);
+		skb_queue_walk(&port->rxq, skb)
+			amount += skb->len;
+		spin_unlock_irqrestore(&port->rxq.lock, flags);
+
+		return put_user(amount, (int __user *)arg);
+	}
+
+	default:
+		return -ENOIOCTLCMD;
+	}
+}
+
 static const struct file_operations wwan_port_fops = {
 	.owner = THIS_MODULE,
 	.open = wwan_port_fops_open,
 	.release = wwan_port_fops_release,
 	.read = wwan_port_fops_read,
 	.write = wwan_port_fops_write,
 	.poll = wwan_port_fops_poll,
+	.unlocked_ioctl = wwan_port_fops_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl = compat_ptr_ioctl,
+#endif
 	.llseek = noop_llseek,
 };
 
@@ -562,7 +757,8 @@ static int __init wwan_init(void)
 		return PTR_ERR(wwan_class);
 
 	/* chrdev used for wwan ports */
-	wwan_major = register_chrdev(0, "wwan_port", &wwan_port_fops);
+	wwan_major = __register_chrdev(0, 0, WWAN_MAX_MINORS, "wwan_port",
+				       &wwan_port_fops);
 	if (wwan_major < 0) {
 		class_destroy(wwan_class);
 		return wwan_major;
@@ -573,7 +769,7 @@ static int __init wwan_init(void)
 
 static void __exit wwan_exit(void)
 {
-	unregister_chrdev(wwan_major, "wwan_port");
+	__unregister_chrdev(wwan_major, 0, WWAN_MAX_MINORS, "wwan_port");
 	class_destroy(wwan_class);
 }