tty: Modem functions for the HSO driver

Makes TIOCM ioctls for Data Carrier Detect & related functions
work like /drivers/serial/serial-core.c potentially needed
for pppd & similar user programs.
Signed-off-by: Denis Joseph Barrow <D.Barow@option.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/net/usb/hso.c

@@ -39,8 +39,11 @@
  *		port is opened, as this have a huge impact on the network port
  *		throughput.
  *
- * Interface 2:	Standard modem interface - circuit switched interface, should
- *		not be used.
+ * Interface 2:	Standard modem interface - circuit switched interface, this
+ *		can be used to make a standard ppp connection however it
+ *              should not be used in conjunction with the IP network interface
+ *              enabled for USB performance reasons i.e. if using this set
+ *              ideally disable_net=1.
  *
  *****************************************************************************/
 
@@ -63,6 +66,8 @@
 #include <linux/usb/cdc.h>
 #include <net/arp.h>
 #include <asm/byteorder.h>
+#include <linux/serial_core.h>
+#include <linux/serial.h>
 
 
 #define DRIVER_VERSION			"1.2"
@@ -182,6 +187,41 @@ enum rx_ctrl_state{
 	RX_PENDING
 };
 
+#define BM_REQUEST_TYPE (0xa1)
+#define B_NOTIFICATION  (0x20)
+#define W_VALUE         (0x0)
+#define W_INDEX         (0x2)
+#define W_LENGTH        (0x2)
+
+#define B_OVERRUN       (0x1<<6)
+#define B_PARITY        (0x1<<5)
+#define B_FRAMING       (0x1<<4)
+#define B_RING_SIGNAL   (0x1<<3)
+#define B_BREAK         (0x1<<2)
+#define B_TX_CARRIER    (0x1<<1)
+#define B_RX_CARRIER    (0x1<<0)
+
+struct hso_serial_state_notification {
+	u8 bmRequestType;
+	u8 bNotification;
+	u16 wValue;
+	u16 wIndex;
+	u16 wLength;
+	u16 UART_state_bitmap;
+} __attribute__((packed));
+
+struct hso_tiocmget {
+	struct mutex mutex;
+	wait_queue_head_t waitq;
+	int    intr_completed;
+	struct usb_endpoint_descriptor *endp;
+	struct urb *urb;
+	struct hso_serial_state_notification serial_state_notification;
+	u16    prev_UART_state_bitmap;
+	struct uart_icount icount;
+};
+
+
 struct hso_serial {
 	struct hso_device *parent;
 	int magic;
@@ -219,6 +259,7 @@ struct hso_serial {
 	spinlock_t serial_lock;
 
 	int (*write_data) (struct hso_serial *serial);
+	struct hso_tiocmget  *tiocmget;
 	/* Hacks required to get flow control
 	 * working on the serial receive buffers
 	 * so as not to drop characters on the floor.
@@ -305,7 +346,7 @@ static void async_get_intf(struct work_struct *data);
 static void async_put_intf(struct work_struct *data);
 static int hso_put_activity(struct hso_device *hso_dev);
 static int hso_get_activity(struct hso_device *hso_dev);
-
+static void tiocmget_intr_callback(struct urb *urb);
 /*****************************************************************************/
 /* Helping functions                                                         */
 /*****************************************************************************/
@@ -1419,25 +1460,217 @@ static int hso_serial_chars_in_buffer(struct tty_struct *tty)
 
 	return chars;
 }
+int tiocmget_submit_urb(struct hso_serial *serial,
+			struct hso_tiocmget  *tiocmget,
+			struct usb_device *usb)
+{
+	int result;
+
+	if (serial->parent->usb_gone)
+		return -ENODEV;
+	usb_fill_int_urb(tiocmget->urb, usb,
+			 usb_rcvintpipe(usb,
+					tiocmget->endp->
+					bEndpointAddress & 0x7F),
+			 &tiocmget->serial_state_notification,
+			 sizeof(struct hso_serial_state_notification),
+			 tiocmget_intr_callback, serial,
+			 tiocmget->endp->bInterval);
+	result = usb_submit_urb(tiocmget->urb, GFP_ATOMIC);
+	if (result) {
+		dev_warn(&usb->dev, "%s usb_submit_urb failed %d\n", __func__,
+			 result);
+	}
+	return result;
+
+}
+
+static void tiocmget_intr_callback(struct urb *urb)
+{
+	struct hso_serial *serial = urb->context;
+	struct hso_tiocmget *tiocmget;
+	int status = urb->status;
+	u16 UART_state_bitmap, prev_UART_state_bitmap;
+	struct uart_icount *icount;
+	struct hso_serial_state_notification *serial_state_notification;
+	struct usb_device *usb;
+
+	/* Sanity checks */
+	if (!serial)
+		return;
+	if (status) {
+		log_usb_status(status, __func__);
+		return;
+	}
+	tiocmget = serial->tiocmget;
+	if (!tiocmget)
+		return;
+	usb = serial->parent->usb;
+	serial_state_notification = &tiocmget->serial_state_notification;
+	if (serial_state_notification->bmRequestType != BM_REQUEST_TYPE ||
+	    serial_state_notification->bNotification != B_NOTIFICATION ||
+	    le16_to_cpu(serial_state_notification->wValue) != W_VALUE ||
+	    le16_to_cpu(serial_state_notification->wIndex) != W_INDEX ||
+	    le16_to_cpu(serial_state_notification->wLength) != W_LENGTH) {
+		dev_warn(&usb->dev,
+			 "hso received invalid serial state notification\n");
+		DUMP(serial_state_notification,
+		     sizeof(hso_serial_state_notifation))
+	} else {
+
+		UART_state_bitmap = le16_to_cpu(serial_state_notification->
+						UART_state_bitmap);
+		prev_UART_state_bitmap = tiocmget->prev_UART_state_bitmap;
+		icount = &tiocmget->icount;
+		spin_lock(&serial->serial_lock);
+		if ((UART_state_bitmap & B_OVERRUN) !=
+		   (prev_UART_state_bitmap & B_OVERRUN))
+			icount->parity++;
+		if ((UART_state_bitmap & B_PARITY) !=
+		   (prev_UART_state_bitmap & B_PARITY))
+			icount->parity++;
+		if ((UART_state_bitmap & B_FRAMING) !=
+		   (prev_UART_state_bitmap & B_FRAMING))
+			icount->frame++;
+		if ((UART_state_bitmap & B_RING_SIGNAL) &&
+		   !(prev_UART_state_bitmap & B_RING_SIGNAL))
+			icount->rng++;
+		if ((UART_state_bitmap & B_BREAK) !=
+		   (prev_UART_state_bitmap & B_BREAK))
+			icount->brk++;
+		if ((UART_state_bitmap & B_TX_CARRIER) !=
+		   (prev_UART_state_bitmap & B_TX_CARRIER))
+			icount->dsr++;
+		if ((UART_state_bitmap & B_RX_CARRIER) !=
+		   (prev_UART_state_bitmap & B_RX_CARRIER))
+			icount->dcd++;
+		tiocmget->prev_UART_state_bitmap = UART_state_bitmap;
+		spin_unlock(&serial->serial_lock);
+		tiocmget->intr_completed = 1;
+		wake_up_interruptible(&tiocmget->waitq);
+	}
+	memset(serial_state_notification, 0,
+	       sizeof(struct hso_serial_state_notification));
+	tiocmget_submit_urb(serial,
+			    tiocmget,
+			    serial->parent->usb);
+}
+
+/*
+ * next few functions largely stolen from drivers/serial/serial_core.c
+ */
+/* Wait for any of the 4 modem inputs (DCD,RI,DSR,CTS) to change
+ * - mask passed in arg for lines of interest
+ *   (use |'ed TIOCM_RNG/DSR/CD/CTS for masking)
+ * Caller should use TIOCGICOUNT to see which one it was
+ */
+static int
+hso_wait_modem_status(struct hso_serial *serial, unsigned long arg)
+{
+	DECLARE_WAITQUEUE(wait, current);
+	struct uart_icount cprev, cnow;
+	struct hso_tiocmget  *tiocmget;
+	int ret;
+
+	tiocmget = serial->tiocmget;
+	if (!tiocmget)
+		return -ENOENT;
+	/*
+	 * note the counters on entry
+	 */
+	spin_lock_irq(&serial->serial_lock);
+	memcpy(&cprev, &tiocmget->icount, sizeof(struct uart_icount));
+	spin_unlock_irq(&serial->serial_lock);
+	add_wait_queue(&tiocmget->waitq, &wait);
+	for (;;) {
+		spin_lock_irq(&serial->serial_lock);
+		memcpy(&cnow, &tiocmget->icount, sizeof(struct uart_icount));
+		spin_unlock_irq(&serial->serial_lock);
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
+		    ((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
+		    ((arg & TIOCM_CD)  && (cnow.dcd != cprev.dcd))) {
+			ret = 0;
+			break;
+		}
+		schedule();
+		/* see if a signal did it */
+		if (signal_pending(current)) {
+			ret = -ERESTARTSYS;
+			break;
+		}
+		cprev = cnow;
+	}
+	current->state = TASK_RUNNING;
+	remove_wait_queue(&tiocmget->waitq, &wait);
+
+	return ret;
+}
+
+/*
+ * Get counter of input serial line interrupts (DCD,RI,DSR,CTS)
+ * Return: write counters to the user passed counter struct
+ * NB: both 1->0 and 0->1 transitions are counted except for
+ *     RI where only 0->1 is counted.
+ */
+static int hso_get_count(struct hso_serial *serial,
+			  struct serial_icounter_struct __user *icnt)
+{
+	struct serial_icounter_struct icount;
+	struct uart_icount cnow;
+	struct hso_tiocmget  *tiocmget = serial->tiocmget;
+
+	if (!tiocmget)
+		 return -ENOENT;
+	spin_lock_irq(&serial->serial_lock);
+	memcpy(&cnow, &tiocmget->icount, sizeof(struct uart_icount));
+	spin_unlock_irq(&serial->serial_lock);
+
+	icount.cts         = cnow.cts;
+	icount.dsr         = cnow.dsr;
+	icount.rng         = cnow.rng;
+	icount.dcd         = cnow.dcd;
+	icount.rx          = cnow.rx;
+	icount.tx          = cnow.tx;
+	icount.frame       = cnow.frame;
+	icount.overrun     = cnow.overrun;
+	icount.parity      = cnow.parity;
+	icount.brk         = cnow.brk;
+	icount.buf_overrun = cnow.buf_overrun;
+
+	return copy_to_user(icnt, &icount, sizeof(icount)) ? -EFAULT : 0;
+}
+
 
 static int hso_serial_tiocmget(struct tty_struct *tty, struct file *file)
 {
-	unsigned int value;
+	int retval;
 	struct hso_serial *serial = get_serial_by_tty(tty);
-	unsigned long flags;
+	struct hso_tiocmget  *tiocmget;
+	u16 UART_state_bitmap;
 
 	/* sanity check */
 	if (!serial) {
 		D1("no tty structures");
 		return -EINVAL;
 	}
-
-	spin_lock_irqsave(&serial->serial_lock, flags);
-	value = ((serial->rts_state) ? TIOCM_RTS : 0) |
+	spin_lock_irq(&serial->serial_lock);
+	retval = ((serial->rts_state) ? TIOCM_RTS : 0) |
 	    ((serial->dtr_state) ? TIOCM_DTR : 0);
-	spin_unlock_irqrestore(&serial->serial_lock, flags);
-
-	return value;
+	tiocmget = serial->tiocmget;
+	if (tiocmget) {
+
+		UART_state_bitmap = le16_to_cpu(
+			tiocmget->prev_UART_state_bitmap);
+		if (UART_state_bitmap & B_RING_SIGNAL)
+			retval |=  TIOCM_RNG;
+		if (UART_state_bitmap & B_RX_CARRIER)
+			retval |=  TIOCM_CD;
+		if (UART_state_bitmap & B_TX_CARRIER)
+			retval |=  TIOCM_DSR;
+	}
+	spin_unlock_irq(&serial->serial_lock);
+	return retval;
 }
 
 static int hso_serial_tiocmset(struct tty_struct *tty, struct file *file,
@@ -1479,6 +1712,32 @@ static int hso_serial_tiocmset(struct tty_struct *tty, struct file *file,
 			       USB_CTRL_SET_TIMEOUT);
 }
 
+static int hso_serial_ioctl(struct tty_struct *tty, struct file *file,
+			    unsigned int cmd, unsigned long arg)
+{
+	struct hso_serial *serial =  get_serial_by_tty(tty);
+	void __user *uarg = (void __user *)arg;
+	int ret = 0;
+	D4("IOCTL cmd: %d, arg: %ld", cmd, arg);
+
+	if (!serial)
+		return -ENODEV;
+	switch (cmd) {
+	case TIOCMIWAIT:
+		ret = hso_wait_modem_status(serial, arg);
+		break;
+
+	case TIOCGICOUNT:
+		ret = hso_get_count(serial, uarg);
+		break;
+	default:
+		ret = -ENOIOCTLCMD;
+		break;
+	}
+	return ret;
+}
+
+
 /* starts a transmit */
 static void hso_kick_transmit(struct hso_serial *serial)
 {
@@ -1956,7 +2215,10 @@ static int hso_start_serial_device(struct hso_device *hso_dev, gfp_t flags)
 		serial->shared_int->use_count++;
 		mutex_unlock(&serial->shared_int->shared_int_lock);
 	}
-
+	if (serial->tiocmget)
+		tiocmget_submit_urb(serial,
+				    serial->tiocmget,
+				    serial->parent->usb);
 	return result;
 }
 
@@ -1964,6 +2226,7 @@ static int hso_stop_serial_device(struct hso_device *hso_dev)
 {
 	int i;
 	struct hso_serial *serial = dev2ser(hso_dev);
+	struct hso_tiocmget  *tiocmget;
 
 	if (!serial)
 		return -ENODEV;
@@ -1992,6 +2255,11 @@ static int hso_stop_serial_device(struct hso_device *hso_dev)
 		}
 		mutex_unlock(&serial->shared_int->shared_int_lock);
 	}
+	tiocmget = serial->tiocmget;
+	if (tiocmget) {
+		wake_up_interruptible(&tiocmget->waitq);
+		usb_kill_urb(tiocmget->urb);
+	}
 
 	return 0;
 }
@@ -2338,6 +2606,20 @@ static struct hso_device *hso_create_net_device(struct usb_interface *interface)
 	return NULL;
 }
 
+static void hso_free_tiomget(struct hso_serial *serial)
+{
+	struct hso_tiocmget *tiocmget = serial->tiocmget;
+	if (tiocmget) {
+		kfree(tiocmget);
+		if (tiocmget->urb) {
+			usb_free_urb(tiocmget->urb);
+			tiocmget->urb = NULL;
+		}
+		serial->tiocmget = NULL;
+
+	}
+}
+
 /* Frees an AT channel ( goes for both mux and non-mux ) */
 static void hso_free_serial_device(struct hso_device *hso_dev)
 {
@@ -2356,6 +2638,7 @@ static void hso_free_serial_device(struct hso_device *hso_dev)
 		else
 			mutex_unlock(&serial->shared_int->shared_int_lock);
 	}
+	hso_free_tiomget(serial);
 	kfree(serial);
 	hso_free_device(hso_dev);
 }
@@ -2367,6 +2650,7 @@ static struct hso_device *hso_create_bulk_serial_device(
 	struct hso_device *hso_dev;
 	struct hso_serial *serial;
 	int num_urbs;
+	struct hso_tiocmget *tiocmget;
 
 	hso_dev = hso_create_device(interface, port);
 	if (!hso_dev)
@@ -2379,8 +2663,27 @@ static struct hso_device *hso_create_bulk_serial_device(
 	serial->parent = hso_dev;
 	hso_dev->port_data.dev_serial = serial;
 
-	if (port & HSO_PORT_MODEM)
+	if (port & HSO_PORT_MODEM) {
 		num_urbs = 2;
+		serial->tiocmget = kzalloc(sizeof(struct hso_tiocmget),
+					   GFP_KERNEL);
+		/* it isn't going to break our heart if serial->tiocmget
+		 *  allocation fails don't bother checking this.
+		 */
+		if (serial->tiocmget) {
+			tiocmget = serial->tiocmget;
+			tiocmget->urb = usb_alloc_urb(0, GFP_KERNEL);
+			if (tiocmget->urb) {
+				mutex_init(&tiocmget->mutex);
+				init_waitqueue_head(&tiocmget->waitq);
+				tiocmget->endp = hso_get_ep(
+					interface,
+					USB_ENDPOINT_XFER_INT,
+					USB_DIR_IN);
+			} else
+				hso_free_tiomget(serial);
+		}
+	}
 	else
 		num_urbs = 1;
 
@@ -2416,6 +2719,7 @@ static struct hso_device *hso_create_bulk_serial_device(
 exit2:
 	hso_serial_common_free(serial);
 exit:
+	hso_free_tiomget(serial);
 	kfree(serial);
 	hso_free_device(hso_dev);
 	return NULL;
@@ -2926,6 +3230,7 @@ static const struct tty_operations hso_serial_ops = {
 	.close = hso_serial_close,
 	.write = hso_serial_write,
 	.write_room = hso_serial_write_room,
+	.ioctl = hso_serial_ioctl,
 	.set_termios = hso_serial_set_termios,
 	.chars_in_buffer = hso_serial_chars_in_buffer,
 	.tiocmget = hso_serial_tiocmget,