USB: serial: mct_u232: added _ioctl, _msr_to_icount and _get_icount functions

Added mct_u232_ioctl (implements TIOCMIWAIT command),
mct_u232_get_icount (implements TIOCGICOUNT command) and
mct_u232_msr_to_icount functions. MCT U232 P9 is one of a few usb to
serail adapters which converts USB +/-5v voltage levels to COM +/-15
voltages. So it can also power COM interfaced devices. This makes it
very usable for legacy COM interfaced data-acquisition hardware. I
tested new implementation with AWARE Electronics RM-60 radiation meter,
which sends pulse via RNG COM line whenever new particle is registered.

Signed-off-by: Vadim Tsozik <tsozik@yahoo.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 105 insertions, 2 deletions

diff --git a/drivers/usb/serial/mct_u232.c b/drivers/usb/serial/mct_u232.c
index 2849f8c32015..1e225aacf46e 100644
--- a/drivers/usb/serial/mct_u232.c
+++ b/drivers/usb/serial/mct_u232.c
@@ -78,6 +78,8 @@
 #include <asm/unaligned.h>
 #include <linux/usb.h>
 #include <linux/usb/serial.h>
+#include <linux/serial.h>
+#include <linux/ioctl.h>
 #include "mct_u232.h"
 
 /*
@@ -104,6 +106,10 @@ static void mct_u232_break_ctl(struct tty_struct *tty, int break_state);
 static int  mct_u232_tiocmget(struct tty_struct *tty, struct file *file);
 static int  mct_u232_tiocmset(struct tty_struct *tty, struct file *file,
                         unsigned int set, unsigned int clear);
+static int  mct_u232_ioctl(struct tty_struct *tty, struct file *file,
+                        unsigned int cmd, unsigned long arg);
+static int  mct_u232_get_icount(struct tty_struct *tty,
+                        struct serial_icounter_struct *icount);
 static void mct_u232_throttle(struct tty_struct *tty);
 static void mct_u232_unthrottle(struct tty_struct *tty);
 
@@ -150,9 +156,10 @@ static struct usb_serial_driver mct_u232_device = {
         .tiocmset =          mct_u232_tiocmset,
         .attach =            mct_u232_startup,
         .release =           mct_u232_release,
+        .ioctl =             mct_u232_ioctl,
+        .get_icount =        mct_u232_get_icount,
 };
 
-
 struct mct_u232_private {
         spinlock_t lock;
         unsigned int         control_state; /* Modem Line Setting (TIOCM) */
@@ -160,6 +167,9 @@ struct mct_u232_private {
         unsigned char        last_lsr;      /* Line Status Register */
         unsigned char        last_msr;      /* Modem Status Register */
         unsigned int         rx_flags;      /* Throttling flags */
+        struct async_icount  icount;
+        wait_queue_head_t    msr_wait;  /* for handling sleeping while waiting
+                                                for msr change to happen */
 };
 
 #define THROTTLED               0x01
@@ -386,6 +396,20 @@ static int mct_u232_get_modem_stat(struct usb_serial *serial,
         return rc;
 } /* mct_u232_get_modem_stat */
 
+static void mct_u232_msr_to_icount(struct async_icount *icount,
+                                                unsigned char msr)
+{
+        /* Translate Control Line states */
+        if (msr & MCT_U232_MSR_DDSR)
+                icount->dsr++;
+        if (msr & MCT_U232_MSR_DCTS)
+                icount->cts++;
+        if (msr & MCT_U232_MSR_DRI)
+                icount->rng++;
+        if (msr & MCT_U232_MSR_DCD)
+                icount->dcd++;
+} /* mct_u232_msr_to_icount */
+
 static void mct_u232_msr_to_state(unsigned int *control_state,
                                                 unsigned char msr)
 {
@@ -422,6 +446,7 @@ static int mct_u232_startup(struct usb_serial *serial)
         if (!priv)
                 return -ENOMEM;
         spin_lock_init(&priv->lock);
+        init_waitqueue_head(&priv->msr_wait);
         usb_set_serial_port_data(serial->port[0], priv);
 
         init_waitqueue_head(&serial->port[0]->write_wait);
@@ -621,6 +646,8 @@ static void mct_u232_read_int_callback(struct urb *urb)
         /* Record Control Line states */
         mct_u232_msr_to_state(&priv->control_state, priv->last_msr);
 
+        mct_u232_msr_to_icount(&priv->icount, priv->last_msr);
+
 #if 0
         /* Not yet handled. See belkin_sa.c for further information */
         /* Now to report any errors */
@@ -647,6 +674,7 @@ static void mct_u232_read_int_callback(struct urb *urb)
                 tty_kref_put(tty);
         }
 #endif
+        wake_up_interruptible(&priv->msr_wait);
         spin_unlock_irqrestore(&priv->lock, flags);
 exit:
         retval = usb_submit_urb(urb, GFP_ATOMIC);
@@ -826,7 +854,6 @@ static void mct_u232_throttle(struct tty_struct *tty)
         }
 }
 
-
 static void mct_u232_unthrottle(struct tty_struct *tty)
 {
         struct usb_serial_port *port = tty->driver_data;
@@ -847,6 +874,82 @@ static void mct_u232_unthrottle(struct tty_struct *tty)
         }
 }
 
+static int  mct_u232_ioctl(struct tty_struct *tty, struct file *file,
+                        unsigned int cmd, unsigned long arg)
+{
+        DEFINE_WAIT(wait);
+        struct usb_serial_port *port = tty->driver_data;
+        struct mct_u232_private *mct_u232_port = usb_get_serial_port_data(port);
+        struct async_icount cnow, cprev;
+        unsigned long flags;
+
+        dbg("%s - port %d, cmd = 0x%x", __func__, port->number, cmd);
+
+        switch (cmd) {
+
+        case TIOCMIWAIT:
+
+                dbg("%s (%d) TIOCMIWAIT", __func__,  port->number);
+
+                spin_lock_irqsave(&mct_u232_port->lock, flags);
+                cprev = mct_u232_port->icount;
+                spin_unlock_irqrestore(&mct_u232_port->lock, flags);
+                for ( ; ; ) {
+                        prepare_to_wait(&mct_u232_port->msr_wait,
+                                        &wait, TASK_INTERRUPTIBLE);
+                        schedule();
+                        finish_wait(&mct_u232_port->msr_wait, &wait);
+                        /* see if a signal did it */
+                        if (signal_pending(current))
+                                return -ERESTARTSYS;
+                        spin_lock_irqsave(&mct_u232_port->lock, flags);
+                        cnow = mct_u232_port->icount;
+                        spin_unlock_irqrestore(&mct_u232_port->lock, flags);
+                        if (cnow.rng == cprev.rng && cnow.dsr == cprev.dsr &&
+                            cnow.dcd == cprev.dcd && cnow.cts == cprev.cts)
+                                return -EIO; /* no change => error */
+                        if (((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
+                            ((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
+                            ((arg & TIOCM_CD)  && (cnow.dcd != cprev.dcd)) ||
+                            ((arg & TIOCM_CTS) && (cnow.cts != cprev.cts))) {
+                                return 0;
+                        }
+                        cprev = cnow;
+                }
+
+        }
+        return -ENOIOCTLCMD;
+}
+
+static int  mct_u232_get_icount(struct tty_struct *tty,
+                        struct serial_icounter_struct *icount)
+{
+        struct usb_serial_port *port = tty->driver_data;
+        struct mct_u232_private *mct_u232_port = usb_get_serial_port_data(port);
+        struct async_icount *ic = &mct_u232_port->icount;
+        unsigned long flags;
+
+        spin_lock_irqsave(&mct_u232_port->lock, flags);
+
+        icount->cts = ic->cts;
+        icount->dsr = ic->dsr;
+        icount->rng = ic->rng;
+        icount->dcd = ic->dcd;
+        icount->rx = ic->rx;
+        icount->tx = ic->tx;
+        icount->frame = ic->frame;
+        icount->overrun = ic->overrun;
+        icount->parity = ic->parity;
+        icount->brk = ic->brk;
+        icount->buf_overrun = ic->buf_overrun;
+
+        spin_unlock_irqrestore(&mct_u232_port->lock, flags);
+
+        dbg("%s (%d) TIOCGICOUNT RX=%d, TX=%d",
+                __func__,  port->number, icount->rx, icount->tx);
+        return 0;
+}
+
 static int __init mct_u232_init(void)
 {
         int retval;