USB: usb-serial ch341: support for DTR/RTS/CTS

Fixup of Werner Cornelius patch to the ch341 USB-serial driver, which adds:
- support all baudrates, not just a hard-coded set
- support for controlling DTR, RTS and CTS

Features still missing:
- character length other than 8 bits
- parity settings
- break control

I adapted his patch for the new usb_serial API introduced in 2.6.25-git8 by
Alan Cox on 22 July 2008. Non-compliance to the new API was a reason for
refusing a similar patch from Tollef Fog Heen.

Usage example by Tollef Fog Heen :
        TEMPer USB thermometer <http://err.no/src/TEMPer.c>

Signed-off-by: Werner Cornelius <Werner.Cornelius@cornelius-consult.de>
Signed-off-by: Boris Hajduk <boris@hajduk.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 302 insertions, 72 deletions

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index f61e3ca64305..d5ea679e1698 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -1,5 +1,7 @@
 /*
  * Copyright 2007, Frank A Kingswood <frank@kingswood-consulting.co.uk>
+ * Copyright 2007, Werner Cornelius <werner@cornelius-consult.de>
+ * Copyright 2009, Boris Hajduk <boris@hajduk.org>
  *
  * ch341.c implements a serial port driver for the Winchiphead CH341.
  *
@@ -21,9 +23,39 @@
 #include <linux/usb/serial.h>
 #include <linux/serial.h>
 
-#define DEFAULT_BAUD_RATE 2400
+#define DEFAULT_BAUD_RATE 9600
 #define DEFAULT_TIMEOUT   1000
 
+/* flags for IO-Bits */
+#define CH341_BIT_RTS (1 << 6)
+#define CH341_BIT_DTR (1 << 5)
+
+/******************************/
+/* interrupt pipe definitions */
+/******************************/
+/* always 4 interrupt bytes */
+/* first irq byte normally 0x08 */
+/* second irq byte base 0x7d + below */
+/* third irq byte base 0x94 + below */
+/* fourth irq byte normally 0xee */
+
+/* second interrupt byte */
+#define CH341_MULT_STAT 0x04 /* multiple status since last interrupt event */
+
+/* status returned in third interrupt answer byte, inverted in data
+   from irq */
+#define CH341_BIT_CTS 0x01
+#define CH341_BIT_DSR 0x02
+#define CH341_BIT_RI  0x04
+#define CH341_BIT_DCD 0x08
+#define CH341_BITS_MODEM_STAT 0x0f /* all bits */
+
+/*******************************/
+/* baudrate calculation factor */
+/*******************************/
+#define CH341_BAUDBASE_FACTOR 1532620800
+#define CH341_BAUDBASE_DIVMAX 3
+
 static int debug;
 
 static struct usb_device_id id_table [] = {
@@ -34,9 +66,12 @@ static struct usb_device_id id_table [] = {
 MODULE_DEVICE_TABLE(usb, id_table);
 
 struct ch341_private {
-        unsigned baud_rate;
-        u8 dtr;
-        u8 rts;
+        spinlock_t lock; /* access lock */
+        wait_queue_head_t delta_msr_wait; /* wait queue for modem status */
+        unsigned baud_rate; /* set baud rate */
+        u8 line_control; /* set line control value RTS/DTR */
+        u8 line_status; /* active status of modem control inputs */
+        u8 multi_status_change; /* status changed multiple since last call */
 };
 
 static int ch341_control_out(struct usb_device *dev, u8 request,
@@ -72,37 +107,28 @@ static int ch341_set_baudrate(struct usb_device *dev,
 {
         short a, b;
         int r;
+        unsigned long factor;
+        short divisor;
 
         dbg("ch341_set_baudrate(%d)", priv->baud_rate);
-        switch (priv->baud_rate) {
-        case 2400:
-                a = 0xd901;
-                b = 0x0038;
-                break;
-        case 4800:
-                a = 0x6402;
-                b = 0x001f;
-                break;
-        case 9600:
-                a = 0xb202;
-                b = 0x0013;
-                break;
-        case 19200:
-                a = 0xd902;
-                b = 0x000d;
-                break;
-        case 38400:
-                a = 0x6403;
-                b = 0x000a;
-                break;
-        case 115200:
-                a = 0xcc03;
-                b = 0x0008;
-                break;
-        default:
+
+        if (!priv->baud_rate)
                 return -EINVAL;
+        factor = (CH341_BAUDBASE_FACTOR / priv->baud_rate);
+        divisor = CH341_BAUDBASE_DIVMAX;
+
+        while ((factor > 0xfff0) && divisor) {
+                factor >>= 3;
+                divisor--;
         }
 
+        if (factor > 0xfff0)
+                return -EINVAL;
+
+        factor = 0x10000 - factor;
+        a = (factor & 0xff00) | divisor;
+        b = factor & 0xff;
+
         r = ch341_control_out(dev, 0x9a, 0x1312, a);
         if (!r)
                 r = ch341_control_out(dev, 0x9a, 0x0f2c, b);
@@ -110,19 +136,18 @@ static int ch341_set_baudrate(struct usb_device *dev,
         return r;
 }
 
-static int ch341_set_handshake(struct usb_device *dev,
-                               struct ch341_private *priv)
+static int ch341_set_handshake(struct usb_device *dev, u8 control)
 {
-        dbg("ch341_set_handshake(%d,%d)", priv->dtr, priv->rts);
-        return ch341_control_out(dev, 0xa4,
-                ~((priv->dtr?1<<5:0)|(priv->rts?1<<6:0)), 0);
+        dbg("ch341_set_handshake(0x%02x)", control);
+        return ch341_control_out(dev, 0xa4, ~control, 0);
 }
 
-static int ch341_get_status(struct usb_device *dev)
+static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
 {
         char *buffer;
         int r;
         const unsigned size = 8;
+        unsigned long flags;
 
         dbg("ch341_get_status()");
 
@@ -134,10 +159,15 @@ static int ch341_get_status(struct usb_device *dev)
         if (r < 0)
                 goto out;
 
-        /* Not having the datasheet for the CH341, we ignore the bytes returned
-         * from the device. Return error if the device did not respond in time.
-         */
-        r = 0;
+        /* setup the private status if available */
+        if (r == 2) {
+                r = 0;
+                spin_lock_irqsave(&priv->lock, flags);
+                priv->line_status = (~(*buffer)) & CH341_BITS_MODEM_STAT;
+                priv->multi_status_change = 0;
+                spin_unlock_irqrestore(&priv->lock, flags);
+        } else
+                r = -EPROTO;
 
 out:    kfree(buffer);
         return r;
@@ -180,7 +210,7 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
                 goto out;
 
         /* expect 0xff 0xee */
-        r = ch341_get_status(dev);
+        r = ch341_get_status(dev, priv);
         if (r < 0)
                 goto out;
 
@@ -192,12 +222,12 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
         if (r < 0)
                 goto out;
 
-        r = ch341_set_handshake(dev, priv);
+        r = ch341_set_handshake(dev, priv->line_control);
         if (r < 0)
                 goto out;
 
         /* expect 0x9f 0xee */
-        r = ch341_get_status(dev);
+        r = ch341_get_status(dev, priv);
 
 out:    kfree(buffer);
         return r;
@@ -216,9 +246,10 @@ static int ch341_attach(struct usb_serial *serial)
         if (!priv)
                 return -ENOMEM;
 
+        spin_lock_init(&priv->lock);
+        init_waitqueue_head(&priv->delta_msr_wait);
         priv->baud_rate = DEFAULT_BAUD_RATE;
-        priv->dtr = 1;
-        priv->rts = 1;
+        priv->line_control = CH341_BIT_RTS | CH341_BIT_DTR;
 
         r = ch341_configure(serial->dev, priv);
         if (r < 0)
@@ -231,6 +262,35 @@ error:	kfree(priv);
         return r;
 }
 
+static void ch341_close(struct tty_struct *tty, struct usb_serial_port *port,
+                                struct file *filp)
+{
+        struct ch341_private *priv = usb_get_serial_port_data(port);
+        unsigned long flags;
+        unsigned int c_cflag;
+
+        dbg("%s - port %d", __func__, port->number);
+
+        /* shutdown our urbs */
+        dbg("%s - shutting down urbs", __func__);
+        usb_kill_urb(port->write_urb);
+        usb_kill_urb(port->read_urb);
+        usb_kill_urb(port->interrupt_in_urb);
+
+        if (tty) {
+                c_cflag = tty->termios->c_cflag;
+                if (c_cflag & HUPCL) {
+                        /* drop DTR and RTS */
+                        spin_lock_irqsave(&priv->lock, flags);
+                        priv->line_control = 0;
+                        spin_unlock_irqrestore(&priv->lock, flags);
+                        ch341_set_handshake(port->serial->dev, 0);
+                }
+        }
+        wake_up_interruptible(&priv->delta_msr_wait);
+}
+
+
 /* open this device, set default parameters */
 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port,
                                 struct file *filp)
@@ -242,14 +302,13 @@ static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port,
         dbg("ch341_open()");
 
         priv->baud_rate = DEFAULT_BAUD_RATE;
-        priv->dtr = 1;
-        priv->rts = 1;
+        priv->line_control = CH341_BIT_RTS | CH341_BIT_DTR;
 
         r = ch341_configure(serial->dev, priv);
         if (r)
                 goto out;
 
-        r = ch341_set_handshake(serial->dev, priv);
+        r = ch341_set_handshake(serial->dev, priv->line_control);
         if (r)
                 goto out;
 
@@ -257,6 +316,16 @@ static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port,
         if (r)
                 goto out;
 
+        dbg("%s - submitting interrupt urb", __func__);
+        port->interrupt_in_urb->dev = serial->dev;
+        r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
+        if (r) {
+                dev_err(&port->dev, "%s - failed submitting interrupt urb,"
+                        " error %d\n", __func__, r);
+                ch341_close(tty, port, NULL);
+                return -EPROTO;
+        }
+
         r = usb_serial_generic_open(tty, port, filp);
 
 out:    return r;
@@ -270,38 +339,194 @@ static void ch341_set_termios(struct tty_struct *tty,
 {
         struct ch341_private *priv = usb_get_serial_port_data(port);
         unsigned baud_rate;
+        unsigned long flags;
 
         dbg("ch341_set_termios()");
 
+        if (!tty || !tty->termios)
+                return;
+
         baud_rate = tty_get_baud_rate(tty);
 
-        switch (baud_rate) {
-        case 2400:
-        case 4800:
-        case 9600:
-        case 19200:
-        case 38400:
-        case 115200:
-                priv->baud_rate = baud_rate;
-                break;
-        default:
-                dbg("Rate %d not supported, using %d",
-                        baud_rate, DEFAULT_BAUD_RATE);
-                priv->baud_rate = DEFAULT_BAUD_RATE;
+        priv->baud_rate = baud_rate;
+
+        if (baud_rate) {
+                spin_lock_irqsave(&priv->lock, flags);
+                priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
+                spin_unlock_irqrestore(&priv->lock, flags);
+                ch341_set_baudrate(port->serial->dev, priv);
+        } else {
+                spin_lock_irqsave(&priv->lock, flags);
+                priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
+                spin_unlock_irqrestore(&priv->lock, flags);
         }
 
-        ch341_set_baudrate(port->serial->dev, priv);
+        ch341_set_handshake(port->serial->dev, priv->line_control);
 
         /* Unimplemented:
          * (cflag & CSIZE) : data bits [5, 8]
          * (cflag & PARENB) : parity {NONE, EVEN, ODD}
          * (cflag & CSTOPB) : stop bits [1, 2]
          */
+}
+
+static int ch341_tiocmset(struct tty_struct *tty, struct file *file,
+                          unsigned int set, unsigned int clear)
+{
+        struct usb_serial_port *port = tty->driver_data;
+        struct ch341_private *priv = usb_get_serial_port_data(port);
+        unsigned long flags;
+        u8 control;
+
+        spin_lock_irqsave(&priv->lock, flags);
+        if (set & TIOCM_RTS)
+                priv->line_control |= CH341_BIT_RTS;
+        if (set & TIOCM_DTR)
+                priv->line_control |= CH341_BIT_DTR;
+        if (clear & TIOCM_RTS)
+                priv->line_control &= ~CH341_BIT_RTS;
+        if (clear & TIOCM_DTR)
+                priv->line_control &= ~CH341_BIT_DTR;
+        control = priv->line_control;
+        spin_unlock_irqrestore(&priv->lock, flags);
+
+        return ch341_set_handshake(port->serial->dev, control);
+}
+
+static void ch341_read_int_callback(struct urb *urb)
+{
+        struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
+        unsigned char *data = urb->transfer_buffer;
+        unsigned int actual_length = urb->actual_length;
+        int status;
+
+        dbg("%s (%d)", __func__, port->number);
+
+        switch (urb->status) {
+        case 0:
+                /* success */
+                break;
+        case -ECONNRESET:
+        case -ENOENT:
+        case -ESHUTDOWN:
+                /* this urb is terminated, clean up */
+                dbg("%s - urb shutting down with status: %d", __func__,
+                    urb->status);
+                return;
+        default:
+                dbg("%s - nonzero urb status received: %d", __func__,
+                    urb->status);
+                goto exit;
+        }
+
+        usb_serial_debug_data(debug, &port->dev, __func__,
+                              urb->actual_length, urb->transfer_buffer);
+
+        if (actual_length >= 4) {
+                struct ch341_private *priv = usb_get_serial_port_data(port);
+                unsigned long flags;
+
+                spin_lock_irqsave(&priv->lock, flags);
+                priv->line_status = (~(data[2])) & CH341_BITS_MODEM_STAT;
+                if ((data[1] & CH341_MULT_STAT))
+                        priv->multi_status_change = 1;
+                spin_unlock_irqrestore(&priv->lock, flags);
+                wake_up_interruptible(&priv->delta_msr_wait);
+        }
+
+exit:
+        status = usb_submit_urb(urb, GFP_ATOMIC);
+        if (status)
+                dev_err(&urb->dev->dev,
+                        "%s - usb_submit_urb failed with result %d\n",
+                        __func__, status);
+}
+
+static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
+{
+        struct ch341_private *priv = usb_get_serial_port_data(port);
+        unsigned long flags;
+        u8 prevstatus;
+        u8 status;
+        u8 changed;
+        u8 multi_change = 0;
+
+        spin_lock_irqsave(&priv->lock, flags);
+        prevstatus = priv->line_status;
+        priv->multi_status_change = 0;
+        spin_unlock_irqrestore(&priv->lock, flags);
+
+        while (!multi_change) {
+                interruptible_sleep_on(&priv->delta_msr_wait);
+                /* see if a signal did it */
+                if (signal_pending(current))
+                        return -ERESTARTSYS;
+
+                spin_lock_irqsave(&priv->lock, flags);
+                status = priv->line_status;
+                multi_change = priv->multi_status_change;
+                spin_unlock_irqrestore(&priv->lock, flags);
+
+                changed = prevstatus ^ status;
+
+                if (((arg & TIOCM_RNG) && (changed & CH341_BIT_RI)) ||
+                    ((arg & TIOCM_DSR) && (changed & CH341_BIT_DSR)) ||
+                    ((arg & TIOCM_CD)  && (changed & CH341_BIT_DCD)) ||
+                    ((arg & TIOCM_CTS) && (changed & CH341_BIT_CTS))) {
+                        return 0;
+                }
+                prevstatus = status;
+        }
+
+        return 0;
+}
+
+/*static int ch341_ioctl(struct usb_serial_port *port, struct file *file,*/
+static int ch341_ioctl(struct tty_struct *tty, struct file *file,
+                        unsigned int cmd, unsigned long arg)
+{
+        struct usb_serial_port *port = tty->driver_data;
+        dbg("%s (%d) cmd = 0x%04x", __func__, port->number, cmd);
+
+        switch (cmd) {
+        case TIOCMIWAIT:
+                dbg("%s (%d) TIOCMIWAIT", __func__,  port->number);
+                return wait_modem_info(port, arg);
+
+        default:
+                dbg("%s not supported = 0x%04x", __func__, cmd);
+                break;
+        }
+
+        return -ENOIOCTLCMD;
+}
+
+static int ch341_tiocmget(struct tty_struct *tty, struct file *file)
+{
+        struct usb_serial_port *port = tty->driver_data;
+        struct ch341_private *priv = usb_get_serial_port_data(port);
+        unsigned long flags;
+        u8 mcr;
+        u8 status;
+        unsigned int result;
+
+        dbg("%s (%d)", __func__, port->number);
+
+        spin_lock_irqsave(&priv->lock, flags);
+        mcr = priv->line_control;
+        status = priv->line_status;
+        spin_unlock_irqrestore(&priv->lock, flags);
+
+        result = ((mcr & CH341_BIT_DTR)         ? TIOCM_DTR : 0)
+                  | ((mcr & CH341_BIT_RTS)      ? TIOCM_RTS : 0)
+                  | ((status & CH341_BIT_CTS)   ? TIOCM_CTS : 0)
+                  | ((status & CH341_BIT_DSR)   ? TIOCM_DSR : 0)
+                  | ((status & CH341_BIT_RI)    ? TIOCM_RI  : 0)
+                  | ((status & CH341_BIT_DCD)   ? TIOCM_CD  : 0);
+
+        dbg("%s - result = %x", __func__, result);
 
-         /* Copy back the old hardware settings */
-         tty_termios_copy_hw(tty->termios, old_termios);
-         /* And re-encode with the new baud */
-         tty_encode_baud_rate(tty, baud_rate, baud_rate);
+        return result;
 }
 
 static struct usb_driver ch341_driver = {
@@ -317,12 +542,17 @@ static struct usb_serial_driver ch341_device = {
                 .owner  = THIS_MODULE,
                 .name   = "ch341-uart",
         },
-        .id_table         = id_table,
-        .usb_driver       = &ch341_driver,
-        .num_ports        = 1,
-        .open             = ch341_open,
-        .set_termios      = ch341_set_termios,
-        .attach           = ch341_attach,
+        .id_table          = id_table,
+        .usb_driver        = &ch341_driver,
+        .num_ports         = 1,
+        .open              = ch341_open,
+        .close             = ch341_close,
+        .ioctl             = ch341_ioctl,
+        .set_termios       = ch341_set_termios,
+        .tiocmget          = ch341_tiocmget,
+        .tiocmset          = ch341_tiocmset,
+        .read_int_callback = ch341_read_int_callback,
+        .attach            = ch341_attach,
 };
 
 static int __init ch341_init(void)