[PATCH] Winchiphead CH340/1: support modem control and status lines, more baudrates

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Tollef Fog Heen

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Jul 22, 2008, 4:00:11 AM7/22/08
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Patch against current git as of last night (so 2.6.26).

* Add support for all baudrates, not just a hard coded set.
* Make it possible to control modem control and status lines.

Signed-off-by: Tollef Fog Heen <tfh...@err.no>

---

This is a cleanup of Werner Conelius' patch in
http://kerneltrap.org/mailarchive/linux-kernel/2007/9/21/265323 which
should be more acceptable to mainline. Feel free to put him as author
rather than me.

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index 1f7c86b..d233146 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -1,5 +1,6 @@
/*
* Copyright 2007, Frank A Kingswood <fr...@kingswood-consulting.co.uk>
+ * Copyright 2007, Werner Cornelius <werner <at> cornelius-consult.de>
*
* ch341.c implements a serial port driver for the Winchiphead CH341.
*
@@ -24,6 +25,36 @@
#define DEFAULT_BAUD_RATE 2400
#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 +65,12 @@ 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 +106,28 @@ 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 +135,18 @@ 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 +158,15 @@ 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 +209,7 @@ 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 +221,12 @@ 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 +245,10 @@ 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 +261,34 @@ error: kfree(priv);
return r;
}

+static void ch341_close(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 (port->tty) {
+ c_cflag = port->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 usb_serial_port *port, struct file *filp)
{
@@ -241,14 +299,13 @@ static int ch341_open(struct usb_serial_port *port, struct file *filp)
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;

@@ -256,6 +313,16 @@ static int ch341_open(struct usb_serial_port *port, struct file *filp)
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(port, NULL);
+ return -EPROTO;
+ }
+
r = usb_serial_generic_open(port, filp);

out: return r;
@@ -270,38 +337,190 @@ static void ch341_set_termios(struct usb_serial_port *port,
struct ch341_private *priv = usb_get_serial_port_data(port);
struct tty_struct *tty = port->tty;
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 usb_serial_port *port, struct file *file,
+ unsigned int set, unsigned int clear)
+{
+ 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,
+ unsigned int cmd, unsigned long arg)
+{
+ 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 usb_serial_port *port, struct file *file)
+{
+ 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 +536,20 @@ 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_interrupt_in = 1,
+ .num_bulk_in = 1,
+ .num_bulk_out = 1,
+ .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)


--
Tollef Fog Heen
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Simon Arlott

unread,
Jul 31, 2008, 6:00:19 PM7/31/08
to
On 22/07/08 08:18, Tollef Fog Heen wrote:
> Patch against current git as of last night (so 2.6.26).
>
> * Add support for all baudrates, not just a hard coded set.
> * Make it possible to control modem control and status lines.
>
> Signed-off-by: Tollef Fog Heen <tfh...@err.no>
>
> ---
>
> This is a cleanup of Werner Conelius' patch in
> http://kerneltrap.org/mailarchive/linux-kernel/2007/9/21/265323 which
> should be more acceptable to mainline. Feel free to put him as author
> rather than me.

The correct format should be:

From: Werner Cornelius <Werner.C...@cornelius-consult.de>

<description>

Signed-off-by: Werner Cornelius <Werner.C...@cornelius-consult.de>


Signed-off-by: Tollef Fog Heen <tfh...@err.no>

However, this patch no longer applies to current git because of usb
serial changes to include a 'tty' function parameter.

--
Simon Arlott

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