USB: Driver for CH341 USB-serial adaptor

This patch implements a USB serial port driver for the Winchiphead
CH341 USB-RS232 Converter. This chip also implements an IEEE 1284
parallel port, I2C and SPI, but that is not supported by the driver.

Signed-off-by: Frank A Kingswood <frank@kingswood-consulting.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 363 insertions, 0 deletions

diff --git a/drivers/usb/serial/Kconfig b/drivers/usb/serial/Kconfig
index 43d6db696f90..99fefed77919 100644
--- a/drivers/usb/serial/Kconfig
+++ b/drivers/usb/serial/Kconfig
@@ -92,6 +92,16 @@ config USB_SERIAL_BELKIN
           To compile this driver as a module, choose M here: the
           module will be called belkin_sa.
 
+config USB_SERIAL_CH341
+        tristate "USB Winchiphead CH341 Single Port Serial Driver"
+        depends on USB_SERIAL
+        help
+          Say Y here if you want to use a Winchiphead CH341 single port
+          USB to serial adapter.
+
+          To compile this driver as a module, choose M here: the
+          module will be called ch341.
+
 config USB_SERIAL_WHITEHEAT
         tristate "USB ConnectTech WhiteHEAT Serial Driver"
         depends on USB_SERIAL
diff --git a/drivers/usb/serial/Makefile b/drivers/usb/serial/Makefile
index 07a976eca6b7..d6fb384e52b2 100644
--- a/drivers/usb/serial/Makefile
+++ b/drivers/usb/serial/Makefile
@@ -15,6 +15,7 @@ obj-$(CONFIG_USB_SERIAL_AIRCABLE)		+= aircable.o
 obj-$(CONFIG_USB_SERIAL_AIRPRIME)               += airprime.o
 obj-$(CONFIG_USB_SERIAL_ARK3116)                += ark3116.o
 obj-$(CONFIG_USB_SERIAL_BELKIN)                 += belkin_sa.o
+obj-$(CONFIG_USB_SERIAL_CH341)                  += ch341.o
 obj-$(CONFIG_USB_SERIAL_CP2101)                 += cp2101.o
 obj-$(CONFIG_USB_SERIAL_CYBERJACK)              += cyberjack.o
 obj-$(CONFIG_USB_SERIAL_CYPRESS_M8)             += cypress_m8.o
diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
new file mode 100644
index 000000000000..eb681069e24e
--- /dev/null
+++ b/drivers/usb/serial/ch341.c
@@ -0,0 +1,352 @@
+/*
+ * Copyright 2007, Frank A Kingswood <frank@kingswood-consulting.co.uk>
+ *
+ * ch341.c implements a serial port driver for the Winchiphead CH341.
+ *
+ * The CH341 device can be used to implement an RS232 asynchronous
+ * serial port, an IEEE-1284 parallel printer port or a memory-like
+ * interface. In all cases the CH341 supports an I2C interface as well.
+ * This driver only supports the asynchronous serial interface.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/tty.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+#include <linux/usb/serial.h>
+#include <linux/serial.h>
+
+#define DEFAULT_BAUD_RATE 2400
+#define DEFAULT_TIMEOUT   1000
+
+static int debug;
+
+static struct usb_device_id id_table [] = {
+        { USB_DEVICE(0x4348, 0x5523) },
+        { },
+};
+MODULE_DEVICE_TABLE(usb, id_table);
+
+struct ch341_private {
+        unsigned baud_rate;
+        u8 dtr;
+        u8 rts;
+};
+
+static int ch341_control_out(struct usb_device *dev, u8 request,
+                             u16 value, u16 index)
+{
+        int r;
+        dbg("ch341_control_out(%02x,%02x,%04x,%04x)", USB_DIR_OUT|0x40,
+                (int)request, (int)value, (int)index);
+
+        r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
+                            USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
+                            value, index, NULL, 0, DEFAULT_TIMEOUT);
+
+        return r;
+}
+
+static int ch341_control_in(struct usb_device *dev,
+                            u8 request, u16 value, u16 index,
+                            char *buf, unsigned bufsize)
+{
+        int r;
+        dbg("ch341_control_in(%02x,%02x,%04x,%04x,%p,%u)", USB_DIR_IN|0x40,
+                (int)request, (int)value, (int)index, buf, (int)bufsize);
+
+        r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
+                            USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
+                            value, index, buf, bufsize, DEFAULT_TIMEOUT);
+        return r;
+}
+
+int ch341_set_baudrate(struct usb_device *dev, struct ch341_private *priv)
+{
+        short a, b;
+        int r;
+
+        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:
+                return -EINVAL;
+        }
+
+        r = ch341_control_out(dev, 0x9a, 0x1312, a);
+        if (!r)
+                r = ch341_control_out(dev, 0x9a, 0x0f2c, b);
+
+        return r;
+}
+
+int ch341_set_handshake(struct usb_device *dev, struct ch341_private *priv)
+{
+        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);
+}
+
+int ch341_get_status(struct usb_device *dev)
+{
+        char *buffer;
+        int r;
+        const unsigned size = 8;
+
+        dbg("ch341_get_status()");
+
+        buffer = kmalloc(size, GFP_KERNEL);
+        if (!buffer)
+                return -ENOMEM;
+
+        r = ch341_control_in(dev, 0x95, 0x0706, 0, buffer, size);
+        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;
+
+out:    kfree(buffer);
+        return r;
+}
+
+/* -------------------------------------------------------------------------- */
+
+int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
+{
+        char *buffer;
+        int r;
+        const unsigned size = 8;
+
+        dbg("ch341_configure()");
+
+        buffer = kmalloc(size, GFP_KERNEL);
+        if (!buffer)
+                return -ENOMEM;
+
+        /* expect two bytes 0x27 0x00 */
+        r = ch341_control_in(dev, 0x5f, 0, 0, buffer, size);
+        if (r < 0)
+                goto out;
+
+        r = ch341_control_out(dev, 0xa1, 0, 0);
+        if (r < 0)
+                goto out;
+
+        r = ch341_set_baudrate(dev, priv);
+        if (r < 0)
+                goto out;
+
+        /* expect two bytes 0x56 0x00 */
+        r = ch341_control_in(dev, 0x95, 0x2518, 0, buffer, size);
+        if (r < 0)
+                goto out;
+
+        r = ch341_control_out(dev, 0x9a, 0x2518, 0x0050);
+        if (r < 0)
+                goto out;
+
+        /* expect 0xff 0xee */
+        r = ch341_get_status(dev);
+        if (r < 0)
+                goto out;
+
+        r = ch341_control_out(dev, 0xa1, 0x501f, 0xd90a);
+        if (r < 0)
+                goto out;
+
+        r = ch341_set_baudrate(dev, priv);
+        if (r < 0)
+                goto out;
+
+        r = ch341_set_handshake(dev, priv);
+        if (r < 0)
+                goto out;
+
+        /* expect 0x9f 0xee */
+        r = ch341_get_status(dev);
+
+out:    kfree(buffer);
+        return r;
+}
+
+/* allocate private data */
+static int ch341_attach(struct usb_serial *serial)
+{
+        struct ch341_private *priv;
+        int r;
+
+        dbg("ch341_attach()");
+
+        /* private data */
+        priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
+        if (!priv)
+                return -ENOMEM;
+
+        priv->baud_rate = DEFAULT_BAUD_RATE;
+        priv->dtr = 1;
+        priv->rts = 1;
+
+        r = ch341_configure(serial->dev, priv);
+        if (r < 0)
+                goto error;
+
+        usb_set_serial_port_data(serial->port[0], priv);
+        return 0;
+
+error:  kfree(priv);
+        return r;
+}
+
+/* open this device, set default parameters */
+static int ch341_open(struct usb_serial_port *port, struct file *filp)
+{
+        struct usb_serial *serial = port->serial;
+        struct ch341_private *priv = usb_get_serial_port_data(serial->port[0]);
+        int r;
+
+        dbg("ch341_open()");
+
+        priv->baud_rate = DEFAULT_BAUD_RATE;
+        priv->dtr = 1;
+        priv->rts = 1;
+
+        r = ch341_configure(serial->dev, priv);
+        if (r)
+                goto out;
+
+        r = ch341_set_handshake(serial->dev, priv);
+        if (r)
+                goto out;
+
+        r = ch341_set_baudrate(serial->dev, priv);
+        if (r)
+                goto out;
+
+        r = usb_serial_generic_open(port, filp);
+
+out:    return r;
+}
+
+/* Old_termios contains the original termios settings and
+ * tty->termios contains the new setting to be used.
+ */
+static void ch341_set_termios(struct usb_serial_port *port,
+                              struct ktermios *old_termios)
+{
+        struct ch341_private *priv = usb_get_serial_port_data(port);
+        struct tty_struct *tty = port->tty;
+        unsigned baud_rate;
+
+        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;
+        }
+
+        ch341_set_baudrate(port->serial->dev, priv);
+
+        /* Unimplemented:
+         * (cflag & CSIZE) : data bits [5, 8]
+         * (cflag & PARENB) : parity {NONE, EVEN, ODD}
+         * (cflag & CSTOPB) : stop bits [1, 2]
+         */
+}
+
+static struct usb_driver ch341_driver = {
+        .name           = "ch341",
+        .probe          = usb_serial_probe,
+        .disconnect     = usb_serial_disconnect,
+        .id_table       = id_table,
+        .no_dynamic_id  = 1,
+};
+
+static struct usb_serial_driver ch341_device = {
+        .driver = {
+                .owner  = THIS_MODULE,
+                .name   = "ch341-uart",
+        },
+        .id_table         = id_table,
+        .usb_driver       = &ch341_driver,
+        .num_interrupt_in = NUM_DONT_CARE,
+        .num_bulk_in      = 1,
+        .num_bulk_out     = 1,
+        .num_ports        = 1,
+        .open             = ch341_open,
+        .set_termios      = ch341_set_termios,
+        .attach           = ch341_attach,
+};
+
+static int __init ch341_init(void)
+{
+        int retval;
+
+        retval = usb_serial_register(&ch341_device);
+        if (retval)
+                return retval;
+        retval = usb_register(&ch341_driver);
+        if (retval)
+                usb_serial_deregister(&ch341_device);
+        return retval;
+}
+
+static void __exit ch341_exit(void)
+{
+        usb_deregister(&ch341_driver);
+        usb_serial_deregister(&ch341_device);
+}
+
+module_init(ch341_init);
+module_exit(ch341_exit);
+MODULE_LICENSE("GPL");
+
+module_param(debug, bool, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(debug, "Debug enabled or not");
+
+/* EOF ch341.c */