Hi, I posted back in February regarding the Silicon Labs CP2101 USB Serial converter. After spending some time figuring out how it works, I have managed to write a simple driver which uses some of the basic functionality of the chip. The attached patch provides cp2101.c, and patches Kconfig and Makefile The code is still unfinished, but functional. I have yet to get flow control working, which is a little difficult since the pins are not connected on my serial converter. Also, a few comments in the code wouldn't go a miss.
Any feedback would be greatly appreciated. -- Craig Shelley EMail: [EMAIL PROTECTED] Jabber: [EMAIL PROTECTED]
diff -Nru a/drivers/usb/serial/cp2101.c b/drivers/usb/serial/cp2101.c
--- a/drivers/usb/serial/cp2101.c 1970-01-01 01:00:00.000000000 +0100
+++ b/drivers/usb/serial/cp2101.c 2005-03-18 00:29:43.837267216 +0000
@@ -0,0 +1,501 @@
+/*
+ * Silicon Laboratories CP2101 USB to RS232 serial adaptor driver
+ *
+ * Copyright (C) 2005 Craig Shelley ([EMAIL PROTECTED])
+ *
+ * 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/config.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/usb.h>
+#include <asm/uaccess.h>
+#include "usb-serial.h"
+
+/*
+ * Version Information
+ */
+#define DRIVER_VERSION "v0.01"
+#define DRIVER_DESC "Silicon Laboratories CP2101 USB to RS232 serial adaptor driver"
+
+/*
+ * Function Prototypes
+ */
+int cp2101_get_config(struct usb_serial_port*, u8);
+int cp2101_set_config(struct usb_serial_port*, u8, u16);
+int cp2101_open(struct usb_serial_port*, struct file*);
+static void cp2101_cleanup(struct usb_serial_port*);
+void cp2101_close(struct usb_serial_port*, struct file*);
+void cp2101_get_termios(struct usb_serial_port*);
+static void cp2101_set_termios(struct usb_serial_port*, struct termios*);
+static void cp2101_break_ctl(struct usb_serial_port*, int);
+void cp2101_shutdown(struct usb_serial*);
+
+
+
+static int debug;
+
+static struct usb_device_id id_table [] = {
+ {USB_DEVICE(0x10c4, 0xea60) },
+ { } /* Terminating Entry*/
+};
+
+MODULE_DEVICE_TABLE (usb, id_table);
+
+static struct usb_driver cp2101_driver = {
+ .owner = THIS_MODULE,
+ .name = "cp2101",
+ .probe = usb_serial_probe,
+ .disconnect = usb_serial_disconnect,
+ .id_table = id_table,
+};
+
+struct usb_serial_device_type cp2101_device = {
+ .owner = THIS_MODULE,
+ .name = "CP-2101",
+ .id_table = id_table,
+ .num_interrupt_in = 0,
+ .num_bulk_in = 0,
+ .num_bulk_out = 0,
+ .num_ports = 1,
+ .open = cp2101_open,
+ .close = cp2101_close,
+// .ioctl = cp2101_ioctl,
+ .break_ctl = cp2101_break_ctl,
+ .set_termios = cp2101_set_termios,
+ .shutdown = cp2101_shutdown,
+};
+
+#define REQTYPE_HOST_TO_DEVICE 0x41
+#define REQTYPE_DEVICE_TO_HOST 0xc1
+
+#define CP2101_UART 0x00
+#define CP2101_BAUDRATE 0x01
+#define CP2101_BITS 0x03
+#define CP2101_BREAK 0x05
+#define CP2101_DTRRTS 0x07
+
+#define CP2101_CONFIG 0x13 /* ??? */
+#define REQ_GET_CONFIG 0x14 /* ??? */
+
+#define UART_ENABLE 0x0001
+#define UART_DISABLE 0x0000
+#define BAUD_RATE_GEN_FREQ 0x384000
+
+#define BITS_DATA_MASK 0X0f00
+#define BITS_DATA_6 0X0600
+#define BITS_DATA_7 0X0700
+#define BITS_DATA_8 0X0800
+#define BITS_DATA_9 0X0900
+
+#define BITS_PARITY_MASK 0x00f0
+#define BITS_PARITY_NONE 0x0000
+#define BITS_PARITY_ODD 0x0010
+#define BITS_PARITY_EVEN 0x0020
+#define BITS_PARITY_MARK 0x0030
+#define BITS_PARITY_SPACE 0x0040
+
+#define BITS_STOP_MASK 0x000f
+#define BITS_STOP_1 0x0000
+#define BITS_STOP_1_5 0x0001
+#define BITS_STOP_2 0x0002
+#define BREAK_ON 0x0000
+#define BREAK_OFF 0x0001
+
+
+int cp2101_get_config(struct usb_serial_port* port, u8 request)
+{
+ struct usb_serial *serial = port->serial;
+ unsigned char buf[4];
+ unsigned int value;
+ int result, i;
+
+ /*Even number required for get*/
+ request++;
+
+ result = usb_control_msg (serial->dev, usb_rcvctrlpipe (serial->dev, 0),
+ request, REQTYPE_DEVICE_TO_HOST, 0x0000,
+ 0, buf, 4, 300);
+
+ if (result < 0)
+ {
+ dev_err(&port->dev, "%s - Unable to send config request, request=0x%x result=%d\n", __FUNCTION__, request, result);
+ return result;
+ }
+
+ value = 0;
+
+ for (i=0; i<4 && i<result; i++)
+ value |= (buf[i] << (i * 8));
+
+ dbg("%s - request=0x%x result=%d value=0x%x", __FUNCTION__, request, result, value);
+
+ return value;
+}
+
+int cp2101_set_config(struct usb_serial_port* port, u8 request, u16 value)
+{
+ struct usb_serial *serial = port->serial;
+ int result;
+ result = usb_control_msg (serial->dev, usb_sndctrlpipe (serial->dev, 0),
+ request, REQTYPE_HOST_TO_DEVICE, value,
+ 0, NULL, 0, 300);
+
+ if (result <0)
+ {
+ dev_err(&port->dev, "%s - Unable to send config request, request=0x%x value=0x%x result=%d\n", __FUNCTION__, request, value, result);
+ return 1;
+ }
+
+ dbg("%s - request=0x%x value=0x%x result=%d", __FUNCTION__, request, value, result);
+
+ return 0;
+}
+
+int cp2101_open (struct usb_serial_port *port, struct file *filp)
+{
+ struct usb_serial *serial = port->serial;
+ int result = 0;
+
+
+ dbg("%s - port %d", __FUNCTION__, port->number);
+
+ if (cp2101_set_config(port, CP2101_UART, UART_ENABLE))
+ {
+ dev_err(&port->dev, "%s - Unable to enable UART\n", __FUNCTION__);
+ return -EPROTO;
+ }
+
+ cp2101_get_termios(port);
+
+ /* Start reading from the device */
+ usb_fill_bulk_urb (port->read_urb, serial->dev,
+ usb_rcvbulkpipe(serial->dev, port->bulk_in_endpointAddress),
+ port->read_urb->transfer_buffer,
+ port->read_urb->transfer_buffer_length,
+ serial->type->read_bulk_callback,
+ port);
+ result = usb_submit_urb(port->read_urb, GFP_KERNEL);
+ if (result)
+ dev_err(&port->dev, "%s - failed resubmitting read urb, error %d\n", __FUNCTION__, result);
+
+
+
+ return result;
+}
+
+static void cp2101_cleanup (struct usb_serial_port *port)
+{
+ struct usb_serial *serial = port->serial;
+
+ dbg("%s - port %d", __FUNCTION__, port->number);
+
+ if (serial->dev) {
+
+ /* shutdown any bulk reads that might be going on */
+ if (serial->num_bulk_out)
+ usb_kill_urb(port->write_urb);
+ if (serial->num_bulk_in)
+ usb_kill_urb(port->read_urb);
+ }
+}
+
+void cp2101_close (struct usb_serial_port *port, struct file * filp)
+{
+ dbg("%s - port %d", __FUNCTION__, port->number);
+ cp2101_set_config(port, CP2101_UART, UART_DISABLE);
+
+ /* shutdown our urbs */
+ dbg("%s - shutting down urbs", __FUNCTION__);
+ usb_kill_urb(port->write_urb);
+ usb_kill_urb(port->read_urb);
+}
+
+void cp2101_get_termios (struct usb_serial_port *port)
+{
+ unsigned int cflag;
+ int baud;
+ int bits;
+
+ dbg("%s - port %d", __FUNCTION__, port->number);
+
+ if ((!port->tty) || (!port->tty->termios)) {
+ dbg("%s - no tty structures", __FUNCTION__);
+ return;
+ }
+
+ cflag = port->tty->termios->c_cflag;
+ cflag &= ~(CBAUD);
+
+ baud = cp2101_get_config(port, CP2101_BAUDRATE);
+ if (baud)
+ {
+ baud = BAUD_RATE_GEN_FREQ / baud;
+ dbg("%s - Device is configured with baud rate of %d baud", __FUNCTION__, baud);
+ }
+
+ switch (baud)
+ {
+ /* The baud rates which are commented out below appear to be supported by the device
+ * but are non-standard
+ */
+ case 600: cflag |= B600; break;
+ case 1200: cflag |= B1200; break;
+ case 1800: cflag |= B1800; break;
+ case 2400: cflag |= B2400; break;
+ case 4800: cflag |= B4800; break;
+ /*case 7200: cflag |= B7200; break;*/
+ case 9600: cflag |= B9600; break;
+ /*case 14400: cflag |= B14400; break;*/
+ case 19200: cflag |= B19200; break;
+ /*case 28800: cflag |= B28800; break;*/
+ case 38400: cflag |= B38400; break;
+ /*case 55854: cflag |= B55054; break;*/
+ case 57600: cflag |= B57600; break;
+ case 115200: cflag |= B115200; break;
+ /*case 127117: cflag |= B127117; break;*/
+ case 230400: cflag |= B230400; break;
+ case 460800: cflag |= B460800; break;
+ case 921600: cflag |= B921600; break;
+ /*case 3686400: cflag |= B3686400; break;*/
+ default:
+ dbg("%s - Baud rate is non-standard, using 9600 baud", __FUNCTION__);
+ cflag |= B9600;
+ baud = 9600;
+ break;
+ }
+
+
+ bits = cp2101_get_config(port, CP2101_BITS);
+
+ switch(bits & BITS_DATA_MASK)
+ {
+ case BITS_DATA_6: cflag |= CS6; break;
+ case BITS_DATA_7: cflag |= CS7; break;
+ case BITS_DATA_8: cflag |= CS8; break;
+ default:
+ dbg("%s - Non-standard number of data bits, using 8", __FUNCTION__);
+ cflag |= CS8;
+ bits &= ~BITS_DATA_MASK;
+ bits |= BITS_DATA_8;
+ break;
+ }
+
+ switch(bits & BITS_PARITY_MASK)
+ {
+ case BITS_PARITY_NONE: break;
+ case BITS_PARITY_ODD: cflag |= (PARENB|PARODD); break;
+ case BITS_PARITY_EVEN: cflag |= PARENB; break;
+ default:
+ dbg("%s - Non-standard parity mode, disabling parity", __FUNCTION__);
+ bits &= ~BITS_PARITY_MASK;
+ break;
+
+ }
+
+ switch(bits & BITS_STOP_MASK)
+ {
+ case BITS_STOP_1: break;
+ case BITS_STOP_2: cflag |= CSTOPB; break;
+ default:
+ dbg("%s - Non-standard number of stop bits, using 1 stop bit", __FUNCTION__);
+ bits &= ~BITS_STOP_MASK;
+ break;
+ }
+
+ cp2101_set_config(port, CP2101_BAUDRATE, (BAUD_RATE_GEN_FREQ / baud));
+ cp2101_set_config(port, CP2101_BITS, bits);
+
+ port->tty->termios->c_cflag = cflag;
+}
+
+static void cp2101_set_termios (struct usb_serial_port *port, struct termios *old_termios)
+{
+ unsigned int cflag, old_cflag=0;
+ int baud=0;
+ int bits=0;
+
+ dbg("%s - port %d", __FUNCTION__, port->number);
+
+ if ((!port->tty) || (!port->tty->termios))
+ {
+ dbg("%s - no tty structures", __FUNCTION__);
+ return;
+ }
+
+ cflag = port->tty->termios->c_cflag;
+
+ /* check that they really want us to change something */
+ if (old_termios)
+ {
+ if ((cflag == old_termios->c_cflag) &&
+ (RELEVANT_IFLAG(port->tty->termios->c_iflag) == RELEVANT_IFLAG(old_termios->c_iflag)))
+ {
+ dbg("%s - nothing to change...", __FUNCTION__);
+ return;
+ }
+
+ old_cflag = old_termios->c_cflag;
+ }
+
+ if ((cflag & CBAUD) != (old_cflag & CBAUD))
+ {
+ switch (cflag & CBAUD)
+ {
+ /* The baud rates which are commented out below appear to be supported by the device
+ * but are non-standard
+ */
+ case B0: baud = 0; break;
+ case B600: baud = 600; break;
+ case B1200: baud = 1200; break;
+ case B1800: baud = 1800; break;
+ case B2400: baud = 2400; break;
+ case B4800: baud = 4800; break;
+ /*case B7200: baud = 7200; break;*/
+ case B9600: baud = 9600; break;
+ /*ase B14400: baud = 14400; break;*/
+ case B19200: baud = 19200; break;
+ /*case B28800: baud = 28800; break;*/
+ case B38400: baud = 38400; break;
+ /*case B55854: baud = 55054; break;*/
+ case B57600: baud = 57600; break;
+ case B115200: baud = 115200; break;
+ /*case B127117: baud = 127117; break;*/
+ case B230400: baud = 230400; break;
+ case B460800: baud = 460800; break;
+ case B921600: baud = 921600; break;
+ /*case B3686400: baud = 3686400; break;*/
+ default:
+ dev_err(&port->dev, "cp2101 driver does not support the baudrate requested\n");
+ break;
+ }
+
+ if (baud)
+ cp2101_set_config(port, CP2101_BAUDRATE, (BAUD_RATE_GEN_FREQ / baud));
+
+
+ }
+
+ if ((cflag & (CSIZE|PARENB|PARODD)) != (old_cflag & (CSIZE|PARENB|PARODD)))
+ {
+ switch (cflag & CSIZE)
+ {
+ case CS6: bits |= BITS_DATA_6; break;
+ case CS7: bits |= BITS_DATA_7; break;
+ case CS8: bits |= BITS_DATA_8; break;
+ /*case CS9: bits |= BITS_DATA_9; break;*/
+ default:
+ dev_err(&port->dev, "cp2101 driver does not support the number of bits required, using 8 bit mode\n");
+ bits |= BITS_DATA_8;
+ break;
+
+ }
+ dbg("%s - data bits = %d", __FUNCTION__, bits);
+
+ if (cflag & PARENB)
+ {
+ if (cflag & PARODD)
+ {
+ bits |= BITS_PARITY_ODD;
+ dbg("%s - parity = ODD", __FUNCTION__);
+ }
+ else
+ {
+ bits |= BITS_PARITY_EVEN;
+ dbg("%s - parity = EVEN", __FUNCTION__);
+ }
+
+ }
+
+ if (cflag & CSTOPB)
+ {
+ bits |= BITS_STOP_2;
+ dbg("%s - stop bits = 2", __FUNCTION__);
+ } else {
+ bits |= BITS_STOP_1;
+ dbg("%s - stop bits = 1", __FUNCTION__);
+ }
+
+ cp2101_set_config(port, CP2101_BITS, bits);
+ }
+}
+
+static void cp2101_break_ctl (struct usb_serial_port *port, int break_state)
+{
+ u16 state;
+
+ dbg("%s - port %d", __FUNCTION__, port->number);
+
+ if (break_state == 0)
+ state = BREAK_OFF;
+ else
+ state = BREAK_ON;
+ dbg("%s - turning break %s", __FUNCTION__, state==BREAK_OFF ? "off" : "on");
+ cp2101_set_config(port, CP2101_BREAK, state);
+
+}
+
+
+
+void cp2101_shutdown (struct usb_serial *serial)
+{
+ int i;
+
+ dbg("%s", __FUNCTION__);
+
+ /* stop reads and writes on all ports */
+ for (i=0; i < serial->num_ports; ++i) {
+ cp2101_cleanup(serial->port[i]);
+ }
+}
+
+
+static int __init cp2101_init (void)
+{
+ int retval;
+
+ retval = usb_serial_register(&cp2101_device);
+ if (retval)
+ return retval; /*Failed to register*/
+
+ retval = usb_register(&cp2101_driver);
+ if (retval)
+ {
+ /*Failed to register*/
+ usb_serial_deregister(&cp2101_device);
+ return retval;
+ }
+
+ /*Success*/
+ info(DRIVER_DESC " " DRIVER_VERSION);
+ return 0;
+}
+
+
+static void __exit cp2101_exit (void)
+{
+ usb_deregister (&cp2101_driver);
+ usb_serial_deregister (&cp2101_device);
+}
+
+
+module_init(cp2101_init);
+module_exit(cp2101_exit);
+
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_VERSION(DRIVER_VERSION);
+MODULE_LICENSE("GPL");
+
+module_param(debug, bool, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(debug, "Enable verbose debugging messages");
+
diff -Nru a/drivers/usb/serial/Kconfig b/drivers/usb/serial/Kconfig
--- a/drivers/usb/serial/Kconfig 2005-03-18 00:39:25.905779352 +0000
+++ b/drivers/usb/serial/Kconfig 2005-03-18 00:40:08.939237272 +0000
@@ -413,6 +413,15 @@
To compile this driver as a module, choose M here: the
module will be called omninet.
+config USB_SERIAL_CP2101
+ tristate "USB CP2101 UART Bridge Controller (EXPERIMENTAL)"
+ depends on USB_SERIAL && EXPERIMENTAL
+ help
+ Say Y here if you want to use a CP2101 based USB to RS232 converter.
+
+ To compile this driver as a module, choose M here: the
+ module will be called cp2101.
+
config USB_EZUSB
bool
depends on USB_SERIAL_KEYSPAN_PDA || USB_SERIAL_XIRCOM || USB_SERIAL_KEYSPAN || USB_SERIAL_WHITEHEAT
diff -Nru a/drivers/usb/serial/Makefile b/drivers/usb/serial/Makefile
--- a/drivers/usb/serial/Makefile 2005-03-18 00:37:33.292899112 +0000
+++ b/drivers/usb/serial/Makefile 2005-01-22 09:47:40.997971000 +0000
@@ -33,4 +33,5 @@
obj-$(CONFIG_USB_SERIAL_VISOR) += visor.o
obj-$(CONFIG_USB_SERIAL_WHITEHEAT) += whiteheat.o
obj-$(CONFIG_USB_SERIAL_XIRCOM) += keyspan_pda.o
+obj-$(CONFIG_USB_SERIAL_CP2101) += cp2101.o
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