initial commit

obj-m = cp210x.o

KVERSION = $(shell uname -r)

all:

	make -C /lib/modules/$(KVERSION)/build M=$(PWD) modules

clean:

	make -C /lib/modules/$(KVERSION)/build M=$(PWD) clean

# CP210x GPIO control

A patch to the CP210x USB to UART Bridges driver that adds GPIO pins control by implementing ioctl function and a python script to program devices.

## Supported OS

* Kubuntu Linux 13.04 (kernel 3.8.0-32)

## Tested devices

* CP2103

* CP2104

## Install

1. Build:

        ./build_driver

2. Reload driver (from the built directory):

        sudo rmmod 210x

        sudo insmod 210x.ko

## Program GPIO_MAS

1. Examples:

    * Set all 1's:

            ./cp210x_gpio.py -d /dev/ttyUSB0 -m 0xff 0xff

    * Set GPIO[3]=1, others - 0:

            ./cp210x_gpio.py -d /dev/ttyUSB1 -m 0xff 0x08

## Changes in the driver

* Changes in the driver cp210x.c are based on the patch found [here](https://lkml.org/lkml/2012/5/1/2)

* GPIO_VALUE=arg[23:16], GPIO_MASK=arg[7:0]

## Unresolved questions

* Silabs drivers in 2.6.x and 3.x.x for GPIOs differ: 

    * 2.6.x: GPIO_VALUE=arg[23:16], GPIO_MASK=arg[7:0] - this matches the patch

    * 3.x.x: GPIO_VALUE=arg[15: 8], GPIO_MASK=arg[7:0]

## Links

* [Silabs CP210x USB to UART Bridge VCP Drivers](http://www.silabs.com/products/mcu/pages/usbtouartbridgevcpdrivers.aspx) - supported kernels 2.6.x, 3.x.x (but 3.x.x are not up-to-date - cannot be built in 3.8.0)

* [cp210x: Add ioctl for GPIO support](https://lkml.org/lkml/2012/5/1/2) - patch

 No newline at end of file

#!/bin/bash

CP210X_NAME="cp210x.c"

CP210X_ADDRESS="https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/plain/drivers/usb/serial/cp210x.c?id=refs/tags/v"

PATCH_NAME="cp210x.patch"

LINUX_KERNEL_VERSION=$(uname -r | cut -f1 -d"-")

LKV_P1=$(echo $LINUX_KERNEL_VERSION | cut -f1 -d".")

LKV_P2=$(echo $LINUX_KERNEL_VERSION | cut -f2 -d".")

LKV_P3=$(echo $LINUX_KERNEL_VERSION | cut -f3 -d".")

if [ $LKV_P3 = 0 ]; then

  CP210X_VERSION=$(echo "$LKV_P1.$LKV_P2")

else

  CP210X_VERSION=$(echo "$LKV_P1.$LKV_P2.$LKV_P3")

fi

#uncomment if patch doesn't work 

#CP210X_VERSION="3.8.0"

#get the file to patch

if [ ! -f $CP210X_NAME ]; then

  wget -O $CP210X_NAME "${CP210X_ADDRESS}${CP210X_VERSION}"

fi

#patch

patch -r - -Np1 < $PATCH_NAME

#run make

make clean

make

--- a/cp210x.c	2013-10-30 18:43:43.000000000 -0600

+++ b/cp210x.c	2013-10-30 19:23:02.410147064 -0600

@@ -31,6 +31,8 @@

  */

 static int cp210x_open(struct tty_struct *tty, struct usb_serial_port *);

 static void cp210x_close(struct usb_serial_port *);

+static int cp210x_ioctl(struct tty_struct *tty,

+	unsigned int cmd, unsigned long arg);

 static void cp210x_get_termios(struct tty_struct *, struct usb_serial_port *);

 static void cp210x_get_termios_port(struct usb_serial_port *port,

 	unsigned int *cflagp, unsigned int *baudp);

@@ -174,6 +176,7 @@

 	.bulk_out_size		= 256,

 	.open			= cp210x_open,

 	.close			= cp210x_close,

+	.ioctl			= cp210x_ioctl,

 	.break_ctl		= cp210x_break_ctl,

 	.set_termios		= cp210x_set_termios,

 	.tiocmget		= cp210x_tiocmget,

@@ -187,6 +190,10 @@

 	&cp210x_device, NULL

 };

+/* IOCTLs */

+#define IOCTL_GPIOGET	 0x8000

+#define IOCTL_GPIOSET	 0x8001

+

 /* Config request types */

 #define REQTYPE_HOST_TO_INTERFACE	0x41

 #define REQTYPE_INTERFACE_TO_HOST	0xc1

@@ -220,11 +227,16 @@

 #define CP210X_SET_CHARS	0x19

 #define CP210X_GET_BAUDRATE	0x1D

 #define CP210X_SET_BAUDRATE	0x1E

+#define CP210X_VENDOR_SPECIFIC	0xFF

 /* CP210X_IFC_ENABLE */

 #define UART_ENABLE		0x0001

 #define UART_DISABLE		0x0000

+/* CP210X_VENDOR_SPECIFIC */

+#define CP210X_WRITE_LATCH	0x37E1

+#define CP210X_READ_LATCH	0x00C2

+

 /* CP210X_(SET|GET)_BAUDDIV */

 #define BAUD_RATE_GEN_FREQ	0x384000

@@ -449,6 +461,54 @@

 	mutex_unlock(&port->serial->disc_mutex);

 }

+static int cp210x_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)

+{

+	struct usb_serial_port *port = tty->driver_data;

+	struct usb_serial *serial = port->serial;

+	int result = 0;

+	struct cp210x_serial_private *spriv = usb_get_serial_data(serial);

+	unsigned int latch_setting = 0;

+

+	switch (cmd) {

+	    case IOCTL_GPIOGET:

+		result = usb_control_msg(

+			      serial->dev,

+			      usb_rcvctrlpipe(serial->dev, 0),

+			      CP210X_VENDOR_SPECIFIC,

+			      REQTYPE_DEVICE_TO_HOST,

+			      CP210X_READ_LATCH,

+			      spriv->bInterfaceNumber,

+			      &latch_setting, 1,

+			      USB_CTRL_GET_TIMEOUT);

+		if (result != 1)

+		    return -EPROTO;

+		*(unsigned long *)arg = (unsigned long)latch_setting;

+		return 0;

+	    break;

+	    case IOCTL_GPIOSET:

+		latch_setting = *(unsigned int *)arg & 0x000000FF;

+		//why [23:16] bits are taken for value is unknown

+		latch_setting |= (*(unsigned int *)arg & 0x00FF0000) >> 8;

+		

+		result = usb_control_msg(

+			      serial->dev,

+			      usb_sndctrlpipe(serial->dev, 0),

+			      CP210X_VENDOR_SPECIFIC,

+			      REQTYPE_HOST_TO_DEVICE,

+			      CP210X_WRITE_LATCH,

+			      latch_setting,

+			      NULL, 0,

+			      USB_CTRL_SET_TIMEOUT);

+		if (result != 0)

+		    return -EPROTO;

+		return 0;

+	    break;

+	    default:

+	    break;

+	}

+	return -ENOIOCTLCMD;

+}

+

 /*

  * cp210x_get_termios

  * Reads the baud rate, data bits, parity, stop bits and flow control mode