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Commit e8c76eed authored by Till Harbaum's avatar Till Harbaum Committed by Jean Delvare
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i2c: New i2c-tiny-usb bus driver 

Add a driver for the i2c-tiny-usb interface. This is a simple
do-it-yourself USB to I2C interface targeted at experimental and
home use. See the i2c-tiny-usb homepage for hardware details:
http://www.harbaum.org/till/i2c_tiny_usb



Signed-off-by: default avatarTill Harbaum <till@harbaum.org>
Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
parent eefcd75e

MAINTAINERS

+7 −0
Original line number Diff line number Diff line
@@ -1643,6 +1643,13 @@ L: i2c@lm-sensors.org 
T:	quilt http://khali.linux-fr.org/devel/linux-2.6/jdelvare-i2c/

S:	Maintained



I2C-TINY-USB DRIVER

P:	Till Harbaum

M:	till@harbaum.org

L:	i2c@lm-sensors.org

T:	http://www.harbaum.org/till/i2c_tiny_usb

S:	Maintained



i386 BOOT CODE

P:	Riley H. Williams

M:	Riley@Williams.Name

drivers/i2c/busses/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -525,6 +525,17 @@ config I2C_STUB 


	  If you don't know what to do here, definitely say N.



config I2C_TINY_USB

	tristate "I2C-Tiny-USB"

	depends on USB

	help

	  If you say yes to this option, support will be included for the

	  i2c-tiny-usb, a simple do-it-yourself USB to I2C interface. See

	  http://www.harbaum.org/till/i2c_tiny_usb for hardware details.



	  This driver can also be built as a module.  If so, the module

	  will be called i2c-tiny-usb.



config I2C_VERSATILE

	tristate "ARM Versatile/Realview I2C bus support"

	depends on ARCH_VERSATILE || ARCH_REALVIEW

drivers/i2c/busses/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -44,6 +44,7 @@ obj-$(CONFIG_I2C_SIS5595) += i2c-sis5595.o 
obj-$(CONFIG_I2C_SIS630)	+= i2c-sis630.o

obj-$(CONFIG_I2C_SIS96X)	+= i2c-sis96x.o

obj-$(CONFIG_I2C_STUB)		+= i2c-stub.o

obj-$(CONFIG_I2C_TINY_USB)	+= i2c-tiny-usb.o

obj-$(CONFIG_I2C_VERSATILE)	+= i2c-versatile.o

obj-$(CONFIG_I2C_ACORN)		+= i2c-acorn.o

obj-$(CONFIG_I2C_VIA)		+= i2c-via.o

drivers/i2c/busses/i2c-tiny-usb.c

0 → 100644
+277 −0
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/*

 * driver for the i2c-tiny-usb adapter - 1.0

 * http://www.harbaum.org/till/i2c_tiny_usb

 *

 * Copyright (C) 2006-2007 Till Harbaum (Till@Harbaum.org)

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License as

 * published by the Free Software Foundation, version 2.

 *

 */



#include <linux/kernel.h>

#include <linux/errno.h>

#include <linux/module.h>



/* include interfaces to usb layer */

#include <linux/usb.h>



/* include interface to i2c layer */

#include <linux/i2c.h>



/* commands via USB, must match command ids in the firmware */

#define CMD_ECHO		0

#define CMD_GET_FUNC		1

#define CMD_SET_DELAY		2

#define CMD_GET_STATUS		3



#define CMD_I2C_IO		4

#define CMD_I2C_IO_BEGIN	(1<<0)

#define CMD_I2C_IO_END		(1<<1)



/* i2c bit delay, default is 10us -> 100kHz */

static int delay = 10;

module_param(delay, int, 0);

MODULE_PARM_DESC(delay, "bit delay in microseconds, "

		 "e.g. 10 for 100kHz (default is 100kHz)");



static int usb_read(struct i2c_adapter *adapter, int cmd,

		    int value, int index, void *data, int len);



static int usb_write(struct i2c_adapter *adapter, int cmd,

		     int value, int index, void *data, int len);



/* ----- begin of i2c layer ---------------------------------------------- */



#define STATUS_IDLE		0

#define STATUS_ADDRESS_ACK	1

#define STATUS_ADDRESS_NAK	2



static int usb_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)

{

	unsigned char status;

	struct i2c_msg *pmsg;

	int i;



	dev_dbg(&adapter->dev, "master xfer %d messages:\n", num);



	for (i = 0 ; i < num ; i++) {

		int cmd = CMD_I2C_IO;



		if (i == 0)

			cmd |= CMD_I2C_IO_BEGIN;



		if (i == num-1)

			cmd |= CMD_I2C_IO_END;



		pmsg = &msgs[i];



		dev_dbg(&adapter->dev,

			"  %d: %s (flags %d) %d bytes to 0x%02x\n",

			i, pmsg->flags & I2C_M_RD ? "read" : "write",

			pmsg->flags, pmsg->len, pmsg->addr);



		/* and directly send the message */

		if (pmsg->flags & I2C_M_RD) {

			/* read data */

			if (usb_read(adapter, cmd,

				     pmsg->flags, pmsg->addr,

				     pmsg->buf, pmsg->len) != pmsg->len) {

				dev_err(&adapter->dev,

					"failure reading data\n");

				return -EREMOTEIO;

			}

		} else {

			/* write data */

			if (usb_write(adapter, cmd,

				      pmsg->flags, pmsg->addr,

				      pmsg->buf, pmsg->len) != pmsg->len) {

				dev_err(&adapter->dev,

					"failure writing data\n");

				return -EREMOTEIO;

			}

		}



		/* read status */

		if (usb_read(adapter, CMD_GET_STATUS, 0, 0, &status, 1) != 1) {

			dev_err(&adapter->dev, "failure reading status\n");

			return -EREMOTEIO;

		}



		dev_dbg(&adapter->dev, "  status = %d\n", status);

		if (status == STATUS_ADDRESS_NAK)

			return -EREMOTEIO;

	}



	return i;

}



static u32 usb_func(struct i2c_adapter *adapter)

{

	u32 func;



	/* get functionality from adapter */

	if (usb_read(adapter, CMD_GET_FUNC, 0, 0, &func, sizeof(func)) !=

	    sizeof(func)) {

		dev_err(&adapter->dev, "failure reading functionality\n");

		return 0;

	}



	return func;

}



/* This is the actual algorithm we define */

static const struct i2c_algorithm usb_algorithm = {

	.master_xfer	= usb_xfer,

	.functionality	= usb_func,

};



/* ----- end of i2c layer ------------------------------------------------ */



/* ----- begin of usb layer ---------------------------------------------- */



/* The usb i2c interface uses a vid/pid pair donated by */

/* Future Technology Devices International Ltd. */

static struct usb_device_id i2c_tiny_usb_table [] = {

	{ USB_DEVICE(0x0403, 0xc631) },

	{ }			/* Terminating entry */

};



MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);



/* Structure to hold all of our device specific stuff */

struct i2c_tiny_usb {

	struct usb_device *usb_dev; /* the usb device for this device */

	struct usb_interface *interface; /* the interface for this device */

	struct i2c_adapter adapter; /* i2c related things */

};



static int usb_read(struct i2c_adapter *adapter, int cmd,

		    int value, int index, void *data, int len)

{

	struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;



	/* do control transfer */

	return usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),

			       cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |

			       USB_DIR_IN, value, index, data, len, 2000);

}



static int usb_write(struct i2c_adapter *adapter, int cmd,

		     int value, int index, void *data, int len)

{

	struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;



	/* do control transfer */

	return usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),

			       cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,

			       value, index, data, len, 2000);

}



static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)

{

	usb_put_dev(dev->usb_dev);

	kfree(dev);

}



static int i2c_tiny_usb_probe(struct usb_interface *interface,

			      const struct usb_device_id *id)

{

	struct i2c_tiny_usb *dev;

	int retval = -ENOMEM;

	u16 version;



	dev_dbg(&interface->dev, "probing usb device\n");



	/* allocate memory for our device state and initialize it */

	dev = kzalloc(sizeof(*dev), GFP_KERNEL);

	if (dev == NULL) {

		dev_err(&interface->dev, "Out of memory\n");

		goto error;

	}



	dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));

	dev->interface = interface;



	/* save our data pointer in this interface device */

	usb_set_intfdata(interface, dev);



	version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice);

	dev_info(&interface->dev,

		 "version %x.%02x found at bus %03d address %03d\n",

		 version >> 8, version & 0xff,

		 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);



	/* setup i2c adapter description */

	dev->adapter.owner = THIS_MODULE;

	dev->adapter.class = I2C_CLASS_HWMON;

	dev->adapter.algo = &usb_algorithm;

	dev->adapter.algo_data = dev;

	snprintf(dev->adapter.name, I2C_NAME_SIZE,

		 "i2c-tiny-usb at bus %03d device %03d",

		 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);



	if (usb_write(&dev->adapter, CMD_SET_DELAY,

		      cpu_to_le16(delay), 0, NULL, 0) != 0) {

		dev_err(&dev->adapter.dev,

			"failure setting delay to %dus\n", delay);

		retval = -EIO;

		goto error;

	}



	dev->adapter.dev.parent = &dev->interface->dev;



	/* and finally attach to i2c layer */

	i2c_add_adapter(&dev->adapter);



	/* inform user about successful attachment to i2c layer */

	dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n");



	return 0;



 error:

	if (dev)

		i2c_tiny_usb_free(dev);



	return retval;

}



static void i2c_tiny_usb_disconnect(struct usb_interface *interface)

{

	struct i2c_tiny_usb *dev = usb_get_intfdata(interface);



	i2c_del_adapter(&dev->adapter);

	usb_set_intfdata(interface, NULL);

	i2c_tiny_usb_free(dev);



	dev_dbg(&interface->dev, "disconnected\n");

}



static struct usb_driver i2c_tiny_usb_driver = {

	.name		= "i2c-tiny-usb",

	.probe		= i2c_tiny_usb_probe,

	.disconnect	= i2c_tiny_usb_disconnect,

	.id_table	= i2c_tiny_usb_table,

};



static int __init usb_i2c_tiny_usb_init(void)

{

	/* register this driver with the USB subsystem */

	return usb_register(&i2c_tiny_usb_driver);

}



static void __exit usb_i2c_tiny_usb_exit(void)

{

	/* deregister this driver with the USB subsystem */

	usb_deregister(&i2c_tiny_usb_driver);

}



module_init(usb_i2c_tiny_usb_init);

module_exit(usb_i2c_tiny_usb_exit);



/* ----- end of usb layer ------------------------------------------------ */



MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");

MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");

MODULE_LICENSE("GPL");