Logo Search packages:      
Sourcecode: linux version File versions  Download package

i2c-tiny-usb.c

/*
 * 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, sizeof(dev->adapter.name),
             "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");

Generated by  Doxygen 1.6.0   Back to index