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

   1/*
   2 * driver for the i2c-tiny-usb adapter - 1.0
   3 * http://www.harbaum.org/till/i2c_tiny_usb
   4 *
   5 * Copyright (C) 2006-2007 Till Harbaum (Till@Harbaum.org)
   6 *
   7 * This program is free software; you can redistribute it and/or
   8 * modify it under the terms of the GNU General Public License as
   9 * published by the Free Software Foundation, version 2.
  10 *
  11 */
  12
  13#include <linux/kernel.h>
  14#include <linux/errno.h>
  15#include <linux/module.h>
  16#include <linux/slab.h>
  17#include <linux/types.h>
  18
  19/* include interfaces to usb layer */
  20#include <linux/usb.h>
  21
  22/* include interface to i2c layer */
  23#include <linux/i2c.h>
  24
  25/* commands via USB, must match command ids in the firmware */
  26#define CMD_ECHO                0
  27#define CMD_GET_FUNC            1
  28#define CMD_SET_DELAY           2
  29#define CMD_GET_STATUS          3
  30
  31#define CMD_I2C_IO              4
  32#define CMD_I2C_IO_BEGIN        (1<<0)
  33#define CMD_I2C_IO_END          (1<<1)
  34
  35/* i2c bit delay, default is 10us -> 100kHz max
  36   (in practice, due to additional delays in the i2c bitbanging
  37   code this results in a i2c clock of about 50kHz) */
  38static unsigned short delay = 10;
  39module_param(delay, ushort, 0);
  40MODULE_PARM_DESC(delay, "bit delay in microseconds "
  41                 "(default is 10us for 100kHz max)");
  42
  43static int usb_read(struct i2c_adapter *adapter, int cmd,
  44                    int value, int index, void *data, int len);
  45
  46static int usb_write(struct i2c_adapter *adapter, int cmd,
  47                     int value, int index, void *data, int len);
  48
  49/* ----- begin of i2c layer ---------------------------------------------- */
  50
  51#define STATUS_IDLE             0
  52#define STATUS_ADDRESS_ACK      1
  53#define STATUS_ADDRESS_NAK      2
  54
  55static int usb_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
  56{
  57        unsigned char status;
  58        struct i2c_msg *pmsg;
  59        int i;
  60
  61        dev_dbg(&adapter->dev, "master xfer %d messages:\n", num);
  62
  63        for (i = 0 ; i < num ; i++) {
  64                int cmd = CMD_I2C_IO;
  65
  66                if (i == 0)
  67                        cmd |= CMD_I2C_IO_BEGIN;
  68
  69                if (i == num-1)
  70                        cmd |= CMD_I2C_IO_END;
  71
  72                pmsg = &msgs[i];
  73
  74                dev_dbg(&adapter->dev,
  75                        "  %d: %s (flags %d) %d bytes to 0x%02x\n",
  76                        i, pmsg->flags & I2C_M_RD ? "read" : "write",
  77                        pmsg->flags, pmsg->len, pmsg->addr);
  78
  79                /* and directly send the message */
  80                if (pmsg->flags & I2C_M_RD) {
  81                        /* read data */
  82                        if (usb_read(adapter, cmd,
  83                                     pmsg->flags, pmsg->addr,
  84                                     pmsg->buf, pmsg->len) != pmsg->len) {
  85                                dev_err(&adapter->dev,
  86                                        "failure reading data\n");
  87                                return -EREMOTEIO;
  88                        }
  89                } else {
  90                        /* write data */
  91                        if (usb_write(adapter, cmd,
  92                                      pmsg->flags, pmsg->addr,
  93                                      pmsg->buf, pmsg->len) != pmsg->len) {
  94                                dev_err(&adapter->dev,
  95                                        "failure writing data\n");
  96                                return -EREMOTEIO;
  97                        }
  98                }
  99
 100                /* read status */
 101                if (usb_read(adapter, CMD_GET_STATUS, 0, 0, &status, 1) != 1) {
 102                        dev_err(&adapter->dev, "failure reading status\n");
 103                        return -EREMOTEIO;
 104                }
 105
 106                dev_dbg(&adapter->dev, "  status = %d\n", status);
 107                if (status == STATUS_ADDRESS_NAK)
 108                        return -EREMOTEIO;
 109        }
 110
 111        return i;
 112}
 113
 114static u32 usb_func(struct i2c_adapter *adapter)
 115{
 116        __le32 func;
 117
 118        /* get functionality from adapter */
 119        if (usb_read(adapter, CMD_GET_FUNC, 0, 0, &func, sizeof(func)) !=
 120            sizeof(func)) {
 121                dev_err(&adapter->dev, "failure reading functionality\n");
 122                return 0;
 123        }
 124
 125        return le32_to_cpu(func);
 126}
 127
 128/* This is the actual algorithm we define */
 129static const struct i2c_algorithm usb_algorithm = {
 130        .master_xfer    = usb_xfer,
 131        .functionality  = usb_func,
 132};
 133
 134/* ----- end of i2c layer ------------------------------------------------ */
 135
 136/* ----- begin of usb layer ---------------------------------------------- */
 137
 138/*
 139 * Initially the usb i2c interface uses a vid/pid pair donated by
 140 * Future Technology Devices International Ltd., later a pair was
 141 * bought from EZPrototypes
 142 */
 143static const struct usb_device_id i2c_tiny_usb_table[] = {
 144        { USB_DEVICE(0x0403, 0xc631) },   /* FTDI */
 145        { USB_DEVICE(0x1c40, 0x0534) },   /* EZPrototypes */
 146        { USB_DEVICE(0x1964, 0x0001) },   /* Robofuzz OSIF */
 147        { }                               /* Terminating entry */
 148};
 149
 150MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);
 151
 152/* Structure to hold all of our device specific stuff */
 153struct i2c_tiny_usb {
 154        struct usb_device *usb_dev; /* the usb device for this device */
 155        struct usb_interface *interface; /* the interface for this device */
 156        struct i2c_adapter adapter; /* i2c related things */
 157};
 158
 159static int usb_read(struct i2c_adapter *adapter, int cmd,
 160                    int value, int index, void *data, int len)
 161{
 162        struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
 163
 164        /* do control transfer */
 165        return usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
 166                               cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
 167                               USB_DIR_IN, value, index, data, len, 2000);
 168}
 169
 170static int usb_write(struct i2c_adapter *adapter, int cmd,
 171                     int value, int index, void *data, int len)
 172{
 173        struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
 174
 175        /* do control transfer */
 176        return usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
 177                               cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
 178                               value, index, data, len, 2000);
 179}
 180
 181static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
 182{
 183        usb_put_dev(dev->usb_dev);
 184        kfree(dev);
 185}
 186
 187static int i2c_tiny_usb_probe(struct usb_interface *interface,
 188                              const struct usb_device_id *id)
 189{
 190        struct i2c_tiny_usb *dev;
 191        int retval = -ENOMEM;
 192        u16 version;
 193
 194        dev_dbg(&interface->dev, "probing usb device\n");
 195
 196        /* allocate memory for our device state and initialize it */
 197        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 198        if (dev == NULL) {
 199                dev_err(&interface->dev, "Out of memory\n");
 200                goto error;
 201        }
 202
 203        dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
 204        dev->interface = interface;
 205
 206        /* save our data pointer in this interface device */
 207        usb_set_intfdata(interface, dev);
 208
 209        version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice);
 210        dev_info(&interface->dev,
 211                 "version %x.%02x found at bus %03d address %03d\n",
 212                 version >> 8, version & 0xff,
 213                 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
 214
 215        /* setup i2c adapter description */
 216        dev->adapter.owner = THIS_MODULE;
 217        dev->adapter.class = I2C_CLASS_HWMON;
 218        dev->adapter.algo = &usb_algorithm;
 219        dev->adapter.algo_data = dev;
 220        snprintf(dev->adapter.name, sizeof(dev->adapter.name),
 221                 "i2c-tiny-usb at bus %03d device %03d",
 222                 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
 223
 224        if (usb_write(&dev->adapter, CMD_SET_DELAY, delay, 0, NULL, 0) != 0) {
 225                dev_err(&dev->adapter.dev,
 226                        "failure setting delay to %dus\n", delay);
 227                retval = -EIO;
 228                goto error;
 229        }
 230
 231        dev->adapter.dev.parent = &dev->interface->dev;
 232
 233        /* and finally attach to i2c layer */
 234        i2c_add_adapter(&dev->adapter);
 235
 236        /* inform user about successful attachment to i2c layer */
 237        dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n");
 238
 239        return 0;
 240
 241 error:
 242        if (dev)
 243                i2c_tiny_usb_free(dev);
 244
 245        return retval;
 246}
 247
 248static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
 249{
 250        struct i2c_tiny_usb *dev = usb_get_intfdata(interface);
 251
 252        i2c_del_adapter(&dev->adapter);
 253        usb_set_intfdata(interface, NULL);
 254        i2c_tiny_usb_free(dev);
 255
 256        dev_dbg(&interface->dev, "disconnected\n");
 257}
 258
 259static struct usb_driver i2c_tiny_usb_driver = {
 260        .name           = "i2c-tiny-usb",
 261        .probe          = i2c_tiny_usb_probe,
 262        .disconnect     = i2c_tiny_usb_disconnect,
 263        .id_table       = i2c_tiny_usb_table,
 264};
 265
 266module_usb_driver(i2c_tiny_usb_driver);
 267
 268/* ----- end of usb layer ------------------------------------------------ */
 269
 270MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
 271MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
 272MODULE_LICENSE("GPL");
 273