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
  17/* include interfaces to usb layer */
  18#include <linux/usb.h>
  19
  20/* include interface to i2c layer */
  21#include <linux/i2c.h>
  22
  23/* commands via USB, must match command ids in the firmware */
  24#define CMD_ECHO                0
  25#define CMD_GET_FUNC            1
  26#define CMD_SET_DELAY           2
  27#define CMD_GET_STATUS          3
  28
  29#define CMD_I2C_IO              4
  30#define CMD_I2C_IO_BEGIN        (1<<0)
  31#define CMD_I2C_IO_END          (1<<1)
  32
  33/* i2c bit delay, default is 10us -> 100kHz */
  34static int delay = 10;
  35module_param(delay, int, 0);
  36MODULE_PARM_DESC(delay, "bit delay in microseconds, "
  37                 "e.g. 10 for 100kHz (default is 100kHz)");
  38
  39static int usb_read(struct i2c_adapter *adapter, int cmd,
  40                    int value, int index, void *data, int len);
  41
  42static int usb_write(struct i2c_adapter *adapter, int cmd,
  43                     int value, int index, void *data, int len);
  44
  45/* ----- begin of i2c layer ---------------------------------------------- */
  46
  47#define STATUS_IDLE             0
  48#define STATUS_ADDRESS_ACK      1
  49#define STATUS_ADDRESS_NAK      2
  50
  51static int usb_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
  52{
  53        unsigned char status;
  54        struct i2c_msg *pmsg;
  55        int i;
  56
  57        dev_dbg(&adapter->dev, "master xfer %d messages:\n", num);
  58
  59        for (i = 0 ; i < num ; i++) {
  60                int cmd = CMD_I2C_IO;
  61
  62                if (i == 0)
  63                        cmd |= CMD_I2C_IO_BEGIN;
  64
  65                if (i == num-1)
  66                        cmd |= CMD_I2C_IO_END;
  67
  68                pmsg = &msgs[i];
  69
  70                dev_dbg(&adapter->dev,
  71                        "  %d: %s (flags %d) %d bytes to 0x%02x\n",
  72                        i, pmsg->flags & I2C_M_RD ? "read" : "write",
  73                        pmsg->flags, pmsg->len, pmsg->addr);
  74
  75                /* and directly send the message */
  76                if (pmsg->flags & I2C_M_RD) {
  77                        /* read data */
  78                        if (usb_read(adapter, cmd,
  79                                     pmsg->flags, pmsg->addr,
  80                                     pmsg->buf, pmsg->len) != pmsg->len) {
  81                                dev_err(&adapter->dev,
  82                                        "failure reading data\n");
  83                                return -EREMOTEIO;
  84                        }
  85                } else {
  86                        /* write data */
  87                        if (usb_write(adapter, cmd,
  88                                      pmsg->flags, pmsg->addr,
  89                                      pmsg->buf, pmsg->len) != pmsg->len) {
  90                                dev_err(&adapter->dev,
  91                                        "failure writing data\n");
  92                                return -EREMOTEIO;
  93                        }
  94                }
  95
  96                /* read status */
  97                if (usb_read(adapter, CMD_GET_STATUS, 0, 0, &status, 1) != 1) {
  98                        dev_err(&adapter->dev, "failure reading status\n");
  99                        return -EREMOTEIO;
 100                }
 101
 102                dev_dbg(&adapter->dev, "  status = %d\n", status);
 103                if (status == STATUS_ADDRESS_NAK)
 104                        return -EREMOTEIO;
 105        }
 106
 107        return i;
 108}
 109
 110static u32 usb_func(struct i2c_adapter *adapter)
 111{
 112        u32 func;
 113
 114        /* get functionality from adapter */
 115        if (usb_read(adapter, CMD_GET_FUNC, 0, 0, &func, sizeof(func)) !=
 116            sizeof(func)) {
 117                dev_err(&adapter->dev, "failure reading functionality\n");
 118                return 0;
 119        }
 120
 121        return func;
 122}
 123
 124/* This is the actual algorithm we define */
 125static const struct i2c_algorithm usb_algorithm = {
 126        .master_xfer    = usb_xfer,
 127        .functionality  = usb_func,
 128};
 129
 130/* ----- end of i2c layer ------------------------------------------------ */
 131
 132/* ----- begin of usb layer ---------------------------------------------- */
 133
 134/*
 135 * Initially the usb i2c interface uses a vid/pid pair donated by
 136 * Future Technology Devices International Ltd., later a pair was
 137 * bought from EZPrototypes
 138 */
 139static struct usb_device_id i2c_tiny_usb_table [] = {
 140        { USB_DEVICE(0x0403, 0xc631) },   /* FTDI */
 141        { USB_DEVICE(0x1c40, 0x0534) },   /* EZPrototypes */
 142        { }                               /* Terminating entry */
 143};
 144
 145MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);
 146
 147/* Structure to hold all of our device specific stuff */
 148struct i2c_tiny_usb {
 149        struct usb_device *usb_dev; /* the usb device for this device */
 150        struct usb_interface *interface; /* the interface for this device */
 151        struct i2c_adapter adapter; /* i2c related things */
 152};
 153
 154static int usb_read(struct i2c_adapter *adapter, int cmd,
 155                    int value, int index, void *data, int len)
 156{
 157        struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
 158
 159        /* do control transfer */
 160        return usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
 161                               cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
 162                               USB_DIR_IN, value, index, data, len, 2000);
 163}
 164
 165static int usb_write(struct i2c_adapter *adapter, int cmd,
 166                     int value, int index, void *data, int len)
 167{
 168        struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
 169
 170        /* do control transfer */
 171        return usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
 172                               cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
 173                               value, index, data, len, 2000);
 174}
 175
 176static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
 177{
 178        usb_put_dev(dev->usb_dev);
 179        kfree(dev);
 180}
 181
 182static int i2c_tiny_usb_probe(struct usb_interface *interface,
 183                              const struct usb_device_id *id)
 184{
 185        struct i2c_tiny_usb *dev;
 186        int retval = -ENOMEM;
 187        u16 version;
 188
 189        dev_dbg(&interface->dev, "probing usb device\n");
 190
 191        /* allocate memory for our device state and initialize it */
 192        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 193        if (dev == NULL) {
 194                dev_err(&interface->dev, "Out of memory\n");
 195                goto error;
 196        }
 197
 198        dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
 199        dev->interface = interface;
 200
 201        /* save our data pointer in this interface device */
 202        usb_set_intfdata(interface, dev);
 203
 204        version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice);
 205        dev_info(&interface->dev,
 206                 "version %x.%02x found at bus %03d address %03d\n",
 207                 version >> 8, version & 0xff,
 208                 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
 209
 210        /* setup i2c adapter description */
 211        dev->adapter.owner = THIS_MODULE;
 212        dev->adapter.class = I2C_CLASS_HWMON;
 213        dev->adapter.algo = &usb_algorithm;
 214        dev->adapter.algo_data = dev;
 215        snprintf(dev->adapter.name, sizeof(dev->adapter.name),
 216                 "i2c-tiny-usb at bus %03d device %03d",
 217                 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
 218
 219        if (usb_write(&dev->adapter, CMD_SET_DELAY,
 220                      cpu_to_le16(delay), 0, NULL, 0) != 0) {
 221                dev_err(&dev->adapter.dev,
 222                        "failure setting delay to %dus\n", delay);
 223                retval = -EIO;
 224                goto error;
 225        }
 226
 227        dev->adapter.dev.parent = &dev->interface->dev;
 228
 229        /* and finally attach to i2c layer */
 230        i2c_add_adapter(&dev->adapter);
 231
 232        /* inform user about successful attachment to i2c layer */
 233        dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n");
 234
 235        return 0;
 236
 237 error:
 238        if (dev)
 239                i2c_tiny_usb_free(dev);
 240
 241        return retval;
 242}
 243
 244static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
 245{
 246        struct i2c_tiny_usb *dev = usb_get_intfdata(interface);
 247
 248        i2c_del_adapter(&dev->adapter);
 249        usb_set_intfdata(interface, NULL);
 250        i2c_tiny_usb_free(dev);
 251
 252        dev_dbg(&interface->dev, "disconnected\n");
 253}
 254
 255static struct usb_driver i2c_tiny_usb_driver = {
 256        .name           = "i2c-tiny-usb",
 257        .probe          = i2c_tiny_usb_probe,
 258        .disconnect     = i2c_tiny_usb_disconnect,
 259        .id_table       = i2c_tiny_usb_table,
 260};
 261
 262static int __init usb_i2c_tiny_usb_init(void)
 263{
 264        /* register this driver with the USB subsystem */
 265        return usb_register(&i2c_tiny_usb_driver);
 266}
 267
 268static void __exit usb_i2c_tiny_usb_exit(void)
 269{
 270        /* deregister this driver with the USB subsystem */
 271        usb_deregister(&i2c_tiny_usb_driver);
 272}
 273
 274module_init(usb_i2c_tiny_usb_init);
 275module_exit(usb_i2c_tiny_usb_exit);
 276
 277/* ----- end of usb layer ------------------------------------------------ */
 278
 279MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
 280MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
 281MODULE_LICENSE("GPL");
 282