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 */
  34 static int delay = 10;
  35 module_param(delay, int, 0);
  36 MODULE_PARM_DESC(delay, "bit delay in microseconds, "
  37                  "e.g. 10 for 100kHz (default is 100kHz)");
  38
  39 static int usb_read(struct i2c_adapter *adapter, int cmd,
  40                     int value, int index, void *data, int len);
  41
  42 static 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
  51 static 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
 110 static 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 */
 125 static 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  */
 139 static 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
 145 MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);
 146
 147 /* Structure to hold all of our device specific stuff */
 148 struct 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
 154 static 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
 165 static 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
 176 static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
 177 {
 178         usb_put_dev(dev->usb_dev);
 179         kfree(dev);
 180 }
 181
 182 static 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
 244 static 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
 255 static 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
 262 static 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
 268 static 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
 274 module_init(usb_i2c_tiny_usb_init);
 275 module_exit(usb_i2c_tiny_usb_exit);
 276
 277 /* ----- end of usb layer ------------------------------------------------ */
 278
 279 MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
 280 MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
 281 MODULE_LICENSE("GPL");