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/types.h>
  17
  18 /* include interfaces to usb layer */
  19 #include <linux/usb.h>
  20
  21 /* include interface to i2c layer */
  22 #include <linux/i2c.h>
  23
  24 /* commands via USB, must match command ids in the firmware */
  25 #define CMD_ECHO                0
  26 #define CMD_GET_FUNC            1
  27 #define CMD_SET_DELAY           2
  28 #define CMD_GET_STATUS          3
  29
  30 #define CMD_I2C_IO              4
  31 #define CMD_I2C_IO_BEGIN        (1<<0)
  32 #define CMD_I2C_IO_END          (1<<1)
  33
  34 /* i2c bit delay, default is 10us -> 100kHz max
  35    (in practice, due to additional delays in the i2c bitbanging
  36    code this results in a i2c clock of about 50kHz) */
  37 static unsigned short delay = 10;
  38 module_param(delay, ushort, 0);
  39 MODULE_PARM_DESC(delay, "bit delay in microseconds "
  40                  "(default is 10us for 100kHz max)");
  41
  42 static int usb_read(struct i2c_adapter *adapter, int cmd,
  43                     int value, int index, void *data, int len);
  44
  45 static int usb_write(struct i2c_adapter *adapter, int cmd,
  46                      int value, int index, void *data, int len);
  47
  48 /* ----- begin of i2c layer ---------------------------------------------- */
  49
  50 #define STATUS_IDLE             0
  51 #define STATUS_ADDRESS_ACK      1
  52 #define STATUS_ADDRESS_NAK      2
  53
  54 static int usb_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
  55 {
  56         unsigned char status;
  57         struct i2c_msg *pmsg;
  58         int i;
  59
  60         dev_dbg(&adapter->dev, "master xfer %d messages:\n", num);
  61
  62         for (i = 0 ; i < num ; i++) {
  63                 int cmd = CMD_I2C_IO;
  64
  65                 if (i == 0)
  66                         cmd |= CMD_I2C_IO_BEGIN;
  67
  68                 if (i == num-1)
  69                         cmd |= CMD_I2C_IO_END;
  70
  71                 pmsg = &msgs[i];
  72
  73                 dev_dbg(&adapter->dev,
  74                         "  %d: %s (flags %d) %d bytes to 0x%02x\n",
  75                         i, pmsg->flags & I2C_M_RD ? "read" : "write",
  76                         pmsg->flags, pmsg->len, pmsg->addr);
  77
  78                 /* and directly send the message */
  79                 if (pmsg->flags & I2C_M_RD) {
  80                         /* read data */
  81                         if (usb_read(adapter, cmd,
  82                                      pmsg->flags, pmsg->addr,
  83                                      pmsg->buf, pmsg->len) != pmsg->len) {
  84                                 dev_err(&adapter->dev,
  85                                         "failure reading data\n");
  86                                 return -EREMOTEIO;
  87                         }
  88                 } else {
  89                         /* write data */
  90                         if (usb_write(adapter, cmd,
  91                                       pmsg->flags, pmsg->addr,
  92                                       pmsg->buf, pmsg->len) != pmsg->len) {
  93                                 dev_err(&adapter->dev,
  94                                         "failure writing data\n");
  95                                 return -EREMOTEIO;
  96                         }
  97                 }
  98
  99                 /* read status */
 100                 if (usb_read(adapter, CMD_GET_STATUS, 0, 0, &status, 1) != 1) {
 101                         dev_err(&adapter->dev, "failure reading status\n");
 102                         return -EREMOTEIO;
 103                 }
 104
 105                 dev_dbg(&adapter->dev, "  status = %d\n", status);
 106                 if (status == STATUS_ADDRESS_NAK)
 107                         return -EREMOTEIO;
 108         }
 109
 110         return i;
 111 }
 112
 113 static u32 usb_func(struct i2c_adapter *adapter)
 114 {
 115         __le32 func;
 116
 117         /* get functionality from adapter */
 118         if (usb_read(adapter, CMD_GET_FUNC, 0, 0, &func, sizeof(func)) !=
 119             sizeof(func)) {
 120                 dev_err(&adapter->dev, "failure reading functionality\n");
 121                 return 0;
 122         }
 123
 124         return le32_to_cpu(func);
 125 }
 126
 127 /* This is the actual algorithm we define */
 128 static const struct i2c_algorithm usb_algorithm = {
 129         .master_xfer    = usb_xfer,
 130         .functionality  = usb_func,
 131 };
 132
 133 /* ----- end of i2c layer ------------------------------------------------ */
 134
 135 /* ----- begin of usb layer ---------------------------------------------- */
 136
 137 /*
 138  * Initially the usb i2c interface uses a vid/pid pair donated by
 139  * Future Technology Devices International Ltd., later a pair was
 140  * bought from EZPrototypes
 141  */
 142 static const struct usb_device_id i2c_tiny_usb_table[] = {
 143         { USB_DEVICE(0x0403, 0xc631) },   /* FTDI */
 144         { USB_DEVICE(0x1c40, 0x0534) },   /* EZPrototypes */
 145         { }                               /* Terminating entry */
 146 };
 147
 148 MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);
 149
 150 /* Structure to hold all of our device specific stuff */
 151 struct i2c_tiny_usb {
 152         struct usb_device *usb_dev; /* the usb device for this device */
 153         struct usb_interface *interface; /* the interface for this device */
 154         struct i2c_adapter adapter; /* i2c related things */
 155 };
 156
 157 static int usb_read(struct i2c_adapter *adapter, int cmd,
 158                     int value, int index, void *data, int len)
 159 {
 160         struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
 161
 162         /* do control transfer */
 163         return usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
 164                                cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
 165                                USB_DIR_IN, value, index, data, len, 2000);
 166 }
 167
 168 static int usb_write(struct i2c_adapter *adapter, int cmd,
 169                      int value, int index, void *data, int len)
 170 {
 171         struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
 172
 173         /* do control transfer */
 174         return usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
 175                                cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
 176                                value, index, data, len, 2000);
 177 }
 178
 179 static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
 180 {
 181         usb_put_dev(dev->usb_dev);
 182         kfree(dev);
 183 }
 184
 185 static int i2c_tiny_usb_probe(struct usb_interface *interface,
 186                               const struct usb_device_id *id)
 187 {
 188         struct i2c_tiny_usb *dev;
 189         int retval = -ENOMEM;
 190         u16 version;
 191
 192         dev_dbg(&interface->dev, "probing usb device\n");
 193
 194         /* allocate memory for our device state and initialize it */
 195         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 196         if (dev == NULL) {
 197                 dev_err(&interface->dev, "Out of memory\n");
 198                 goto error;
 199         }
 200
 201         dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
 202         dev->interface = interface;
 203
 204         /* save our data pointer in this interface device */
 205         usb_set_intfdata(interface, dev);
 206
 207         version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice);
 208         dev_info(&interface->dev,
 209                  "version %x.%02x found at bus %03d address %03d\n",
 210                  version >> 8, version & 0xff,
 211                  dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
 212
 213         /* setup i2c adapter description */
 214         dev->adapter.owner = THIS_MODULE;
 215         dev->adapter.class = I2C_CLASS_HWMON;
 216         dev->adapter.algo = &usb_algorithm;
 217         dev->adapter.algo_data = dev;
 218         snprintf(dev->adapter.name, sizeof(dev->adapter.name),
 219                  "i2c-tiny-usb at bus %03d device %03d",
 220                  dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
 221
 222         if (usb_write(&dev->adapter, CMD_SET_DELAY, delay, 0, NULL, 0) != 0) {
 223                 dev_err(&dev->adapter.dev,
 224                         "failure setting delay to %dus\n", delay);
 225                 retval = -EIO;
 226                 goto error;
 227         }
 228
 229         dev->adapter.dev.parent = &dev->interface->dev;
 230
 231         /* and finally attach to i2c layer */
 232         i2c_add_adapter(&dev->adapter);
 233
 234         /* inform user about successful attachment to i2c layer */
 235         dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n");
 236
 237         return 0;
 238
 239  error:
 240         if (dev)
 241                 i2c_tiny_usb_free(dev);
 242
 243         return retval;
 244 }
 245
 246 static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
 247 {
 248         struct i2c_tiny_usb *dev = usb_get_intfdata(interface);
 249
 250         i2c_del_adapter(&dev->adapter);
 251         usb_set_intfdata(interface, NULL);
 252         i2c_tiny_usb_free(dev);
 253
 254         dev_dbg(&interface->dev, "disconnected\n");
 255 }
 256
 257 static struct usb_driver i2c_tiny_usb_driver = {
 258         .name           = "i2c-tiny-usb",
 259         .probe          = i2c_tiny_usb_probe,
 260         .disconnect     = i2c_tiny_usb_disconnect,
 261         .id_table       = i2c_tiny_usb_table,
 262 };
 263
 264 static int __init usb_i2c_tiny_usb_init(void)
 265 {
 266         /* register this driver with the USB subsystem */
 267         return usb_register(&i2c_tiny_usb_driver);
 268 }
 269
 270 static void __exit usb_i2c_tiny_usb_exit(void)
 271 {
 272         /* deregister this driver with the USB subsystem */
 273         usb_deregister(&i2c_tiny_usb_driver);
 274 }
 275
 276 module_init(usb_i2c_tiny_usb_init);
 277 module_exit(usb_i2c_tiny_usb_exit);
 278
 279 /* ----- end of usb layer ------------------------------------------------ */
 280
 281 MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
 282 MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
 283 MODULE_LICENSE("GPL");