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) */
  38 static unsigned short delay = 10;
  39 module_param(delay, ushort, 0);
  40 MODULE_PARM_DESC(delay, "bit delay in microseconds "
  41                  "(default is 10us for 100kHz max)");
  42
  43 static int usb_read(struct i2c_adapter *adapter, int cmd,
  44                     int value, int index, void *data, int len);
  45
  46 static 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
  55 static 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
 114 static 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 */
 129 static 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  */
 143 static const struct usb_device_id i2c_tiny_usb_table[] = {
 144         { USB_DEVICE(0x0403, 0xc631) },   /* FTDI */
 145         { USB_DEVICE(0x1c40, 0x0534) },   /* EZPrototypes */
 146         { }                               /* Terminating entry */
 147 };
 148
 149 MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);
 150
 151 /* Structure to hold all of our device specific stuff */
 152 struct i2c_tiny_usb {
 153         struct usb_device *usb_dev; /* the usb device for this device */
 154         struct usb_interface *interface; /* the interface for this device */
 155         struct i2c_adapter adapter; /* i2c related things */
 156 };
 157
 158 static int usb_read(struct i2c_adapter *adapter, int cmd,
 159                     int value, int index, void *data, int len)
 160 {
 161         struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
 162
 163         /* do control transfer */
 164         return usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
 165                                cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
 166                                USB_DIR_IN, value, index, data, len, 2000);
 167 }
 168
 169 static int usb_write(struct i2c_adapter *adapter, int cmd,
 170                      int value, int index, void *data, int len)
 171 {
 172         struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
 173
 174         /* do control transfer */
 175         return usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
 176                                cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
 177                                value, index, data, len, 2000);
 178 }
 179
 180 static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
 181 {
 182         usb_put_dev(dev->usb_dev);
 183         kfree(dev);
 184 }
 185
 186 static int i2c_tiny_usb_probe(struct usb_interface *interface,
 187                               const struct usb_device_id *id)
 188 {
 189         struct i2c_tiny_usb *dev;
 190         int retval = -ENOMEM;
 191         u16 version;
 192
 193         dev_dbg(&interface->dev, "probing usb device\n");
 194
 195         /* allocate memory for our device state and initialize it */
 196         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 197         if (dev == NULL) {
 198                 dev_err(&interface->dev, "Out of memory\n");
 199                 goto error;
 200         }
 201
 202         dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
 203         dev->interface = interface;
 204
 205         /* save our data pointer in this interface device */
 206         usb_set_intfdata(interface, dev);
 207
 208         version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice);
 209         dev_info(&interface->dev,
 210                  "version %x.%02x found at bus %03d address %03d\n",
 211                  version >> 8, version & 0xff,
 212                  dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
 213
 214         /* setup i2c adapter description */
 215         dev->adapter.owner = THIS_MODULE;
 216         dev->adapter.class = I2C_CLASS_HWMON;
 217         dev->adapter.algo = &usb_algorithm;
 218         dev->adapter.algo_data = dev;
 219         snprintf(dev->adapter.name, sizeof(dev->adapter.name),
 220                  "i2c-tiny-usb at bus %03d device %03d",
 221                  dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
 222
 223         if (usb_write(&dev->adapter, CMD_SET_DELAY, delay, 0, NULL, 0) != 0) {
 224                 dev_err(&dev->adapter.dev,
 225                         "failure setting delay to %dus\n", delay);
 226                 retval = -EIO;
 227                 goto error;
 228         }
 229
 230         dev->adapter.dev.parent = &dev->interface->dev;
 231
 232         /* and finally attach to i2c layer */
 233         i2c_add_adapter(&dev->adapter);
 234
 235         /* inform user about successful attachment to i2c layer */
 236         dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n");
 237
 238         return 0;
 239
 240  error:
 241         if (dev)
 242                 i2c_tiny_usb_free(dev);
 243
 244         return retval;
 245 }
 246
 247 static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
 248 {
 249         struct i2c_tiny_usb *dev = usb_get_intfdata(interface);
 250
 251         i2c_del_adapter(&dev->adapter);
 252         usb_set_intfdata(interface, NULL);
 253         i2c_tiny_usb_free(dev);
 254
 255         dev_dbg(&interface->dev, "disconnected\n");
 256 }
 257
 258 static struct usb_driver i2c_tiny_usb_driver = {
 259         .name           = "i2c-tiny-usb",
 260         .probe          = i2c_tiny_usb_probe,
 261         .disconnect     = i2c_tiny_usb_disconnect,
 262         .id_table       = i2c_tiny_usb_table,
 263 };
 264
 265 static int __init usb_i2c_tiny_usb_init(void)
 266 {
 267         /* register this driver with the USB subsystem */
 268         return usb_register(&i2c_tiny_usb_driver);
 269 }
 270
 271 static void __exit usb_i2c_tiny_usb_exit(void)
 272 {
 273         /* deregister this driver with the USB subsystem */
 274         usb_deregister(&i2c_tiny_usb_driver);
 275 }
 276
 277 module_init(usb_i2c_tiny_usb_init);
 278 module_exit(usb_i2c_tiny_usb_exit);
 279
 280 /* ----- end of usb layer ------------------------------------------------ */
 281
 282 MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
 283 MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
 284 MODULE_LICENSE("GPL");