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 *pstatus;
  58         struct i2c_msg *pmsg;
  59         int i, ret;
  60
  61         dev_dbg(&adapter->dev, "master xfer %d messages:\n", num);
  62
  63         pstatus = kmalloc(sizeof(*pstatus), GFP_KERNEL);
  64         if (!pstatus)
  65                 return -ENOMEM;
  66
  67         for (i = 0 ; i < num ; i++) {
  68                 int cmd = CMD_I2C_IO;
  69
  70                 if (i == 0)
  71                         cmd |= CMD_I2C_IO_BEGIN;
  72
  73                 if (i == num-1)
  74                         cmd |= CMD_I2C_IO_END;
  75
  76                 pmsg = &msgs[i];
  77
  78                 dev_dbg(&adapter->dev,
  79                         "  %d: %s (flags %d) %d bytes to 0x%02x\n",
  80                         i, pmsg->flags & I2C_M_RD ? "read" : "write",
  81                         pmsg->flags, pmsg->len, pmsg->addr);
  82
  83                 /* and directly send the message */
  84                 if (pmsg->flags & I2C_M_RD) {
  85                         /* read data */
  86                         if (usb_read(adapter, cmd,
  87                                      pmsg->flags, pmsg->addr,
  88                                      pmsg->buf, pmsg->len) != pmsg->len) {
  89                                 dev_err(&adapter->dev,
  90                                         "failure reading data\n");
  91                                 ret = -EREMOTEIO;
  92                                 goto out;
  93                         }
  94                 } else {
  95                         /* write data */
  96                         if (usb_write(adapter, cmd,
  97                                       pmsg->flags, pmsg->addr,
  98                                       pmsg->buf, pmsg->len) != pmsg->len) {
  99                                 dev_err(&adapter->dev,
 100                                         "failure writing data\n");
 101                                 ret = -EREMOTEIO;
 102                                 goto out;
 103                         }
 104                 }
 105
 106                 /* read status */
 107                 if (usb_read(adapter, CMD_GET_STATUS, 0, 0, pstatus, 1) != 1) {
 108                         dev_err(&adapter->dev, "failure reading status\n");
 109                         ret = -EREMOTEIO;
 110                         goto out;
 111                 }
 112
 113                 dev_dbg(&adapter->dev, "  status = %d\n", *pstatus);
 114                 if (*pstatus == STATUS_ADDRESS_NAK) {
 115                         ret = -EREMOTEIO;
 116                         goto out;
 117                 }
 118         }
 119
 120         ret = i;
 121 out:
 122         kfree(pstatus);
 123         return ret;
 124 }
 125
 126 static u32 usb_func(struct i2c_adapter *adapter)
 127 {
 128         __le32 *pfunc;
 129         u32 ret;
 130
 131         pfunc = kmalloc(sizeof(*pfunc), GFP_KERNEL);
 132
 133         /* get functionality from adapter */
 134         if (!pfunc || usb_read(adapter, CMD_GET_FUNC, 0, 0, pfunc,
 135                                sizeof(*pfunc)) != sizeof(*pfunc)) {
 136                 dev_err(&adapter->dev, "failure reading functionality\n");
 137                 ret = 0;
 138                 goto out;
 139         }
 140
 141         ret = le32_to_cpup(pfunc);
 142 out:
 143         kfree(pfunc);
 144         return ret;
 145 }
 146
 147 /* This is the actual algorithm we define */
 148 static const struct i2c_algorithm usb_algorithm = {
 149         .master_xfer    = usb_xfer,
 150         .functionality  = usb_func,
 151 };
 152
 153 /* ----- end of i2c layer ------------------------------------------------ */
 154
 155 /* ----- begin of usb layer ---------------------------------------------- */
 156
 157 /*
 158  * Initially the usb i2c interface uses a vid/pid pair donated by
 159  * Future Technology Devices International Ltd., later a pair was
 160  * bought from EZPrototypes
 161  */
 162 static const struct usb_device_id i2c_tiny_usb_table[] = {
 163         { USB_DEVICE(0x0403, 0xc631) },   /* FTDI */
 164         { USB_DEVICE(0x1c40, 0x0534) },   /* EZPrototypes */
 165         { }                               /* Terminating entry */
 166 };
 167
 168 MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);
 169
 170 /* Structure to hold all of our device specific stuff */
 171 struct i2c_tiny_usb {
 172         struct usb_device *usb_dev; /* the usb device for this device */
 173         struct usb_interface *interface; /* the interface for this device */
 174         struct i2c_adapter adapter; /* i2c related things */
 175 };
 176
 177 static int usb_read(struct i2c_adapter *adapter, int cmd,
 178                     int value, int index, void *data, int len)
 179 {
 180         struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
 181
 182         /* do control transfer */
 183         return usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
 184                                cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
 185                                USB_DIR_IN, value, index, data, len, 2000);
 186 }
 187
 188 static int usb_write(struct i2c_adapter *adapter, int cmd,
 189                      int value, int index, void *data, int len)
 190 {
 191         struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
 192
 193         /* do control transfer */
 194         return usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
 195                                cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
 196                                value, index, data, len, 2000);
 197 }
 198
 199 static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
 200 {
 201         usb_put_dev(dev->usb_dev);
 202         kfree(dev);
 203 }
 204
 205 static int i2c_tiny_usb_probe(struct usb_interface *interface,
 206                               const struct usb_device_id *id)
 207 {
 208         struct i2c_tiny_usb *dev;
 209         int retval = -ENOMEM;
 210         u16 version;
 211
 212         dev_dbg(&interface->dev, "probing usb device\n");
 213
 214         /* allocate memory for our device state and initialize it */
 215         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 216         if (dev == NULL) {
 217                 dev_err(&interface->dev, "Out of memory\n");
 218                 goto error;
 219         }
 220
 221         dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
 222         dev->interface = interface;
 223
 224         /* save our data pointer in this interface device */
 225         usb_set_intfdata(interface, dev);
 226
 227         version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice);
 228         dev_info(&interface->dev,
 229                  "version %x.%02x found at bus %03d address %03d\n",
 230                  version >> 8, version & 0xff,
 231                  dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
 232
 233         /* setup i2c adapter description */
 234         dev->adapter.owner = THIS_MODULE;
 235         dev->adapter.class = I2C_CLASS_HWMON;
 236         dev->adapter.algo = &usb_algorithm;
 237         dev->adapter.algo_data = dev;
 238         snprintf(dev->adapter.name, sizeof(dev->adapter.name),
 239                  "i2c-tiny-usb at bus %03d device %03d",
 240                  dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
 241
 242         if (usb_write(&dev->adapter, CMD_SET_DELAY, delay, 0, NULL, 0) != 0) {
 243                 dev_err(&dev->adapter.dev,
 244                         "failure setting delay to %dus\n", delay);
 245                 retval = -EIO;
 246                 goto error;
 247         }
 248
 249         dev->adapter.dev.parent = &dev->interface->dev;
 250
 251         /* and finally attach to i2c layer */
 252         i2c_add_adapter(&dev->adapter);
 253
 254         /* inform user about successful attachment to i2c layer */
 255         dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n");
 256
 257         return 0;
 258
 259  error:
 260         if (dev)
 261                 i2c_tiny_usb_free(dev);
 262
 263         return retval;
 264 }
 265
 266 static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
 267 {
 268         struct i2c_tiny_usb *dev = usb_get_intfdata(interface);
 269
 270         i2c_del_adapter(&dev->adapter);
 271         usb_set_intfdata(interface, NULL);
 272         i2c_tiny_usb_free(dev);
 273
 274         dev_dbg(&interface->dev, "disconnected\n");
 275 }
 276
 277 static struct usb_driver i2c_tiny_usb_driver = {
 278         .name           = "i2c-tiny-usb",
 279         .probe          = i2c_tiny_usb_probe,
 280         .disconnect     = i2c_tiny_usb_disconnect,
 281         .id_table       = i2c_tiny_usb_table,
 282 };
 283
 284 module_usb_driver(i2c_tiny_usb_driver);
 285
 286 /* ----- end of usb layer ------------------------------------------------ */
 287
 288 MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
 289 MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
 290 MODULE_LICENSE("GPL");