drivers/i2c/busses/i2c-tiny-usb.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * driver for the i2c-tiny-usb adapter - 1.0
   4  * http://www.harbaum.org/till/i2c_tiny_usb
   5  *
   6  * Copyright (C) 2006-2007 Till Harbaum (Till@Harbaum.org)
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/errno.h>
  11 #include <linux/module.h>
  12 #include <linux/slab.h>
  13 #include <linux/types.h>
  14
  15 /* include interfaces to usb layer */
  16 #include <linux/usb.h>
  17
  18 /* include interface to i2c layer */
  19 #include <linux/i2c.h>
  20
  21 /* commands via USB, must match command ids in the firmware */
  22 #define CMD_ECHO                0
  23 #define CMD_GET_FUNC            1
  24 #define CMD_SET_DELAY           2
  25 #define CMD_GET_STATUS          3
  26
  27 #define CMD_I2C_IO              4
  28 #define CMD_I2C_IO_BEGIN        (1<<0)
  29 #define CMD_I2C_IO_END          (1<<1)
  30
  31 /* i2c bit delay, default is 10us -> 100kHz max
  32    (in practice, due to additional delays in the i2c bitbanging
  33    code this results in a i2c clock of about 50kHz) */
  34 static unsigned short delay = 10;
  35 module_param(delay, ushort, 0);
  36 MODULE_PARM_DESC(delay, "bit delay in microseconds "
  37                  "(default is 10us for 100kHz max)");
  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 *pstatus;
  54         struct i2c_msg *pmsg;
  55         int i, ret;
  56
  57         dev_dbg(&adapter->dev, "master xfer %d messages:\n", num);
  58
  59         pstatus = kmalloc(sizeof(*pstatus), GFP_KERNEL);
  60         if (!pstatus)
  61                 return -ENOMEM;
  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                                 ret = -EIO;
  88                                 goto out;
  89                         }
  90                 } else {
  91                         /* write data */
  92                         if (usb_write(adapter, cmd,
  93                                       pmsg->flags, pmsg->addr,
  94                                       pmsg->buf, pmsg->len) != pmsg->len) {
  95                                 dev_err(&adapter->dev,
  96                                         "failure writing data\n");
  97                                 ret = -EIO;
  98                                 goto out;
  99                         }
 100                 }
 101
 102                 /* read status */
 103                 if (usb_read(adapter, CMD_GET_STATUS, 0, 0, pstatus, 1) != 1) {
 104                         dev_err(&adapter->dev, "failure reading status\n");
 105                         ret = -EIO;
 106                         goto out;
 107                 }
 108
 109                 dev_dbg(&adapter->dev, "  status = %d\n", *pstatus);
 110                 if (*pstatus == STATUS_ADDRESS_NAK) {
 111                         ret = -ENXIO;
 112                         goto out;
 113                 }
 114         }
 115
 116         ret = i;
 117 out:
 118         kfree(pstatus);
 119         return ret;
 120 }
 121
 122 static u32 usb_func(struct i2c_adapter *adapter)
 123 {
 124         __le32 *pfunc;
 125         u32 ret;
 126
 127         pfunc = kmalloc(sizeof(*pfunc), GFP_KERNEL);
 128
 129         /* get functionality from adapter */
 130         if (!pfunc || usb_read(adapter, CMD_GET_FUNC, 0, 0, pfunc,
 131                                sizeof(*pfunc)) != sizeof(*pfunc)) {
 132                 dev_err(&adapter->dev, "failure reading functionality\n");
 133                 ret = 0;
 134                 goto out;
 135         }
 136
 137         ret = le32_to_cpup(pfunc);
 138 out:
 139         kfree(pfunc);
 140         return ret;
 141 }
 142
 143 /* This is the actual algorithm we define */
 144 static const struct i2c_algorithm usb_algorithm = {
 145         .master_xfer    = usb_xfer,
 146         .functionality  = usb_func,
 147 };
 148
 149 /* ----- end of i2c layer ------------------------------------------------ */
 150
 151 /* ----- begin of usb layer ---------------------------------------------- */
 152
 153 /*
 154  * Initially the usb i2c interface uses a vid/pid pair donated by
 155  * Future Technology Devices International Ltd., later a pair was
 156  * bought from EZPrototypes
 157  */
 158 static const struct usb_device_id i2c_tiny_usb_table[] = {
 159         { USB_DEVICE(0x0403, 0xc631) },   /* FTDI */
 160         { USB_DEVICE(0x1c40, 0x0534) },   /* EZPrototypes */
 161         { }                               /* Terminating entry */
 162 };
 163
 164 MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);
 165
 166 /* Structure to hold all of our device specific stuff */
 167 struct i2c_tiny_usb {
 168         struct usb_device *usb_dev; /* the usb device for this device */
 169         struct usb_interface *interface; /* the interface for this device */
 170         struct i2c_adapter adapter; /* i2c related things */
 171 };
 172
 173 static int usb_read(struct i2c_adapter *adapter, int cmd,
 174                     int value, int index, void *data, int len)
 175 {
 176         struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
 177         void *dmadata = kmalloc(len, GFP_KERNEL);
 178         int ret;
 179
 180         if (!dmadata)
 181                 return -ENOMEM;
 182
 183         /* do control transfer */
 184         ret = usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
 185                                cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
 186                                USB_DIR_IN, value, index, dmadata, len, 2000);
 187
 188         memcpy(data, dmadata, len);
 189         kfree(dmadata);
 190         return ret;
 191 }
 192
 193 static int usb_write(struct i2c_adapter *adapter, int cmd,
 194                      int value, int index, void *data, int len)
 195 {
 196         struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
 197         void *dmadata = kmemdup(data, len, GFP_KERNEL);
 198         int ret;
 199
 200         if (!dmadata)
 201                 return -ENOMEM;
 202
 203         /* do control transfer */
 204         ret = usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
 205                                cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
 206                                value, index, dmadata, len, 2000);
 207
 208         kfree(dmadata);
 209         return ret;
 210 }
 211
 212 static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
 213 {
 214         usb_put_dev(dev->usb_dev);
 215         kfree(dev);
 216 }
 217
 218 static int i2c_tiny_usb_probe(struct usb_interface *interface,
 219                               const struct usb_device_id *id)
 220 {
 221         struct i2c_tiny_usb *dev;
 222         int retval = -ENOMEM;
 223         u16 version;
 224
 225         if (interface->intf_assoc &&
 226             interface->intf_assoc->bFunctionClass != USB_CLASS_VENDOR_SPEC)
 227                 return -ENODEV;
 228
 229         dev_dbg(&interface->dev, "probing usb device\n");
 230
 231         /* allocate memory for our device state and initialize it */
 232         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 233         if (!dev)
 234                 goto error;
 235
 236         dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
 237         dev->interface = interface;
 238
 239         /* save our data pointer in this interface device */
 240         usb_set_intfdata(interface, dev);
 241
 242         version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice);
 243         dev_info(&interface->dev,
 244                  "version %x.%02x found at bus %03d address %03d\n",
 245                  version >> 8, version & 0xff,
 246                  dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
 247
 248         /* setup i2c adapter description */
 249         dev->adapter.owner = THIS_MODULE;
 250         dev->adapter.class = I2C_CLASS_HWMON;
 251         dev->adapter.algo = &usb_algorithm;
 252         dev->adapter.algo_data = dev;
 253         snprintf(dev->adapter.name, sizeof(dev->adapter.name),
 254                  "i2c-tiny-usb at bus %03d device %03d",
 255                  dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
 256
 257         if (usb_write(&dev->adapter, CMD_SET_DELAY, delay, 0, NULL, 0) != 0) {
 258                 dev_err(&dev->adapter.dev,
 259                         "failure setting delay to %dus\n", delay);
 260                 retval = -EIO;
 261                 goto error;
 262         }
 263
 264         dev->adapter.dev.parent = &dev->interface->dev;
 265
 266         /* and finally attach to i2c layer */
 267         i2c_add_adapter(&dev->adapter);
 268
 269         /* inform user about successful attachment to i2c layer */
 270         dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n");
 271
 272         return 0;
 273
 274  error:
 275         if (dev)
 276                 i2c_tiny_usb_free(dev);
 277
 278         return retval;
 279 }
 280
 281 static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
 282 {
 283         struct i2c_tiny_usb *dev = usb_get_intfdata(interface);
 284
 285         i2c_del_adapter(&dev->adapter);
 286         usb_set_intfdata(interface, NULL);
 287         i2c_tiny_usb_free(dev);
 288
 289         dev_dbg(&interface->dev, "disconnected\n");
 290 }
 291
 292 static struct usb_driver i2c_tiny_usb_driver = {
 293         .name           = "i2c-tiny-usb",
 294         .probe          = i2c_tiny_usb_probe,
 295         .disconnect     = i2c_tiny_usb_disconnect,
 296         .id_table       = i2c_tiny_usb_table,
 297 };
 298
 299 module_usb_driver(i2c_tiny_usb_driver);
 300
 301 /* ----- end of usb layer ------------------------------------------------ */
 302
 303 MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
 304 MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
 305 MODULE_LICENSE("GPL");