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         pstatus = kmalloc(sizeof(*pstatus), GFP_KERNEL);
  58         if (!pstatus)
  59                 return -ENOMEM;
  60
  61         for (i = 0 ; i < num ; i++) {
  62                 int cmd = CMD_I2C_IO;
  63
  64                 if (i == 0)
  65                         cmd |= CMD_I2C_IO_BEGIN;
  66
  67                 if (i == num-1)
  68                         cmd |= CMD_I2C_IO_END;
  69
  70                 pmsg = &msgs[i];
  71
  72                 dev_dbg(&adapter->dev,
  73                         "  %d: %s (flags %d) %d bytes to 0x%02x\n",
  74                         i, pmsg->flags & I2C_M_RD ? "read" : "write",
  75                         pmsg->flags, pmsg->len, pmsg->addr);
  76
  77                 /* and directly send the message */
  78                 if (pmsg->flags & I2C_M_RD) {
  79                         /* read data */
  80                         if (usb_read(adapter, cmd,
  81                                      pmsg->flags, pmsg->addr,
  82                                      pmsg->buf, pmsg->len) != pmsg->len) {
  83                                 dev_err(&adapter->dev,
  84                                         "failure reading data\n");
  85                                 ret = -EIO;
  86                                 goto out;
  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                                 ret = -EIO;
  96                                 goto out;
  97                         }
  98                 }
  99
 100                 /* read status */
 101                 if (usb_read(adapter, CMD_GET_STATUS, 0, 0, pstatus, 1) != 1) {
 102                         dev_err(&adapter->dev, "failure reading status\n");
 103                         ret = -EIO;
 104                         goto out;
 105                 }
 106
 107                 dev_dbg(&adapter->dev, "  status = %d\n", *pstatus);
 108                 if (*pstatus == STATUS_ADDRESS_NAK) {
 109                         ret = -ENXIO;
 110                         goto out;
 111                 }
 112         }
 113
 114         ret = i;
 115 out:
 116         kfree(pstatus);
 117         return ret;
 118 }
 119
 120 static u32 usb_func(struct i2c_adapter *adapter)
 121 {
 122         __le32 *pfunc;
 123         u32 ret;
 124
 125         pfunc = kmalloc(sizeof(*pfunc), GFP_KERNEL);
 126
 127         /* get functionality from adapter */
 128         if (!pfunc || usb_read(adapter, CMD_GET_FUNC, 0, 0, pfunc,
 129                                sizeof(*pfunc)) != sizeof(*pfunc)) {
 130                 dev_err(&adapter->dev, "failure reading functionality\n");
 131                 ret = 0;
 132                 goto out;
 133         }
 134
 135         ret = le32_to_cpup(pfunc);
 136 out:
 137         kfree(pfunc);
 138         return ret;
 139 }
 140
 141 /* This is the actual algorithm we define */
 142 static const struct i2c_algorithm usb_algorithm = {
 143         .xfer = usb_xfer,
 144         .functionality = usb_func,
 145 };
 146
 147 /* ----- end of i2c layer ------------------------------------------------ */
 148
 149 /* ----- begin of usb layer ---------------------------------------------- */
 150
 151 /*
 152  * Initially the usb i2c interface uses a vid/pid pair donated by
 153  * Future Technology Devices International Ltd., later a pair was
 154  * bought from EZPrototypes
 155  */
 156 static const struct usb_device_id i2c_tiny_usb_table[] = {
 157         { USB_DEVICE(0x0403, 0xc631) },   /* FTDI */
 158         { USB_DEVICE(0x1c40, 0x0534) },   /* EZPrototypes */
 159         { }                               /* Terminating entry */
 160 };
 161
 162 MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);
 163
 164 /* Structure to hold all of our device specific stuff */
 165 struct i2c_tiny_usb {
 166         struct usb_device *usb_dev; /* the usb device for this device */
 167         struct usb_interface *interface; /* the interface for this device */
 168         struct i2c_adapter adapter; /* i2c related things */
 169 };
 170
 171 static int usb_read(struct i2c_adapter *adapter, int cmd,
 172                     int value, int index, void *data, int len)
 173 {
 174         struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
 175         void *dmadata = kmalloc(len, GFP_KERNEL);
 176         int ret;
 177
 178         if (!dmadata)
 179                 return -ENOMEM;
 180
 181         /* do control transfer */
 182         ret = usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
 183                                cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
 184                                USB_DIR_IN, value, index, dmadata, len, 2000);
 185
 186         memcpy(data, dmadata, len);
 187         kfree(dmadata);
 188         return ret;
 189 }
 190
 191 static int usb_write(struct i2c_adapter *adapter, int cmd,
 192                      int value, int index, void *data, int len)
 193 {
 194         struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
 195         void *dmadata = kmemdup(data, len, GFP_KERNEL);
 196         int ret;
 197
 198         if (!dmadata)
 199                 return -ENOMEM;
 200
 201         /* do control transfer */
 202         ret = usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
 203                                cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
 204                                value, index, dmadata, len, 2000);
 205
 206         kfree(dmadata);
 207         return ret;
 208 }
 209
 210 static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
 211 {
 212         usb_put_dev(dev->usb_dev);
 213         kfree(dev);
 214 }
 215
 216 static int i2c_tiny_usb_probe(struct usb_interface *interface,
 217                               const struct usb_device_id *id)
 218 {
 219         struct i2c_tiny_usb *dev;
 220         int retval = -ENOMEM;
 221         u16 version;
 222
 223         if (interface->intf_assoc &&
 224             interface->intf_assoc->bFunctionClass != USB_CLASS_VENDOR_SPEC)
 225                 return -ENODEV;
 226
 227         dev_dbg(&interface->dev, "probing usb device\n");
 228
 229         /* allocate memory for our device state and initialize it */
 230         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 231         if (!dev)
 232                 goto error;
 233
 234         dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
 235         dev->interface = interface;
 236
 237         /* save our data pointer in this interface device */
 238         usb_set_intfdata(interface, dev);
 239
 240         version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice);
 241         dev_info(&interface->dev,
 242                  "version %x.%02x found at bus %03d address %03d\n",
 243                  version >> 8, version & 0xff,
 244                  dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
 245
 246         /* setup i2c adapter description */
 247         dev->adapter.owner = THIS_MODULE;
 248         dev->adapter.class = I2C_CLASS_HWMON;
 249         dev->adapter.algo = &usb_algorithm;
 250         dev->adapter.algo_data = dev;
 251         snprintf(dev->adapter.name, sizeof(dev->adapter.name),
 252                  "i2c-tiny-usb at bus %03d device %03d",
 253                  dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
 254
 255         if (usb_write(&dev->adapter, CMD_SET_DELAY, delay, 0, NULL, 0) != 0) {
 256                 dev_err(&dev->adapter.dev,
 257                         "failure setting delay to %dus\n", delay);
 258                 retval = -EIO;
 259                 goto error;
 260         }
 261
 262         dev->adapter.dev.parent = &dev->interface->dev;
 263
 264         /* and finally attach to i2c layer */
 265         i2c_add_adapter(&dev->adapter);
 266
 267         /* inform user about successful attachment to i2c layer */
 268         dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n");
 269
 270         return 0;
 271
 272  error:
 273         if (dev)
 274                 i2c_tiny_usb_free(dev);
 275
 276         return retval;
 277 }
 278
 279 static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
 280 {
 281         struct i2c_tiny_usb *dev = usb_get_intfdata(interface);
 282
 283         i2c_del_adapter(&dev->adapter);
 284         usb_set_intfdata(interface, NULL);
 285         i2c_tiny_usb_free(dev);
 286
 287         dev_dbg(&interface->dev, "disconnected\n");
 288 }
 289
 290 static struct usb_driver i2c_tiny_usb_driver = {
 291         .name           = "i2c-tiny-usb",
 292         .probe          = i2c_tiny_usb_probe,
 293         .disconnect     = i2c_tiny_usb_disconnect,
 294         .id_table       = i2c_tiny_usb_table,
 295 };
 296
 297 module_usb_driver(i2c_tiny_usb_driver);
 298
 299 /* ----- end of usb layer ------------------------------------------------ */
 300
 301 MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
 302 MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
 303 MODULE_LICENSE("GPL");