linux/drivers/i2c/busses/i2c-tiny-usb.c
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   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) */
  34static unsigned short delay = 10;
  35module_param(delay, ushort, 0);
  36MODULE_PARM_DESC(delay, "bit delay in microseconds "
  37                 "(default is 10us for 100kHz max)");
  38
  39static int usb_read(struct i2c_adapter *adapter, int cmd,
  40                    int value, int index, void *data, int len);
  41
  42static 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
  51static 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;
 117out:
 118        kfree(pstatus);
 119        return ret;
 120}
 121
 122static 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);
 138out:
 139        kfree(pfunc);
 140        return ret;
 141}
 142
 143/* This is the actual algorithm we define */
 144static 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 */
 158static 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
 164MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);
 165
 166/* Structure to hold all of our device specific stuff */
 167struct 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
 173static 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
 193static 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
 212static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
 213{
 214        usb_put_dev(dev->usb_dev);
 215        kfree(dev);
 216}
 217
 218static 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        dev_dbg(&interface->dev, "probing usb device\n");
 226
 227        /* allocate memory for our device state and initialize it */
 228        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 229        if (dev == NULL) {
 230                dev_err(&interface->dev, "Out of memory\n");
 231                goto error;
 232        }
 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
 279static 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
 290static 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
 297module_usb_driver(i2c_tiny_usb_driver);
 298
 299/* ----- end of usb layer ------------------------------------------------ */
 300
 301MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
 302MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
 303MODULE_LICENSE("GPL");
 304
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