i2c/busses/i2c-tiny-usb.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * driver for the i2c-tiny-usb adapter - 1.0
0004  * http://www.harbaum.org/till/i2c_tiny_usb
0005  *
0006  * Copyright (C) 2006-2007 Till Harbaum (Till@Harbaum.org)
0007  */
0008
0009 #include <linux/kernel.h>
0010 #include <linux/errno.h>
0011 #include <linux/module.h>
0012 #include <linux/slab.h>
0013 #include <linux/types.h>
0014
0015 /* include interfaces to usb layer */
0016 #include <linux/usb.h>
0017
0018 /* include interface to i2c layer */
0019 #include <linux/i2c.h>
0020
0021 /* commands via USB, must match command ids in the firmware */
0022 #define CMD_ECHO        0
0023 #define CMD_GET_FUNC        1
0024 #define CMD_SET_DELAY       2
0025 #define CMD_GET_STATUS      3
0026
0027 #define CMD_I2C_IO      4
0028 #define CMD_I2C_IO_BEGIN    (1<<0)
0029 #define CMD_I2C_IO_END      (1<<1)
0030
0031 /* i2c bit delay, default is 10us -> 100kHz max
0032    (in practice, due to additional delays in the i2c bitbanging
0033    code this results in a i2c clock of about 50kHz) */
0034 static unsigned short delay = 10;
0035 module_param(delay, ushort, 0);
0036 MODULE_PARM_DESC(delay, "bit delay in microseconds "
0037          "(default is 10us for 100kHz max)");
0038
0039 static int usb_read(struct i2c_adapter *adapter, int cmd,
0040             int value, int index, void *data, int len);
0041
0042 static int usb_write(struct i2c_adapter *adapter, int cmd,
0043              int value, int index, void *data, int len);
0044
0045 /* ----- begin of i2c layer ---------------------------------------------- */
0046
0047 #define STATUS_IDLE     0
0048 #define STATUS_ADDRESS_ACK  1
0049 #define STATUS_ADDRESS_NAK  2
0050
0051 static int usb_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
0052 {
0053     unsigned char *pstatus;
0054     struct i2c_msg *pmsg;
0055     int i, ret;
0056
0057     dev_dbg(&adapter->dev, "master xfer %d messages:\n", num);
0058
0059     pstatus = kmalloc(sizeof(*pstatus), GFP_KERNEL);
0060     if (!pstatus)
0061         return -ENOMEM;
0062
0063     for (i = 0 ; i < num ; i++) {
0064         int cmd = CMD_I2C_IO;
0065
0066         if (i == 0)
0067             cmd |= CMD_I2C_IO_BEGIN;
0068
0069         if (i == num-1)
0070             cmd |= CMD_I2C_IO_END;
0071
0072         pmsg = &msgs[i];
0073
0074         dev_dbg(&adapter->dev,
0075             "  %d: %s (flags %d) %d bytes to 0x%02x\n",
0076             i, pmsg->flags & I2C_M_RD ? "read" : "write",
0077             pmsg->flags, pmsg->len, pmsg->addr);
0078
0079         /* and directly send the message */
0080         if (pmsg->flags & I2C_M_RD) {
0081             /* read data */
0082             if (usb_read(adapter, cmd,
0083                      pmsg->flags, pmsg->addr,
0084                      pmsg->buf, pmsg->len) != pmsg->len) {
0085                 dev_err(&adapter->dev,
0086                     "failure reading data\n");
0087                 ret = -EIO;
0088                 goto out;
0089             }
0090         } else {
0091             /* write data */
0092             if (usb_write(adapter, cmd,
0093                       pmsg->flags, pmsg->addr,
0094                       pmsg->buf, pmsg->len) != pmsg->len) {
0095                 dev_err(&adapter->dev,
0096                     "failure writing data\n");
0097                 ret = -EIO;
0098                 goto out;
0099             }
0100         }
0101
0102         /* read status */
0103         if (usb_read(adapter, CMD_GET_STATUS, 0, 0, pstatus, 1) != 1) {
0104             dev_err(&adapter->dev, "failure reading status\n");
0105             ret = -EIO;
0106             goto out;
0107         }
0108
0109         dev_dbg(&adapter->dev, "  status = %d\n", *pstatus);
0110         if (*pstatus == STATUS_ADDRESS_NAK) {
0111             ret = -ENXIO;
0112             goto out;
0113         }
0114     }
0115
0116     ret = i;
0117 out:
0118     kfree(pstatus);
0119     return ret;
0120 }
0121
0122 static u32 usb_func(struct i2c_adapter *adapter)
0123 {
0124     __le32 *pfunc;
0125     u32 ret;
0126
0127     pfunc = kmalloc(sizeof(*pfunc), GFP_KERNEL);
0128
0129     /* get functionality from adapter */
0130     if (!pfunc || usb_read(adapter, CMD_GET_FUNC, 0, 0, pfunc,
0131                    sizeof(*pfunc)) != sizeof(*pfunc)) {
0132         dev_err(&adapter->dev, "failure reading functionality\n");
0133         ret = 0;
0134         goto out;
0135     }
0136
0137     ret = le32_to_cpup(pfunc);
0138 out:
0139     kfree(pfunc);
0140     return ret;
0141 }
0142
0143 /* This is the actual algorithm we define */
0144 static const struct i2c_algorithm usb_algorithm = {
0145     .master_xfer    = usb_xfer,
0146     .functionality  = usb_func,
0147 };
0148
0149 /* ----- end of i2c layer ------------------------------------------------ */
0150
0151 /* ----- begin of usb layer ---------------------------------------------- */
0152
0153 /*
0154  * Initially the usb i2c interface uses a vid/pid pair donated by
0155  * Future Technology Devices International Ltd., later a pair was
0156  * bought from EZPrototypes
0157  */
0158 static const struct usb_device_id i2c_tiny_usb_table[] = {
0159     { USB_DEVICE(0x0403, 0xc631) },   /* FTDI */
0160     { USB_DEVICE(0x1c40, 0x0534) },   /* EZPrototypes */
0161     { }                               /* Terminating entry */
0162 };
0163
0164 MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);
0165
0166 /* Structure to hold all of our device specific stuff */
0167 struct i2c_tiny_usb {
0168     struct usb_device *usb_dev; /* the usb device for this device */
0169     struct usb_interface *interface; /* the interface for this device */
0170     struct i2c_adapter adapter; /* i2c related things */
0171 };
0172
0173 static int usb_read(struct i2c_adapter *adapter, int cmd,
0174             int value, int index, void *data, int len)
0175 {
0176     struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
0177     void *dmadata = kmalloc(len, GFP_KERNEL);
0178     int ret;
0179
0180     if (!dmadata)
0181         return -ENOMEM;
0182
0183     /* do control transfer */
0184     ret = usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
0185                    cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
0186                    USB_DIR_IN, value, index, dmadata, len, 2000);
0187
0188     memcpy(data, dmadata, len);
0189     kfree(dmadata);
0190     return ret;
0191 }
0192
0193 static int usb_write(struct i2c_adapter *adapter, int cmd,
0194              int value, int index, void *data, int len)
0195 {
0196     struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
0197     void *dmadata = kmemdup(data, len, GFP_KERNEL);
0198     int ret;
0199
0200     if (!dmadata)
0201         return -ENOMEM;
0202
0203     /* do control transfer */
0204     ret = usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
0205                    cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
0206                    value, index, dmadata, len, 2000);
0207
0208     kfree(dmadata);
0209     return ret;
0210 }
0211
0212 static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
0213 {
0214     usb_put_dev(dev->usb_dev);
0215     kfree(dev);
0216 }
0217
0218 static int i2c_tiny_usb_probe(struct usb_interface *interface,
0219                   const struct usb_device_id *id)
0220 {
0221     struct i2c_tiny_usb *dev;
0222     int retval = -ENOMEM;
0223     u16 version;
0224
0225     dev_dbg(&interface->dev, "probing usb device\n");
0226
0227     /* allocate memory for our device state and initialize it */
0228     dev = kzalloc(sizeof(*dev), GFP_KERNEL);
0229     if (dev == NULL) {
0230         dev_err(&interface->dev, "Out of memory\n");
0231         goto error;
0232     }
0233
0234     dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
0235     dev->interface = interface;
0236
0237     /* save our data pointer in this interface device */
0238     usb_set_intfdata(interface, dev);
0239
0240     version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice);
0241     dev_info(&interface->dev,
0242          "version %x.%02x found at bus %03d address %03d\n",
0243          version >> 8, version & 0xff,
0244          dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
0245
0246     /* setup i2c adapter description */
0247     dev->adapter.owner = THIS_MODULE;
0248     dev->adapter.class = I2C_CLASS_HWMON;
0249     dev->adapter.algo = &usb_algorithm;
0250     dev->adapter.algo_data = dev;
0251     snprintf(dev->adapter.name, sizeof(dev->adapter.name),
0252          "i2c-tiny-usb at bus %03d device %03d",
0253          dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
0254
0255     if (usb_write(&dev->adapter, CMD_SET_DELAY, delay, 0, NULL, 0) != 0) {
0256         dev_err(&dev->adapter.dev,
0257             "failure setting delay to %dus\n", delay);
0258         retval = -EIO;
0259         goto error;
0260     }
0261
0262     dev->adapter.dev.parent = &dev->interface->dev;
0263
0264     /* and finally attach to i2c layer */
0265     i2c_add_adapter(&dev->adapter);
0266
0267     /* inform user about successful attachment to i2c layer */
0268     dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n");
0269
0270     return 0;
0271
0272  error:
0273     if (dev)
0274         i2c_tiny_usb_free(dev);
0275
0276     return retval;
0277 }
0278
0279 static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
0280 {
0281     struct i2c_tiny_usb *dev = usb_get_intfdata(interface);
0282
0283     i2c_del_adapter(&dev->adapter);
0284     usb_set_intfdata(interface, NULL);
0285     i2c_tiny_usb_free(dev);
0286
0287     dev_dbg(&interface->dev, "disconnected\n");
0288 }
0289
0290 static struct usb_driver i2c_tiny_usb_driver = {
0291     .name       = "i2c-tiny-usb",
0292     .probe      = i2c_tiny_usb_probe,
0293     .disconnect = i2c_tiny_usb_disconnect,
0294     .id_table   = i2c_tiny_usb_table,
0295 };
0296
0297 module_usb_driver(i2c_tiny_usb_driver);
0298
0299 /* ----- end of usb layer ------------------------------------------------ */
0300
0301 MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
0302 MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
0303 MODULE_LICENSE("GPL");