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Linux/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");
291 

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