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/types.h> 17 18 /* include interfaces to usb layer */ 19 #include <linux/usb.h> 20 21 /* include interface to i2c layer */ 22 #include <linux/i2c.h> 23 24 /* commands via USB, must match command ids in the firmware */ 25 #define CMD_ECHO 0 26 #define CMD_GET_FUNC 1 27 #define CMD_SET_DELAY 2 28 #define CMD_GET_STATUS 3 29 30 #define CMD_I2C_IO 4 31 #define CMD_I2C_IO_BEGIN (1<<0) 32 #define CMD_I2C_IO_END (1<<1) 33 34 /* i2c bit delay, default is 10us -> 100kHz */ 35 static unsigned short delay = 10; 36 module_param(delay, ushort, 0); 37 MODULE_PARM_DESC(delay, "bit delay in microseconds, " 38 "e.g. 10 for 100kHz (default is 100kHz)"); 39 40 static int usb_read(struct i2c_adapter *adapter, int cmd, 41 int value, int index, void *data, int len); 42 43 static int usb_write(struct i2c_adapter *adapter, int cmd, 44 int value, int index, void *data, int len); 45 46 /* ----- begin of i2c layer ---------------------------------------------- */ 47 48 #define STATUS_IDLE 0 49 #define STATUS_ADDRESS_ACK 1 50 #define STATUS_ADDRESS_NAK 2 51 52 static int usb_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num) 53 { 54 unsigned char status; 55 struct i2c_msg *pmsg; 56 int i; 57 58 dev_dbg(&adapter->dev, "master xfer %d messages:\n", num); 59 60 for (i = 0 ; i < num ; i++) { 61 int cmd = CMD_I2C_IO; 62 63 if (i == 0) 64 cmd |= CMD_I2C_IO_BEGIN; 65 66 if (i == num-1) 67 cmd |= CMD_I2C_IO_END; 68 69 pmsg = &msgs[i]; 70 71 dev_dbg(&adapter->dev, 72 " %d: %s (flags %d) %d bytes to 0x%02x\n", 73 i, pmsg->flags & I2C_M_RD ? "read" : "write", 74 pmsg->flags, pmsg->len, pmsg->addr); 75 76 /* and directly send the message */ 77 if (pmsg->flags & I2C_M_RD) { 78 /* read data */ 79 if (usb_read(adapter, cmd, 80 pmsg->flags, pmsg->addr, 81 pmsg->buf, pmsg->len) != pmsg->len) { 82 dev_err(&adapter->dev, 83 "failure reading data\n"); 84 return -EREMOTEIO; 85 } 86 } else { 87 /* write data */ 88 if (usb_write(adapter, cmd, 89 pmsg->flags, pmsg->addr, 90 pmsg->buf, pmsg->len) != pmsg->len) { 91 dev_err(&adapter->dev, 92 "failure writing data\n"); 93 return -EREMOTEIO; 94 } 95 } 96 97 /* read status */ 98 if (usb_read(adapter, CMD_GET_STATUS, 0, 0, &status, 1) != 1) { 99 dev_err(&adapter->dev, "failure reading status\n"); 100 return -EREMOTEIO; 101 } 102 103 dev_dbg(&adapter->dev, " status = %d\n", status); 104 if (status == STATUS_ADDRESS_NAK) 105 return -EREMOTEIO; 106 } 107 108 return i; 109 } 110 111 static u32 usb_func(struct i2c_adapter *adapter) 112 { 113 __le32 func; 114 115 /* get functionality from adapter */ 116 if (usb_read(adapter, CMD_GET_FUNC, 0, 0, &func, sizeof(func)) != 117 sizeof(func)) { 118 dev_err(&adapter->dev, "failure reading functionality\n"); 119 return 0; 120 } 121 122 return le32_to_cpu(func); 123 } 124 125 /* This is the actual algorithm we define */ 126 static const struct i2c_algorithm usb_algorithm = { 127 .master_xfer = usb_xfer, 128 .functionality = usb_func, 129 }; 130 131 /* ----- end of i2c layer ------------------------------------------------ */ 132 133 /* ----- begin of usb layer ---------------------------------------------- */ 134 135 /* 136 * Initially the usb i2c interface uses a vid/pid pair donated by 137 * Future Technology Devices International Ltd., later a pair was 138 * bought from EZPrototypes 139 */ 140 static struct usb_device_id i2c_tiny_usb_table [] = { 141 { USB_DEVICE(0x0403, 0xc631) }, /* FTDI */ 142 { USB_DEVICE(0x1c40, 0x0534) }, /* EZPrototypes */ 143 { } /* Terminating entry */ 144 }; 145 146 MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table); 147 148 /* Structure to hold all of our device specific stuff */ 149 struct i2c_tiny_usb { 150 struct usb_device *usb_dev; /* the usb device for this device */ 151 struct usb_interface *interface; /* the interface for this device */ 152 struct i2c_adapter adapter; /* i2c related things */ 153 }; 154 155 static int usb_read(struct i2c_adapter *adapter, int cmd, 156 int value, int index, void *data, int len) 157 { 158 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data; 159 160 /* do control transfer */ 161 return usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0), 162 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE | 163 USB_DIR_IN, value, index, data, len, 2000); 164 } 165 166 static int usb_write(struct i2c_adapter *adapter, int cmd, 167 int value, int index, void *data, int len) 168 { 169 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data; 170 171 /* do control transfer */ 172 return usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0), 173 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE, 174 value, index, data, len, 2000); 175 } 176 177 static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev) 178 { 179 usb_put_dev(dev->usb_dev); 180 kfree(dev); 181 } 182 183 static int i2c_tiny_usb_probe(struct usb_interface *interface, 184 const struct usb_device_id *id) 185 { 186 struct i2c_tiny_usb *dev; 187 int retval = -ENOMEM; 188 u16 version; 189 190 dev_dbg(&interface->dev, "probing usb device\n"); 191 192 /* allocate memory for our device state and initialize it */ 193 dev = kzalloc(sizeof(*dev), GFP_KERNEL); 194 if (dev == NULL) { 195 dev_err(&interface->dev, "Out of memory\n"); 196 goto error; 197 } 198 199 dev->usb_dev = usb_get_dev(interface_to_usbdev(interface)); 200 dev->interface = interface; 201 202 /* save our data pointer in this interface device */ 203 usb_set_intfdata(interface, dev); 204 205 version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice); 206 dev_info(&interface->dev, 207 "version %x.%02x found at bus %03d address %03d\n", 208 version >> 8, version & 0xff, 209 dev->usb_dev->bus->busnum, dev->usb_dev->devnum); 210 211 /* setup i2c adapter description */ 212 dev->adapter.owner = THIS_MODULE; 213 dev->adapter.class = I2C_CLASS_HWMON; 214 dev->adapter.algo = &usb_algorithm; 215 dev->adapter.algo_data = dev; 216 snprintf(dev->adapter.name, sizeof(dev->adapter.name), 217 "i2c-tiny-usb at bus %03d device %03d", 218 dev->usb_dev->bus->busnum, dev->usb_dev->devnum); 219 220 if (usb_write(&dev->adapter, CMD_SET_DELAY, delay, 0, NULL, 0) != 0) { 221 dev_err(&dev->adapter.dev, 222 "failure setting delay to %dus\n", delay); 223 retval = -EIO; 224 goto error; 225 } 226 227 dev->adapter.dev.parent = &dev->interface->dev; 228 229 /* and finally attach to i2c layer */ 230 i2c_add_adapter(&dev->adapter); 231 232 /* inform user about successful attachment to i2c layer */ 233 dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n"); 234 235 return 0; 236 237 error: 238 if (dev) 239 i2c_tiny_usb_free(dev); 240 241 return retval; 242 } 243 244 static void i2c_tiny_usb_disconnect(struct usb_interface *interface) 245 { 246 struct i2c_tiny_usb *dev = usb_get_intfdata(interface); 247 248 i2c_del_adapter(&dev->adapter); 249 usb_set_intfdata(interface, NULL); 250 i2c_tiny_usb_free(dev); 251 252 dev_dbg(&interface->dev, "disconnected\n"); 253 } 254 255 static struct usb_driver i2c_tiny_usb_driver = { 256 .name = "i2c-tiny-usb", 257 .probe = i2c_tiny_usb_probe, 258 .disconnect = i2c_tiny_usb_disconnect, 259 .id_table = i2c_tiny_usb_table, 260 }; 261 262 static int __init usb_i2c_tiny_usb_init(void) 263 { 264 /* register this driver with the USB subsystem */ 265 return usb_register(&i2c_tiny_usb_driver); 266 } 267 268 static void __exit usb_i2c_tiny_usb_exit(void) 269 { 270 /* deregister this driver with the USB subsystem */ 271 usb_deregister(&i2c_tiny_usb_driver); 272 } 273 274 module_init(usb_i2c_tiny_usb_init); 275 module_exit(usb_i2c_tiny_usb_exit); 276 277 /* ----- end of usb layer ------------------------------------------------ */ 278 279 MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>"); 280 MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0"); 281 MODULE_LICENSE("GPL"); 282