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 17 /* include interfaces to usb layer */ 18 #include <linux/usb.h> 19 20 /* include interface to i2c layer */ 21 #include <linux/i2c.h> 22 23 /* commands via USB, must match command ids in the firmware */ 24 #define CMD_ECHO 0 25 #define CMD_GET_FUNC 1 26 #define CMD_SET_DELAY 2 27 #define CMD_GET_STATUS 3 28 29 #define CMD_I2C_IO 4 30 #define CMD_I2C_IO_BEGIN (1<<0) 31 #define CMD_I2C_IO_END (1<<1) 32 33 /* i2c bit delay, default is 10us -> 100kHz */ 34 static int delay = 10; 35 module_param(delay, int, 0); 36 MODULE_PARM_DESC(delay, "bit delay in microseconds, " 37 "e.g. 10 for 100kHz (default is 100kHz)"); 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 status; 54 struct i2c_msg *pmsg; 55 int i; 56 57 dev_dbg(&adapter->dev, "master xfer %d messages:\n", num); 58 59 for (i = 0 ; i < num ; i++) { 60 int cmd = CMD_I2C_IO; 61 62 if (i == 0) 63 cmd |= CMD_I2C_IO_BEGIN; 64 65 if (i == num-1) 66 cmd |= CMD_I2C_IO_END; 67 68 pmsg = &msgs[i]; 69 70 dev_dbg(&adapter->dev, 71 " %d: %s (flags %d) %d bytes to 0x%02x\n", 72 i, pmsg->flags & I2C_M_RD ? "read" : "write", 73 pmsg->flags, pmsg->len, pmsg->addr); 74 75 /* and directly send the message */ 76 if (pmsg->flags & I2C_M_RD) { 77 /* read data */ 78 if (usb_read(adapter, cmd, 79 pmsg->flags, pmsg->addr, 80 pmsg->buf, pmsg->len) != pmsg->len) { 81 dev_err(&adapter->dev, 82 "failure reading data\n"); 83 return -EREMOTEIO; 84 } 85 } else { 86 /* write data */ 87 if (usb_write(adapter, cmd, 88 pmsg->flags, pmsg->addr, 89 pmsg->buf, pmsg->len) != pmsg->len) { 90 dev_err(&adapter->dev, 91 "failure writing data\n"); 92 return -EREMOTEIO; 93 } 94 } 95 96 /* read status */ 97 if (usb_read(adapter, CMD_GET_STATUS, 0, 0, &status, 1) != 1) { 98 dev_err(&adapter->dev, "failure reading status\n"); 99 return -EREMOTEIO; 100 } 101 102 dev_dbg(&adapter->dev, " status = %d\n", status); 103 if (status == STATUS_ADDRESS_NAK) 104 return -EREMOTEIO; 105 } 106 107 return i; 108 } 109 110 static u32 usb_func(struct i2c_adapter *adapter) 111 { 112 u32 func; 113 114 /* get functionality from adapter */ 115 if (usb_read(adapter, CMD_GET_FUNC, 0, 0, &func, sizeof(func)) != 116 sizeof(func)) { 117 dev_err(&adapter->dev, "failure reading functionality\n"); 118 return 0; 119 } 120 121 return func; 122 } 123 124 /* This is the actual algorithm we define */ 125 static const struct i2c_algorithm usb_algorithm = { 126 .master_xfer = usb_xfer, 127 .functionality = usb_func, 128 }; 129 130 /* ----- end of i2c layer ------------------------------------------------ */ 131 132 /* ----- begin of usb layer ---------------------------------------------- */ 133 134 /* 135 * Initially the usb i2c interface uses a vid/pid pair donated by 136 * Future Technology Devices International Ltd., later a pair was 137 * bought from EZPrototypes 138 */ 139 static struct usb_device_id i2c_tiny_usb_table [] = { 140 { USB_DEVICE(0x0403, 0xc631) }, /* FTDI */ 141 { USB_DEVICE(0x1c40, 0x0534) }, /* EZPrototypes */ 142 { } /* Terminating entry */ 143 }; 144 145 MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table); 146 147 /* Structure to hold all of our device specific stuff */ 148 struct i2c_tiny_usb { 149 struct usb_device *usb_dev; /* the usb device for this device */ 150 struct usb_interface *interface; /* the interface for this device */ 151 struct i2c_adapter adapter; /* i2c related things */ 152 }; 153 154 static int usb_read(struct i2c_adapter *adapter, int cmd, 155 int value, int index, void *data, int len) 156 { 157 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data; 158 159 /* do control transfer */ 160 return usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0), 161 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE | 162 USB_DIR_IN, value, index, data, len, 2000); 163 } 164 165 static int usb_write(struct i2c_adapter *adapter, int cmd, 166 int value, int index, void *data, int len) 167 { 168 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data; 169 170 /* do control transfer */ 171 return usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0), 172 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE, 173 value, index, data, len, 2000); 174 } 175 176 static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev) 177 { 178 usb_put_dev(dev->usb_dev); 179 kfree(dev); 180 } 181 182 static int i2c_tiny_usb_probe(struct usb_interface *interface, 183 const struct usb_device_id *id) 184 { 185 struct i2c_tiny_usb *dev; 186 int retval = -ENOMEM; 187 u16 version; 188 189 dev_dbg(&interface->dev, "probing usb device\n"); 190 191 /* allocate memory for our device state and initialize it */ 192 dev = kzalloc(sizeof(*dev), GFP_KERNEL); 193 if (dev == NULL) { 194 dev_err(&interface->dev, "Out of memory\n"); 195 goto error; 196 } 197 198 dev->usb_dev = usb_get_dev(interface_to_usbdev(interface)); 199 dev->interface = interface; 200 201 /* save our data pointer in this interface device */ 202 usb_set_intfdata(interface, dev); 203 204 version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice); 205 dev_info(&interface->dev, 206 "version %x.%02x found at bus %03d address %03d\n", 207 version >> 8, version & 0xff, 208 dev->usb_dev->bus->busnum, dev->usb_dev->devnum); 209 210 /* setup i2c adapter description */ 211 dev->adapter.owner = THIS_MODULE; 212 dev->adapter.class = I2C_CLASS_HWMON; 213 dev->adapter.algo = &usb_algorithm; 214 dev->adapter.algo_data = dev; 215 snprintf(dev->adapter.name, sizeof(dev->adapter.name), 216 "i2c-tiny-usb at bus %03d device %03d", 217 dev->usb_dev->bus->busnum, dev->usb_dev->devnum); 218 219 if (usb_write(&dev->adapter, CMD_SET_DELAY, 220 cpu_to_le16(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