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 /* The usb i2c interface uses a vid/pid pair donated by */ 135 /* Future Technology Devices International Ltd. */ 136 static struct usb_device_id i2c_tiny_usb_table [] = { 137 { USB_DEVICE(0x0403, 0xc631) }, 138 { } /* Terminating entry */ 139 }; 140 141 MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table); 142 143 /* Structure to hold all of our device specific stuff */ 144 struct i2c_tiny_usb { 145 struct usb_device *usb_dev; /* the usb device for this device */ 146 struct usb_interface *interface; /* the interface for this device */ 147 struct i2c_adapter adapter; /* i2c related things */ 148 }; 149 150 static int usb_read(struct i2c_adapter *adapter, int cmd, 151 int value, int index, void *data, int len) 152 { 153 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data; 154 155 /* do control transfer */ 156 return usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0), 157 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE | 158 USB_DIR_IN, value, index, data, len, 2000); 159 } 160 161 static int usb_write(struct i2c_adapter *adapter, int cmd, 162 int value, int index, void *data, int len) 163 { 164 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data; 165 166 /* do control transfer */ 167 return usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0), 168 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE, 169 value, index, data, len, 2000); 170 } 171 172 static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev) 173 { 174 usb_put_dev(dev->usb_dev); 175 kfree(dev); 176 } 177 178 static int i2c_tiny_usb_probe(struct usb_interface *interface, 179 const struct usb_device_id *id) 180 { 181 struct i2c_tiny_usb *dev; 182 int retval = -ENOMEM; 183 u16 version; 184 185 dev_dbg(&interface->dev, "probing usb device\n"); 186 187 /* allocate memory for our device state and initialize it */ 188 dev = kzalloc(sizeof(*dev), GFP_KERNEL); 189 if (dev == NULL) { 190 dev_err(&interface->dev, "Out of memory\n"); 191 goto error; 192 } 193 194 dev->usb_dev = usb_get_dev(interface_to_usbdev(interface)); 195 dev->interface = interface; 196 197 /* save our data pointer in this interface device */ 198 usb_set_intfdata(interface, dev); 199 200 version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice); 201 dev_info(&interface->dev, 202 "version %x.%02x found at bus %03d address %03d\n", 203 version >> 8, version & 0xff, 204 dev->usb_dev->bus->busnum, dev->usb_dev->devnum); 205 206 /* setup i2c adapter description */ 207 dev->adapter.owner = THIS_MODULE; 208 dev->adapter.class = I2C_CLASS_HWMON; 209 dev->adapter.algo = &usb_algorithm; 210 dev->adapter.algo_data = dev; 211 snprintf(dev->adapter.name, sizeof(dev->adapter.name), 212 "i2c-tiny-usb at bus %03d device %03d", 213 dev->usb_dev->bus->busnum, dev->usb_dev->devnum); 214 215 if (usb_write(&dev->adapter, CMD_SET_DELAY, 216 cpu_to_le16(delay), 0, NULL, 0) != 0) { 217 dev_err(&dev->adapter.dev, 218 "failure setting delay to %dus\n", delay); 219 retval = -EIO; 220 goto error; 221 } 222 223 dev->adapter.dev.parent = &dev->interface->dev; 224 225 /* and finally attach to i2c layer */ 226 i2c_add_adapter(&dev->adapter); 227 228 /* inform user about successful attachment to i2c layer */ 229 dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n"); 230 231 return 0; 232 233 error: 234 if (dev) 235 i2c_tiny_usb_free(dev); 236 237 return retval; 238 } 239 240 static void i2c_tiny_usb_disconnect(struct usb_interface *interface) 241 { 242 struct i2c_tiny_usb *dev = usb_get_intfdata(interface); 243 244 i2c_del_adapter(&dev->adapter); 245 usb_set_intfdata(interface, NULL); 246 i2c_tiny_usb_free(dev); 247 248 dev_dbg(&interface->dev, "disconnected\n"); 249 } 250 251 static struct usb_driver i2c_tiny_usb_driver = { 252 .name = "i2c-tiny-usb", 253 .probe = i2c_tiny_usb_probe, 254 .disconnect = i2c_tiny_usb_disconnect, 255 .id_table = i2c_tiny_usb_table, 256 }; 257 258 static int __init usb_i2c_tiny_usb_init(void) 259 { 260 /* register this driver with the USB subsystem */ 261 return usb_register(&i2c_tiny_usb_driver); 262 } 263 264 static void __exit usb_i2c_tiny_usb_exit(void) 265 { 266 /* deregister this driver with the USB subsystem */ 267 usb_deregister(&i2c_tiny_usb_driver); 268 } 269 270 module_init(usb_i2c_tiny_usb_init); 271 module_exit(usb_i2c_tiny_usb_exit); 272 273 /* ----- end of usb layer ------------------------------------------------ */ 274 275 MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>"); 276 MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0"); 277 MODULE_LICENSE("GPL"); 278