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) */ 38static unsigned short delay = 10; 39module_param(delay, ushort, 0); 40MODULE_PARM_DESC(delay, "bit delay in microseconds " 41 "(default is 10us for 100kHz max)"); 42 43static int usb_read(struct i2c_adapter *adapter, int cmd, 44 int value, int index, void *data, int len); 45 46static 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 55static int usb_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num) 56{ 57 unsigned char status; 58 struct i2c_msg *pmsg; 59 int i; 60 61 dev_dbg(&adapter->dev, "master xfer %d messages:\n", num); 62 63 for (i = 0 ; i < num ; i++) { 64 int cmd = CMD_I2C_IO; 65 66 if (i == 0) 67 cmd |= CMD_I2C_IO_BEGIN; 68 69 if (i == num-1) 70 cmd |= CMD_I2C_IO_END; 71 72 pmsg = &msgs[i]; 73 74 dev_dbg(&adapter->dev, 75 " %d: %s (flags %d) %d bytes to 0x%02x\n", 76 i, pmsg->flags & I2C_M_RD ? "read" : "write", 77 pmsg->flags, pmsg->len, pmsg->addr); 78 79 /* and directly send the message */ 80 if (pmsg->flags & I2C_M_RD) { 81 /* read data */ 82 if (usb_read(adapter, cmd, 83 pmsg->flags, pmsg->addr, 84 pmsg->buf, pmsg->len) != pmsg->len) { 85 dev_err(&adapter->dev, 86 "failure reading data\n"); 87 return -EREMOTEIO; 88 } 89 } else { 90 /* write data */ 91 if (usb_write(adapter, cmd, 92 pmsg->flags, pmsg->addr, 93 pmsg->buf, pmsg->len) != pmsg->len) { 94 dev_err(&adapter->dev, 95 "failure writing data\n"); 96 return -EREMOTEIO; 97 } 98 } 99 100 /* read status */ 101 if (usb_read(adapter, CMD_GET_STATUS, 0, 0, &status, 1) != 1) { 102 dev_err(&adapter->dev, "failure reading status\n"); 103 return -EREMOTEIO; 104 } 105 106 dev_dbg(&adapter->dev, " status = %d\n", status); 107 if (status == STATUS_ADDRESS_NAK) 108 return -EREMOTEIO; 109 } 110 111 return i; 112} 113 114static u32 usb_func(struct i2c_adapter *adapter) 115{ 116 __le32 func; 117 118 /* get functionality from adapter */ 119 if (usb_read(adapter, CMD_GET_FUNC, 0, 0, &func, sizeof(func)) != 120 sizeof(func)) { 121 dev_err(&adapter->dev, "failure reading functionality\n"); 122 return 0; 123 } 124 125 return le32_to_cpu(func); 126} 127 128/* This is the actual algorithm we define */ 129static const struct i2c_algorithm usb_algorithm = { 130 .master_xfer = usb_xfer, 131 .functionality = usb_func, 132}; 133 134/* ----- end of i2c layer ------------------------------------------------ */ 135 136/* ----- begin of usb layer ---------------------------------------------- */ 137 138/* 139 * Initially the usb i2c interface uses a vid/pid pair donated by 140 * Future Technology Devices International Ltd., later a pair was 141 * bought from EZPrototypes 142 */ 143static const struct usb_device_id i2c_tiny_usb_table[] = { 144 { USB_DEVICE(0x0403, 0xc631) }, /* FTDI */ 145 { USB_DEVICE(0x1c40, 0x0534) }, /* EZPrototypes */ 146 { } /* Terminating entry */ 147}; 148 149MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table); 150 151/* Structure to hold all of our device specific stuff */ 152struct i2c_tiny_usb { 153 struct usb_device *usb_dev; /* the usb device for this device */ 154 struct usb_interface *interface; /* the interface for this device */ 155 struct i2c_adapter adapter; /* i2c related things */ 156}; 157 158static int usb_read(struct i2c_adapter *adapter, int cmd, 159 int value, int index, void *data, int len) 160{ 161 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data; 162 163 /* do control transfer */ 164 return usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0), 165 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE | 166 USB_DIR_IN, value, index, data, len, 2000); 167} 168 169static int usb_write(struct i2c_adapter *adapter, int cmd, 170 int value, int index, void *data, int len) 171{ 172 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data; 173 174 /* do control transfer */ 175 return usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0), 176 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE, 177 value, index, data, len, 2000); 178} 179 180static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev) 181{ 182 usb_put_dev(dev->usb_dev); 183 kfree(dev); 184} 185 186static int i2c_tiny_usb_probe(struct usb_interface *interface, 187 const struct usb_device_id *id) 188{ 189 struct i2c_tiny_usb *dev; 190 int retval = -ENOMEM; 191 u16 version; 192 193 dev_dbg(&interface->dev, "probing usb device\n"); 194 195 /* allocate memory for our device state and initialize it */ 196 dev = kzalloc(sizeof(*dev), GFP_KERNEL); 197 if (dev == NULL) { 198 dev_err(&interface->dev, "Out of memory\n"); 199 goto error; 200 } 201 202 dev->usb_dev = usb_get_dev(interface_to_usbdev(interface)); 203 dev->interface = interface; 204 205 /* save our data pointer in this interface device */ 206 usb_set_intfdata(interface, dev); 207 208 version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice); 209 dev_info(&interface->dev, 210 "version %x.%02x found at bus %03d address %03d\n", 211 version >> 8, version & 0xff, 212 dev->usb_dev->bus->busnum, dev->usb_dev->devnum); 213 214 /* setup i2c adapter description */ 215 dev->adapter.owner = THIS_MODULE; 216 dev->adapter.class = I2C_CLASS_HWMON; 217 dev->adapter.algo = &usb_algorithm; 218 dev->adapter.algo_data = dev; 219 snprintf(dev->adapter.name, sizeof(dev->adapter.name), 220 "i2c-tiny-usb at bus %03d device %03d", 221 dev->usb_dev->bus->busnum, dev->usb_dev->devnum); 222 223 if (usb_write(&dev->adapter, CMD_SET_DELAY, delay, 0, NULL, 0) != 0) { 224 dev_err(&dev->adapter.dev, 225 "failure setting delay to %dus\n", delay); 226 retval = -EIO; 227 goto error; 228 } 229 230 dev->adapter.dev.parent = &dev->interface->dev; 231 232 /* and finally attach to i2c layer */ 233 i2c_add_adapter(&dev->adapter); 234 235 /* inform user about successful attachment to i2c layer */ 236 dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n"); 237 238 return 0; 239 240 error: 241 if (dev) 242 i2c_tiny_usb_free(dev); 243 244 return retval; 245} 246 247static void i2c_tiny_usb_disconnect(struct usb_interface *interface) 248{ 249 struct i2c_tiny_usb *dev = usb_get_intfdata(interface); 250 251 i2c_del_adapter(&dev->adapter); 252 usb_set_intfdata(interface, NULL); 253 i2c_tiny_usb_free(dev); 254 255 dev_dbg(&interface->dev, "disconnected\n"); 256} 257 258static struct usb_driver i2c_tiny_usb_driver = { 259 .name = "i2c-tiny-usb", 260 .probe = i2c_tiny_usb_probe, 261 .disconnect = i2c_tiny_usb_disconnect, 262 .id_table = i2c_tiny_usb_table, 263}; 264 265static int __init usb_i2c_tiny_usb_init(void) 266{ 267 /* register this driver with the USB subsystem */ 268 return usb_register(&i2c_tiny_usb_driver); 269} 270 271static void __exit usb_i2c_tiny_usb_exit(void) 272{ 273 /* deregister this driver with the USB subsystem */ 274 usb_deregister(&i2c_tiny_usb_driver); 275} 276 277module_init(usb_i2c_tiny_usb_init); 278module_exit(usb_i2c_tiny_usb_exit); 279 280/* ----- end of usb layer ------------------------------------------------ */ 281 282MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>"); 283MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0"); 284MODULE_LICENSE("GPL"); 285