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