1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * driver for the i2c-tiny-usb adapter - 1.0 4 * http://www.harbaum.org/till/i2c_tiny_usb 5 * 6 * Copyright (C) 2006-2007 Till Harbaum (Till@Harbaum.org) 7 */ 8 9 #include <linux/kernel.h> 10 #include <linux/errno.h> 11 #include <linux/module.h> 12 #include <linux/slab.h> 13 #include <linux/string_choices.h> 14 #include <linux/types.h> 15 16 /* include interfaces to usb layer */ 17 #include <linux/usb.h> 18 19 /* include interface to i2c layer */ 20 #include <linux/i2c.h> 21 22 /* commands via USB, must match command ids in the firmware */ 23 #define CMD_ECHO 0 24 #define CMD_GET_FUNC 1 25 #define CMD_SET_DELAY 2 26 #define CMD_GET_STATUS 3 27 28 #define CMD_I2C_IO 4 29 #define CMD_I2C_IO_BEGIN (1<<0) 30 #define CMD_I2C_IO_END (1<<1) 31 32 /* i2c bit delay, default is 10us -> 100kHz max 33 (in practice, due to additional delays in the i2c bitbanging 34 code this results in a i2c clock of about 50kHz) */ 35 static unsigned short delay = 10; 36 module_param(delay, ushort, 0); 37 MODULE_PARM_DESC(delay, "bit delay in microseconds " 38 "(default is 10us for 100kHz max)"); 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 *pstatus; 55 struct i2c_msg *pmsg; 56 int i, ret; 57 58 pstatus = kmalloc_obj(*pstatus); 59 if (!pstatus) 60 return -ENOMEM; 61 62 for (i = 0 ; i < num ; i++) { 63 int cmd = CMD_I2C_IO; 64 65 if (i == 0) 66 cmd |= CMD_I2C_IO_BEGIN; 67 68 if (i == num-1) 69 cmd |= CMD_I2C_IO_END; 70 71 pmsg = &msgs[i]; 72 73 dev_dbg(&adapter->dev, 74 " %d: %s (flags %d) %d bytes to 0x%02x\n", 75 i, str_read_write(pmsg->flags & I2C_M_RD), 76 pmsg->flags, pmsg->len, pmsg->addr); 77 78 /* and directly send the message */ 79 if (pmsg->flags & I2C_M_RD) { 80 /* read data */ 81 if (usb_read(adapter, cmd, 82 pmsg->flags, pmsg->addr, 83 pmsg->buf, pmsg->len) != pmsg->len) { 84 dev_err(&adapter->dev, 85 "failure reading data\n"); 86 ret = -EIO; 87 goto out; 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 ret = -EIO; 97 goto out; 98 } 99 } 100 101 /* read status */ 102 if (usb_read(adapter, CMD_GET_STATUS, 0, 0, pstatus, 1) != 1) { 103 dev_err(&adapter->dev, "failure reading status\n"); 104 ret = -EIO; 105 goto out; 106 } 107 108 dev_dbg(&adapter->dev, " status = %d\n", *pstatus); 109 if (*pstatus == STATUS_ADDRESS_NAK) { 110 ret = -ENXIO; 111 goto out; 112 } 113 } 114 115 ret = i; 116 out: 117 kfree(pstatus); 118 return ret; 119 } 120 121 static u32 usb_func(struct i2c_adapter *adapter) 122 { 123 __le32 *pfunc; 124 u32 ret; 125 126 pfunc = kmalloc_obj(*pfunc); 127 128 /* get functionality from adapter */ 129 if (!pfunc || usb_read(adapter, CMD_GET_FUNC, 0, 0, pfunc, 130 sizeof(*pfunc)) != sizeof(*pfunc)) { 131 dev_err(&adapter->dev, "failure reading functionality\n"); 132 ret = 0; 133 goto out; 134 } 135 136 ret = le32_to_cpup(pfunc); 137 out: 138 kfree(pfunc); 139 return ret; 140 } 141 142 /* prevent invalid 0-length usb_control_msg */ 143 static const struct i2c_adapter_quirks usb_quirks = { 144 .flags = I2C_AQ_NO_ZERO_LEN_READ, 145 }; 146 147 /* This is the actual algorithm we define */ 148 static const struct i2c_algorithm usb_algorithm = { 149 .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 void *dmadata = kmalloc(len, GFP_KERNEL); 182 int ret; 183 184 if (!dmadata) 185 return -ENOMEM; 186 187 /* do control transfer */ 188 ret = usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0), 189 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE | 190 USB_DIR_IN, value, index, dmadata, len, 2000); 191 192 memcpy(data, dmadata, len); 193 kfree(dmadata); 194 return ret; 195 } 196 197 static int usb_write(struct i2c_adapter *adapter, int cmd, 198 int value, int index, void *data, int len) 199 { 200 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data; 201 void *dmadata = kmemdup(data, len, GFP_KERNEL); 202 int ret; 203 204 if (!dmadata) 205 return -ENOMEM; 206 207 /* do control transfer */ 208 ret = usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0), 209 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE, 210 value, index, dmadata, len, 2000); 211 212 kfree(dmadata); 213 return ret; 214 } 215 216 static int i2c_tiny_usb_probe(struct usb_interface *interface, 217 const struct usb_device_id *id) 218 { 219 struct i2c_tiny_usb *dev; 220 int retval = -ENOMEM; 221 u16 version; 222 223 if (interface->intf_assoc && 224 interface->intf_assoc->bFunctionClass != USB_CLASS_VENDOR_SPEC) 225 return -ENODEV; 226 227 dev_dbg(&interface->dev, "probing usb device\n"); 228 229 /* allocate memory for our device state and initialize it */ 230 dev = kzalloc_obj(*dev); 231 if (!dev) 232 goto error; 233 234 dev->usb_dev = interface_to_usbdev(interface); 235 dev->interface = interface; 236 237 /* save our data pointer in this interface device */ 238 usb_set_intfdata(interface, dev); 239 240 version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice); 241 dev_info(&interface->dev, 242 "version %x.%02x found at bus %03d address %03d\n", 243 version >> 8, version & 0xff, 244 dev->usb_dev->bus->busnum, dev->usb_dev->devnum); 245 246 /* setup i2c adapter description */ 247 dev->adapter.owner = THIS_MODULE; 248 dev->adapter.class = I2C_CLASS_HWMON; 249 dev->adapter.quirks = &usb_quirks; 250 dev->adapter.algo = &usb_algorithm; 251 dev->adapter.algo_data = dev; 252 snprintf(dev->adapter.name, sizeof(dev->adapter.name), 253 "i2c-tiny-usb at bus %03d device %03d", 254 dev->usb_dev->bus->busnum, dev->usb_dev->devnum); 255 256 if (usb_write(&dev->adapter, CMD_SET_DELAY, delay, 0, NULL, 0) != 0) { 257 dev_err(&dev->adapter.dev, 258 "failure setting delay to %dus\n", delay); 259 retval = -EIO; 260 goto error; 261 } 262 263 dev->adapter.dev.parent = &dev->interface->dev; 264 265 /* and finally attach to i2c layer */ 266 i2c_add_adapter(&dev->adapter); 267 268 /* inform user about successful attachment to i2c layer */ 269 dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n"); 270 271 return 0; 272 273 error: 274 kfree(dev); 275 276 return retval; 277 } 278 279 static void i2c_tiny_usb_disconnect(struct usb_interface *interface) 280 { 281 struct i2c_tiny_usb *dev = usb_get_intfdata(interface); 282 283 i2c_del_adapter(&dev->adapter); 284 usb_set_intfdata(interface, NULL); 285 kfree(dev); 286 287 dev_dbg(&interface->dev, "disconnected\n"); 288 } 289 290 static struct usb_driver i2c_tiny_usb_driver = { 291 .name = "i2c-tiny-usb", 292 .probe = i2c_tiny_usb_probe, 293 .disconnect = i2c_tiny_usb_disconnect, 294 .id_table = i2c_tiny_usb_table, 295 }; 296 297 module_usb_driver(i2c_tiny_usb_driver); 298 299 /* ----- end of usb layer ------------------------------------------------ */ 300 301 MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>"); 302 MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0"); 303 MODULE_LICENSE("GPL"); 304