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(sizeof(*pstatus), GFP_KERNEL); 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(sizeof(*pfunc), GFP_KERNEL); 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 /* This is the actual algorithm we define */ 143 static const struct i2c_algorithm usb_algorithm = { 144 .xfer = usb_xfer, 145 .functionality = usb_func, 146 }; 147 148 /* ----- end of i2c layer ------------------------------------------------ */ 149 150 /* ----- begin of usb layer ---------------------------------------------- */ 151 152 /* 153 * Initially the usb i2c interface uses a vid/pid pair donated by 154 * Future Technology Devices International Ltd., later a pair was 155 * bought from EZPrototypes 156 */ 157 static const struct usb_device_id i2c_tiny_usb_table[] = { 158 { USB_DEVICE(0x0403, 0xc631) }, /* FTDI */ 159 { USB_DEVICE(0x1c40, 0x0534) }, /* EZPrototypes */ 160 { } /* Terminating entry */ 161 }; 162 163 MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table); 164 165 /* Structure to hold all of our device specific stuff */ 166 struct i2c_tiny_usb { 167 struct usb_device *usb_dev; /* the usb device for this device */ 168 struct usb_interface *interface; /* the interface for this device */ 169 struct i2c_adapter adapter; /* i2c related things */ 170 }; 171 172 static int usb_read(struct i2c_adapter *adapter, int cmd, 173 int value, int index, void *data, int len) 174 { 175 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data; 176 void *dmadata = kmalloc(len, GFP_KERNEL); 177 int ret; 178 179 if (!dmadata) 180 return -ENOMEM; 181 182 /* do control transfer */ 183 ret = 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, dmadata, len, 2000); 186 187 memcpy(data, dmadata, len); 188 kfree(dmadata); 189 return ret; 190 } 191 192 static int usb_write(struct i2c_adapter *adapter, int cmd, 193 int value, int index, void *data, int len) 194 { 195 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data; 196 void *dmadata = kmemdup(data, len, GFP_KERNEL); 197 int ret; 198 199 if (!dmadata) 200 return -ENOMEM; 201 202 /* do control transfer */ 203 ret = usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0), 204 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE, 205 value, index, dmadata, len, 2000); 206 207 kfree(dmadata); 208 return ret; 209 } 210 211 static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev) 212 { 213 usb_put_dev(dev->usb_dev); 214 kfree(dev); 215 } 216 217 static int i2c_tiny_usb_probe(struct usb_interface *interface, 218 const struct usb_device_id *id) 219 { 220 struct i2c_tiny_usb *dev; 221 int retval = -ENOMEM; 222 u16 version; 223 224 if (interface->intf_assoc && 225 interface->intf_assoc->bFunctionClass != USB_CLASS_VENDOR_SPEC) 226 return -ENODEV; 227 228 dev_dbg(&interface->dev, "probing usb device\n"); 229 230 /* allocate memory for our device state and initialize it */ 231 dev = kzalloc(sizeof(*dev), GFP_KERNEL); 232 if (!dev) 233 goto error; 234 235 dev->usb_dev = usb_get_dev(interface_to_usbdev(interface)); 236 dev->interface = interface; 237 238 /* save our data pointer in this interface device */ 239 usb_set_intfdata(interface, dev); 240 241 version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice); 242 dev_info(&interface->dev, 243 "version %x.%02x found at bus %03d address %03d\n", 244 version >> 8, version & 0xff, 245 dev->usb_dev->bus->busnum, dev->usb_dev->devnum); 246 247 /* setup i2c adapter description */ 248 dev->adapter.owner = THIS_MODULE; 249 dev->adapter.class = I2C_CLASS_HWMON; 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 if (dev) 275 i2c_tiny_usb_free(dev); 276 277 return retval; 278 } 279 280 static void i2c_tiny_usb_disconnect(struct usb_interface *interface) 281 { 282 struct i2c_tiny_usb *dev = usb_get_intfdata(interface); 283 284 i2c_del_adapter(&dev->adapter); 285 usb_set_intfdata(interface, NULL); 286 i2c_tiny_usb_free(dev); 287 288 dev_dbg(&interface->dev, "disconnected\n"); 289 } 290 291 static struct usb_driver i2c_tiny_usb_driver = { 292 .name = "i2c-tiny-usb", 293 .probe = i2c_tiny_usb_probe, 294 .disconnect = i2c_tiny_usb_disconnect, 295 .id_table = i2c_tiny_usb_table, 296 }; 297 298 module_usb_driver(i2c_tiny_usb_driver); 299 300 /* ----- end of usb layer ------------------------------------------------ */ 301 302 MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>"); 303 MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0"); 304 MODULE_LICENSE("GPL"); 305