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/types.h> 14 15 /* include interfaces to usb layer */ 16 #include <linux/usb.h> 17 18 /* include interface to i2c layer */ 19 #include <linux/i2c.h> 20 21 /* commands via USB, must match command ids in the firmware */ 22 #define CMD_ECHO 0 23 #define CMD_GET_FUNC 1 24 #define CMD_SET_DELAY 2 25 #define CMD_GET_STATUS 3 26 27 #define CMD_I2C_IO 4 28 #define CMD_I2C_IO_BEGIN (1<<0) 29 #define CMD_I2C_IO_END (1<<1) 30 31 /* i2c bit delay, default is 10us -> 100kHz max 32 (in practice, due to additional delays in the i2c bitbanging 33 code this results in a i2c clock of about 50kHz) */ 34 static unsigned short delay = 10; 35 module_param(delay, ushort, 0); 36 MODULE_PARM_DESC(delay, "bit delay in microseconds " 37 "(default is 10us for 100kHz max)"); 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 *pstatus; 54 struct i2c_msg *pmsg; 55 int i, ret; 56 57 pstatus = kmalloc(sizeof(*pstatus), GFP_KERNEL); 58 if (!pstatus) 59 return -ENOMEM; 60 61 for (i = 0 ; i < num ; i++) { 62 int cmd = CMD_I2C_IO; 63 64 if (i == 0) 65 cmd |= CMD_I2C_IO_BEGIN; 66 67 if (i == num-1) 68 cmd |= CMD_I2C_IO_END; 69 70 pmsg = &msgs[i]; 71 72 dev_dbg(&adapter->dev, 73 " %d: %s (flags %d) %d bytes to 0x%02x\n", 74 i, pmsg->flags & I2C_M_RD ? "read" : "write", 75 pmsg->flags, pmsg->len, pmsg->addr); 76 77 /* and directly send the message */ 78 if (pmsg->flags & I2C_M_RD) { 79 /* read data */ 80 if (usb_read(adapter, cmd, 81 pmsg->flags, pmsg->addr, 82 pmsg->buf, pmsg->len) != pmsg->len) { 83 dev_err(&adapter->dev, 84 "failure reading data\n"); 85 ret = -EIO; 86 goto out; 87 } 88 } else { 89 /* write data */ 90 if (usb_write(adapter, cmd, 91 pmsg->flags, pmsg->addr, 92 pmsg->buf, pmsg->len) != pmsg->len) { 93 dev_err(&adapter->dev, 94 "failure writing data\n"); 95 ret = -EIO; 96 goto out; 97 } 98 } 99 100 /* read status */ 101 if (usb_read(adapter, CMD_GET_STATUS, 0, 0, pstatus, 1) != 1) { 102 dev_err(&adapter->dev, "failure reading status\n"); 103 ret = -EIO; 104 goto out; 105 } 106 107 dev_dbg(&adapter->dev, " status = %d\n", *pstatus); 108 if (*pstatus == STATUS_ADDRESS_NAK) { 109 ret = -ENXIO; 110 goto out; 111 } 112 } 113 114 ret = i; 115 out: 116 kfree(pstatus); 117 return ret; 118 } 119 120 static u32 usb_func(struct i2c_adapter *adapter) 121 { 122 __le32 *pfunc; 123 u32 ret; 124 125 pfunc = kmalloc(sizeof(*pfunc), GFP_KERNEL); 126 127 /* get functionality from adapter */ 128 if (!pfunc || usb_read(adapter, CMD_GET_FUNC, 0, 0, pfunc, 129 sizeof(*pfunc)) != sizeof(*pfunc)) { 130 dev_err(&adapter->dev, "failure reading functionality\n"); 131 ret = 0; 132 goto out; 133 } 134 135 ret = le32_to_cpup(pfunc); 136 out: 137 kfree(pfunc); 138 return ret; 139 } 140 141 /* This is the actual algorithm we define */ 142 static const struct i2c_algorithm usb_algorithm = { 143 .xfer = usb_xfer, 144 .functionality = usb_func, 145 }; 146 147 /* ----- end of i2c layer ------------------------------------------------ */ 148 149 /* ----- begin of usb layer ---------------------------------------------- */ 150 151 /* 152 * Initially the usb i2c interface uses a vid/pid pair donated by 153 * Future Technology Devices International Ltd., later a pair was 154 * bought from EZPrototypes 155 */ 156 static const struct usb_device_id i2c_tiny_usb_table[] = { 157 { USB_DEVICE(0x0403, 0xc631) }, /* FTDI */ 158 { USB_DEVICE(0x1c40, 0x0534) }, /* EZPrototypes */ 159 { } /* Terminating entry */ 160 }; 161 162 MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table); 163 164 /* Structure to hold all of our device specific stuff */ 165 struct i2c_tiny_usb { 166 struct usb_device *usb_dev; /* the usb device for this device */ 167 struct usb_interface *interface; /* the interface for this device */ 168 struct i2c_adapter adapter; /* i2c related things */ 169 }; 170 171 static int usb_read(struct i2c_adapter *adapter, int cmd, 172 int value, int index, void *data, int len) 173 { 174 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data; 175 void *dmadata = kmalloc(len, GFP_KERNEL); 176 int ret; 177 178 if (!dmadata) 179 return -ENOMEM; 180 181 /* do control transfer */ 182 ret = usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0), 183 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE | 184 USB_DIR_IN, value, index, dmadata, len, 2000); 185 186 memcpy(data, dmadata, len); 187 kfree(dmadata); 188 return ret; 189 } 190 191 static int usb_write(struct i2c_adapter *adapter, int cmd, 192 int value, int index, void *data, int len) 193 { 194 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data; 195 void *dmadata = kmemdup(data, len, GFP_KERNEL); 196 int ret; 197 198 if (!dmadata) 199 return -ENOMEM; 200 201 /* do control transfer */ 202 ret = usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0), 203 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE, 204 value, index, dmadata, len, 2000); 205 206 kfree(dmadata); 207 return ret; 208 } 209 210 static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev) 211 { 212 usb_put_dev(dev->usb_dev); 213 kfree(dev); 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(sizeof(*dev), GFP_KERNEL); 231 if (!dev) 232 goto error; 233 234 dev->usb_dev = usb_get_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.algo = &usb_algorithm; 250 dev->adapter.algo_data = dev; 251 snprintf(dev->adapter.name, sizeof(dev->adapter.name), 252 "i2c-tiny-usb at bus %03d device %03d", 253 dev->usb_dev->bus->busnum, dev->usb_dev->devnum); 254 255 if (usb_write(&dev->adapter, CMD_SET_DELAY, delay, 0, NULL, 0) != 0) { 256 dev_err(&dev->adapter.dev, 257 "failure setting delay to %dus\n", delay); 258 retval = -EIO; 259 goto error; 260 } 261 262 dev->adapter.dev.parent = &dev->interface->dev; 263 264 /* and finally attach to i2c layer */ 265 i2c_add_adapter(&dev->adapter); 266 267 /* inform user about successful attachment to i2c layer */ 268 dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n"); 269 270 return 0; 271 272 error: 273 if (dev) 274 i2c_tiny_usb_free(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 i2c_tiny_usb_free(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