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 dev_dbg(&adapter->dev, "master xfer %d messages:\n", num); 58 59 pstatus = kmalloc(sizeof(*pstatus), GFP_KERNEL); 60 if (!pstatus) 61 return -ENOMEM; 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 ret = -EREMOTEIO; 88 goto out; 89 } 90 } else { 91 /* write data */ 92 if (usb_write(adapter, cmd, 93 pmsg->flags, pmsg->addr, 94 pmsg->buf, pmsg->len) != pmsg->len) { 95 dev_err(&adapter->dev, 96 "failure writing data\n"); 97 ret = -EREMOTEIO; 98 goto out; 99 } 100 } 101 102 /* read status */ 103 if (usb_read(adapter, CMD_GET_STATUS, 0, 0, pstatus, 1) != 1) { 104 dev_err(&adapter->dev, "failure reading status\n"); 105 ret = -EREMOTEIO; 106 goto out; 107 } 108 109 dev_dbg(&adapter->dev, " status = %d\n", *pstatus); 110 if (*pstatus == STATUS_ADDRESS_NAK) { 111 ret = -EREMOTEIO; 112 goto out; 113 } 114 } 115 116 ret = i; 117 out: 118 kfree(pstatus); 119 return ret; 120 } 121 122 static u32 usb_func(struct i2c_adapter *adapter) 123 { 124 __le32 *pfunc; 125 u32 ret; 126 127 pfunc = kmalloc(sizeof(*pfunc), GFP_KERNEL); 128 129 /* get functionality from adapter */ 130 if (!pfunc || usb_read(adapter, CMD_GET_FUNC, 0, 0, pfunc, 131 sizeof(*pfunc)) != sizeof(*pfunc)) { 132 dev_err(&adapter->dev, "failure reading functionality\n"); 133 ret = 0; 134 goto out; 135 } 136 137 ret = le32_to_cpup(pfunc); 138 out: 139 kfree(pfunc); 140 return ret; 141 } 142 143 /* This is the actual algorithm we define */ 144 static const struct i2c_algorithm usb_algorithm = { 145 .master_xfer = usb_xfer, 146 .functionality = usb_func, 147 }; 148 149 /* ----- end of i2c layer ------------------------------------------------ */ 150 151 /* ----- begin of usb layer ---------------------------------------------- */ 152 153 /* 154 * Initially the usb i2c interface uses a vid/pid pair donated by 155 * Future Technology Devices International Ltd., later a pair was 156 * bought from EZPrototypes 157 */ 158 static const struct usb_device_id i2c_tiny_usb_table[] = { 159 { USB_DEVICE(0x0403, 0xc631) }, /* FTDI */ 160 { USB_DEVICE(0x1c40, 0x0534) }, /* EZPrototypes */ 161 { } /* Terminating entry */ 162 }; 163 164 MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table); 165 166 /* Structure to hold all of our device specific stuff */ 167 struct i2c_tiny_usb { 168 struct usb_device *usb_dev; /* the usb device for this device */ 169 struct usb_interface *interface; /* the interface for this device */ 170 struct i2c_adapter adapter; /* i2c related things */ 171 }; 172 173 static int usb_read(struct i2c_adapter *adapter, int cmd, 174 int value, int index, void *data, int len) 175 { 176 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data; 177 void *dmadata = kmalloc(len, GFP_KERNEL); 178 int ret; 179 180 if (!dmadata) 181 return -ENOMEM; 182 183 /* do control transfer */ 184 ret = usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0), 185 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE | 186 USB_DIR_IN, value, index, dmadata, len, 2000); 187 188 memcpy(data, dmadata, len); 189 kfree(dmadata); 190 return ret; 191 } 192 193 static int usb_write(struct i2c_adapter *adapter, int cmd, 194 int value, int index, void *data, int len) 195 { 196 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data; 197 void *dmadata = kmemdup(data, len, GFP_KERNEL); 198 int ret; 199 200 if (!dmadata) 201 return -ENOMEM; 202 203 /* do control transfer */ 204 ret = usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0), 205 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE, 206 value, index, dmadata, len, 2000); 207 208 kfree(dmadata); 209 return ret; 210 } 211 212 static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev) 213 { 214 usb_put_dev(dev->usb_dev); 215 kfree(dev); 216 } 217 218 static int i2c_tiny_usb_probe(struct usb_interface *interface, 219 const struct usb_device_id *id) 220 { 221 struct i2c_tiny_usb *dev; 222 int retval = -ENOMEM; 223 u16 version; 224 225 dev_dbg(&interface->dev, "probing usb device\n"); 226 227 /* allocate memory for our device state and initialize it */ 228 dev = kzalloc(sizeof(*dev), GFP_KERNEL); 229 if (dev == NULL) { 230 dev_err(&interface->dev, "Out of memory\n"); 231 goto error; 232 } 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