drivers/i2c/busses/i2c-taos-evm.c

   1 /*
   2  * Driver for the TAOS evaluation modules
   3  * These devices include an I2C master which can be controlled over the
   4  * serial port.
   5  *
   6  * Copyright (C) 2007 Jean Delvare <khali@linux-fr.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; version 2 of the License.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  20  */
  21
  22 #include <linux/delay.h>
  23 #include <linux/module.h>
  24 #include <linux/slab.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/input.h>
  27 #include <linux/serio.h>
  28 #include <linux/init.h>
  29 #include <linux/i2c.h>
  30
  31 #define TAOS_BUFFER_SIZE        63
  32
  33 #define TAOS_STATE_INIT         0
  34 #define TAOS_STATE_IDLE         1
  35 #define TAOS_STATE_EOFF         2
  36 #define TAOS_STATE_RECV         3
  37
  38 #define TAOS_CMD_RESET          0x12
  39 #define TAOS_CMD_ECHO_ON        '+'
  40 #define TAOS_CMD_ECHO_OFF       '-'
  41
  42 static DECLARE_WAIT_QUEUE_HEAD(wq);
  43
  44 struct taos_data {
  45         struct i2c_adapter adapter;
  46         struct i2c_client *client;
  47         int state;
  48         u8 addr;                /* last used address */
  49         unsigned char buffer[TAOS_BUFFER_SIZE];
  50         unsigned int pos;       /* position inside the buffer */
  51 };
  52
  53 /* TAOS TSL2550 EVM */
  54 static struct i2c_board_info tsl2550_info = {
  55         I2C_BOARD_INFO("tsl2550", 0x39),
  56 };
  57
  58 /* Instantiate i2c devices based on the adapter name */
  59 static struct i2c_client *taos_instantiate_device(struct i2c_adapter *adapter)
  60 {
  61         if (!strncmp(adapter->name, "TAOS TSL2550 EVM", 16)) {
  62                 dev_info(&adapter->dev, "Instantiating device %s at 0x%02x\n",
  63                         tsl2550_info.type, tsl2550_info.addr);
  64                 return i2c_new_device(adapter, &tsl2550_info);
  65         }
  66
  67         return NULL;
  68 }
  69
  70 static int taos_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
  71                            unsigned short flags, char read_write, u8 command,
  72                            int size, union i2c_smbus_data *data)
  73 {
  74         struct serio *serio = adapter->algo_data;
  75         struct taos_data *taos = serio_get_drvdata(serio);
  76         char *p;
  77
  78         /* Encode our transaction. "@" is for the device address, "$" for the
  79            SMBus command and "#" for the data. */
  80         p = taos->buffer;
  81
  82         /* The device remembers the last used address, no need to send it
  83            again if it's the same */
  84         if (addr != taos->addr)
  85                 p += sprintf(p, "@%02X", addr);
  86
  87         switch (size) {
  88         case I2C_SMBUS_BYTE:
  89                 if (read_write == I2C_SMBUS_WRITE)
  90                         sprintf(p, "$#%02X", command);
  91                 else
  92                         sprintf(p, "$");
  93                 break;
  94         case I2C_SMBUS_BYTE_DATA:
  95                 if (read_write == I2C_SMBUS_WRITE)
  96                         sprintf(p, "$%02X#%02X", command, data->byte);
  97                 else
  98                         sprintf(p, "$%02X", command);
  99                 break;
 100         default:
 101                 dev_warn(&adapter->dev, "Unsupported transaction %d\n", size);
 102                 return -EOPNOTSUPP;
 103         }
 104
 105         /* Send the transaction to the TAOS EVM */
 106         dev_dbg(&adapter->dev, "Command buffer: %s\n", taos->buffer);
 107         for (p = taos->buffer; *p; p++)
 108                 serio_write(serio, *p);
 109
 110         taos->addr = addr;
 111
 112         /* Start the transaction and read the answer */
 113         taos->pos = 0;
 114         taos->state = TAOS_STATE_RECV;
 115         serio_write(serio, read_write == I2C_SMBUS_WRITE ? '>' : '<');
 116         wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
 117                                          msecs_to_jiffies(150));
 118         if (taos->state != TAOS_STATE_IDLE
 119          || taos->pos != 5) {
 120                 dev_err(&adapter->dev, "Transaction timeout (pos=%d)\n",
 121                         taos->pos);
 122                 return -EIO;
 123         }
 124         dev_dbg(&adapter->dev, "Answer buffer: %s\n", taos->buffer);
 125
 126         /* Interpret the returned string */
 127         p = taos->buffer + 1;
 128         p[3] = '\0';
 129         if (!strcmp(p, "NAK"))
 130                 return -ENODEV;
 131
 132         if (read_write == I2C_SMBUS_WRITE) {
 133                 if (!strcmp(p, "ACK"))
 134                         return 0;
 135         } else {
 136                 if (p[0] == 'x') {
 137                         data->byte = simple_strtol(p + 1, NULL, 16);
 138                         return 0;
 139                 }
 140         }
 141
 142         return -EIO;
 143 }
 144
 145 static u32 taos_smbus_func(struct i2c_adapter *adapter)
 146 {
 147         return I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_BYTE_DATA;
 148 }
 149
 150 static const struct i2c_algorithm taos_algorithm = {
 151         .smbus_xfer     = taos_smbus_xfer,
 152         .functionality  = taos_smbus_func,
 153 };
 154
 155 static irqreturn_t taos_interrupt(struct serio *serio, unsigned char data,
 156                                   unsigned int flags)
 157 {
 158         struct taos_data *taos = serio_get_drvdata(serio);
 159
 160         switch (taos->state) {
 161         case TAOS_STATE_INIT:
 162                 taos->buffer[taos->pos++] = data;
 163                 if (data == ':'
 164                  || taos->pos == TAOS_BUFFER_SIZE - 1) {
 165                         taos->buffer[taos->pos] = '\0';
 166                         taos->state = TAOS_STATE_IDLE;
 167                         wake_up_interruptible(&wq);
 168                 }
 169                 break;
 170         case TAOS_STATE_EOFF:
 171                 taos->state = TAOS_STATE_IDLE;
 172                 wake_up_interruptible(&wq);
 173                 break;
 174         case TAOS_STATE_RECV:
 175                 taos->buffer[taos->pos++] = data;
 176                 if (data == ']') {
 177                         taos->buffer[taos->pos] = '\0';
 178                         taos->state = TAOS_STATE_IDLE;
 179                         wake_up_interruptible(&wq);
 180                 }
 181                 break;
 182         }
 183
 184         return IRQ_HANDLED;
 185 }
 186
 187 /* Extract the adapter name from the buffer received after reset.
 188    The buffer is modified and a pointer inside the buffer is returned. */
 189 static char *taos_adapter_name(char *buffer)
 190 {
 191         char *start, *end;
 192
 193         start = strstr(buffer, "TAOS ");
 194         if (!start)
 195                 return NULL;
 196
 197         end = strchr(start, '\r');
 198         if (!end)
 199                 return NULL;
 200         *end = '\0';
 201
 202         return start;
 203 }
 204
 205 static int taos_connect(struct serio *serio, struct serio_driver *drv)
 206 {
 207         struct taos_data *taos;
 208         struct i2c_adapter *adapter;
 209         char *name;
 210         int err;
 211
 212         taos = kzalloc(sizeof(struct taos_data), GFP_KERNEL);
 213         if (!taos) {
 214                 err = -ENOMEM;
 215                 goto exit;
 216         }
 217         taos->state = TAOS_STATE_INIT;
 218         serio_set_drvdata(serio, taos);
 219
 220         err = serio_open(serio, drv);
 221         if (err)
 222                 goto exit_kfree;
 223
 224         adapter = &taos->adapter;
 225         adapter->owner = THIS_MODULE;
 226         adapter->algo = &taos_algorithm;
 227         adapter->algo_data = serio;
 228         adapter->dev.parent = &serio->dev;
 229
 230         /* Reset the TAOS evaluation module to identify it */
 231         serio_write(serio, TAOS_CMD_RESET);
 232         wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
 233                                          msecs_to_jiffies(2000));
 234
 235         if (taos->state != TAOS_STATE_IDLE) {
 236                 err = -ENODEV;
 237                 dev_err(&serio->dev, "TAOS EVM reset failed (state=%d, "
 238                         "pos=%d)\n", taos->state, taos->pos);
 239                 goto exit_close;
 240         }
 241
 242         name = taos_adapter_name(taos->buffer);
 243         if (!name) {
 244                 err = -ENODEV;
 245                 dev_err(&serio->dev, "TAOS EVM identification failed\n");
 246                 goto exit_close;
 247         }
 248         strlcpy(adapter->name, name, sizeof(adapter->name));
 249
 250         /* Turn echo off for better performance */
 251         taos->state = TAOS_STATE_EOFF;
 252         serio_write(serio, TAOS_CMD_ECHO_OFF);
 253
 254         wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
 255                                          msecs_to_jiffies(250));
 256         if (taos->state != TAOS_STATE_IDLE) {
 257                 err = -ENODEV;
 258                 dev_err(&serio->dev, "TAOS EVM echo off failed "
 259                         "(state=%d)\n", taos->state);
 260                 goto exit_close;
 261         }
 262
 263         err = i2c_add_adapter(adapter);
 264         if (err)
 265                 goto exit_close;
 266         dev_info(&serio->dev, "Connected to TAOS EVM\n");
 267
 268         taos->client = taos_instantiate_device(adapter);
 269         return 0;
 270
 271  exit_close:
 272         serio_close(serio);
 273  exit_kfree:
 274         kfree(taos);
 275  exit:
 276         return err;
 277 }
 278
 279 static void taos_disconnect(struct serio *serio)
 280 {
 281         struct taos_data *taos = serio_get_drvdata(serio);
 282
 283         if (taos->client)
 284                 i2c_unregister_device(taos->client);
 285         i2c_del_adapter(&taos->adapter);
 286         serio_close(serio);
 287         kfree(taos);
 288
 289         dev_info(&serio->dev, "Disconnected from TAOS EVM\n");
 290 }
 291
 292 static struct serio_device_id taos_serio_ids[] = {
 293         {
 294                 .type   = SERIO_RS232,
 295                 .proto  = SERIO_TAOSEVM,
 296                 .id     = SERIO_ANY,
 297                 .extra  = SERIO_ANY,
 298         },
 299         { 0 }
 300 };
 301 MODULE_DEVICE_TABLE(serio, taos_serio_ids);
 302
 303 static struct serio_driver taos_drv = {
 304         .driver         = {
 305                 .name   = "taos-evm",
 306         },
 307         .description    = "TAOS evaluation module driver",
 308         .id_table       = taos_serio_ids,
 309         .connect        = taos_connect,
 310         .disconnect     = taos_disconnect,
 311         .interrupt      = taos_interrupt,
 312 };
 313
 314 static int __init taos_init(void)
 315 {
 316         return serio_register_driver(&taos_drv);
 317 }
 318
 319 static void __exit taos_exit(void)
 320 {
 321         serio_unregister_driver(&taos_drv);
 322 }
 323
 324 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
 325 MODULE_DESCRIPTION("TAOS evaluation module driver");
 326 MODULE_LICENSE("GPL");
 327
 328 module_init(taos_init);
 329 module_exit(taos_exit);