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