drivers/i2c/algos/i2c-algo-pca.c

   1 /*
   2  *  i2c-algo-pca.c i2c driver algorithms for PCA9564 adapters
   3  *    Copyright (C) 2004 Arcom Control Systems
   4  *
   5  *  This program is free software; you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation; either version 2 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, write to the Free Software
  17  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18  */
  19
  20 #include <linux/kernel.h>
  21 #include <linux/module.h>
  22 #include <linux/moduleparam.h>
  23 #include <linux/delay.h>
  24 #include <linux/slab.h>
  25 #include <linux/init.h>
  26 #include <linux/errno.h>
  27 #include <linux/i2c.h>
  28 #include <linux/i2c-algo-pca.h>
  29 #include "i2c-algo-pca.h"
  30
  31 #define DRIVER "i2c-algo-pca"
  32
  33 #define DEB1(fmt, args...) do { if (i2c_debug>=1) printk(fmt, ## args); } while(0)
  34 #define DEB2(fmt, args...) do { if (i2c_debug>=2) printk(fmt, ## args); } while(0)
  35 #define DEB3(fmt, args...) do { if (i2c_debug>=3) printk(fmt, ## args); } while(0)
  36
  37 static int i2c_debug;
  38
  39 #define pca_outw(adap, reg, val) adap->write_byte(adap, reg, val)
  40 #define pca_inw(adap, reg) adap->read_byte(adap, reg)
  41
  42 #define pca_status(adap) pca_inw(adap, I2C_PCA_STA)
  43 #define pca_clock(adap) adap->get_clock(adap)
  44 #define pca_own(adap) adap->get_own(adap)
  45 #define pca_set_con(adap, val) pca_outw(adap, I2C_PCA_CON, val)
  46 #define pca_get_con(adap) pca_inw(adap, I2C_PCA_CON)
  47 #define pca_wait(adap) adap->wait_for_interrupt(adap)
  48
  49 /*
  50  * Generate a start condition on the i2c bus.
  51  *
  52  * returns after the start condition has occurred
  53  */
  54 static void pca_start(struct i2c_algo_pca_data *adap)
  55 {
  56         int sta = pca_get_con(adap);
  57         DEB2("=== START\n");
  58         sta |= I2C_PCA_CON_STA;
  59         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
  60         pca_set_con(adap, sta);
  61         pca_wait(adap);
  62 }
  63
  64 /*
  65  * Generate a repeated start condition on the i2c bus
  66  *
  67  * return after the repeated start condition has occurred
  68  */
  69 static void pca_repeated_start(struct i2c_algo_pca_data *adap)
  70 {
  71         int sta = pca_get_con(adap);
  72         DEB2("=== REPEATED START\n");
  73         sta |= I2C_PCA_CON_STA;
  74         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
  75         pca_set_con(adap, sta);
  76         pca_wait(adap);
  77 }
  78
  79 /*
  80  * Generate a stop condition on the i2c bus
  81  *
  82  * returns after the stop condition has been generated
  83  *
  84  * STOPs do not generate an interrupt or set the SI flag, since the
  85  * part returns the idle state (0xf8). Hence we don't need to
  86  * pca_wait here.
  87  */
  88 static void pca_stop(struct i2c_algo_pca_data *adap)
  89 {
  90         int sta = pca_get_con(adap);
  91         DEB2("=== STOP\n");
  92         sta |= I2C_PCA_CON_STO;
  93         sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI);
  94         pca_set_con(adap, sta);
  95 }
  96
  97 /*
  98  * Send the slave address and R/W bit
  99  *
 100  * returns after the address has been sent
 101  */
 102 static void pca_address(struct i2c_algo_pca_data *adap,
 103                         struct i2c_msg *msg)
 104 {
 105         int sta = pca_get_con(adap);
 106         int addr;
 107
 108         addr = ( (0x7f & msg->addr) << 1 );
 109         if (msg->flags & I2C_M_RD )
 110                 addr |= 1;
 111         DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n",
 112              msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr);
 113
 114         pca_outw(adap, I2C_PCA_DAT, addr);
 115
 116         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 117         pca_set_con(adap, sta);
 118
 119         pca_wait(adap);
 120 }
 121
 122 /*
 123  * Transmit a byte.
 124  *
 125  * Returns after the byte has been transmitted
 126  */
 127 static void pca_tx_byte(struct i2c_algo_pca_data *adap,
 128                         __u8 b)
 129 {
 130         int sta = pca_get_con(adap);
 131         DEB2("=== WRITE %#04x\n", b);
 132         pca_outw(adap, I2C_PCA_DAT, b);
 133
 134         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 135         pca_set_con(adap, sta);
 136
 137         pca_wait(adap);
 138 }
 139
 140 /*
 141  * Receive a byte
 142  *
 143  * returns immediately.
 144  */
 145 static void pca_rx_byte(struct i2c_algo_pca_data *adap,
 146                         __u8 *b, int ack)
 147 {
 148         *b = pca_inw(adap, I2C_PCA_DAT);
 149         DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK");
 150 }
 151
 152 /*
 153  * Setup ACK or NACK for next received byte and wait for it to arrive.
 154  *
 155  * Returns after next byte has arrived.
 156  */
 157 static void pca_rx_ack(struct i2c_algo_pca_data *adap,
 158                        int ack)
 159 {
 160         int sta = pca_get_con(adap);
 161
 162         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA);
 163
 164         if ( ack )
 165                 sta |= I2C_PCA_CON_AA;
 166
 167         pca_set_con(adap, sta);
 168         pca_wait(adap);
 169 }
 170
 171 /*
 172  * Reset the i2c bus / SIO
 173  */
 174 static void pca_reset(struct i2c_algo_pca_data *adap)
 175 {
 176         /* apparently only an external reset will do it. not a lot can be done */
 177         printk(KERN_ERR DRIVER ": Haven't figured out how to do a reset yet\n");
 178 }
 179
 180 static int pca_xfer(struct i2c_adapter *i2c_adap,
 181                     struct i2c_msg *msgs,
 182                     int num)
 183 {
 184         struct i2c_algo_pca_data *adap = i2c_adap->algo_data;
 185         struct i2c_msg *msg = NULL;
 186         int curmsg;
 187         int numbytes = 0;
 188         int state;
 189         int ret;
 190         int timeout = 100;
 191
 192         while ((state = pca_status(adap)) != 0xf8 && timeout--) {
 193                 msleep(10);
 194         }
 195         if (state != 0xf8) {
 196                 dev_dbg(&i2c_adap->dev, "bus is not idle. status is %#04x\n", state);
 197                 return -EIO;
 198         }
 199
 200         DEB1("{{{ XFER %d messages\n", num);
 201
 202         if (i2c_debug>=2) {
 203                 for (curmsg = 0; curmsg < num; curmsg++) {
 204                         int addr, i;
 205                         msg = &msgs[curmsg];
 206
 207                         addr = (0x7f & msg->addr) ;
 208
 209                         if (msg->flags & I2C_M_RD )
 210                                 printk(KERN_INFO "    [%02d] RD %d bytes from %#02x [%#02x, ...]\n",
 211                                        curmsg, msg->len, addr, (addr<<1) | 1);
 212                         else {
 213                                 printk(KERN_INFO "    [%02d] WR %d bytes to %#02x [%#02x%s",
 214                                        curmsg, msg->len, addr, addr<<1,
 215                                        msg->len == 0 ? "" : ", ");
 216                                 for(i=0; i < msg->len; i++)
 217                                         printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
 218                                 printk("]\n");
 219                         }
 220                 }
 221         }
 222
 223         curmsg = 0;
 224         ret = -EREMOTEIO;
 225         while (curmsg < num) {
 226                 state = pca_status(adap);
 227
 228                 DEB3("STATE is 0x%02x\n", state);
 229                 msg = &msgs[curmsg];
 230
 231                 switch (state) {
 232                 case 0xf8: /* On reset or stop the bus is idle */
 233                         pca_start(adap);
 234                         break;
 235
 236                 case 0x08: /* A START condition has been transmitted */
 237                 case 0x10: /* A repeated start condition has been transmitted */
 238                         pca_address(adap, msg);
 239                         break;
 240
 241                 case 0x18: /* SLA+W has been transmitted; ACK has been received */
 242                 case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
 243                         if (numbytes < msg->len) {
 244                                 pca_tx_byte(adap, msg->buf[numbytes]);
 245                                 numbytes++;
 246                                 break;
 247                         }
 248                         curmsg++; numbytes = 0;
 249                         if (curmsg == num)
 250                                 pca_stop(adap);
 251                         else
 252                                 pca_repeated_start(adap);
 253                         break;
 254
 255                 case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
 256                         DEB2("NOT ACK received after SLA+W\n");
 257                         pca_stop(adap);
 258                         goto out;
 259
 260                 case 0x40: /* SLA+R has been transmitted; ACK has been received */
 261                         pca_rx_ack(adap, msg->len > 1);
 262                         break;
 263
 264                 case 0x50: /* Data bytes has been received; ACK has been returned */
 265                         if (numbytes < msg->len) {
 266                                 pca_rx_byte(adap, &msg->buf[numbytes], 1);
 267                                 numbytes++;
 268                                 pca_rx_ack(adap, numbytes < msg->len - 1);
 269                                 break;
 270                         }
 271                         curmsg++; numbytes = 0;
 272                         if (curmsg == num)
 273                                 pca_stop(adap);
 274                         else
 275                                 pca_repeated_start(adap);
 276                         break;
 277
 278                 case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
 279                         DEB2("NOT ACK received after SLA+R\n");
 280                         pca_stop(adap);
 281                         goto out;
 282
 283                 case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
 284                         DEB2("NOT ACK received after data byte\n");
 285                         goto out;
 286
 287                 case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
 288                         DEB2("Arbitration lost\n");
 289                         goto out;
 290
 291                 case 0x58: /* Data byte has been received; NOT ACK has been returned */
 292                         if ( numbytes == msg->len - 1 ) {
 293                                 pca_rx_byte(adap, &msg->buf[numbytes], 0);
 294                                 curmsg++; numbytes = 0;
 295                                 if (curmsg == num)
 296                                         pca_stop(adap);
 297                                 else
 298                                         pca_repeated_start(adap);
 299                         } else {
 300                                 DEB2("NOT ACK sent after data byte received. "
 301                                      "Not final byte. numbytes %d. len %d\n",
 302                                      numbytes, msg->len);
 303                                 pca_stop(adap);
 304                                 goto out;
 305                         }
 306                         break;
 307                 case 0x70: /* Bus error - SDA stuck low */
 308                         DEB2("BUS ERROR - SDA Stuck low\n");
 309                         pca_reset(adap);
 310                         goto out;
 311                 case 0x90: /* Bus error - SCL stuck low */
 312                         DEB2("BUS ERROR - SCL Stuck low\n");
 313                         pca_reset(adap);
 314                         goto out;
 315                 case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
 316                         DEB2("BUS ERROR - Illegal START or STOP\n");
 317                         pca_reset(adap);
 318                         goto out;
 319                 default:
 320                         printk(KERN_ERR DRIVER ": unhandled SIO state 0x%02x\n", state);
 321                         break;
 322                 }
 323
 324         }
 325
 326         ret = curmsg;
 327  out:
 328         DEB1(KERN_CRIT "}}} transfered %d/%d messages. "
 329              "status is %#04x. control is %#04x\n",
 330              curmsg, num, pca_status(adap),
 331              pca_get_con(adap));
 332         return ret;
 333 }
 334
 335 static u32 pca_func(struct i2c_adapter *adap)
 336 {
 337         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 338 }
 339
 340 static int pca_init(struct i2c_algo_pca_data *adap)
 341 {
 342         static int freqs[] = {330,288,217,146,88,59,44,36};
 343         int own, clock;
 344
 345         own = pca_own(adap);
 346         clock = pca_clock(adap);
 347         DEB1(KERN_INFO DRIVER ": own address is %#04x\n", own);
 348         DEB1(KERN_INFO DRIVER ": clock freqeuncy is %dkHz\n", freqs[clock]);
 349
 350         pca_outw(adap, I2C_PCA_ADR, own << 1);
 351
 352         pca_set_con(adap, I2C_PCA_CON_ENSIO | clock);
 353         udelay(500); /* 500 µs for oscilator to stabilise */
 354
 355         return 0;
 356 }
 357
 358 static const struct i2c_algorithm pca_algo = {
 359         .master_xfer    = pca_xfer,
 360         .functionality  = pca_func,
 361 };
 362
 363 /*
 364  * registering functions to load algorithms at runtime
 365  */
 366 int i2c_pca_add_bus(struct i2c_adapter *adap)
 367 {
 368         struct i2c_algo_pca_data *pca_adap = adap->algo_data;
 369         int rval;
 370
 371         /* register new adapter to i2c module... */
 372         adap->algo = &pca_algo;
 373
 374         adap->timeout = 100;            /* default values, should       */
 375         adap->retries = 3;              /* be replaced by defines       */
 376
 377         if ((rval = pca_init(pca_adap)))
 378                 return rval;
 379
 380         rval = i2c_add_adapter(adap);
 381
 382         return rval;
 383 }
 384 EXPORT_SYMBOL(i2c_pca_add_bus);
 385
 386 MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>");
 387 MODULE_DESCRIPTION("I2C-Bus PCA9564 algorithm");
 388 MODULE_LICENSE("GPL");
 389
 390 module_param(i2c_debug, int, 0);