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  *    Copyright (C) 2008 Pengutronix
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; either version 2 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 #include <linux/kernel.h>
  22 #include <linux/module.h>
  23 #include <linux/moduleparam.h>
  24 #include <linux/delay.h>
  25 #include <linux/init.h>
  26 #include <linux/errno.h>
  27 #include <linux/i2c.h>
  28 #include <linux/i2c-algo-pca.h>
  29
  30 #define DEB1(fmt, args...) do { if (i2c_debug>=1) printk(fmt, ## args); } while(0)
  31 #define DEB2(fmt, args...) do { if (i2c_debug>=2) printk(fmt, ## args); } while(0)
  32 #define DEB3(fmt, args...) do { if (i2c_debug>=3) printk(fmt, ## args); } while(0)
  33
  34 static int i2c_debug;
  35
  36 #define pca_outw(adap, reg, val) adap->write_byte(adap->data, reg, val)
  37 #define pca_inw(adap, reg) adap->read_byte(adap->data, reg)
  38
  39 #define pca_status(adap) pca_inw(adap, I2C_PCA_STA)
  40 #define pca_clock(adap) adap->i2c_clock
  41 #define pca_set_con(adap, val) pca_outw(adap, I2C_PCA_CON, val)
  42 #define pca_get_con(adap) pca_inw(adap, I2C_PCA_CON)
  43 #define pca_wait(adap) adap->wait_for_completion(adap->data)
  44 #define pca_reset(adap) adap->reset_chip(adap->data)
  45
  46 /*
  47  * Generate a start condition on the i2c bus.
  48  *
  49  * returns after the start condition has occurred
  50  */
  51 static void pca_start(struct i2c_algo_pca_data *adap)
  52 {
  53         int sta = pca_get_con(adap);
  54         DEB2("=== START\n");
  55         sta |= I2C_PCA_CON_STA;
  56         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
  57         pca_set_con(adap, sta);
  58         pca_wait(adap);
  59 }
  60
  61 /*
  62  * Generate a repeated start condition on the i2c bus
  63  *
  64  * return after the repeated start condition has occurred
  65  */
  66 static void pca_repeated_start(struct i2c_algo_pca_data *adap)
  67 {
  68         int sta = pca_get_con(adap);
  69         DEB2("=== REPEATED START\n");
  70         sta |= I2C_PCA_CON_STA;
  71         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
  72         pca_set_con(adap, sta);
  73         pca_wait(adap);
  74 }
  75
  76 /*
  77  * Generate a stop condition on the i2c bus
  78  *
  79  * returns after the stop condition has been generated
  80  *
  81  * STOPs do not generate an interrupt or set the SI flag, since the
  82  * part returns the idle state (0xf8). Hence we don't need to
  83  * pca_wait here.
  84  */
  85 static void pca_stop(struct i2c_algo_pca_data *adap)
  86 {
  87         int sta = pca_get_con(adap);
  88         DEB2("=== STOP\n");
  89         sta |= I2C_PCA_CON_STO;
  90         sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI);
  91         pca_set_con(adap, sta);
  92 }
  93
  94 /*
  95  * Send the slave address and R/W bit
  96  *
  97  * returns after the address has been sent
  98  */
  99 static void pca_address(struct i2c_algo_pca_data *adap,
 100                         struct i2c_msg *msg)
 101 {
 102         int sta = pca_get_con(adap);
 103         int addr;
 104
 105         addr = ( (0x7f & msg->addr) << 1 );
 106         if (msg->flags & I2C_M_RD )
 107                 addr |= 1;
 108         DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n",
 109              msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr);
 110
 111         pca_outw(adap, I2C_PCA_DAT, addr);
 112
 113         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 114         pca_set_con(adap, sta);
 115
 116         pca_wait(adap);
 117 }
 118
 119 /*
 120  * Transmit a byte.
 121  *
 122  * Returns after the byte has been transmitted
 123  */
 124 static void pca_tx_byte(struct i2c_algo_pca_data *adap,
 125                         __u8 b)
 126 {
 127         int sta = pca_get_con(adap);
 128         DEB2("=== WRITE %#04x\n", b);
 129         pca_outw(adap, I2C_PCA_DAT, b);
 130
 131         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 132         pca_set_con(adap, sta);
 133
 134         pca_wait(adap);
 135 }
 136
 137 /*
 138  * Receive a byte
 139  *
 140  * returns immediately.
 141  */
 142 static void pca_rx_byte(struct i2c_algo_pca_data *adap,
 143                         __u8 *b, int ack)
 144 {
 145         *b = pca_inw(adap, I2C_PCA_DAT);
 146         DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK");
 147 }
 148
 149 /*
 150  * Setup ACK or NACK for next received byte and wait for it to arrive.
 151  *
 152  * Returns after next byte has arrived.
 153  */
 154 static void pca_rx_ack(struct i2c_algo_pca_data *adap,
 155                        int ack)
 156 {
 157         int sta = pca_get_con(adap);
 158
 159         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA);
 160
 161         if ( ack )
 162                 sta |= I2C_PCA_CON_AA;
 163
 164         pca_set_con(adap, sta);
 165         pca_wait(adap);
 166 }
 167
 168 static int pca_xfer(struct i2c_adapter *i2c_adap,
 169                     struct i2c_msg *msgs,
 170                     int num)
 171 {
 172         struct i2c_algo_pca_data *adap = i2c_adap->algo_data;
 173         struct i2c_msg *msg = NULL;
 174         int curmsg;
 175         int numbytes = 0;
 176         int state;
 177         int ret;
 178         int timeout = i2c_adap->timeout;
 179
 180         while ((state = pca_status(adap)) != 0xf8 && timeout--) {
 181                 msleep(10);
 182         }
 183         if (state != 0xf8) {
 184                 dev_dbg(&i2c_adap->dev, "bus is not idle. status is %#04x\n", state);
 185                 return -EAGAIN;
 186         }
 187
 188         DEB1("{{{ XFER %d messages\n", num);
 189
 190         if (i2c_debug>=2) {
 191                 for (curmsg = 0; curmsg < num; curmsg++) {
 192                         int addr, i;
 193                         msg = &msgs[curmsg];
 194
 195                         addr = (0x7f & msg->addr) ;
 196
 197                         if (msg->flags & I2C_M_RD )
 198                                 printk(KERN_INFO "    [%02d] RD %d bytes from %#02x [%#02x, ...]\n",
 199                                        curmsg, msg->len, addr, (addr<<1) | 1);
 200                         else {
 201                                 printk(KERN_INFO "    [%02d] WR %d bytes to %#02x [%#02x%s",
 202                                        curmsg, msg->len, addr, addr<<1,
 203                                        msg->len == 0 ? "" : ", ");
 204                                 for(i=0; i < msg->len; i++)
 205                                         printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
 206                                 printk("]\n");
 207                         }
 208                 }
 209         }
 210
 211         curmsg = 0;
 212         ret = -EREMOTEIO;
 213         while (curmsg < num) {
 214                 state = pca_status(adap);
 215
 216                 DEB3("STATE is 0x%02x\n", state);
 217                 msg = &msgs[curmsg];
 218
 219                 switch (state) {
 220                 case 0xf8: /* On reset or stop the bus is idle */
 221                         pca_start(adap);
 222                         break;
 223
 224                 case 0x08: /* A START condition has been transmitted */
 225                 case 0x10: /* A repeated start condition has been transmitted */
 226                         pca_address(adap, msg);
 227                         break;
 228
 229                 case 0x18: /* SLA+W has been transmitted; ACK has been received */
 230                 case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
 231                         if (numbytes < msg->len) {
 232                                 pca_tx_byte(adap, msg->buf[numbytes]);
 233                                 numbytes++;
 234                                 break;
 235                         }
 236                         curmsg++; numbytes = 0;
 237                         if (curmsg == num)
 238                                 pca_stop(adap);
 239                         else
 240                                 pca_repeated_start(adap);
 241                         break;
 242
 243                 case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
 244                         DEB2("NOT ACK received after SLA+W\n");
 245                         pca_stop(adap);
 246                         goto out;
 247
 248                 case 0x40: /* SLA+R has been transmitted; ACK has been received */
 249                         pca_rx_ack(adap, msg->len > 1);
 250                         break;
 251
 252                 case 0x50: /* Data bytes has been received; ACK has been returned */
 253                         if (numbytes < msg->len) {
 254                                 pca_rx_byte(adap, &msg->buf[numbytes], 1);
 255                                 numbytes++;
 256                                 pca_rx_ack(adap, numbytes < msg->len - 1);
 257                                 break;
 258                         }
 259                         curmsg++; numbytes = 0;
 260                         if (curmsg == num)
 261                                 pca_stop(adap);
 262                         else
 263                                 pca_repeated_start(adap);
 264                         break;
 265
 266                 case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
 267                         DEB2("NOT ACK received after SLA+R\n");
 268                         pca_stop(adap);
 269                         goto out;
 270
 271                 case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
 272                         DEB2("NOT ACK received after data byte\n");
 273                         goto out;
 274
 275                 case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
 276                         DEB2("Arbitration lost\n");
 277                         goto out;
 278
 279                 case 0x58: /* Data byte has been received; NOT ACK has been returned */
 280                         if ( numbytes == msg->len - 1 ) {
 281                                 pca_rx_byte(adap, &msg->buf[numbytes], 0);
 282                                 curmsg++; numbytes = 0;
 283                                 if (curmsg == num)
 284                                         pca_stop(adap);
 285                                 else
 286                                         pca_repeated_start(adap);
 287                         } else {
 288                                 DEB2("NOT ACK sent after data byte received. "
 289                                      "Not final byte. numbytes %d. len %d\n",
 290                                      numbytes, msg->len);
 291                                 pca_stop(adap);
 292                                 goto out;
 293                         }
 294                         break;
 295                 case 0x70: /* Bus error - SDA stuck low */
 296                         DEB2("BUS ERROR - SDA Stuck low\n");
 297                         pca_reset(adap);
 298                         goto out;
 299                 case 0x90: /* Bus error - SCL stuck low */
 300                         DEB2("BUS ERROR - SCL Stuck low\n");
 301                         pca_reset(adap);
 302                         goto out;
 303                 case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
 304                         DEB2("BUS ERROR - Illegal START or STOP\n");
 305                         pca_reset(adap);
 306                         goto out;
 307                 default:
 308                         dev_err(&i2c_adap->dev, "unhandled SIO state 0x%02x\n", state);
 309                         break;
 310                 }
 311
 312         }
 313
 314         ret = curmsg;
 315  out:
 316         DEB1(KERN_CRIT "}}} transfered %d/%d messages. "
 317              "status is %#04x. control is %#04x\n",
 318              curmsg, num, pca_status(adap),
 319              pca_get_con(adap));
 320         return ret;
 321 }
 322
 323 static u32 pca_func(struct i2c_adapter *adap)
 324 {
 325         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 326 }
 327
 328 static const struct i2c_algorithm pca_algo = {
 329         .master_xfer    = pca_xfer,
 330         .functionality  = pca_func,
 331 };
 332
 333 static int pca_init(struct i2c_adapter *adap)
 334 {
 335         static int freqs[] = {330,288,217,146,88,59,44,36};
 336         int clock;
 337         struct i2c_algo_pca_data *pca_data = adap->algo_data;
 338
 339         if (pca_data->i2c_clock > 7) {
 340                 printk(KERN_WARNING "%s: Invalid I2C clock speed selected. Trying default.\n",
 341                         adap->name);
 342                 pca_data->i2c_clock = I2C_PCA_CON_59kHz;
 343         }
 344
 345         adap->algo = &pca_algo;
 346
 347         pca_reset(pca_data);
 348
 349         clock = pca_clock(pca_data);
 350         DEB1(KERN_INFO "%s: Clock frequency is %dkHz\n", adap->name, freqs[clock]);
 351
 352         pca_set_con(pca_data, I2C_PCA_CON_ENSIO | clock);
 353         udelay(500); /* 500 us for oscilator to stabilise */
 354
 355         return 0;
 356 }
 357
 358 /*
 359  * registering functions to load algorithms at runtime
 360  */
 361 int i2c_pca_add_bus(struct i2c_adapter *adap)
 362 {
 363         int rval;
 364
 365         rval = pca_init(adap);
 366         if (rval)
 367                 return rval;
 368
 369         return i2c_add_adapter(adap);
 370 }
 371 EXPORT_SYMBOL(i2c_pca_add_bus);
 372
 373 int i2c_pca_add_numbered_bus(struct i2c_adapter *adap)
 374 {
 375         int rval;
 376
 377         rval = pca_init(adap);
 378         if (rval)
 379                 return rval;
 380
 381         return i2c_add_numbered_adapter(adap);
 382 }
 383 EXPORT_SYMBOL(i2c_pca_add_numbered_bus);
 384
 385 MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>, "
 386         "Wolfram Sang <w.sang@pengutronix.de>");
 387 MODULE_DESCRIPTION("I2C-Bus PCA9564 algorithm");
 388 MODULE_LICENSE("GPL");
 389
 390 module_param(i2c_debug, int, 0);