arch/cris/arch-v10/drivers/i2c.c

   1 /*!***************************************************************************
   2 *!
   3 *! FILE NAME  : i2c.c
   4 *!
   5 *! DESCRIPTION: implements an interface for IIC/I2C, both directly from other
   6 *!              kernel modules (i2c_writereg/readreg) and from userspace using
   7 *!              ioctl()'s
   8 *!
   9 *! (C) Copyright 1999-2007 Axis Communications AB, LUND, SWEDEN
  10 *!
  11 *!***************************************************************************/
  12
  13 /****************** INCLUDE FILES SECTION ***********************************/
  14
  15 #include <linux/module.h>
  16 #include <linux/sched.h>
  17 #include <linux/slab.h>
  18 #include <linux/errno.h>
  19 #include <linux/kernel.h>
  20 #include <linux/fs.h>
  21 #include <linux/string.h>
  22 #include <linux/init.h>
  23
  24 #include <asm/etraxi2c.h>
  25
  26 #include <asm/system.h>
  27 #include <asm/arch/svinto.h>
  28 #include <asm/io.h>
  29 #include <asm/delay.h>
  30 #include <asm/arch/io_interface_mux.h>
  31
  32 #include "i2c.h"
  33
  34 /****************** I2C DEFINITION SECTION *************************/
  35
  36 #define D(x)
  37
  38 #define I2C_MAJOR 123  /* LOCAL/EXPERIMENTAL */
  39 static const char i2c_name[] = "i2c";
  40
  41 #define CLOCK_LOW_TIME            8
  42 #define CLOCK_HIGH_TIME           8
  43 #define START_CONDITION_HOLD_TIME 8
  44 #define STOP_CONDITION_HOLD_TIME  8
  45 #define ENABLE_OUTPUT 0x01
  46 #define ENABLE_INPUT 0x00
  47 #define I2C_CLOCK_HIGH 1
  48 #define I2C_CLOCK_LOW 0
  49 #define I2C_DATA_HIGH 1
  50 #define I2C_DATA_LOW 0
  51
  52 #ifdef CONFIG_ETRAX_I2C_USES_PB_NOT_PB_I2C
  53 /* Use PB and not PB_I2C */
  54 #ifndef CONFIG_ETRAX_I2C_DATA_PORT
  55 #define CONFIG_ETRAX_I2C_DATA_PORT 0
  56 #endif
  57 #ifndef CONFIG_ETRAX_I2C_CLK_PORT
  58 #define CONFIG_ETRAX_I2C_CLK_PORT 1
  59 #endif
  60
  61 #define SDABIT CONFIG_ETRAX_I2C_DATA_PORT
  62 #define SCLBIT CONFIG_ETRAX_I2C_CLK_PORT
  63 #define i2c_enable()
  64 #define i2c_disable()
  65
  66 /* enable or disable output-enable, to select output or input on the i2c bus */
  67
  68 #define i2c_dir_out() \
  69   REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, SDABIT, 1)
  70 #define i2c_dir_in()  \
  71   REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, SDABIT, 0)
  72
  73 /* control the i2c clock and data signals */
  74
  75 #define i2c_clk(x) \
  76   REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, SCLBIT, x)
  77 #define i2c_data(x) \
  78   REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, SDABIT, x)
  79
  80 /* read a bit from the i2c interface */
  81
  82 #define i2c_getbit() (((*R_PORT_PB_READ & (1 << SDABIT))) >> SDABIT)
  83
  84 #else
  85 /* enable or disable the i2c interface */
  86
  87 #define i2c_enable() *R_PORT_PB_I2C = (port_pb_i2c_shadow |= IO_MASK(R_PORT_PB_I2C, i2c_en))
  88 #define i2c_disable() *R_PORT_PB_I2C = (port_pb_i2c_shadow &= ~IO_MASK(R_PORT_PB_I2C, i2c_en))
  89
  90 /* enable or disable output-enable, to select output or input on the i2c bus */
  91
  92 #define i2c_dir_out() \
  93         *R_PORT_PB_I2C = (port_pb_i2c_shadow &= ~IO_MASK(R_PORT_PB_I2C, i2c_oe_)); \
  94         REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, 0, 1);
  95 #define i2c_dir_in() \
  96         *R_PORT_PB_I2C = (port_pb_i2c_shadow |= IO_MASK(R_PORT_PB_I2C, i2c_oe_)); \
  97         REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, 0, 0);
  98
  99 /* control the i2c clock and data signals */
 100
 101 #define i2c_clk(x) \
 102         *R_PORT_PB_I2C = (port_pb_i2c_shadow = (port_pb_i2c_shadow & \
 103        ~IO_MASK(R_PORT_PB_I2C, i2c_clk)) | IO_FIELD(R_PORT_PB_I2C, i2c_clk, (x))); \
 104        REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, 1, x);
 105
 106 #define i2c_data(x) \
 107         *R_PORT_PB_I2C = (port_pb_i2c_shadow = (port_pb_i2c_shadow & \
 108            ~IO_MASK(R_PORT_PB_I2C, i2c_d)) | IO_FIELD(R_PORT_PB_I2C, i2c_d, (x))); \
 109         REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, 0, x);
 110
 111 /* read a bit from the i2c interface */
 112
 113 #define i2c_getbit() (*R_PORT_PB_READ & 0x1)
 114 #endif
 115
 116 /* use the kernels delay routine */
 117
 118 #define i2c_delay(usecs) udelay(usecs)
 119
 120 static DEFINE_SPINLOCK(i2c_lock); /* Protect directions etc */
 121
 122 /****************** FUNCTION DEFINITION SECTION *************************/
 123
 124
 125 /* generate i2c start condition */
 126
 127 void
 128 i2c_start(void)
 129 {
 130         /*
 131          * SCL=1 SDA=1
 132          */
 133         i2c_dir_out();
 134         i2c_delay(CLOCK_HIGH_TIME/6);
 135         i2c_data(I2C_DATA_HIGH);
 136         i2c_clk(I2C_CLOCK_HIGH);
 137         i2c_delay(CLOCK_HIGH_TIME);
 138         /*
 139          * SCL=1 SDA=0
 140          */
 141         i2c_data(I2C_DATA_LOW);
 142         i2c_delay(START_CONDITION_HOLD_TIME);
 143         /*
 144          * SCL=0 SDA=0
 145          */
 146         i2c_clk(I2C_CLOCK_LOW);
 147         i2c_delay(CLOCK_LOW_TIME);
 148 }
 149
 150 /* generate i2c stop condition */
 151
 152 void
 153 i2c_stop(void)
 154 {
 155         i2c_dir_out();
 156
 157         /*
 158          * SCL=0 SDA=0
 159          */
 160         i2c_clk(I2C_CLOCK_LOW);
 161         i2c_data(I2C_DATA_LOW);
 162         i2c_delay(CLOCK_LOW_TIME*2);
 163         /*
 164          * SCL=1 SDA=0
 165          */
 166         i2c_clk(I2C_CLOCK_HIGH);
 167         i2c_delay(CLOCK_HIGH_TIME*2);
 168         /*
 169          * SCL=1 SDA=1
 170          */
 171         i2c_data(I2C_DATA_HIGH);
 172         i2c_delay(STOP_CONDITION_HOLD_TIME);
 173
 174         i2c_dir_in();
 175 }
 176
 177 /* write a byte to the i2c interface */
 178
 179 void
 180 i2c_outbyte(unsigned char x)
 181 {
 182         int i;
 183
 184         i2c_dir_out();
 185
 186         for (i = 0; i < 8; i++) {
 187                 if (x & 0x80) {
 188                         i2c_data(I2C_DATA_HIGH);
 189                 } else {
 190                         i2c_data(I2C_DATA_LOW);
 191                 }
 192
 193                 i2c_delay(CLOCK_LOW_TIME/2);
 194                 i2c_clk(I2C_CLOCK_HIGH);
 195                 i2c_delay(CLOCK_HIGH_TIME);
 196                 i2c_clk(I2C_CLOCK_LOW);
 197                 i2c_delay(CLOCK_LOW_TIME/2);
 198                 x <<= 1;
 199         }
 200         i2c_data(I2C_DATA_LOW);
 201         i2c_delay(CLOCK_LOW_TIME/2);
 202
 203         /*
 204          * enable input
 205          */
 206         i2c_dir_in();
 207 }
 208
 209 /* read a byte from the i2c interface */
 210
 211 unsigned char
 212 i2c_inbyte(void)
 213 {
 214         unsigned char aBitByte = 0;
 215         int i;
 216
 217         /* Switch off I2C to get bit */
 218         i2c_disable();
 219         i2c_dir_in();
 220         i2c_delay(CLOCK_HIGH_TIME/2);
 221
 222         /* Get bit */
 223         aBitByte |= i2c_getbit();
 224
 225         /* Enable I2C */
 226         i2c_enable();
 227         i2c_delay(CLOCK_LOW_TIME/2);
 228
 229         for (i = 1; i < 8; i++) {
 230                 aBitByte <<= 1;
 231                 /* Clock pulse */
 232                 i2c_clk(I2C_CLOCK_HIGH);
 233                 i2c_delay(CLOCK_HIGH_TIME);
 234                 i2c_clk(I2C_CLOCK_LOW);
 235                 i2c_delay(CLOCK_LOW_TIME);
 236
 237                 /* Switch off I2C to get bit */
 238                 i2c_disable();
 239                 i2c_dir_in();
 240                 i2c_delay(CLOCK_HIGH_TIME/2);
 241
 242                 /* Get bit */
 243                 aBitByte |= i2c_getbit();
 244
 245                 /* Enable I2C */
 246                 i2c_enable();
 247                 i2c_delay(CLOCK_LOW_TIME/2);
 248         }
 249         i2c_clk(I2C_CLOCK_HIGH);
 250         i2c_delay(CLOCK_HIGH_TIME);
 251
 252         /*
 253          * we leave the clock low, getbyte is usually followed
 254          * by sendack/nack, they assume the clock to be low
 255          */
 256         i2c_clk(I2C_CLOCK_LOW);
 257         return aBitByte;
 258 }
 259
 260 /*#---------------------------------------------------------------------------
 261 *#
 262 *# FUNCTION NAME: i2c_getack
 263 *#
 264 *# DESCRIPTION  : checks if ack was received from ic2
 265 *#
 266 *#--------------------------------------------------------------------------*/
 267
 268 int
 269 i2c_getack(void)
 270 {
 271         int ack = 1;
 272         /*
 273          * enable output
 274          */
 275         i2c_dir_out();
 276         /*
 277          * Release data bus by setting
 278          * data high
 279          */
 280         i2c_data(I2C_DATA_HIGH);
 281         /*
 282          * enable input
 283          */
 284         i2c_dir_in();
 285         i2c_delay(CLOCK_HIGH_TIME/4);
 286         /*
 287          * generate ACK clock pulse
 288          */
 289         i2c_clk(I2C_CLOCK_HIGH);
 290         /*
 291          * Use PORT PB instead of I2C
 292          * for input. (I2C not working)
 293          */
 294         i2c_clk(1);
 295         i2c_data(1);
 296         /*
 297          * switch off I2C
 298          */
 299         i2c_data(1);
 300         i2c_disable();
 301         i2c_dir_in();
 302         /*
 303          * now wait for ack
 304          */
 305         i2c_delay(CLOCK_HIGH_TIME/2);
 306         /*
 307          * check for ack
 308          */
 309         if(i2c_getbit())
 310                 ack = 0;
 311         i2c_delay(CLOCK_HIGH_TIME/2);
 312         if(!ack){
 313                 if(!i2c_getbit()) /* receiver pulld SDA low */
 314                         ack = 1;
 315                 i2c_delay(CLOCK_HIGH_TIME/2);
 316         }
 317
 318         /*
 319          * our clock is high now, make sure data is low
 320          * before we enable our output. If we keep data high
 321          * and enable output, we would generate a stop condition.
 322          */
 323         i2c_data(I2C_DATA_LOW);
 324
 325         /*
 326          * end clock pulse
 327          */
 328         i2c_enable();
 329         i2c_dir_out();
 330         i2c_clk(I2C_CLOCK_LOW);
 331         i2c_delay(CLOCK_HIGH_TIME/4);
 332         /*
 333          * enable output
 334          */
 335         i2c_dir_out();
 336         /*
 337          * remove ACK clock pulse
 338          */
 339         i2c_data(I2C_DATA_HIGH);
 340         i2c_delay(CLOCK_LOW_TIME/2);
 341         return ack;
 342 }
 343
 344 /*#---------------------------------------------------------------------------
 345 *#
 346 *# FUNCTION NAME: I2C::sendAck
 347 *#
 348 *# DESCRIPTION  : Send ACK on received data
 349 *#
 350 *#--------------------------------------------------------------------------*/
 351 void
 352 i2c_sendack(void)
 353 {
 354         /*
 355          * enable output
 356          */
 357         i2c_delay(CLOCK_LOW_TIME);
 358         i2c_dir_out();
 359         /*
 360          * set ack pulse high
 361          */
 362         i2c_data(I2C_DATA_LOW);
 363         /*
 364          * generate clock pulse
 365          */
 366         i2c_delay(CLOCK_HIGH_TIME/6);
 367         i2c_clk(I2C_CLOCK_HIGH);
 368         i2c_delay(CLOCK_HIGH_TIME);
 369         i2c_clk(I2C_CLOCK_LOW);
 370         i2c_delay(CLOCK_LOW_TIME/6);
 371         /*
 372          * reset data out
 373          */
 374         i2c_data(I2C_DATA_HIGH);
 375         i2c_delay(CLOCK_LOW_TIME);
 376
 377         i2c_dir_in();
 378 }
 379
 380 /*#---------------------------------------------------------------------------
 381 *#
 382 *# FUNCTION NAME: i2c_sendnack
 383 *#
 384 *# DESCRIPTION  : Sends NACK on received data
 385 *#
 386 *#--------------------------------------------------------------------------*/
 387 void
 388 i2c_sendnack(void)
 389 {
 390         /*
 391          * enable output
 392          */
 393         i2c_delay(CLOCK_LOW_TIME);
 394         i2c_dir_out();
 395         /*
 396          * set data high
 397          */
 398         i2c_data(I2C_DATA_HIGH);
 399         /*
 400          * generate clock pulse
 401          */
 402         i2c_delay(CLOCK_HIGH_TIME/6);
 403         i2c_clk(I2C_CLOCK_HIGH);
 404         i2c_delay(CLOCK_HIGH_TIME);
 405         i2c_clk(I2C_CLOCK_LOW);
 406         i2c_delay(CLOCK_LOW_TIME);
 407
 408         i2c_dir_in();
 409 }
 410
 411 /*#---------------------------------------------------------------------------
 412 *#
 413 *# FUNCTION NAME: i2c_writereg
 414 *#
 415 *# DESCRIPTION  : Writes a value to an I2C device
 416 *#
 417 *#--------------------------------------------------------------------------*/
 418 int
 419 i2c_writereg(unsigned char theSlave, unsigned char theReg,
 420              unsigned char theValue)
 421 {
 422         int error, cntr = 3;
 423         unsigned long flags;
 424
 425         spin_lock(&i2c_lock);
 426
 427         do {
 428                 error = 0;
 429                 /*
 430                  * we don't like to be interrupted
 431                  */
 432                 local_irq_save(flags);
 433
 434                 i2c_start();
 435                 /*
 436                  * send slave address
 437                  */
 438                 i2c_outbyte((theSlave & 0xfe));
 439                 /*
 440                  * wait for ack
 441                  */
 442                 if(!i2c_getack())
 443                         error = 1;
 444                 /*
 445                  * now select register
 446                  */
 447                 i2c_dir_out();
 448                 i2c_outbyte(theReg);
 449                 /*
 450                  * now it's time to wait for ack
 451                  */
 452                 if(!i2c_getack())
 453                         error |= 2;
 454                 /*
 455                  * send register register data
 456                  */
 457                 i2c_outbyte(theValue);
 458                 /*
 459                  * now it's time to wait for ack
 460                  */
 461                 if(!i2c_getack())
 462                         error |= 4;
 463                 /*
 464                  * end byte stream
 465                  */
 466                 i2c_stop();
 467                 /*
 468                  * enable interrupt again
 469                  */
 470                 local_irq_restore(flags);
 471
 472         } while(error && cntr--);
 473
 474         i2c_delay(CLOCK_LOW_TIME);
 475
 476         spin_unlock(&i2c_lock);
 477
 478         return -error;
 479 }
 480
 481 /*#---------------------------------------------------------------------------
 482 *#
 483 *# FUNCTION NAME: i2c_readreg
 484 *#
 485 *# DESCRIPTION  : Reads a value from the decoder registers.
 486 *#
 487 *#--------------------------------------------------------------------------*/
 488 unsigned char
 489 i2c_readreg(unsigned char theSlave, unsigned char theReg)
 490 {
 491         unsigned char b = 0;
 492         int error, cntr = 3;
 493         unsigned long flags;
 494
 495         spin_lock(&i2c_lock);
 496
 497         do {
 498                 error = 0;
 499                 /*
 500                  * we don't like to be interrupted
 501                  */
 502                 local_irq_save(flags);
 503                 /*
 504                  * generate start condition
 505                  */
 506                 i2c_start();
 507
 508                 /*
 509                  * send slave address
 510                  */
 511                 i2c_outbyte((theSlave & 0xfe));
 512                 /*
 513                  * wait for ack
 514                  */
 515                 if(!i2c_getack())
 516                         error = 1;
 517                 /*
 518                  * now select register
 519                  */
 520                 i2c_dir_out();
 521                 i2c_outbyte(theReg);
 522                 /*
 523                  * now it's time to wait for ack
 524                  */
 525                 if(!i2c_getack())
 526                         error = 1;
 527                 /*
 528                  * repeat start condition
 529                  */
 530                 i2c_delay(CLOCK_LOW_TIME);
 531                 i2c_start();
 532                 /*
 533                  * send slave address
 534                  */
 535                 i2c_outbyte(theSlave | 0x01);
 536                 /*
 537                  * wait for ack
 538                  */
 539                 if(!i2c_getack())
 540                         error = 1;
 541                 /*
 542                  * fetch register
 543                  */
 544                 b = i2c_inbyte();
 545                 /*
 546                  * last received byte needs to be nacked
 547                  * instead of acked
 548                  */
 549                 i2c_sendnack();
 550                 /*
 551                  * end sequence
 552                  */
 553                 i2c_stop();
 554                 /*
 555                  * enable interrupt again
 556                  */
 557                 local_irq_restore(flags);
 558
 559         } while(error && cntr--);
 560
 561         spin_unlock(&i2c_lock);
 562
 563         return b;
 564 }
 565
 566 static int
 567 i2c_open(struct inode *inode, struct file *filp)
 568 {
 569         return 0;
 570 }
 571
 572 static int
 573 i2c_release(struct inode *inode, struct file *filp)
 574 {
 575         return 0;
 576 }
 577
 578 /* Main device API. ioctl's to write or read to/from i2c registers.
 579  */
 580
 581 static int
 582 i2c_ioctl(struct inode *inode, struct file *file,
 583           unsigned int cmd, unsigned long arg)
 584 {
 585         if(_IOC_TYPE(cmd) != ETRAXI2C_IOCTYPE) {
 586                 return -EINVAL;
 587         }
 588
 589         switch (_IOC_NR(cmd)) {
 590                 case I2C_WRITEREG:
 591                         /* write to an i2c slave */
 592                         D(printk("i2cw %d %d %d\n",
 593                                  I2C_ARGSLAVE(arg),
 594                                  I2C_ARGREG(arg),
 595                                  I2C_ARGVALUE(arg)));
 596
 597                         return i2c_writereg(I2C_ARGSLAVE(arg),
 598                                             I2C_ARGREG(arg),
 599                                             I2C_ARGVALUE(arg));
 600                 case I2C_READREG:
 601                 {
 602                         unsigned char val;
 603                         /* read from an i2c slave */
 604                         D(printk("i2cr %d %d ",
 605                                 I2C_ARGSLAVE(arg),
 606                                 I2C_ARGREG(arg)));
 607                         val = i2c_readreg(I2C_ARGSLAVE(arg), I2C_ARGREG(arg));
 608                         D(printk("= %d\n", val));
 609                         return val;
 610                 }
 611                 default:
 612                         return -EINVAL;
 613
 614         }
 615
 616         return 0;
 617 }
 618
 619 static const struct file_operations i2c_fops = {
 620         .owner    = THIS_MODULE,
 621         .ioctl    = i2c_ioctl,
 622         .open     = i2c_open,
 623         .release  = i2c_release,
 624 };
 625
 626 int __init
 627 i2c_init(void)
 628 {
 629         static int res = 0;
 630         static int first = 1;
 631
 632         if (!first) {
 633                 return res;
 634         }
 635         first = 0;
 636
 637         /* Setup and enable the Port B I2C interface */
 638
 639 #ifndef CONFIG_ETRAX_I2C_USES_PB_NOT_PB_I2C
 640         if ((res = cris_request_io_interface(if_i2c, "I2C"))) {
 641                 printk(KERN_CRIT "i2c_init: Failed to get IO interface\n");
 642                 return res;
 643         }
 644
 645         *R_PORT_PB_I2C = port_pb_i2c_shadow |=
 646                 IO_STATE(R_PORT_PB_I2C, i2c_en,  on) |
 647                 IO_FIELD(R_PORT_PB_I2C, i2c_d,   1)  |
 648                 IO_FIELD(R_PORT_PB_I2C, i2c_clk, 1)  |
 649                 IO_STATE(R_PORT_PB_I2C, i2c_oe_, enable);
 650
 651         port_pb_dir_shadow &= ~IO_MASK(R_PORT_PB_DIR, dir0);
 652         port_pb_dir_shadow &= ~IO_MASK(R_PORT_PB_DIR, dir1);
 653
 654         *R_PORT_PB_DIR = (port_pb_dir_shadow |=
 655                           IO_STATE(R_PORT_PB_DIR, dir0, input)  |
 656                           IO_STATE(R_PORT_PB_DIR, dir1, output));
 657 #else
 658         if ((res = cris_io_interface_allocate_pins(if_i2c,
 659                                                    'b',
 660                                                    CONFIG_ETRAX_I2C_DATA_PORT,
 661                                                    CONFIG_ETRAX_I2C_DATA_PORT))) {
 662                 printk(KERN_WARNING "i2c_init: Failed to get IO pin for I2C data port\n");
 663                 return res;
 664         } else if ((res = cris_io_interface_allocate_pins(if_i2c,
 665                                                           'b',
 666                                                           CONFIG_ETRAX_I2C_CLK_PORT,
 667                                                           CONFIG_ETRAX_I2C_CLK_PORT))) {
 668                 cris_io_interface_free_pins(if_i2c,
 669                                             'b',
 670                                             CONFIG_ETRAX_I2C_DATA_PORT,
 671                                             CONFIG_ETRAX_I2C_DATA_PORT);
 672                 printk(KERN_WARNING "i2c_init: Failed to get IO pin for I2C clk port\n");
 673         }
 674 #endif
 675
 676         return res;
 677 }
 678
 679 static int __init
 680 i2c_register(void)
 681 {
 682         int res;
 683
 684         res = i2c_init();
 685         if (res < 0)
 686                 return res;
 687         res = register_chrdev(I2C_MAJOR, i2c_name, &i2c_fops);
 688         if(res < 0) {
 689                 printk(KERN_ERR "i2c: couldn't get a major number.\n");
 690                 return res;
 691         }
 692
 693         printk(KERN_INFO "I2C driver v2.2, (c) 1999-2004 Axis Communications AB\n");
 694
 695         return 0;
 696 }
 697
 698 /* this makes sure that i2c_register is called during boot */
 699
 700 module_init(i2c_register);
 701
 702 /****************** END OF FILE i2c.c ********************************/