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