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/smp_lock.h>
  19 #include <linux/errno.h>
  20 #include <linux/kernel.h>
  21 #include <linux/fs.h>
  22 #include <linux/string.h>
  23 #include <linux/init.h>
  24
  25 #include <asm/etraxi2c.h>
  26
  27 #include <asm/system.h>
  28 #include <arch/svinto.h>
  29 #include <asm/io.h>
  30 #include <asm/delay.h>
  31 #include <arch/io_interface_mux.h>
  32
  33 #include "i2c.h"
  34
  35 /****************** I2C DEFINITION SECTION *************************/
  36
  37 #define D(x)
  38
  39 #define I2C_MAJOR 123  /* LOCAL/EXPERIMENTAL */
  40 static const char i2c_name[] = "i2c";
  41
  42 #define CLOCK_LOW_TIME            8
  43 #define CLOCK_HIGH_TIME           8
  44 #define START_CONDITION_HOLD_TIME 8
  45 #define STOP_CONDITION_HOLD_TIME  8
  46 #define ENABLE_OUTPUT 0x01
  47 #define ENABLE_INPUT 0x00
  48 #define I2C_CLOCK_HIGH 1
  49 #define I2C_CLOCK_LOW 0
  50 #define I2C_DATA_HIGH 1
  51 #define I2C_DATA_LOW 0
  52
  53 #ifdef CONFIG_ETRAX_I2C_USES_PB_NOT_PB_I2C
  54 /* Use PB and not PB_I2C */
  55 #ifndef CONFIG_ETRAX_I2C_DATA_PORT
  56 #define CONFIG_ETRAX_I2C_DATA_PORT 0
  57 #endif
  58 #ifndef CONFIG_ETRAX_I2C_CLK_PORT
  59 #define CONFIG_ETRAX_I2C_CLK_PORT 1
  60 #endif
  61
  62 #define SDABIT CONFIG_ETRAX_I2C_DATA_PORT
  63 #define SCLBIT CONFIG_ETRAX_I2C_CLK_PORT
  64 #define i2c_enable()
  65 #define i2c_disable()
  66
  67 /* enable or disable output-enable, to select output or input on the i2c bus */
  68
  69 #define i2c_dir_out() \
  70   REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, SDABIT, 1)
  71 #define i2c_dir_in()  \
  72   REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, SDABIT, 0)
  73
  74 /* control the i2c clock and data signals */
  75
  76 #define i2c_clk(x) \
  77   REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, SCLBIT, x)
  78 #define i2c_data(x) \
  79   REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, SDABIT, x)
  80
  81 /* read a bit from the i2c interface */
  82
  83 #define i2c_getbit() (((*R_PORT_PB_READ & (1 << SDABIT))) >> SDABIT)
  84
  85 #else
  86 /* enable or disable the i2c interface */
  87
  88 #define i2c_enable() *R_PORT_PB_I2C = (port_pb_i2c_shadow |= IO_MASK(R_PORT_PB_I2C, i2c_en))
  89 #define i2c_disable() *R_PORT_PB_I2C = (port_pb_i2c_shadow &= ~IO_MASK(R_PORT_PB_I2C, i2c_en))
  90
  91 /* enable or disable output-enable, to select output or input on the i2c bus */
  92
  93 #define i2c_dir_out() \
  94         *R_PORT_PB_I2C = (port_pb_i2c_shadow &= ~IO_MASK(R_PORT_PB_I2C, i2c_oe_)); \
  95         REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, 0, 1);
  96 #define i2c_dir_in() \
  97         *R_PORT_PB_I2C = (port_pb_i2c_shadow |= IO_MASK(R_PORT_PB_I2C, i2c_oe_)); \
  98         REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, 0, 0);
  99
 100 /* control the i2c clock and data signals */
 101
 102 #define i2c_clk(x) \
 103         *R_PORT_PB_I2C = (port_pb_i2c_shadow = (port_pb_i2c_shadow & \
 104        ~IO_MASK(R_PORT_PB_I2C, i2c_clk)) | IO_FIELD(R_PORT_PB_I2C, i2c_clk, (x))); \
 105        REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, 1, x);
 106
 107 #define i2c_data(x) \
 108         *R_PORT_PB_I2C = (port_pb_i2c_shadow = (port_pb_i2c_shadow & \
 109            ~IO_MASK(R_PORT_PB_I2C, i2c_d)) | IO_FIELD(R_PORT_PB_I2C, i2c_d, (x))); \
 110         REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, 0, x);
 111
 112 /* read a bit from the i2c interface */
 113
 114 #define i2c_getbit() (*R_PORT_PB_READ & 0x1)
 115 #endif
 116
 117 /* use the kernels delay routine */
 118
 119 #define i2c_delay(usecs) udelay(usecs)
 120
 121 static DEFINE_SPINLOCK(i2c_lock); /* Protect directions etc */
 122
 123 /****************** FUNCTION DEFINITION SECTION *************************/
 124
 125
 126 /* generate i2c start condition */
 127
 128 void
 129 i2c_start(void)
 130 {
 131         /*
 132          * SCL=1 SDA=1
 133          */
 134         i2c_dir_out();
 135         i2c_delay(CLOCK_HIGH_TIME/6);
 136         i2c_data(I2C_DATA_HIGH);
 137         i2c_clk(I2C_CLOCK_HIGH);
 138         i2c_delay(CLOCK_HIGH_TIME);
 139         /*
 140          * SCL=1 SDA=0
 141          */
 142         i2c_data(I2C_DATA_LOW);
 143         i2c_delay(START_CONDITION_HOLD_TIME);
 144         /*
 145          * SCL=0 SDA=0
 146          */
 147         i2c_clk(I2C_CLOCK_LOW);
 148         i2c_delay(CLOCK_LOW_TIME);
 149 }
 150
 151 /* generate i2c stop condition */
 152
 153 void
 154 i2c_stop(void)
 155 {
 156         i2c_dir_out();
 157
 158         /*
 159          * SCL=0 SDA=0
 160          */
 161         i2c_clk(I2C_CLOCK_LOW);
 162         i2c_data(I2C_DATA_LOW);
 163         i2c_delay(CLOCK_LOW_TIME*2);
 164         /*
 165          * SCL=1 SDA=0
 166          */
 167         i2c_clk(I2C_CLOCK_HIGH);
 168         i2c_delay(CLOCK_HIGH_TIME*2);
 169         /*
 170          * SCL=1 SDA=1
 171          */
 172         i2c_data(I2C_DATA_HIGH);
 173         i2c_delay(STOP_CONDITION_HOLD_TIME);
 174
 175         i2c_dir_in();
 176 }
 177
 178 /* write a byte to the i2c interface */
 179
 180 void
 181 i2c_outbyte(unsigned char x)
 182 {
 183         int i;
 184
 185         i2c_dir_out();
 186
 187         for (i = 0; i < 8; i++) {
 188                 if (x & 0x80) {
 189                         i2c_data(I2C_DATA_HIGH);
 190                 } else {
 191                         i2c_data(I2C_DATA_LOW);
 192                 }
 193
 194                 i2c_delay(CLOCK_LOW_TIME/2);
 195                 i2c_clk(I2C_CLOCK_HIGH);
 196                 i2c_delay(CLOCK_HIGH_TIME);
 197                 i2c_clk(I2C_CLOCK_LOW);
 198                 i2c_delay(CLOCK_LOW_TIME/2);
 199                 x <<= 1;
 200         }
 201         i2c_data(I2C_DATA_LOW);
 202         i2c_delay(CLOCK_LOW_TIME/2);
 203
 204         /*
 205          * enable input
 206          */
 207         i2c_dir_in();
 208 }
 209
 210 /* read a byte from the i2c interface */
 211
 212 unsigned char
 213 i2c_inbyte(void)
 214 {
 215         unsigned char aBitByte = 0;
 216         int i;
 217
 218         /* Switch off I2C to get bit */
 219         i2c_disable();
 220         i2c_dir_in();
 221         i2c_delay(CLOCK_HIGH_TIME/2);
 222
 223         /* Get bit */
 224         aBitByte |= i2c_getbit();
 225
 226         /* Enable I2C */
 227         i2c_enable();
 228         i2c_delay(CLOCK_LOW_TIME/2);
 229
 230         for (i = 1; i < 8; i++) {
 231                 aBitByte <<= 1;
 232                 /* Clock pulse */
 233                 i2c_clk(I2C_CLOCK_HIGH);
 234                 i2c_delay(CLOCK_HIGH_TIME);
 235                 i2c_clk(I2C_CLOCK_LOW);
 236                 i2c_delay(CLOCK_LOW_TIME);
 237
 238                 /* Switch off I2C to get bit */
 239                 i2c_disable();
 240                 i2c_dir_in();
 241                 i2c_delay(CLOCK_HIGH_TIME/2);
 242
 243                 /* Get bit */
 244                 aBitByte |= i2c_getbit();
 245
 246                 /* Enable I2C */
 247                 i2c_enable();
 248                 i2c_delay(CLOCK_LOW_TIME/2);
 249         }
 250         i2c_clk(I2C_CLOCK_HIGH);
 251         i2c_delay(CLOCK_HIGH_TIME);
 252
 253         /*
 254          * we leave the clock low, getbyte is usually followed
 255          * by sendack/nack, they assume the clock to be low
 256          */
 257         i2c_clk(I2C_CLOCK_LOW);
 258         return aBitByte;
 259 }
 260
 261 /*#---------------------------------------------------------------------------
 262 *#
 263 *# FUNCTION NAME: i2c_getack
 264 *#
 265 *# DESCRIPTION  : checks if ack was received from ic2
 266 *#
 267 *#--------------------------------------------------------------------------*/
 268
 269 int
 270 i2c_getack(void)
 271 {
 272         int ack = 1;
 273         /*
 274          * enable output
 275          */
 276         i2c_dir_out();
 277         /*
 278          * Release data bus by setting
 279          * data high
 280          */
 281         i2c_data(I2C_DATA_HIGH);
 282         /*
 283          * enable input
 284          */
 285         i2c_dir_in();
 286         i2c_delay(CLOCK_HIGH_TIME/4);
 287         /*
 288          * generate ACK clock pulse
 289          */
 290         i2c_clk(I2C_CLOCK_HIGH);
 291         /*
 292          * Use PORT PB instead of I2C
 293          * for input. (I2C not working)
 294          */
 295         i2c_clk(1);
 296         i2c_data(1);
 297         /*
 298          * switch off I2C
 299          */
 300         i2c_data(1);
 301         i2c_disable();
 302         i2c_dir_in();
 303         /*
 304          * now wait for ack
 305          */
 306         i2c_delay(CLOCK_HIGH_TIME/2);
 307         /*
 308          * check for ack
 309          */
 310         if(i2c_getbit())
 311                 ack = 0;
 312         i2c_delay(CLOCK_HIGH_TIME/2);
 313         if(!ack){
 314                 if(!i2c_getbit()) /* receiver pulld SDA low */
 315                         ack = 1;
 316                 i2c_delay(CLOCK_HIGH_TIME/2);
 317         }
 318
 319         /*
 320          * our clock is high now, make sure data is low
 321          * before we enable our output. If we keep data high
 322          * and enable output, we would generate a stop condition.
 323          */
 324         i2c_data(I2C_DATA_LOW);
 325
 326         /*
 327          * end clock pulse
 328          */
 329         i2c_enable();
 330         i2c_dir_out();
 331         i2c_clk(I2C_CLOCK_LOW);
 332         i2c_delay(CLOCK_HIGH_TIME/4);
 333         /*
 334          * enable output
 335          */
 336         i2c_dir_out();
 337         /*
 338          * remove ACK clock pulse
 339          */
 340         i2c_data(I2C_DATA_HIGH);
 341         i2c_delay(CLOCK_LOW_TIME/2);
 342         return ack;
 343 }
 344
 345 /*#---------------------------------------------------------------------------
 346 *#
 347 *# FUNCTION NAME: I2C::sendAck
 348 *#
 349 *# DESCRIPTION  : Send ACK on received data
 350 *#
 351 *#--------------------------------------------------------------------------*/
 352 void
 353 i2c_sendack(void)
 354 {
 355         /*
 356          * enable output
 357          */
 358         i2c_delay(CLOCK_LOW_TIME);
 359         i2c_dir_out();
 360         /*
 361          * set ack pulse high
 362          */
 363         i2c_data(I2C_DATA_LOW);
 364         /*
 365          * generate clock pulse
 366          */
 367         i2c_delay(CLOCK_HIGH_TIME/6);
 368         i2c_clk(I2C_CLOCK_HIGH);
 369         i2c_delay(CLOCK_HIGH_TIME);
 370         i2c_clk(I2C_CLOCK_LOW);
 371         i2c_delay(CLOCK_LOW_TIME/6);
 372         /*
 373          * reset data out
 374          */
 375         i2c_data(I2C_DATA_HIGH);
 376         i2c_delay(CLOCK_LOW_TIME);
 377
 378         i2c_dir_in();
 379 }
 380
 381 /*#---------------------------------------------------------------------------
 382 *#
 383 *# FUNCTION NAME: i2c_sendnack
 384 *#
 385 *# DESCRIPTION  : Sends NACK on received data
 386 *#
 387 *#--------------------------------------------------------------------------*/
 388 void
 389 i2c_sendnack(void)
 390 {
 391         /*
 392          * enable output
 393          */
 394         i2c_delay(CLOCK_LOW_TIME);
 395         i2c_dir_out();
 396         /*
 397          * set data high
 398          */
 399         i2c_data(I2C_DATA_HIGH);
 400         /*
 401          * generate clock pulse
 402          */
 403         i2c_delay(CLOCK_HIGH_TIME/6);
 404         i2c_clk(I2C_CLOCK_HIGH);
 405         i2c_delay(CLOCK_HIGH_TIME);
 406         i2c_clk(I2C_CLOCK_LOW);
 407         i2c_delay(CLOCK_LOW_TIME);
 408
 409         i2c_dir_in();
 410 }
 411
 412 /*#---------------------------------------------------------------------------
 413 *#
 414 *# FUNCTION NAME: i2c_writereg
 415 *#
 416 *# DESCRIPTION  : Writes a value to an I2C device
 417 *#
 418 *#--------------------------------------------------------------------------*/
 419 int
 420 i2c_writereg(unsigned char theSlave, unsigned char theReg,
 421              unsigned char theValue)
 422 {
 423         int error, cntr = 3;
 424         unsigned long flags;
 425
 426         spin_lock(&i2c_lock);
 427
 428         do {
 429                 error = 0;
 430                 /*
 431                  * we don't like to be interrupted
 432                  */
 433                 local_irq_save(flags);
 434
 435                 i2c_start();
 436                 /*
 437                  * send slave address
 438                  */
 439                 i2c_outbyte((theSlave & 0xfe));
 440                 /*
 441                  * wait for ack
 442                  */
 443                 if(!i2c_getack())
 444                         error = 1;
 445                 /*
 446                  * now select register
 447                  */
 448                 i2c_dir_out();
 449                 i2c_outbyte(theReg);
 450                 /*
 451                  * now it's time to wait for ack
 452                  */
 453                 if(!i2c_getack())
 454                         error |= 2;
 455                 /*
 456                  * send register register data
 457                  */
 458                 i2c_outbyte(theValue);
 459                 /*
 460                  * now it's time to wait for ack
 461                  */
 462                 if(!i2c_getack())
 463                         error |= 4;
 464                 /*
 465                  * end byte stream
 466                  */
 467                 i2c_stop();
 468                 /*
 469                  * enable interrupt again
 470                  */
 471                 local_irq_restore(flags);
 472
 473         } while(error && cntr--);
 474
 475         i2c_delay(CLOCK_LOW_TIME);
 476
 477         spin_unlock(&i2c_lock);
 478
 479         return -error;
 480 }
 481
 482 /*#---------------------------------------------------------------------------
 483 *#
 484 *# FUNCTION NAME: i2c_readreg
 485 *#
 486 *# DESCRIPTION  : Reads a value from the decoder registers.
 487 *#
 488 *#--------------------------------------------------------------------------*/
 489 unsigned char
 490 i2c_readreg(unsigned char theSlave, unsigned char theReg)
 491 {
 492         unsigned char b = 0;
 493         int error, cntr = 3;
 494         unsigned long flags;
 495
 496         spin_lock(&i2c_lock);
 497
 498         do {
 499                 error = 0;
 500                 /*
 501                  * we don't like to be interrupted
 502                  */
 503                 local_irq_save(flags);
 504                 /*
 505                  * generate start condition
 506                  */
 507                 i2c_start();
 508
 509                 /*
 510                  * send slave address
 511                  */
 512                 i2c_outbyte((theSlave & 0xfe));
 513                 /*
 514                  * wait for ack
 515                  */
 516                 if(!i2c_getack())
 517                         error = 1;
 518                 /*
 519                  * now select register
 520                  */
 521                 i2c_dir_out();
 522                 i2c_outbyte(theReg);
 523                 /*
 524                  * now it's time to wait for ack
 525                  */
 526                 if(!i2c_getack())
 527                         error = 1;
 528                 /*
 529                  * repeat start condition
 530                  */
 531                 i2c_delay(CLOCK_LOW_TIME);
 532                 i2c_start();
 533                 /*
 534                  * send slave address
 535                  */
 536                 i2c_outbyte(theSlave | 0x01);
 537                 /*
 538                  * wait for ack
 539                  */
 540                 if(!i2c_getack())
 541                         error = 1;
 542                 /*
 543                  * fetch register
 544                  */
 545                 b = i2c_inbyte();
 546                 /*
 547                  * last received byte needs to be nacked
 548                  * instead of acked
 549                  */
 550                 i2c_sendnack();
 551                 /*
 552                  * end sequence
 553                  */
 554                 i2c_stop();
 555                 /*
 556                  * enable interrupt again
 557                  */
 558                 local_irq_restore(flags);
 559
 560         } while(error && cntr--);
 561
 562         spin_unlock(&i2c_lock);
 563
 564         return b;
 565 }
 566
 567 static int
 568 i2c_open(struct inode *inode, struct file *filp)
 569 {
 570         cycle_kernel_lock();
 571         return 0;
 572 }
 573
 574 static int
 575 i2c_release(struct inode *inode, struct file *filp)
 576 {
 577         return 0;
 578 }
 579
 580 /* Main device API. ioctl's to write or read to/from i2c registers.
 581  */
 582
 583 static int
 584 i2c_ioctl(struct inode *inode, struct file *file,
 585           unsigned int cmd, unsigned long arg)
 586 {
 587         if(_IOC_TYPE(cmd) != ETRAXI2C_IOCTYPE) {
 588                 return -EINVAL;
 589         }
 590
 591         switch (_IOC_NR(cmd)) {
 592                 case I2C_WRITEREG:
 593                         /* write to an i2c slave */
 594                         D(printk("i2cw %d %d %d\n",
 595                                  I2C_ARGSLAVE(arg),
 596                                  I2C_ARGREG(arg),
 597                                  I2C_ARGVALUE(arg)));
 598
 599                         return i2c_writereg(I2C_ARGSLAVE(arg),
 600                                             I2C_ARGREG(arg),
 601                                             I2C_ARGVALUE(arg));
 602                 case I2C_READREG:
 603                 {
 604                         unsigned char val;
 605                         /* read from an i2c slave */
 606                         D(printk("i2cr %d %d ",
 607                                 I2C_ARGSLAVE(arg),
 608                                 I2C_ARGREG(arg)));
 609                         val = i2c_readreg(I2C_ARGSLAVE(arg), I2C_ARGREG(arg));
 610                         D(printk("= %d\n", val));
 611                         return val;
 612                 }
 613                 default:
 614                         return -EINVAL;
 615
 616         }
 617
 618         return 0;
 619 }
 620
 621 static const struct file_operations i2c_fops = {
 622         .owner    = THIS_MODULE,
 623         .ioctl    = i2c_ioctl,
 624         .open     = i2c_open,
 625         .release  = i2c_release,
 626 };
 627
 628 int __init
 629 i2c_init(void)
 630 {
 631         static int res = 0;
 632         static int first = 1;
 633
 634         if (!first) {
 635                 return res;
 636         }
 637         first = 0;
 638
 639         /* Setup and enable the Port B I2C interface */
 640
 641 #ifndef CONFIG_ETRAX_I2C_USES_PB_NOT_PB_I2C
 642         if ((res = cris_request_io_interface(if_i2c, "I2C"))) {
 643                 printk(KERN_CRIT "i2c_init: Failed to get IO interface\n");
 644                 return res;
 645         }
 646
 647         *R_PORT_PB_I2C = port_pb_i2c_shadow |=
 648                 IO_STATE(R_PORT_PB_I2C, i2c_en,  on) |
 649                 IO_FIELD(R_PORT_PB_I2C, i2c_d,   1)  |
 650                 IO_FIELD(R_PORT_PB_I2C, i2c_clk, 1)  |
 651                 IO_STATE(R_PORT_PB_I2C, i2c_oe_, enable);
 652
 653         port_pb_dir_shadow &= ~IO_MASK(R_PORT_PB_DIR, dir0);
 654         port_pb_dir_shadow &= ~IO_MASK(R_PORT_PB_DIR, dir1);
 655
 656         *R_PORT_PB_DIR = (port_pb_dir_shadow |=
 657                           IO_STATE(R_PORT_PB_DIR, dir0, input)  |
 658                           IO_STATE(R_PORT_PB_DIR, dir1, output));
 659 #else
 660         if ((res = cris_io_interface_allocate_pins(if_i2c,
 661                                                    'b',
 662                                                    CONFIG_ETRAX_I2C_DATA_PORT,
 663                                                    CONFIG_ETRAX_I2C_DATA_PORT))) {
 664                 printk(KERN_WARNING "i2c_init: Failed to get IO pin for I2C data port\n");
 665                 return res;
 666         } else if ((res = cris_io_interface_allocate_pins(if_i2c,
 667                                                           'b',
 668                                                           CONFIG_ETRAX_I2C_CLK_PORT,
 669                                                           CONFIG_ETRAX_I2C_CLK_PORT))) {
 670                 cris_io_interface_free_pins(if_i2c,
 671                                             'b',
 672                                             CONFIG_ETRAX_I2C_DATA_PORT,
 673                                             CONFIG_ETRAX_I2C_DATA_PORT);
 674                 printk(KERN_WARNING "i2c_init: Failed to get IO pin for I2C clk port\n");
 675         }
 676 #endif
 677
 678         return res;
 679 }
 680
 681 static int __init
 682 i2c_register(void)
 683 {
 684         int res;
 685
 686         res = i2c_init();
 687         if (res < 0)
 688                 return res;
 689         res = register_chrdev(I2C_MAJOR, i2c_name, &i2c_fops);
 690         if(res < 0) {
 691                 printk(KERN_ERR "i2c: couldn't get a major number.\n");
 692                 return res;
 693         }
 694
 695         printk(KERN_INFO "I2C driver v2.2, (c) 1999-2004 Axis Communications AB\n");
 696
 697         return 0;
 698 }
 699
 700 /* this makes sure that i2c_register is called during boot */
 701
 702 module_init(i2c_register);
 703
 704 /****************** END OF FILE i2c.c ********************************/