firmware/target/arm/tms320dm320/i2c-dm320.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2008 by Maurus Cuelenaere
  11  *
  12  * DM320 I²C driver
  13  *
  14  * All files in this archive are subject to the GNU General Public License.
  15  * See the file COPYING in the source tree root for full license agreement.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21 #include "system.h"
  22 #include "thread.h"
  23 #include "i2c-dm320.h"
  24
  25 #define I2C_SCS_COND_START  0x0001
  26 #define I2C_SCS_COND_STOP   0x0002
  27 #define I2C_SCS_XMIT        0x0004
  28
  29 #define I2C_TX_ACK          (1 << 20)
  30
  31 static struct mutex i2c_mtx;
  32
  33 static inline void i2c_begin(void)
  34 {
  35     mutex_lock(&i2c_mtx);
  36 }
  37
  38 static inline void i2c_end(void)
  39 {
  40     mutex_unlock(&i2c_mtx);
  41 }
  42
  43 static inline bool i2c_getack(void)
  44 {
  45     return (IO_I2C_RXDATA & 0x100)>>8;
  46 }
  47
  48 #define WAIT_FOR_I2C    if(IO_I2C_SCS & 0x4){ \
  49                             while(IO_I2C_SCS & 0x4) { \
  50                                 asm volatile("nop"); \
  51                             } \
  52                         } \
  53
  54 static inline void i2c_start(void)
  55 {
  56     IO_I2C_SCS |= I2C_SCS_XMIT;
  57     return;
  58 }
  59
  60 int i2c_write(unsigned short address, const unsigned char *buf, int count)
  61 {
  62     int i;
  63     int ret=0;
  64     i2c_begin();
  65     IO_I2C_TXDATA = ( (address << 1) & 0xFF ) | (address>0x7F ? 0 : 1 ) | I2C_TX_ACK;
  66     IO_I2C_SCS &= ~0x3; //clear conditions
  67     IO_I2C_SCS |= I2C_SCS_COND_START; // write 'start condition'
  68     i2c_start();
  69     WAIT_FOR_I2C;
  70     /* experimental */
  71     if(address>0x7F){ // check if it is 10-bit instead of 7-bit
  72         IO_I2C_TXDATA = ( (address >> 7) & 0xFF) | I2C_TX_ACK;
  73         IO_I2C_SCS &= ~0x3; //normal transfer
  74         i2c_start();
  75         WAIT_FOR_I2C;
  76         IO_I2C_TXDATA = ( (address << 1) & 0xFF) | 1 | I2C_TX_ACK;
  77         IO_I2C_SCS &= ~0x3; //clear conditions
  78         IO_I2C_SCS |= I2C_SCS_COND_START; //write 'start condition'
  79         i2c_start();
  80         WAIT_FOR_I2C;
  81     }
  82
  83     for(i=0; i<count; i++){
  84         IO_I2C_TXDATA = buf[i] | I2C_TX_ACK;
  85         IO_I2C_SCS &= ~0x3; //normal transfer
  86         i2c_start();
  87         WAIT_FOR_I2C;
  88         if(!i2c_getack())
  89             ret = -1;
  90     }
  91     IO_I2C_SCS &= ~0x3; //clear conditions
  92     IO_I2C_SCS |= I2C_SCS_COND_STOP; //write 'stop condition'
  93     i2c_start();
  94     WAIT_FOR_I2C;
  95     i2c_end();
  96     return ret;
  97 }
  98
  99 int i2c_read(unsigned short address, unsigned char* buf, int count)
 100 {
 101     int i;
 102     int ack=0;
 103     i2c_begin();
 104     IO_I2C_TXDATA = ( (address << 1) & 0xFF ) | (address>0x7F ? 0 : 1 ) | I2C_TX_ACK;
 105     IO_I2C_SCS &= ~0x3; //clear conditions
 106     IO_I2C_SCS |= I2C_SCS_COND_START; // write 'start condition'
 107     i2c_start();
 108     WAIT_FOR_I2C;
 109     /* experimental */
 110     if(address>0x7F){ // check if it is 10-bit instead of 7-bit
 111         IO_I2C_TXDATA = ( (address >> 7) & 0xFF ) | I2C_TX_ACK;
 112         IO_I2C_SCS &= ~0x3; //normal transfer
 113         i2c_start();
 114         WAIT_FOR_I2C;
 115         IO_I2C_TXDATA = ( (address << 1) & 0xFF ) | 1 | I2C_TX_ACK;
 116         IO_I2C_SCS &= ~0x3; //clear conditions
 117         IO_I2C_SCS |= I2C_SCS_COND_START; //write 'start condition'
 118         i2c_start();
 119         WAIT_FOR_I2C;
 120     }
 121
 122     for(i=0; i<count; i++){
 123         unsigned short temp;
 124         IO_I2C_TXDATA = 0xFF | ( (count-1)==i ? I2C_TX_ACK : 0);
 125         IO_I2C_SCS &= ~0x3; //normal transfer
 126         i2c_start();
 127         WAIT_FOR_I2C;
 128         temp = IO_I2C_RXDATA;
 129         buf[i] = temp & 0xFF;
 130         ack = (temp & 0x100) >> 8;
 131     }
 132     IO_I2C_SCS &= ~0x3; //clear conditions
 133     IO_I2C_SCS |= I2C_SCS_COND_STOP; //write 'stop condition'
 134     i2c_start();
 135     WAIT_FOR_I2C;
 136     i2c_end();
 137     return ack;
 138 }
 139
 140 void i2c_init(void)
 141 {
 142 #if 0 //TODO: mimic OF I2C clock settings; currently this is done by the bootloader
 143     IO_CLK_MOD2 &= ~CLK_MOD2_I2C; // turn I²C clock off (just to be sure)
 144     IO_CLK_LPCTL1 &= ~1; // set Powerdown mode to off
 145     IO_CLK_SEL0 &= ~0x800; // set I²C clock to PLLA
 146     IO_CLK_DIV4 &= ~0x1F; // I²C clock division = 1
 147     IO_CLK_MOD2 |= CLK_MOD2_I2C; // enable I²C clock
 148 #endif
 149     IO_I2C_SCS &= ~0x8; //set clock to 100 kHz
 150     IO_INTC_EINT2 &= ~INTR_EINT2_I2C; // disable I²C interrupt
 151 }