git.zerfleddert.de Git - rsbs2/blob - bmc/i2c.c

   1 #include <util/twi.h>
   2 #include <avr/interrupt.h>
   3 #include <stdio.h>
   4 #include "i2c.h"
   5 #include "bmc.h"
   6 #include "ipmb.h"
   7
   8 #define TWCR_ACK TWCR = (1<<TWEN)|(1<<TWIE)|(1<<TWINT)|(1<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|(0<<TWWC);
   9 #define TWCR_NACK TWCR = (1<<TWEN)|(1<<TWIE)|(1<<TWINT)|(0<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|(0<<TWWC);
  10 #define TWCR_RESET TWCR = (1<<TWEN)|(1<<TWIE)|(1<<TWINT)|(1<<TWEA)|(0<<TWSTA)|(1<<TWSTO)|(0<<TWWC);
  11
  12 volatile unsigned char i2c_databuf[24];
  13 volatile uint8_t i2c_len = 0x00;
  14 static volatile uint8_t i2c_pos = 0x00;
  15 volatile uint8_t i2c_done = 0x00;
  16
  17 void i2c_init()
  18 {
  19         TWBR = 0xff;
  20         TWAR = BMC_ADDR & 0xfe;
  21         TWDR = 0x00;
  22         TWCR &= ~((1<<TWSTA) | (1<<TWSTO));
  23         TWCR |= ((1<<TWEA) | (1<<TWEN) | (1<<TWIE));
  24 #ifdef __AVR_ATmega16__
  25         PORTC = 0x03;
  26 #else
  27 #error "Don't know how to set pullups for this chip, please add support"
  28 #endif
  29 }
  30
  31 void i2c_send(unsigned char *buf, int len)
  32 {
  33         uint8_t old_TWCR = TWCR;
  34         uint8_t old_SREG = SREG;
  35         int i;
  36
  37         cli();
  38
  39         TWCR = ((1<<TWINT) | (1<<TWSTA) | (1<<TWEN)); /* Send start */
  40
  41         while(!(TWCR & (1<<TWINT))) {}
  42         if (TW_STATUS != TW_START) {
  43 #ifdef DEBUG
  44                 printf("I2C: error sending START\n");
  45 #endif
  46                 goto out;
  47         }
  48
  49         TWDR = buf[0]; /* SLA_W */
  50         TWCR = ((1<<TWINT) | (1<<TWEN));
  51
  52         while(!(TWCR & (1<<TWINT))) {}
  53         if (TW_STATUS != TW_MT_SLA_ACK) {
  54 #ifdef DEBUG
  55                 printf("I2C: error sending SLA_W\n");
  56 #endif
  57                 goto out2;
  58         }
  59
  60         for(i = 1; i < len; i++) {
  61                 TWDR = buf[i]; /* Send Data */
  62                 TWCR = ((1<<TWINT) | (1<<TWEN));
  63
  64                 while(!(TWCR & (1<<TWINT))) {}
  65                 if (TW_STATUS != TW_MT_DATA_ACK) {
  66 #ifdef DEBUG
  67                         printf("I2C: error sending DATA byte %d\n", i);
  68 #endif
  69                         goto out2;
  70                 }
  71         }
  72
  73 #ifdef DEBUG
  74         printf("I2C Data sent\n");
  75 #endif
  76
  77 out2:
  78         TWCR = ((1<<TWINT) | (1<<TWEN) | (1<<TWSTO));
  79         while(TWCR & (1<<TWSTO)) {}
  80
  81 out:
  82         SREG = old_SREG;
  83         TWCR = old_TWCR | (1<<TWINT);
  84 }
  85
  86 ISR (TWI_vect, ISR_BLOCK)
  87 {
  88         if (i2c_done)
  89                 TWCR_RESET;
  90
  91         switch (TW_STATUS) {
  92                 case TW_SR_SLA_ACK:
  93 #ifdef DEBUG
  94                         printf("I2C: Slave 0x%02x adressed\n", TWDR);
  95 #endif
  96                         i2c_pos = 0x00;
  97                         i2c_databuf[i2c_pos] = TWDR;
  98                         i2c_pos++;
  99                         TWCR_ACK;
 100                         break;
 101
 102                 case TW_SR_DATA_ACK:
 103 #ifdef DEBUG
 104                         printf("I2C: Data received: 0x%02x\n", TWDR);
 105 #endif
 106                         if (i2c_pos >= sizeof(i2c_databuf)) {
 107                                 TWCR_RESET;
 108                                 i2c_pos = 0x00;
 109                                 break;
 110                         }
 111                         i2c_databuf[i2c_pos] = TWDR;
 112                         i2c_pos++;
 113                         TWCR_ACK;
 114                         break;
 115
 116                 case TW_SR_STOP:
 117 #ifdef DEBUG
 118                         printf("I2C: STOP received\n");
 119 #endif
 120                         i2c_len = i2c_pos;
 121                         i2c_pos = 0x00;
 122                         i2c_done = 0x01;
 123                         TWCR_RESET;
 124                         break;
 125
 126                 case TW_NO_INFO:
 127 #ifdef DEBUG
 128                         printf("I2C: TW_NO_INFO received status 0x%2x\n", TW_STATUS);
 129 #endif
 130                         TWCR |= (1<<TWINT);
 131                         break;
 132
 133                 default:
 134 #ifdef DEBUG
 135                         printf("I2C: Unimplemented status 0x%02x\n", TW_STATUS);
 136 #endif
 137                         TWCR_RESET;
 138                         break;
 139         }
 140 }