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 & 0xf8) != TW_START)
  43                 goto out;
  44
  45         TWDR = buf[0]; /* SLA_W */
  46         TWCR = ((1<<TWINT) | (1<<TWEN));
  47
  48         while(!(TWCR & (1<<TWINT))) {}
  49         if ((TW_STATUS & 0xf8) != TW_MT_SLA_ACK)
  50                 goto out;
  51
  52         for(i = 1; i < len; i++) {
  53                 TWDR = buf[i]; /* Send Data */
  54                 TWCR = ((1<<TWINT) | (1<<TWEN));
  55
  56                 while(!(TWCR & (1<<TWINT))) {}
  57                 if ((TW_STATUS & 0xf8) != TW_MT_DATA_ACK)
  58                         goto out;
  59         }
  60
  61         TWCR = ((1<<TWINT) | (1<<TWEN) | (1<<TWSTO));
  62         while(TWCR & (1<<TWSTO)) {}
  63
  64 #ifdef DEBUG
  65         printf("I2C Data sent\n");
  66 #endif
  67
  68 out:
  69         TWDR = 0x00;
  70         TWCR = old_TWCR;
  71         SREG = old_SREG;
  72 }
  73
  74 ISR (TWI_vect, ISR_BLOCK)
  75 {
  76         if (i2c_done)
  77                 TWCR_RESET;
  78
  79         switch (TW_STATUS & 0xf8) {
  80                 case TW_SR_SLA_ACK:
  81 #ifdef DEBUG
  82                         printf("I2C: Slave 0x%02x adressed\n", TWDR);
  83 #endif
  84                         i2c_pos = 0x00;
  85                         i2c_databuf[i2c_pos] = TWDR;
  86                         i2c_pos++;
  87                         TWCR_ACK;
  88                         break;
  89
  90                 case TW_SR_DATA_ACK:
  91 #ifdef DEBUG
  92                         printf("I2C: Data received: 0x%02x\n", TWDR);
  93 #endif
  94                         if (i2c_pos >= sizeof(i2c_databuf)) {
  95                                 TWCR_RESET;
  96                                 i2c_pos = 0x00;
  97                                 break;
  98                         }
  99                         i2c_databuf[i2c_pos] = TWDR;
 100                         i2c_pos++;
 101                         TWCR_ACK;
 102                         break;
 103
 104                 case TW_SR_STOP:
 105 #ifdef DEBUG
 106                         printf("I2C: STOP received\n");
 107 #endif
 108                         i2c_len = i2c_pos;
 109                         i2c_pos = 0x00;
 110                         i2c_done = 0x01;
 111                         TWCR_RESET;
 112                         break;
 113
 114                 default:
 115 #ifdef DEBUG
 116                         printf("I2C: Unimplemented status 0x%02x\n", (TW_STATUS & 0xf8));
 117 #endif
 118                         TWCR_RESET;
 119                         break;
 120         }
 121 }