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         PORTC = 0x03;
  25 }
  26
  27 void i2c_send(unsigned char *buf, int len)
  28 {
  29         uint8_t old_TWCR = TWCR;
  30         uint8_t old_SREG = SREG;
  31         int i;
  32
  33         cli();
  34
  35         TWCR = ((1<<TWINT) | (1<<TWSTA) | (1<<TWEN)); /* Send start */
  36
  37         while(!(TWCR & (1<<TWINT))) {}
  38         if ((TW_STATUS & 0xf8) != TW_START)
  39                 goto out;
  40
  41         TWDR = buf[0]; /* SLA_W */
  42         TWCR = ((1<<TWINT) | (1<<TWEN));
  43
  44         while(!(TWCR & (1<<TWINT))) {}
  45         if ((TW_STATUS & 0xf8) != TW_MT_SLA_ACK)
  46                 goto out;
  47
  48         for(i = 1; i < len; i++) {
  49                 TWDR = buf[i]; /* Send Data */
  50                 TWCR = ((1<<TWINT) | (1<<TWEN));
  51
  52                 while(!(TWCR & (1<<TWINT))) {}
  53                 if ((TW_STATUS & 0xf8) != TW_MT_DATA_ACK)
  54                         goto out;
  55         }
  56
  57         TWCR = ((1<<TWINT) | (1<<TWEN) | (1<<TWSTO));
  58         while(TWCR & (1<<TWSTO)) {}
  59
  60 #ifdef DEBUG
  61         printf("I2C Data sent\n");
  62 #endif
  63
  64 out:
  65         TWDR = 0x00;
  66         TWCR = old_TWCR;
  67         SREG = old_SREG;
  68 }
  69
  70 ISR (TWI_vect, ISR_BLOCK)
  71 {
  72         if (i2c_done)
  73                 TWCR_RESET;
  74
  75         switch (TW_STATUS) {
  76                 case TW_SR_SLA_ACK:
  77 #ifdef DEBUG
  78                         printf("I2C: Slave 0x%02x adressed\n", TWDR);
  79 #endif
  80                         i2c_pos = 0x00;
  81                         i2c_databuf[i2c_pos] = TWDR;
  82                         i2c_pos++;
  83                         TWCR_ACK;
  84                         break;
  85
  86                 case TW_SR_DATA_ACK:
  87 #ifdef DEBUG
  88                         printf("I2C: Data received: 0x%02x\n", TWDR);
  89 #endif
  90                         if (i2c_pos >= sizeof(i2c_databuf)) {
  91                                 TWCR_RESET;
  92                                 i2c_pos = 0x00;
  93                                 break;
  94                         }
  95                         i2c_databuf[i2c_pos] = TWDR;
  96                         i2c_pos++;
  97                         TWCR_ACK;
  98                         break;
  99
 100                 case TW_SR_STOP:
 101 #ifdef DEBUG
 102                         printf("I2C: STOP received\n");
 103 #endif
 104                         i2c_len = i2c_pos;
 105                         i2c_pos = 0x00;
 106                         i2c_done = 0x01;
 107                         TWCR_RESET;
 108                         break;
 109
 110                 default:
 111 #ifdef DEBUG
 112                         printf("I2C: Unimplemented status 0x%02x\n", TW_STATUS);
 113 #endif
 114                         TWCR_RESET;
 115                         break;
 116         }
 117 }