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 #define I2C_FREQ 20000UL
  18
  19 void i2c_init()
  20 {
  21         /* SCLf = F_CPU / (16 + 2 * TWBR * 4^TWPS)
  22          * TWPS is 0 =>
  23          * TWBR = (F_CPU/(2 * SCL)) - 8
  24          */
  25         TWBR = (F_CPU/(2*I2C_FREQ))-8;
  26         TWAR = BMC_ADDR & 0xfe;
  27         TWDR = 0x00;
  28         TWCR &= ~((1<<TWSTA) | (1<<TWSTO));
  29         TWCR |= ((1<<TWEA) | (1<<TWEN) | (1<<TWIE));
  30 #ifdef __AVR_ATmega16__
  31         PORTC = 0x03;
  32 #else
  33 #error "Don't know how to set pullups for this chip, please add support"
  34 #endif
  35 }
  36
  37 void i2c_send(unsigned char *buf, int len)
  38 {
  39         uint8_t old_TWCR = TWCR;
  40         uint8_t old_SREG = SREG;
  41         int i;
  42
  43         cli();
  44
  45         TWCR = ((1<<TWINT) | (1<<TWSTA) | (1<<TWEN)); /* Send start */
  46
  47         while(!(TWCR & (1<<TWINT))) {}
  48         if (TW_STATUS != TW_START) {
  49 #ifdef DEBUG
  50                 printf("I2C: error sending START\n");
  51 #endif
  52                 goto out;
  53         }
  54
  55         TWDR = buf[0]; /* SLA_W */
  56         TWCR = ((1<<TWINT) | (1<<TWEN));
  57
  58         while(!(TWCR & (1<<TWINT))) {}
  59         if (TW_STATUS != TW_MT_SLA_ACK) {
  60 #ifdef DEBUG
  61                 printf("I2C: error sending SLA_W\n");
  62 #endif
  63                 goto out2;
  64         }
  65
  66         for(i = 1; i < len; i++) {
  67                 TWDR = buf[i]; /* Send Data */
  68                 TWCR = ((1<<TWINT) | (1<<TWEN));
  69
  70                 while(!(TWCR & (1<<TWINT))) {}
  71                 if (TW_STATUS != TW_MT_DATA_ACK) {
  72 #ifdef DEBUG
  73                         printf("I2C: error sending DATA byte %d\n", i);
  74 #endif
  75                         goto out2;
  76                 }
  77         }
  78
  79 #ifdef DEBUG
  80         printf("I2C Data sent\n");
  81 #endif
  82
  83 out2:
  84         TWCR = ((1<<TWINT) | (1<<TWEN) | (1<<TWSTO));
  85         while(TWCR & (1<<TWSTO)) {}
  86
  87 out:
  88         SREG = old_SREG;
  89         TWCR = old_TWCR | (1<<TWINT);
  90 }
  91
  92 ISR (TWI_vect, ISR_BLOCK)
  93 {
  94         if (i2c_done)
  95                 TWCR_RESET;
  96
  97         switch (TW_STATUS) {
  98                 case TW_SR_SLA_ACK:
  99 #ifdef DEBUG
 100                         printf("I2C: Slave 0x%02x adressed\n", TWDR);
 101 #endif
 102                         i2c_pos = 0x00;
 103                         i2c_databuf[i2c_pos] = TWDR;
 104                         i2c_pos++;
 105                         TWCR_ACK;
 106                         break;
 107
 108                 case TW_SR_DATA_ACK:
 109 #ifdef DEBUG
 110                         printf("I2C: Data received: 0x%02x\n", TWDR);
 111 #endif
 112                         if (i2c_pos >= sizeof(i2c_databuf)) {
 113                                 TWCR_RESET;
 114                                 i2c_pos = 0x00;
 115                                 break;
 116                         }
 117                         i2c_databuf[i2c_pos] = TWDR;
 118                         i2c_pos++;
 119                         TWCR_ACK;
 120                         break;
 121
 122                 case TW_SR_STOP:
 123 #ifdef DEBUG
 124                         printf("I2C: STOP received\n");
 125 #endif
 126                         i2c_len = i2c_pos;
 127                         i2c_pos = 0x00;
 128                         i2c_done = 0x01;
 129                         TWCR_RESET;
 130                         break;
 131
 132                 case TW_NO_INFO:
 133 #ifdef DEBUG
 134                         printf("I2C: TW_NO_INFO received status 0x%2x\n", TW_STATUS);
 135 #endif
 136                         TWCR |= (1<<TWINT);
 137                         break;
 138
 139                 default:
 140 #ifdef DEBUG
 141                         printf("I2C: Unimplemented status 0x%02x\n", TW_STATUS);
 142 #endif
 143                         TWCR_RESET;
 144                         break;
 145         }
 146 }