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 "config.h"
   7 #include "ipmb.h"
   8
   9 #define TWCR_ACK TWCR = (1<<TWEN)|(1<<TWIE)|(1<<TWINT)|(1<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|(0<<TWWC);
  10 #define TWCR_NACK TWCR = (1<<TWEN)|(1<<TWIE)|(1<<TWINT)|(0<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|(0<<TWWC);
  11 #define TWCR_RESET TWCR = (1<<TWEN)|(1<<TWIE)|(1<<TWINT)|(1<<TWEA)|(0<<TWSTA)|(1<<TWSTO)|(0<<TWWC);
  12
  13 volatile unsigned char i2c_databuf[24];
  14 volatile uint8_t i2c_len = 0x00;
  15 static volatile uint8_t i2c_pos = 0x00;
  16 volatile uint8_t i2c_done = 0x00;
  17
  18 #define I2C_FREQ 20000UL
  19
  20 void i2c_init()
  21 {
  22         /* SCLf = F_CPU / (16 + 2 * TWBR * 4^TWPS)
  23          * TWPS is 0 =>
  24          * TWBR = (F_CPU/(2 * SCL)) - 8
  25          */
  26         TWBR = (F_CPU/(2*I2C_FREQ))-8;
  27         TWAR = BMC_ADDR & 0xfe;
  28         TWDR = 0x00;
  29         TWCR &= ~((1<<TWSTA) | (1<<TWSTO));
  30         TWCR |= ((1<<TWEA) | (1<<TWEN) | (1<<TWIE));
  31 #ifdef __AVR_ATmega16__
  32         PORTC = 0x03;
  33 #else
  34 #error "Don't know how to set pullups for this chip, please add support"
  35 #endif
  36 }
  37
  38 void i2c_send(unsigned char *buf, int len)
  39 {
  40         uint8_t old_TWCR = TWCR;
  41         uint8_t old_SREG = SREG;
  42         int i;
  43
  44         cli();
  45
  46         TWCR = ((1<<TWINT) | (1<<TWSTA) | (1<<TWEN)); /* Send start */
  47
  48         while(!(TWCR & (1<<TWINT))) {}
  49         if (TW_STATUS != TW_START) {
  50 #ifdef DEBUG
  51                 printf("I2C: error sending START\n");
  52 #endif
  53                 goto out;
  54         }
  55
  56         TWDR = buf[0]; /* SLA_W */
  57         TWCR = ((1<<TWINT) | (1<<TWEN));
  58
  59         while(!(TWCR & (1<<TWINT))) {}
  60         if (TW_STATUS != TW_MT_SLA_ACK) {
  61 #ifdef DEBUG
  62                 printf("I2C: error sending SLA_W\n");
  63 #endif
  64                 goto out2;
  65         }
  66
  67         for(i = 1; i < len; i++) {
  68                 TWDR = buf[i]; /* Send Data */
  69                 TWCR = ((1<<TWINT) | (1<<TWEN));
  70
  71                 while(!(TWCR & (1<<TWINT))) {}
  72                 if (TW_STATUS != TW_MT_DATA_ACK) {
  73 #ifdef DEBUG
  74                         printf("I2C: error sending DATA byte %d\n", i);
  75 #endif
  76                         goto out2;
  77                 }
  78         }
  79
  80 #ifdef DEBUG
  81         printf("I2C Data sent\n");
  82 #endif
  83
  84 out2:
  85         TWCR = ((1<<TWINT) | (1<<TWEN) | (1<<TWSTO));
  86         while(TWCR & (1<<TWSTO)) {}
  87
  88 out:
  89         SREG = old_SREG;
  90         TWCR = old_TWCR | (1<<TWINT);
  91 }
  92
  93 ISR (TWI_vect, ISR_BLOCK)
  94 {
  95         if (i2c_done)
  96                 TWCR_RESET;
  97
  98         switch (TW_STATUS) {
  99                 case TW_SR_SLA_ACK:
 100 #ifdef DEBUG
 101                         printf("I2C: Slave 0x%02x adressed\n", TWDR);
 102 #endif
 103                         i2c_pos = 0x00;
 104                         i2c_databuf[i2c_pos] = TWDR;
 105                         i2c_pos++;
 106                         TWCR_ACK;
 107                         break;
 108
 109                 case TW_SR_DATA_ACK:
 110 #ifdef DEBUG
 111                         printf("I2C: Data received: 0x%02x\n", TWDR);
 112 #endif
 113                         if (i2c_pos >= sizeof(i2c_databuf)) {
 114                                 TWCR_RESET;
 115                                 i2c_pos = 0x00;
 116                                 break;
 117                         }
 118                         i2c_databuf[i2c_pos] = TWDR;
 119                         i2c_pos++;
 120                         TWCR_ACK;
 121                         break;
 122
 123                 case TW_SR_STOP:
 124 #ifdef DEBUG
 125                         printf("I2C: STOP received\n");
 126 #endif
 127                         i2c_len = i2c_pos;
 128                         i2c_pos = 0x00;
 129                         i2c_done = 0x01;
 130                         TWCR_RESET;
 131                         break;
 132
 133                 case TW_NO_INFO:
 134 #ifdef DEBUG
 135                         printf("I2C: TW_NO_INFO received status 0x%2x\n", TW_STATUS);
 136 #endif
 137                         TWCR |= (1<<TWINT);
 138                         break;
 139
 140                 default:
 141 #ifdef DEBUG
 142                         printf("I2C: Unimplemented status 0x%02x\n", TW_STATUS);
 143 #endif
 144                         TWCR_RESET;
 145                         break;
 146         }
 147 }