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[rsbs2] / 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 }
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