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Offload I2C work onto interrupts. For now, we just spin while waiting

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for the I2C activity to complete.
This commit is contained in:
Gavan Fantom
2011-05-26 01:57:16 +00:00
parent 6a3c096bc5
commit 0f508fb424
5 changed files with 197 additions and 135 deletions
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165
i2c.c
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@@ -1,5 +1,6 @@
#include "i2c.h"
#include "interrupt.h"
#define I2CBASE 0xE001C000
@@ -21,6 +22,11 @@
#define SI (IREG(I2CONSET) & SIFLAG)
void __attribute__((interrupt("IRQ"))) i2c_interrupt_handler(void);
struct i2c_transaction *i2c_transaction;
int i2c_bytes;
void init_i2c(void)
{
IREG(I2CONSET) = 0x40; /* Enable I2C ready for Master Tx */
@@ -32,17 +38,7 @@ void init_i2c(void)
IWREG(I2SCLL) = 73; /* ~100kHz */
IWREG(I2SCLH) = 73;
#endif
}
int i2cstat;
int i2c_wait(void)
{
int stat;
while (!SI);
stat = IREG(I2STAT);
i2cstat = stat;
return stat;
interrupt_register(I2C0, i2c_interrupt_handler);
}
int i2c_conreg(void)
@@ -55,61 +51,110 @@ int i2c_statreg(void)
return IREG(I2STAT);
}
bool i2c_send_start(void)
bool i2c_busy(void)
{
return i2c_transaction != NULL;
}
bool i2c_start_transaction(struct i2c_transaction *t)
{
if (i2c_transaction)
return FALSE;
i2c_transaction = t;
*(t->result) = I2C_IN_PROGRESS;
/* Paranoia in case we left things in a bad state */
IREG(I2CONCLR) = STOFLAG | STAFLAG;
/* Set it all going */
IREG(I2CONSET) = STAFLAG;
switch (i2c_wait()) {
case 0x08:
case 0x10:
return TRUE;
default:
i2c_send_stop();
return FALSE;
return TRUE;
}
void __attribute__((interrupt("IRQ"))) i2c_interrupt_handler(void)
{
int stat = IREG(I2STAT);
if (!i2c_transaction) {
IREG(I2CONSET) = STOFLAG;
IREG(I2CONCLR) = STAFLAG | AAFLAG | SIFLAG;
interrupt_clear();
return;
}
}
bool i2c_send_address(int addr, bool write)
{
return i2c_send_data((addr<<1) + (write?0:1));
}
switch (stat) {
bool i2c_send_data(unsigned int data)
{
IREG(I2DAT) = data;
IREG(I2CONCLR) = STAFLAG | STOFLAG | SIFLAG;
switch (i2c_wait()) {
case 0x18:
case 0x28:
case 0x40:
return TRUE;
default:
i2c_send_stop();
return FALSE;
case 0x08: /* START transmitted */
case 0x10: /* repeated START transmitted */
IREG(I2DAT) = i2c_transaction->address;
IREG(I2CONCLR) = STAFLAG | STOFLAG | SIFLAG;
i2c_bytes = 0;
break;
case 0x18: /* SA+W transmitted, ACK received */
case 0x28: /* data transmitted, ACK received */
if (i2c_bytes < i2c_transaction->bytes) {
IREG(I2DAT) = i2c_transaction->data[i2c_bytes++];
IREG(I2CONCLR) = STAFLAG | STOFLAG | SIFLAG;
} else {
*(i2c_transaction->result) = I2C_SUCCESS;
if (i2c_transaction->next) {
i2c_transaction = i2c_transaction->next;
i2c_bytes = 0;
IREG(I2CONSET) = STAFLAG;
IREG(I2CONCLR) = STOFLAG | AAFLAG | SIFLAG;
} else {
i2c_transaction = NULL;
IREG(I2CONSET) = STOFLAG;
IREG(I2CONCLR) = STAFLAG | AAFLAG | SIFLAG;
}
}
break;
case 0x50: /* data received, ACK returned */
i2c_transaction->data[i2c_bytes++] = IREG(I2DAT);
/* fall through */
case 0x40: /* SA+R transmitted, ACK received */
if (i2c_bytes < (i2c_transaction->bytes-1)) {
IREG(I2CONSET) = AAFLAG;
IREG(I2CONCLR) = STAFLAG | STOFLAG | SIFLAG;
} else {
IREG(I2CONCLR) = STAFLAG | STOFLAG | SIFLAG
| AAFLAG;
}
break;
case 0x58: /* data received, NACK returned */
i2c_transaction->data[i2c_bytes] = IREG(I2DAT);
*(i2c_transaction->result) = I2C_SUCCESS;
if (i2c_transaction->next) {
i2c_transaction = i2c_transaction->next;
i2c_bytes = 0;
IREG(I2CONSET) = STAFLAG;
IREG(I2CONCLR) = STOFLAG | AAFLAG | SIFLAG;
} else {
i2c_transaction = NULL;
IREG(I2CONSET) = STOFLAG;
IREG(I2CONCLR) = STAFLAG | AAFLAG | SIFLAG;
}
break;
case 0x20: /* SA+W transmitted, NACK received */
case 0x30: /* data transmitted, NACK received */
case 0x48: /* SA+R transmitted, NACK received */
case 0x38: /* arbitration lost during SA+W or data */
case 0x00: /* bus error */
*(i2c_transaction->result) = I2C_FAIL;
i2c_transaction = NULL;
IREG(I2CONSET) = STOFLAG;
IREG(I2CONCLR) = STAFLAG | AAFLAG | SIFLAG;
break;
/* We don't handle slave mode */
}
}
bool i2c_receive_data(unsigned int *data, bool last)
{
if (!last)
IREG(I2CONSET) = AAFLAG;
IREG(I2CONCLR) = STAFLAG | STOFLAG | SIFLAG | (last?AAFLAG:0);
switch (i2c_wait()) {
case 0x50:
case 0x58:
*data = IREG(I2DAT);
return TRUE;
default:
i2c_send_stop();
return FALSE;
}
}
void i2c_send_stop(void)
{
IREG(I2CONCLR) = STAFLAG | AAFLAG;
IREG(I2CONSET) = STOFLAG;
IREG(I2CONCLR) = SIFLAG;
/* Don't think we need to wait here. Could be wrong. */
interrupt_clear();
}