From 35e9ec0c03a150e3fe6a3350549573e4c02be67b Mon Sep 17 00:00:00 2001
From: Leo C
Date: Sun, 24 Aug 2014 14:16:18 +0200
Subject: getenv_ulong(), TWI int opt

---
 avr/i2c.c | 91 +++++++++++++++++++++++++++++++++++----------------------------
 1 file changed, 50 insertions(+), 41 deletions(-)

(limited to 'avr/i2c.c')

diff --git a/avr/i2c.c b/avr/i2c.c
index df97fea..3ab222a 100644
--- a/avr/i2c.c
+++ b/avr/i2c.c
@@ -99,12 +99,17 @@
 	uint8_t buf[CONFIG_SYS_I2C_BUFSIZE];
 } i2c_msg_t;
 
-static i2c_msg_t xmit;
+static volatile i2c_msg_t xmit;
 
 ISR(TWI_vect)
 {
-	uint8_t next_twcr;
+	uint8_t tmp_stat;
 	uint8_t tmp_idx;
+	uint8_t next_twcr;
+	uint8_t n;
+
+	tmp_idx = xmit.idx;
+	tmp_stat = xmit.stat;
 
 	uint8_t twsr = TWSR;
 		
@@ -112,62 +117,59 @@ ISR(TWI_vect)
 
 	case TWI_START:
 	case TWI_REP_START:
-		xmit.idx = 0;			/* reset xmit_buf index */
-		xmit.stat = BUSY | START;
+		tmp_stat = BUSY | START;
+		tmp_idx = 0;			/* reset xmit_buf index */
 
-		tmp_idx = xmit.idx;
 		if (tmp_idx < xmit.len) {		/* all bytes transmited? */
 			TWDR = xmit.buf[tmp_idx];
-			xmit.idx = ++tmp_idx;
+			++tmp_idx;
 			next_twcr = (1<<TWEN)|(1<<TWIE)|(1<<TWINT);
 		} else {
-			xmit.stat |= XMIT_DONE;
-			xmit.stat &= ~BUSY;
+			tmp_stat |= XMIT_DONE;
+			tmp_stat &= ~BUSY;
 			next_twcr = (1<<TWEN)|(0<<TWIE)|(1<<TWINT)|(1<<TWSTO);
 		}
 		break;
 
 	case TWI_MTX_ADR_ACK:
-		xmit.stat |= ADDR_ACK;
+		tmp_stat |= ADDR_ACK;
 		
-		tmp_idx = xmit.idx;
 		if (tmp_idx < xmit.len) {		/* all bytes transmited? */
 			TWDR = xmit.buf[tmp_idx];
-			xmit.idx = ++tmp_idx;
+			++tmp_idx;
 			next_twcr = (1<<TWEN)|(1<<TWIE)|(1<<TWINT);
 		} else {
-			xmit.stat |= XMIT_DONE;
-			xmit.stat &= ~BUSY;
+			tmp_stat |= XMIT_DONE;
+			tmp_stat &= ~BUSY;
 			next_twcr = (1<<TWEN)|(0<<TWIE)|(1<<TWINT)|(1<<TWSTO);
 		}
 		break;
 
 	case TWI_MTX_DATA_ACK:
-		xmit.stat |= DATA_ACK;
+		tmp_stat |= DATA_ACK;
 
-		tmp_idx = xmit.idx;
 		if (tmp_idx < xmit.len) {		/* all bytes transmited? */
 			TWDR = xmit.buf[tmp_idx];
-			xmit.idx = ++tmp_idx;
+			++tmp_idx;
 			next_twcr = (1<<TWEN)|(1<<TWIE)|(1<<TWINT);
 		} else {
-			xmit.stat |= XMIT_DONE;
-			xmit.stat &= ~BUSY;
+			tmp_stat |= XMIT_DONE;
+			tmp_stat &= ~BUSY;
 			next_twcr = (1<<TWEN)|(0<<TWIE)|(1<<TWINT)|(1<<TWSTO);
 		}
 
 		break;
 
 	case TWI_MTX_DATA_NACK:
-		xmit.stat |= XMIT_DONE;
-		xmit.stat &= ~BUSY;
+		tmp_stat |= XMIT_DONE;
+		tmp_stat &= ~BUSY;
 		next_twcr = (1<<TWEN)|(0<<TWIE)|(1<<TWINT)|(1<<TWSTO);
 		break;
 
 	case TWI_MRX_ADR_ACK:
-		xmit.stat |= ADDR_ACK;
-		tmp_idx = xmit.idx;
-		if (tmp_idx < xmit.len-1) {
+		tmp_stat |= ADDR_ACK;
+		n = xmit.len-1;
+		if (tmp_idx < n) {
 			next_twcr = (1<<TWEN)|(1<<TWIE)|(1<<TWINT)|(1<<TWEA);
 		} else {
 			next_twcr = (1<<TWEN)|(1<<TWIE)|(1<<TWINT);
@@ -175,11 +177,11 @@ ISR(TWI_vect)
 		break;
 
 	case TWI_MRX_DATA_ACK:
-		xmit.stat |= DATA_ACK;
-		tmp_idx = xmit.idx;
+		tmp_stat |= DATA_ACK;
 		xmit.buf[tmp_idx] = TWDR;
-		xmit.idx = ++tmp_idx;
-		if (tmp_idx < xmit.len-1) {
+		++tmp_idx;
+		n = xmit.len-1;
+		if (tmp_idx < n) {
 			next_twcr = (1<<TWEN)|(1<<TWIE)|(1<<TWINT)|(1<<TWEA);
 		} else {
 		
@@ -188,19 +190,21 @@ ISR(TWI_vect)
 		break;
 
 	case TWI_MRX_DATA_NACK:
-		xmit.stat |= ADDR_ACK | DATA_ACK;
+		tmp_stat |= ADDR_ACK | DATA_ACK;
 
-		tmp_idx = xmit.idx;
 		xmit.buf[tmp_idx] = TWDR;
-		xmit.idx = ++tmp_idx;
+		++tmp_idx;
 		/* fall thru */
 
 	default:
-		xmit.stat &= ~BUSY;
+		tmp_stat &= ~BUSY;
 		next_twcr = (1<<TWEN)|(0<<TWIE)|(1<<TWINT)|(1<<TWSTO);
 		break;
 	}
 
+	xmit.stat = tmp_stat;
+	xmit.idx = tmp_idx;
+
 #ifdef DEBUG_I2C	
 	debug("|%02x", twsr);
 #endif
@@ -217,32 +221,37 @@ static uint8_t twbr;
 static void _init(void)
 {
 	xmit.stat = 0;
-#ifdef DEBUG_I2C
-	memset((void *) xmit.buf, 0xdf, sizeof(xmit.buf));
-#endif
 
 	/* Disable TWI, disable TWI interrupt. */
 	/* (Reset TWI hardware state machine.) */
 	TWCR = TWI_C_DISABLE;
 	_delay_us(5);
+#ifdef DEBUG_I2C
+	memset((void *) xmit.buf, 0xdf, sizeof(xmit.buf));
+#endif
 
-	TWBR = twbr;
 	TWDR = 0xff;
-	TWCR = TWI_C_ENABLE + twps;
+	TWBR = twbr;
+	TWSR = twps & 0x03;
+	TWCR = TWI_C_ENABLE;
 }
 
 void i2c_init(uint32_t speed)
 {
 	twps = 0;
-	uint32_t tmptwbr = F_CPU /2 / speed - 8;
+	uint32_t tmp_twbr = F_CPU /2 / speed - 8;
 	
-	while (tmptwbr > 255) {
-		tmptwbr >>= 4;
+	while (tmp_twbr > 255) {
+		tmp_twbr >>= 4;
 		twps += 1;
 	}
-	debug_cond((twps > 3), "TWCLK too low: %lu Hz\n", speed);
+	debug_cond((twps > 3), "*** TWCLK too low: %lu Hz\n", speed);
+
+	twbr = (uint8_t) tmp_twbr;
+
+	debug("*** i2c_init: i2c_speed: %lu, twbr: %u, twps: %u\n",
+		speed, twbr, twps);
 
-	twbr = (uint8_t) tmptwbr;
 	_init();
 }
 
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