Merge pull request #5 from xdever/i2c_fix

Fix i2c hangs when disconnecting the left half.

shared/i2c_adddresses.c

@@ -1,28 +1,219 @@
 #include "fsl_i2c.h"
 #include "i2c_addresses.h"
 
+/**
+ * This file has couple of hacks in it, because the blocking i2c api provided by kinetis does not handle
+ * i2c errors properly. Because of this, there were some stalls when keyboards were disconnected in middle
+ * of a transfer.
+ *
+ */
+
+#define TO_CLEAR_FLAGS (kI2C_ArbitrationLostFlag | kI2C_IntPendingFlag | kI2C_StartDetectFlag | kI2C_StopDetectFlag)
+
+static status_t I2C_CheckAndClearError(I2C_Type *base, uint32_t status)
+{
+    status_t result = kStatus_Success;
+
+    /* Check arbitration lost. */
+    if (status & kI2C_ArbitrationLostFlag)
+    {
+        /* Clear arbitration lost flag. */
+        base->S = kI2C_ArbitrationLostFlag;
+        result = kStatus_I2C_ArbitrationLost;
+    }
+    /* Check NAK */
+    else if (status & kI2C_ReceiveNakFlag)
+    {
+        result = kStatus_I2C_Nak;
+    }
+    else
+    {
+    }
+
+    return result;
+}
+
+status_t pollForFlag(I2C_Type *baseAddress, uint32_t flag){
+	uint16_t timeout=-1;
+	status_t result = kStatus_Success;
+
+	while ((!(baseAddress->S & flag)) && (timeout!=0))
+	{
+		timeout--;
+	}
+
+	if (timeout==0){
+		result=I2C_CheckAndClearError(baseAddress, baseAddress->S);
+		I2C_MasterStop(baseAddress);
+
+		if (result!=kStatus_Success){
+			result=kStatus_I2C_Timeout;
+		}
+	}
+
+	return result;
+}
+
+status_t i2c_preamble(I2C_Type *baseAddress, uint8_t i2cAddress, i2c_direction_t dir){
+
+	I2C_MasterClearStatusFlags(baseAddress, TO_CLEAR_FLAGS);
+	/* Wait until ready to complete. */
+
+	status_t result=pollForFlag(baseAddress, kI2C_TransferCompleteFlag);
+	if (result){
+		return result;
+	}
+
+	result = I2C_MasterStart(baseAddress, i2cAddress, dir);
+	if (result){
+		return result;
+	}
+	/* Wait until address + command transfer complete. */
+	result=pollForFlag(baseAddress, kI2C_IntPendingFlag);
+	if (result){
+		return result;
+	}
+
+	/* Check if there's transfer error. */
+	result = I2C_CheckAndClearError(baseAddress, baseAddress->S);
+
+	/* Return if error. */
+	if (result == kStatus_I2C_Nak) {
+		I2C_MasterStop(baseAddress);
+	}
+
+	if (result){
+		return result;
+	}
+
+	/* Wait until the data register is ready for transmit. */
+	result=pollForFlag(baseAddress, kI2C_TransferCompleteFlag);
+
+	return result;
+}
+
 status_t I2cRead(I2C_Type *baseAddress, uint8_t i2cAddress, uint8_t *data, uint8_t size)
 {
-    i2c_master_transfer_t masterXfer;
-    masterXfer.slaveAddress = i2cAddress;
-    masterXfer.direction = kI2C_Read;
-    masterXfer.subaddress = 0;
-    masterXfer.subaddressSize = 0;
-    masterXfer.data = data;
-    masterXfer.dataSize = size;
-    masterXfer.flags = kI2C_TransferDefaultFlag;
-    return I2C_MasterTransferBlocking(baseAddress, &masterXfer);
+	status_t result = i2c_preamble(baseAddress, i2cAddress, kI2C_Read);
+	if (result){
+		return result;
+	}
+
+	result = kStatus_Success;
+	volatile uint8_t dummy = 0;
+
+	/* Add this to avoid build warning. */
+	dummy++;
+
+	/* Clear the IICIF flag. */
+	baseAddress->S = kI2C_IntPendingFlag;
+
+	/* Setup the I2C peripheral to receive data. */
+	baseAddress->C1 &= ~(I2C_C1_TX_MASK | I2C_C1_TXAK_MASK);
+
+	/* If rxSize equals 1, configure to send NAK. */
+	if (size == 1)
+	{
+		/* Issue NACK on read. */
+		baseAddress->C1 |= I2C_C1_TXAK_MASK;
+	}
+
+	/* Do dummy read. */
+	dummy = baseAddress->D;
+
+	while ((size--))
+	{
+		/* Wait until data transfer complete. */
+		result=pollForFlag(baseAddress, kI2C_IntPendingFlag);
+		if (result){
+			return result;
+		}
+
+		/* Clear the IICIF flag. */
+		baseAddress->S = kI2C_IntPendingFlag;
+
+		/* Single byte use case. */
+		if (size == 0)
+		{
+			/* Read the final byte. */
+			result = I2C_MasterStop(baseAddress);
+		}
+
+		if (size == 1)
+		{
+			/* Issue NACK on read. */
+			baseAddress->C1 |= I2C_C1_TXAK_MASK;
+		}
+
+		/* Read from the data register. */
+		*data++ = baseAddress->D;
+	}
+
+	return result;
 }
 
 status_t I2cWrite(I2C_Type *baseAddress, uint8_t i2cAddress, uint8_t *data, uint8_t size)
 {
-    i2c_master_transfer_t masterXfer;
-    masterXfer.slaveAddress = i2cAddress;
-    masterXfer.direction = kI2C_Write;
-    masterXfer.subaddress = 0;
-    masterXfer.subaddressSize = 0;
-    masterXfer.data = data;
-    masterXfer.dataSize = size;
-    masterXfer.flags = kI2C_TransferDefaultFlag;
-    return I2C_MasterTransferBlocking(baseAddress, &masterXfer);
+	status_t result = i2c_preamble(baseAddress, i2cAddress, kI2C_Read);
+	if (result){
+		return result;
+	}
+
+	uint8_t statusFlags = 0;
+
+	/* Clear the IICIF flag. */
+	baseAddress->S = kI2C_IntPendingFlag;
+
+	/* Setup the I2C peripheral to transmit data. */
+	baseAddress->C1 |= I2C_C1_TX_MASK;
+
+	while (size--)
+	{
+		/* Send a byte of data. */
+		baseAddress->D = *data++;
+
+		/* Wait until data transfer complete. */
+		result=pollForFlag(baseAddress, kI2C_IntPendingFlag);
+		if (result){
+			return result;
+		}
+
+		statusFlags = baseAddress->S;
+
+		/* Clear the IICIF flag. */
+		baseAddress->S = kI2C_IntPendingFlag;
+
+		/* Check if arbitration lost or no acknowledgement (NAK), return failure status. */
+		if (statusFlags & kI2C_ArbitrationLostFlag)
+		{
+			baseAddress->S = kI2C_ArbitrationLostFlag;
+			result = kStatus_I2C_ArbitrationLost;
+		}
+
+		if (statusFlags & kI2C_ReceiveNakFlag)
+		{
+			baseAddress->S = kI2C_ReceiveNakFlag;
+			result = kStatus_I2C_Nak;
+		}
+
+		if (result != kStatus_Success)
+		{
+			/* Breaking out of the send loop. */
+			break;
+		}
+	}
+
+
+
+	if ((result == kStatus_Success) || (result == kStatus_I2C_Nak))
+	{
+		/* Clear the IICIF flag. */
+		baseAddress->S = kI2C_IntPendingFlag;
+
+		/* Send stop. */
+		result = I2C_MasterStop(baseAddress);
+	}
+
+	return result;
 }
+