uart: Replace Init calls with Enable/Disable

* Enable/Disable makes more sense and matches
  platform loader serial functions.
* Rework PL011 code after finding a PDF covering
  the details of it.
* Rename UART global defines in loader to be more
  exact about location

headers/private/kernel/arch/arm/uart_8250.h

@@ -37,6 +37,9 @@ public:
 	void					Init();
 	void					InitPort(uint32 baud);
 
+	void					Enable();
+	void					Disable();
+
 	int						PutChar(char c);
 	int						GetChar(bool wait);
 
@@ -47,6 +50,7 @@ private:
 	void					WriteUart(uint32 reg, unsigned char data);
 	unsigned char			ReadUart(uint32 reg);
 
+	bool					fUARTEnabled;
 	addr_t					fUARTBase;
 };
 

headers/private/kernel/arch/arm/uart_pl011.h

@@ -93,9 +93,11 @@ public:
 							~UartPL011();
 
 	void					InitEarly();
-	void					Init();
 	void					InitPort(uint32 baud);
 
+	void					Enable();
+	void					Disable();
+
 	int						PutChar(char c);
 	int						GetChar(bool wait);
 
@@ -106,6 +108,7 @@ private:
 	void					WriteUart(uint32 reg, unsigned char data);
 	unsigned char			ReadUart(uint32 reg);
 
+	bool					fUARTEnabled;
 	addr_t					fUARTBase;
 };
 

src/system/boot/platform/raspberrypi_arm/serial.cpp

@@ -17,7 +17,7 @@
 #include <string.h>
 
 
-UartPL011* gUART;
+UartPL011* gLoaderUART;
 
 static int32 sSerialEnabled = 0;
 static char sBuffer[16384];
@@ -27,7 +27,7 @@ static uint32 sBufferPosition;
 static void
 serial_putc(char c)
 {
-	gUART->PutChar(c);
+	gLoaderUART->PutChar(c);
 }
 
 
@@ -80,13 +80,12 @@ serial_cleanup(void)
 extern "C" void
 serial_init(void)
 {
-	gUART = new(nothrow) UartPL011(uart_base_debug());
-	if (gUART == 0)
+	gLoaderUART = new(nothrow) UartPL011(uart_base_debug());
+	if (gLoaderUART == 0)
 		return;
 
-	gUART->InitEarly();
-	gUART->Init();
-	gUART->InitPort(9600);
+	gLoaderUART->InitEarly();
+	gLoaderUART->InitPort(9600);
 
 	serial_enable();
 

src/system/boot/platform/u-boot/serial.cpp

@@ -16,7 +16,7 @@
 #include <string.h>
 
 
-gUart8250* gUART;
+Uart8250* gLoaderUART;
 
 static int32 sSerialEnabled = 0;
 static char sBuffer[16384];
@@ -26,7 +26,7 @@ static uint32 sBufferPosition;
 static void
 serial_putc(char c)
 {
-	gUART->PutChar(c);
+	gLoaderUART->PutChar(c);
 }
 
 
@@ -67,9 +67,8 @@ serial_enable(void)
 {
 	/* should already be initialized by U-Boot */
 	/*
-	gUART->InitEarly();
-	gUART->Init();
-	gUART->InitPort(9600);
+	gLoaderUART->InitEarly();
+	gLoaderUART->InitPort(9600);
 	*/
 	sSerialEnabled++;
 }
@@ -93,7 +92,9 @@ extern "C" void
 serial_init(void)
 {
 	// Setup information on uart
-	gUART = new Uart8250(uart_base_debug());
+	gLoaderUART = new(nothrow) Uart8250(uart_base_debug());
+	if (gLoaderUART == 0)
+		return;
 
 	serial_enable();
 }

src/system/kernel/arch/arm/uart_8250.cpp

@@ -34,6 +34,7 @@
 
 Uart8250::Uart8250(addr_t base)
 	:
+	fUARTEnabled(true),
 	fUARTBase(base)
 {
 }
@@ -95,6 +96,8 @@ Uart8250::ReadUart(uint32 reg)
 void
 Uart8250::InitPort(uint32 baud)
 {
+	Disable();
+
 	uint16 baudDivisor = BOARD_UART_CLOCK / (16 * baud);
 
 	// Write standard uart settings
@@ -118,6 +121,8 @@ Uart8250::InitPort(uint32 baud)
 //	WriteUart(UART_LCR, 0xBF); // config mode B
 //	WriteUart(UART_EFR, (1<<7)|(1<<6)); // hw flow control
 //	WriteUart(UART_LCR, LCR_8N1); // operational mode
+
+	Enable();
 }
 
 
@@ -145,9 +150,16 @@ Uart8250::InitEarly()
 
 
 void
-Uart8250::Init()
+Uart8250::Enable()
 {
-	InitPort(115200);
+	fUARTEnabled = true;
+}
+
+
+void
+Uart8250::Disable()
+{
+	fUARTEnabled = false;
 }
 
 

src/system/kernel/arch/arm/uart_pl011.cpp

@@ -16,6 +16,7 @@
 
 UartPL011::UartPL011(addr_t base)
 	:
+	fUARTEnabled(true),
 	fUARTBase(base)
 {
 }
@@ -43,28 +44,22 @@ UartPL011::ReadUart(uint32 reg)
 void
 UartPL011::InitPort(uint32 baud)
 {
-	uint16 clockDiv
-		= (baud > BOARD_UART_CLOCK / 16) ? 8 : 4;
-	uint16 baudDivisor = BOARD_UART_CLOCK * clockDiv / baud;
-		// TODO: Round to closest baud divisor
-	uint16 lcr = PL01x_LCRH_WLEN_8;
+	// Disable UART
+	Disable();
 
-	// Disable everything
-	unsigned char originalCR
-		= ReadUart(PL011_CR);
-	WriteUart(PL011_CR, 0);
+	// Calculate baud divisor
+	uint16 baudDivisor = BOARD_UART_CLOCK / (16 * baud);
+	uint16 baudFractional = BOARD_UART_CLOCK % (16 * baud);
 
 	// Set baud divisor
-	WriteUart(PL011_FBRD, baudDivisor & 0x3f);
-	WriteUart(PL011_IBRD, baudDivisor >> 6);
+	WriteUart(PL011_IBRD, baudDivisor);
+	WriteUart(PL011_FBRD, baudFractional);
 
 	// Set LCR
-	WriteUart(PL011_LCRH, lcr);
+	WriteUart(PL011_LCRH, PL01x_LCRH_WLEN_8);
 
-	// Disable auto RTS / CTS in original CR
-	originalCR &= ~(PL011_CR_CTSEN | PL011_CR_RTSEN);
-
-	WriteUart(PL011_CR, originalCR);
+	// Enable UART
+	Enable();
 }
 
 
@@ -77,36 +72,48 @@ UartPL011::InitEarly()
 
 
 void
-UartPL011::Init()
+UartPL011::Enable()
 {
 	// TODO: Enable clock producer?
-	// TODO: Clear pending error and receive interrupts
 
-	// Provoke TX FIFO into asserting
-	uint32 cr = PL011_CR_UARTEN | PL011_CR_TXE | PL011_IFLS;
+	unsigned char cr = PL011_CR_UARTEN;
+		// Enable UART
+	cr |= PL011_CR_TXE; // | PL011_CR_RXE;
+		// Enable TX and RX
 	WriteUart(PL011_CR, cr);
-	WriteUart(PL011_FBRD, 0);
-	WriteUart(PL011_IBRD, 1);
 
 	// TODO: For arm vendor, st different rx vs tx
-	WriteUart(PL011_LCRH, 0);
+	// WriteUart(PL011_LCRH, 0);
 
 	WriteUart(PL01x_DR, 0);
 
 	while (ReadUart(PL01x_FR) & PL01x_FR_BUSY);
 		// Wait for xmit
+
+	fUARTEnabled = true;
+}
+
+
+void
+UartPL011::Disable()
+{
+	// Disable everything
+	WriteUart(PL011_CR, 0);
+	fUARTEnabled = false;
 }
 
 
 int
 UartPL011::PutChar(char c)
 {
-	WriteUart(PL01x_DR, (unsigned int)c);
+	if (fUARTEnabled == true) {
+		WriteUart(PL01x_DR, (unsigned int)c);
+		while (ReadUart(PL01x_FR) & PL01x_FR_TXFF);
+			// wait for the last char to get out
+		return 0;
+	}
 
-	while (ReadUart(PL01x_FR) & PL01x_FR_TXFF);
-		// wait for the last char to get out
-
-	return 0;
+	return -1;
 }