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dm36x: More fully-featured UART driver, does not require previous initialisation by u-boot.

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This commit is contained in:
Kelvin Lawson
2013-10-21 01:51:42 +01:00
parent ae3397deb4
commit 5d54ff8f9b
2 changed files with 48 additions and 8 deletions
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2
ports/arm/platforms/dm36x/Makefile
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@@ -69,7 +69,7 @@ vpath %.o ./$(BUILD_DIR)
vpath %.elf ./$(BUILD_DIR)
# GCC flags
CFLAGS=-g -c -mcpu=arm926ej-s -ffreestanding -Wall -Werror
CFLAGS=-g -c -mcpu=arm926ej-s -ffreestanding -Wall -Werror -Wno-unused-but-set-variable
AFLAGS=$(CFLAGS) -x assembler-with-cpp
LFLAGS=-mcpu=arm926ej-s -Tsystem.ld -Wall

54
ports/arm/platforms/dm36x/uart.c
View File

@@ -46,16 +46,27 @@
/* Constants */
/** Baudrate */
#define BAUDRATE 115200
/** Select relevant UART for this platform */
#define UART_BASE DM36X_UART0_BASE
#define UART_BASE DM36X_UART0_BASE
/** FR Register bits */
#define UART_FR_RXFE 0x10
#define UART_LSR_TEMT 0x40
/** UART register access macros */
#define UART_DR(baseaddr) (*(unsigned int *)(baseaddr))
#define UART_LSR(baseaddr) (*(((unsigned int *)(baseaddr))+0x14))
#define UART_RBR(baseaddr) (*(unsigned int *)(baseaddr))
#define UART_THR(baseaddr) (*(unsigned int *)(baseaddr))
#define UART_IER(baseaddr) (*(((unsigned int *)(baseaddr + 0x04))))
#define UART_FCR(baseaddr) (*(((unsigned int *)(baseaddr + 0x08))))
#define UART_LCR(baseaddr) (*(((unsigned int *)(baseaddr + 0x0C))))
#define UART_MCR(baseaddr) (*(((unsigned int *)(baseaddr + 0x10))))
#define UART_LSR(baseaddr) (*(((unsigned int *)(baseaddr + 0x14))))
#define UART_DLL(baseaddr) (*(((unsigned int *)(baseaddr + 0x20))))
#define UART_DLH(baseaddr) (*(((unsigned int *)(baseaddr + 0x24))))
#define UART_PWR(baseaddr) (*(((unsigned int *)(baseaddr + 0x30))))
/* Local data */
@@ -90,6 +101,8 @@ static void uart_write_char (const char c);
static int uart_init (void)
{
int status;
uint32_t dummy;
uint32_t divisor;
/* Check we are not already initialised */
if (initialised == FALSE)
@@ -102,6 +115,33 @@ static int uart_init (void)
}
else
{
/* Reset Tx/Rx in PWREMU_MGMT */
UART_PWR(UART_BASE) = 0x0;
/* Set baudrate */
divisor = (TIMER_CLK / BAUDRATE) / 16;
UART_DLL(UART_BASE) = (divisor & 0xFF);
UART_DLH(UART_BASE) = (divisor >> 8);
/* Clear Tx/Rx FIFOs and enter non-FIFO mode */
UART_FCR(UART_BASE) = 0x7;
UART_FCR(UART_BASE) = 0x0;
/* Set 8N1 */
UART_LCR(UART_BASE) = 0x3;
/* Disable loopback, flow-control, RTS/CTS */
UART_MCR(UART_BASE) = 0x0;
/* Disable interrupts */
UART_IER(UART_BASE) = 0x0;
/* Take Tx/Rx out of reset in PWREMU_MGMT */
UART_PWR(UART_BASE) = 0xE001;
/* Clear any receive characters */
dummy = UART_RBR(UART_BASE);
/* Success */
initialised = TRUE;
status = ATOM_OK;
@@ -149,7 +189,7 @@ int uart_read (char *ptr, int len)
;
/* Read first byte */
*ptr++ = UART_DR(UART_BASE);
*ptr++ = UART_RBR(UART_BASE);
/* Loop over remaining bytes until empty */
for (todo = 1; todo < len; todo++)
@@ -161,7 +201,7 @@ int uart_read (char *ptr, int len)
}
/* Read next byte */
*ptr++ = UART_DR(UART_BASE);
*ptr++ = UART_RBR(UART_BASE);
}
#endif
@@ -278,9 +318,9 @@ void uart_write_halt (const char *ptr)
static void uart_write_char (const char c)
{
/* Wait for empty */
while(UART_LSR(UART_BASE) & UART_LSR_TEMT)
while ((UART_LSR(UART_BASE) & UART_LSR_TEMT) != UART_LSR_TEMT)
;
/* Write byte to UART */
UART_DR(UART_BASE) = c;
UART_THR(UART_BASE) = (c & 0xFF);
}