#include <arch/io.h>
#include <uart8250.h>
#include <pc80/mc146818rtc.h>
+#include <trace.h>
+
#if CONFIG_USE_OPTION_TABLE
#include "option_table.h"
#endif
/* Should support 8250, 16450, 16550, 16550A type UARTs */
+/* Expected character delay at 1200bps is 9ms for a working UART
+ * and no flow-control. Assume UART as stuck if shift register
+ * or FIFO takes more than 50ms per character to appear empty.
+ *
+ * Estimated that inb() from UART takes 1 microsecond.
+ */
+#define SINGLE_CHAR_TIMEOUT (50 * 1000)
+#define FIFO_TIMEOUT (16 * SINGLE_CHAR_TIMEOUT)
+
static inline int uart8250_can_tx_byte(unsigned base_port)
{
- return inb(base_port + UART_LSR) & UART_MSR_DSR;
+ return inb(base_port + UART_LSR) & UART_LSR_THRE;
}
static inline void uart8250_wait_to_tx_byte(unsigned base_port)
{
- while(!uart8250_can_tx_byte(base_port))
- ;
+ unsigned long int i = SINGLE_CHAR_TIMEOUT;
+ while (i-- && !uart8250_can_tx_byte(base_port));
}
static inline void uart8250_wait_until_sent(unsigned base_port)
{
- while(!(inb(base_port + UART_LSR) & UART_LSR_TEMT))
- ;
+ unsigned long int i = FIFO_TIMEOUT;
+ while (i-- && !(inb(base_port + UART_LSR) & UART_LSR_TEMT));
}
void uart8250_tx_byte(unsigned base_port, unsigned char data)
{
uart8250_wait_to_tx_byte(base_port);
outb(data, base_port + UART_TBR);
- /* Make certain the data clears the fifos */
+}
+
+void uart8250_tx_flush(unsigned base_port)
+{
uart8250_wait_until_sent(base_port);
}
unsigned char uart8250_rx_byte(unsigned base_port)
{
- while(!uart8250_can_rx_byte(base_port))
- ;
- return inb(base_port + UART_RBR);
+ unsigned long int i = SINGLE_CHAR_TIMEOUT;
+ while (i-- && !uart8250_can_rx_byte(base_port));
+
+ if (i)
+ return inb(base_port + UART_RBR);
+ else
+ return 0x0;
}
void uart8250_init(unsigned base_port, unsigned divisor)
{
+ DISABLE_TRACE;
/* Disable interrupts */
outb(0x0, base_port + UART_IER);
/* Enable FIFOs */
/* DLAB on */
outb(UART_LCR_DLAB | CONFIG_TTYS0_LCS, base_port + UART_LCR);
- /* Set Baud Rate Divisor. 12 ==> 115200 Baud */
+ /* Set Baud Rate Divisor. 12 ==> 9600 Baud */
outb(divisor & 0xFF, base_port + UART_DLL);
outb((divisor >> 8) & 0xFF, base_port + UART_DLM);
/* Set to 3 for 8N1 */
outb(CONFIG_TTYS0_LCS, base_port + UART_LCR);
+ ENABLE_TRACE;
}
void uart_init(void)
static const unsigned char divisor[8] = { 1, 2, 3, 6, 12, 24, 48, 96 };
unsigned b_index = 0;
#if defined(__PRE_RAM__)
- b_index = read_option(CMOS_VSTART_baud_rate, CMOS_VLEN_baud_rate, 0);
+ b_index = read_option(baud_rate, 0);
b_index &= 7;
div = divisor[b_index];
#else