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microwatt/hello_world/console.c

126 lines
2.2 KiB
C

#include <stdint.h>
#include <stdbool.h>
#include "console.h"
/*
* Core UART functions to implement for a port
*/
static uint64_t potato_uart_base;
#define PROC_FREQ 50000000
#define UART_FREQ 115200
#define UART_BASE 0xc0002000
#define POTATO_CONSOLE_TX 0x00
#define POTATO_CONSOLE_RX 0x08
#define POTATO_CONSOLE_STATUS 0x10
#define POTATO_CONSOLE_STATUS_RX_EMPTY 0x01
#define POTATO_CONSOLE_STATUS_TX_EMPTY 0x02
#define POTATO_CONSOLE_STATUS_RX_FULL 0x04
#define POTATO_CONSOLE_STATUS_TX_FULL 0x08
#define POTATO_CONSOLE_CLOCK_DIV 0x18
#define POTATO_CONSOLE_IRQ_EN 0x20
static uint64_t potato_uart_reg_read(int offset)
{
uint64_t val;
__asm__ volatile("ldcix %0,%1,%2" : "=r" (val) : "b" (potato_uart_base), "r" (offset));
return val;
}
static void potato_uart_reg_write(int offset, uint64_t val)
{
__asm__ volatile("stdcix %0,%1,%2" : : "r" (val), "b" (potato_uart_base), "r" (offset));
}
static int potato_uart_rx_empty(void)
{
uint64_t val;
val = potato_uart_reg_read(POTATO_CONSOLE_STATUS);
if (val & POTATO_CONSOLE_STATUS_RX_EMPTY)
return 1;
return 0;
}
static int potato_uart_tx_full(void)
{
uint64_t val;
val = potato_uart_reg_read(POTATO_CONSOLE_STATUS);
if (val & POTATO_CONSOLE_STATUS_TX_FULL)
return 1;
return 0;
}
static char potato_uart_read(void)
{
uint64_t val;
val = potato_uart_reg_read(POTATO_CONSOLE_RX);
return (char)(val & 0x000000ff);
}
static void potato_uart_write(char c)
{
uint64_t val;
val = c;
potato_uart_reg_write(POTATO_CONSOLE_TX, val);
}
static unsigned long potato_uart_divisor(unsigned long proc_freq, unsigned long uart_freq)
{
return proc_freq / (uart_freq * 16) - 1;
}
void potato_uart_init(void)
{
potato_uart_base = UART_BASE;
potato_uart_reg_write(POTATO_CONSOLE_CLOCK_DIV, potato_uart_divisor(PROC_FREQ, UART_FREQ));
}
int getchar(void)
{
while (potato_uart_rx_empty())
/* Do nothing */ ;
return potato_uart_read();
}
void putchar(unsigned char c)
{
while (potato_uart_tx_full())
/* Do Nothing */;
potato_uart_write(c);
}
void putstr(const char *str, unsigned long len)
{
for (unsigned long i = 0; i < len; i++) {
putchar(str[i]);
}
}
size_t strlen(const char *s)
{
size_t len = 0;
while (*s++)
len++;
return len;
}