You cannot select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
microwatt/hello_world/hello_world.c

147 lines
2.4 KiB
C

#include <unistd.h>
#include <string.h>
#include <stdint.h>
#include <stdbool.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 addr;
uint64_t val;
addr = potato_uart_base + offset;
val = *(volatile uint64_t *)addr;
return val;
}
static void potato_uart_reg_write(int offset, uint64_t val)
{
uint64_t addr;
addr = potato_uart_base + offset;
*(volatile uint64_t *)addr = val;
}
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;
}
#define HELLO_WORLD "Hello World\r\n"
int main(void)
{
potato_uart_init();
putstr(HELLO_WORLD, strlen(HELLO_WORLD));
while (1) {
unsigned char c = getchar();
putchar(c);
}
}