Change the default cross compiler prefix to powerpc64le-linux-gnu-

[microwatt.git] / hello_world / console.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;
}