circuitpython/ports/powerpc/uart_potato.c

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2019, Michael Neuling, IBM Corporation.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
/*
* This is a driver for the potato UART used by the microwatt core.
* The original potato UART came from here
* https://github.com/skordal/potato
*/
#include <unistd.h>
#include <stdbool.h>
#include "py/mpconfig.h"
#define SYSCON_BASE 0xc0000000 /* System control regs */
#define SYS_REG_CLKINFO 0x20
#define UART_FREQ 115200
#define POTATO_UART_BASE 0xc0002000
static uint64_t potato_uart_base;
#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 unsigned long potato_uart_divisor(unsigned long proc_freq, unsigned long uart_freq) {
return proc_freq / (uart_freq * 16) - 1;
}
void uart_init_ppc(void) {
uint64_t proc_freq;
potato_uart_base = POTATO_UART_BASE;
proc_freq = *(volatile uint64_t *)(SYSCON_BASE + SYS_REG_CLKINFO);
potato_uart_reg_write(POTATO_CONSOLE_CLOCK_DIV, potato_uart_divisor(proc_freq, UART_FREQ));
}
int mp_hal_stdin_rx_chr(void) {
uint64_t val;
while (potato_uart_rx_empty()) {
;
}
val = potato_uart_reg_read(POTATO_CONSOLE_RX);
return (char)(val & 0x000000ff);
}
void mp_hal_stdout_tx_strn(const char *str, mp_uint_t len) {
int i;
for (i = 0; i < len; i++) {
uint64_t val = str[i];
while (potato_uart_tx_full()) {
;
}
potato_uart_reg_write(POTATO_CONSOLE_TX, val);
}
}