dc1cfc0b33
Only tested with SBI and supervisor mode, but that's all I have now. Add checked in copies of the device tree needed for a uboot uimage needed to start it.
101 lines
2.3 KiB
C
101 lines
2.3 KiB
C
/*
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* Copyright (c) 2018 Travis Geiselbrecht
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*
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* Use of this source code is governed by a MIT-style
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* license that can be found in the LICENSE file or at
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* https://opensource.org/licenses/MIT
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*/
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#include <lk/reg.h>
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#include <lk/trace.h>
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#include <lib/cbuf.h>
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#include <kernel/thread.h>
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#include <platform.h>
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#include <platform/interrupts.h>
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#include <platform/debug.h>
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#include <platform/sifive.h>
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#include <sys/types.h>
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#include "platform_p.h"
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#define LOCAL_TRACE 0
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#define POLLING_RX 0
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static volatile unsigned int *const uart_base = (unsigned int *)UART0_BASE;
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#define UART_TXDATA 0
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#define UART_RXDATA 1
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#define UART_TXCTRL 2
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#define UART_RXCTRL 3
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#define UART_IE 4
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#define UART_IP 5
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#define UART_DIV 6
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#define RXBUF_SIZE 128
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static char uart_rx_buf_data[RXBUF_SIZE];
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static struct cbuf uart_rx_buf;
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static spin_lock_t uart_tx_spin_lock = 0;
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void sifive_uart_write(int c) {
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spin_lock_saved_state_t state;
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spin_lock_irqsave(&uart_tx_spin_lock, state);
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// wait for tx fifo to clear
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while (uart_base[UART_TXDATA] & (1<<31))
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;
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uart_base[UART_TXDATA] = (c & 0xff);
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spin_unlock_irqrestore(&uart_tx_spin_lock, state);
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}
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int sifive_uart_read(char *c, bool wait) {
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#if !POLLING_RX
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if (cbuf_read_char(&uart_rx_buf, c, wait) == 1) {
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return 0;
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}
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return -1;
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#else
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// full polling mode for reads
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int i = uart_base[UART_RXDATA];
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if (i & (1<<31))
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return -1;
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*c = i & 0xff;
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return 0;
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#endif
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}
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static enum handler_return sifive_uart_irq(void *unused) {
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LTRACE;
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enum handler_return ret = INT_NO_RESCHEDULE;
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for (;;) {
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int c = uart_base[UART_RXDATA];
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if (c & (1<<31))
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break; // nothing in the fifo
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// stuff this char in the cbuf and try again
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cbuf_write_char(&uart_rx_buf, c & 0xff, false);
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ret = INT_RESCHEDULE;
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}
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return ret;
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}
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void sifive_uart_early_init(void) {
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uart_base[UART_DIV] = SIFIVE_FREQ / 115200;
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uart_base[UART_TXCTRL] = 1; // txen
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}
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void sifive_uart_init(void) {
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cbuf_initialize_etc(&uart_rx_buf, RXBUF_SIZE, uart_rx_buf_data);
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register_int_handler(SIFIVE_IRQ_UART0, sifive_uart_irq, NULL);
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uart_base[UART_RXCTRL] = 1; // rxen, rxcnt = 0
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uart_base[UART_IE] |= (1<<1); // rxwvm
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#if !POLLING_RX
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unmask_interrupt(SIFIVE_IRQ_UART0);
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#endif
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}
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