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57 lines
1.2 KiB
C
57 lines
1.2 KiB
C
/*
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* Copyright (c) 2020 Olof Kindgren <olof.kindgren@gmail.com>
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <kernel.h>
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#include <arch/cpu.h>
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#include <drivers/uart.h>
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#define reg_uart_data (*(volatile uint32_t*)UART_BITBANG_BASE)
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static struct k_spinlock lock;
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static void uart_bitbang_poll_out(const struct device *dev, unsigned char c)
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{
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ARG_UNUSED(dev);
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k_spinlock_key_t key = k_spin_lock(&lock);
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int cout = (c|0x100) << 1;
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do {
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reg_uart_data = cout;
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cout >>= 1;
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__asm__ __volatile__ ("nop");
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__asm__ __volatile__ ("nop");
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} while (cout);
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k_spin_unlock(&lock, key);
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}
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static int uart_bitbang_poll_in(const struct device *dev, unsigned char *c)
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{
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ARG_UNUSED(dev);
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*c = reg_uart_data;
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return 0;
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}
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static int uart_bitbang_init(const struct device *dev)
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{
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ARG_UNUSED(dev);
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reg_uart_data = 1;
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return 0;
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}
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static const struct uart_driver_api uart_bitbang_driver_api = {
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.poll_in = uart_bitbang_poll_in,
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.poll_out = uart_bitbang_poll_out,
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.err_check = NULL,
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};
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DEVICE_AND_API_INIT(uart_bitbang, "uart0", &uart_bitbang_init,
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NULL, NULL,
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PRE_KERNEL_1, CONFIG_KERNEL_INIT_PRIORITY_DEVICE,
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&uart_bitbang_driver_api);
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