diff options
Diffstat (limited to 'fw/src/usart_helpers.c')
| -rw-r--r-- | fw/src/usart_helpers.c | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/fw/src/usart_helpers.c b/fw/src/usart_helpers.c new file mode 100644 index 0000000..0cfc2d5 --- /dev/null +++ b/fw/src/usart_helpers.c @@ -0,0 +1,149 @@ +/*
+ * This file is part of the libusbhost library
+ * hosted at http://github.com/libusbhost/libusbhost
+ *
+ * Copyright (C) 2015 Amir Hammad <amir.hammad@hotmail.com>
+ *
+ *
+ * libusbhost is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+
+#include "usart_helpers.h"
+#define TINYPRINTF_OVERRIDE_LIBC 0
+#define TINYPRINTF_DEFINE_TFP_SPRINTF 0
+#include "tinyprintf.h"
+#include "cobs.h"
+
+#include <string.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <libopencm3/stm32/usart.h>
+#include <libopencm3/stm32/dma.h>
+#include <libopencm3/cm3/nvic.h>
+#include <libopencmsis/core_cm3.h>
+
+
+void usart_fprintf(struct dma_usart_file *f, const char *str, ...) {
+ va_list va;
+ va_start(va, str);
+ tfp_format(f, (void (*)(void *, char c))putf, str, va);
+ va_end(va);
+ flush(f);
+}
+
+void usart_init(uint32_t arg_usart, uint32_t baudrate) {
+ usart_set_baudrate(arg_usart, baudrate);
+ usart_set_databits(arg_usart, 8);
+ usart_set_flow_control(arg_usart, USART_FLOWCONTROL_NONE);
+ usart_set_mode(arg_usart, USART_MODE_TX | USART_MODE_RX);
+ usart_set_parity(arg_usart, USART_PARITY_NONE);
+ usart_set_stopbits(arg_usart, USART_STOPBITS_1);
+ usart_enable(arg_usart);
+}
+
+void usart_dma_init(struct dma_usart_file *f) {
+ usart_init(f->usart, f->baudrate);
+
+ f->buf->xfr_start = -1,
+ f->buf->xfr_end = 0,
+ f->buf->wr_pos = 0,
+
+ dma_stream_reset(f->dma, f->stream);
+ dma_channel_select(f->dma, f->stream, DMA_SxCR_CHSEL(f->channel));
+ dma_set_peripheral_address(f->dma, f->stream, (uint32_t)&USART_DR(f->usart));
+ dma_set_transfer_mode(f->dma, f->stream, DMA_SxCR_DIR_MEM_TO_PERIPHERAL);
+ dma_enable_memory_increment_mode(f->dma, f->stream);
+ dma_set_peripheral_size(f->dma, f->stream, DMA_SxCR_PSIZE_8BIT);
+ dma_set_memory_size(f->dma, f->stream, DMA_SxCR_MSIZE_8BIT);
+ dma_set_priority(f->dma, f->stream, DMA_SxCR_PL_VERY_HIGH);
+ dma_enable_transfer_complete_interrupt(f->dma, f->stream);
+ dma_enable_fifo_error_interrupt(f->dma, f->stream);
+ usart_enable_tx_dma(f->usart);
+}
+
+void usart_kickoff_dma(uint32_t dma, uint8_t stream, volatile uint8_t *buf, size_t len) {
+ /* initiate transmission of new buffer */
+ dma_set_memory_address(dma, stream, (uint32_t)buf); /* select active buffer address */
+ dma_set_number_of_data(dma, stream, len);
+ dma_enable_stream(dma, stream);
+}
+
+void schedule_dma(volatile struct dma_usart_file *f) {
+ volatile struct dma_buf *buf = f->buf;
+
+ uint32_t xfr_len, xfr_start = buf->xfr_end;
+ if (buf->wr_pos > xfr_start) /* no wraparound */
+ xfr_len = buf->wr_pos - xfr_start;
+ else /* wraparound */
+ xfr_len = buf->len - xfr_start; /* schedule transfer until end of buffer */
+
+ buf->xfr_start = xfr_start;
+ buf->xfr_end = (xfr_start + xfr_len) % buf->len; /* handle wraparound */
+ usart_kickoff_dma(f->dma, f->stream, buf->data + xfr_start, xfr_len);
+}
+
+int dma_fifo_push(volatile struct dma_buf *buf, char c) {
+ if (buf->wr_pos == buf->xfr_start)
+ return -EBUSY;
+
+ buf->data[buf->wr_pos] = c;
+ buf->wr_pos = (buf->wr_pos + 1) % buf->len;
+ return 0;
+}
+
+int putf(void *file, char c) {
+ volatile struct dma_usart_file *f = (struct dma_usart_file *)file;
+
+ nvic_disable_irq(f->irqn);
+ /* push char to fifo, busy-loop if stalled to wait for USART to empty fifo via DMA */
+ while (dma_fifo_push(f->buf, c) == -EBUSY) {
+ nvic_enable_irq(f->irqn);
+ flush(f);
+ nvic_disable_irq(f->irqn);
+ }
+ nvic_enable_irq(f->irqn);
+ return 0;
+}
+
+int putb(void *file, const uint8_t *buf, size_t len) {
+ volatile struct dma_usart_file *f = (struct dma_usart_file *)file;
+
+ nvic_disable_irq(f->irqn);
+ for (size_t i=0; i<len; i++) {
+ /* push char to fifo, busy-loop if stalled to wait for USART to empty fifo via DMA */
+ while (dma_fifo_push(f->buf, buf[i]) == -EBUSY) {
+ nvic_enable_irq(f->irqn);
+ nvic_disable_irq(f->irqn);
+ }
+ }
+ nvic_enable_irq(f->irqn);
+ return 0;
+}
+
+void flush(void *file) {
+ volatile struct dma_usart_file *f = (struct dma_usart_file *)file;
+
+ nvic_disable_irq(f->irqn);
+ /* If the DMA stream is idle right now, schedule a transfer */
+ if (!(DMA_SCR(f->dma, f->stream) & DMA_SxCR_EN)) { /* DMA is not running */
+ //&& !dma_get_interrupt_flag(f->dma, f->stream, DMA_TCIF)/* DMA interrupt is clear */) {
+ dma_clear_interrupt_flags(f->dma, f->stream, DMA_TCIF);
+ schedule_dma(f);
+ }
+ nvic_enable_irq(f->irqn);
+}
+
|