serial: prepare for I/O thread integration

arch/at91sam3x8e/serial.c

@@ -1,15 +1,18 @@
 /* SPDX-License-Identifier: BSD-3-Clause */
 /* See the end of this file for copyright, licensing, and warranty information. */
 
+#include <ardix/io.h>
+#include <ardix/ringbuf.h>
 #include <ardix/serial.h>
 #include <ardix/string.h>
 #include <ardix/types.h>
-#include <ardix/ringbuf.h>
 
 #include <arch/at91sam3x8e/hardware.h>
 #include <arch/at91sam3x8e/interrupt.h>
+#include <arch/at91sam3x8e/sched.h>
 #include <arch/serial.h>
 
+#include <errno.h>
 #include <stddef.h>
 
 struct arch_serial_interface arch_serial_default_interface = {
@@ -86,35 +89,49 @@ void arch_serial_exit(struct serial_interface *interface)
 	interface->id = -1;
 }
 
-int arch_serial_txbuf_rotate(struct serial_interface *interface)
+int arch_serial_txbuf_rotate(struct arch_serial_interface *interface)
 {
-	struct arch_serial_interface *arch_iface = to_arch_serial_interface(interface);
-
-	if (!arch_iface->hw_txrdy)
+	if (!interface->hw_txrdy)
 		return -EBUSY;
-	arch_iface->hw_txrdy = false;
+	interface->hw_txrdy = false;
 
-	if (arch_iface->current_txbuf == ARCH_SERIAL_BUF1) {
+	if (interface->current_txbuf == ARCH_SERIAL_BUF1) {
 		/* buf1 has been written to, DMA has been reading from buf2 */
-		arch_iface->current_txbuf = ARCH_SERIAL_BUF2;
+		interface->current_txbuf = ARCH_SERIAL_BUF2;
 		/* pass buf1 to the DMA controller */
-		REG_UART_PDC_TPR = (uint32_t)&arch_iface->tx1[0];
+		REG_UART_PDC_TPR = (uint32_t)&interface->tx1[0];
 	} else {
 		/* buf2 has been written to, DMA has been reading from buf1 */
-		arch_iface->current_txbuf = ARCH_SERIAL_BUF1;
+		interface->current_txbuf = ARCH_SERIAL_BUF1;
 		/* pass buf2 to the DMA controller */
-		REG_UART_PDC_TPR = (uint32_t)&arch_iface->tx2[0];
+		REG_UART_PDC_TPR = (uint32_t)&interface->tx2[0];
 	}
 
-	REG_UART_PDC_TCR = arch_iface->current_len;
-	arch_iface->current_len = 0;
-
-	/* re-enable the transmitter DMA controller */
-	REG_UART_PDC_PTCR = REG_UART_PDC_PTCR_TXTEN_MASK;
+	REG_UART_PDC_TCR = interface->current_len;
+	interface->current_len = 0;
 
 	return 0;
 }
 
+void io_serial_buf_update(struct serial_interface *interface)
+{
+	void *buf;
+	struct arch_serial_interface *arch_iface = to_arch_serial_interface(interface);
+
+	if (arch_iface->current_len)
+		arch_serial_txbuf_rotate(arch_iface);
+	if (!arch_iface->current_len) {
+		if (arch_iface->current_txbuf == ARCH_SERIAL_BUF1)
+			buf = &arch_iface->tx1[0];
+		else
+			buf = &arch_iface->tx2[0];
+
+		sched_atomic_enter();
+		arch_iface->current_len = (uint16_t)ringbuf_read(buf, interface->tx, SERIAL_BUFSZ);
+		sched_atomic_leave();
+	}
+}
+
 void irq_uart(void)
 {
 	uint8_t tmp;
@@ -123,7 +140,7 @@ void irq_uart(void)
 	/* RX has received a byte, store it into the ring buffer */
 	if (state & REG_UART_SR_RXRDY_MASK) {
 		tmp = REG_UART_RHR;
-		ringbuf_write(serial_default_interface->rx, &tmp, sizeof(tmp));
+		ringbuf_write(arch_serial_default_interface.interface.rx, &tmp, sizeof(tmp));
 	}
 
 	/* TX buffer has been sent */

include/arch/at91sam3x8e/sched.h

@@ -4,7 +4,6 @@
 #pragma once
 
 #include <arch/at91sam3x8e/interrupt.h>
-#include <ardix/sched.h>
 #include <toolchain.h>
 
 /** Enter atomic context, i.e. disable preemption */

include/arch/serial.h

@@ -8,23 +8,6 @@
 int arch_serial_init(struct serial_interface *interface);
 void arch_serial_exit(struct serial_interface *interface);
 
-/**
- * Notify the serial interface about new data in the TX buffer.
- * This is required because if the transmitter is sleeping due to the TX queue being empty,
- * we need some way to tell it to turn on and fire interrupts again.
- *
- * @param interface: The serial interface to notify about new data.
- */
-void arch_serial_notify(struct serial_interface *interface);
-
-/**
- * Copy the current TX ring buffer content to a new hardware buffer.
- *
- * @param interface: The serial interface to rotate the hardware buffer of.
- * @returns 0 on success, or a negative number on failure.
- */
-int arch_serial_txbuf_rotate(struct serial_interface *interface);
-
 #ifdef ARCH_AT91SAM3X8E
 #include <arch/at91sam3x8e/serial.h>
 #else

include/ardix/io.h

@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/* See the end of this file for copyright, licensing, and warranty information. */
+
+#pragma once
+
+#include <ardix/serial.h>
+
+/**
+ * Initialize the I/O thread and subsystems.
+ * Must be called after all I/O components have been initialized.
+ *
+ * @returns 0 on success, or a negative number on failure.
+ */
+int io_init(void);
+
+void io_thread_entry(void);
+
+/**
+ * Update the hardware serial buffers if necessary.
+ * This includes copying to and from the main ring buffers.
+ *
+ * @param interface: The serial interface.
+ */
+void io_serial_buf_update(struct serial_interface *interface);
+
+/*
+ * Copyright (c) 2020 Felix Kopp <sandtler@sandtler.club>
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are permitted
+ * provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this list of
+ *    conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
+ *    conditions and the following disclaimer in the documentation and/or other materials
+ *    provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software without specific prior
+ *    written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
+ * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */