hw/char/grlib_apbuart.c - qemu - Git at Google

 /*
  * QEMU GRLIB APB UART Emulator
  *
  * SPDX-License-Identifier: MIT
  *
  * Copyright (c) 2010-2024 AdaCore
  *
  * 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.
  */

 #include "qemu/osdep.h"
 #include "hw/irq.h"
 #include "hw/qdev-properties.h"
 #include "hw/qdev-properties-system.h"
 #include "hw/char/grlib_uart.h"
 #include "hw/sysbus.h"
 #include "qemu/module.h"
 #include "chardev/char-fe.h"

 #include "trace.h"
 #include "qom/object.h"

 #define UART_REG_SIZE 20     /* Size of memory mapped registers */

 /* UART status register fields */
 #define UART_DATA_READY           (1 <<  0)
 #define UART_TRANSMIT_SHIFT_EMPTY (1 <<  1)
 #define UART_TRANSMIT_FIFO_EMPTY  (1 <<  2)
 #define UART_BREAK_RECEIVED       (1 <<  3)
 #define UART_OVERRUN              (1 <<  4)
 #define UART_PARITY_ERROR         (1 <<  5)
 #define UART_FRAMING_ERROR        (1 <<  6)
 #define UART_TRANSMIT_FIFO_HALF   (1 <<  7)
 #define UART_RECEIVE_FIFO_HALF    (1 <<  8)
 #define UART_TRANSMIT_FIFO_FULL   (1 <<  9)
 #define UART_RECEIVE_FIFO_FULL    (1 << 10)

 /* UART control register fields */
 #define UART_RECEIVE_ENABLE          (1 <<  0)
 #define UART_TRANSMIT_ENABLE         (1 <<  1)
 #define UART_RECEIVE_INTERRUPT       (1 <<  2)
 #define UART_TRANSMIT_INTERRUPT      (1 <<  3)
 #define UART_PARITY_SELECT           (1 <<  4)
 #define UART_PARITY_ENABLE           (1 <<  5)
 #define UART_FLOW_CONTROL            (1 <<  6)
 #define UART_LOOPBACK                (1 <<  7)
 #define UART_EXTERNAL_CLOCK          (1 <<  8)
 #define UART_RECEIVE_FIFO_INTERRUPT  (1 <<  9)
 #define UART_TRANSMIT_FIFO_INTERRUPT (1 << 10)
 #define UART_FIFO_DEBUG_MODE         (1 << 11)
 #define UART_OUTPUT_ENABLE           (1 << 12)
 #define UART_FIFO_AVAILABLE          (1 << 31)

 /* Memory mapped register offsets */
 #define DATA_OFFSET       0x00
 #define STATUS_OFFSET     0x04
 #define CONTROL_OFFSET    0x08
 #define SCALER_OFFSET     0x0C  /* not supported */
 #define FIFO_DEBUG_OFFSET 0x10  /* not supported */

 #define FIFO_LENGTH 1024

 OBJECT_DECLARE_SIMPLE_TYPE(UART, GRLIB_APB_UART)

 struct UART {
     SysBusDevice parent_obj;

     MemoryRegion iomem;
     qemu_irq irq;

     CharBackend chr;

     /* registers */
     uint32_t status;
     uint32_t control;

     /* FIFO */
     char buffer[FIFO_LENGTH];
     int  len;
     int  current;
 };

 static int uart_data_to_read(UART *uart)
 {
     return uart->current < uart->len;
 }

 static char uart_pop(UART *uart)
 {
     char ret;

     if (uart->len == 0) {
         uart->status &= ~UART_DATA_READY;
         return 0;
     }

     ret = uart->buffer[uart->current++];

     if (uart->current >= uart->len) {
         /* Flush */
         uart->len     = 0;
         uart->current = 0;
     }

     if (!uart_data_to_read(uart)) {
         uart->status &= ~UART_DATA_READY;
     }

     return ret;
 }

 static void uart_add_to_fifo(UART          *uart,
                              const uint8_t *buffer,
                              int            length)
 {
     if (uart->len + length > FIFO_LENGTH) {
         abort();
     }
     memcpy(uart->buffer + uart->len, buffer, length);
     uart->len += length;
 }

 static int grlib_apbuart_can_receive(void *opaque)
 {
     UART *uart = opaque;

     return FIFO_LENGTH - uart->len;
 }

 static void grlib_apbuart_receive(void *opaque, const uint8_t *buf, int size)
 {
     UART *uart = opaque;

     if (uart->control & UART_RECEIVE_ENABLE) {
         uart_add_to_fifo(uart, buf, size);

         uart->status |= UART_DATA_READY;

         if (uart->control & UART_RECEIVE_INTERRUPT) {
             qemu_irq_pulse(uart->irq);
         }
     }
 }

 static void grlib_apbuart_event(void *opaque, QEMUChrEvent event)
 {
     trace_grlib_apbuart_event(event);
 }


 static uint64_t grlib_apbuart_read(void *opaque, hwaddr addr,
                                    unsigned size)
 {
     UART     *uart = opaque;

     addr &= 0xff;

     /* Unit registers */
     switch (addr) {
     case DATA_OFFSET:
     case DATA_OFFSET + 3:       /* when only one byte read */
         return uart_pop(uart);

     case STATUS_OFFSET:
         /* Read Only */
         return uart->status;

     case CONTROL_OFFSET:
         return uart->control;

     case SCALER_OFFSET:
         /* Not supported */
         return 0;

     default:
         trace_grlib_apbuart_readl_unknown(addr);
         return 0;
     }
 }

 static void grlib_apbuart_write(void *opaque, hwaddr addr,
                                 uint64_t value, unsigned size)
 {
     UART          *uart = opaque;
     unsigned char  c    = 0;

     addr &= 0xff;

     /* Unit registers */
     switch (addr) {
     case DATA_OFFSET:
     case DATA_OFFSET + 3:       /* When only one byte write */
         /* Transmit when character device available and transmitter enabled */
         if (qemu_chr_fe_backend_connected(&uart->chr) &&
             (uart->control & UART_TRANSMIT_ENABLE)) {
             c = value & 0xFF;
             /* XXX this blocks entire thread. Rewrite to use
              * qemu_chr_fe_write and background I/O callbacks */
             qemu_chr_fe_write_all(&uart->chr, &c, 1);
             /* Generate interrupt */
             if (uart->control & UART_TRANSMIT_INTERRUPT) {
                 qemu_irq_pulse(uart->irq);
             }
         }
         return;

     case STATUS_OFFSET:
         /* Read Only */
         return;

     case CONTROL_OFFSET:
         uart->control = value;
         return;

     case SCALER_OFFSET:
         /* Not supported */
         return;

     default:
         break;
     }

     trace_grlib_apbuart_writel_unknown(addr, value);
 }

 static const MemoryRegionOps grlib_apbuart_ops = {
     .write      = grlib_apbuart_write,
     .read       = grlib_apbuart_read,
     .endianness = DEVICE_NATIVE_ENDIAN,
 };

 static void grlib_apbuart_realize(DeviceState *dev, Error **errp)
 {
     UART *uart = GRLIB_APB_UART(dev);
     SysBusDevice *sbd = SYS_BUS_DEVICE(dev);

     qemu_chr_fe_set_handlers(&uart->chr,
                              grlib_apbuart_can_receive,
                              grlib_apbuart_receive,
                              grlib_apbuart_event,
                              NULL, uart, NULL, true);

     sysbus_init_irq(sbd, &uart->irq);

     memory_region_init_io(&uart->iomem, OBJECT(uart), &grlib_apbuart_ops, uart,
                           "uart", UART_REG_SIZE);

     sysbus_init_mmio(sbd, &uart->iomem);
 }

 static void grlib_apbuart_reset(DeviceState *d)
 {
     UART *uart = GRLIB_APB_UART(d);

     /* Transmitter FIFO and shift registers are always empty in QEMU */
     uart->status =  UART_TRANSMIT_FIFO_EMPTY | UART_TRANSMIT_SHIFT_EMPTY;
     /* Everything is off */
     uart->control = 0;
     /* Flush receive FIFO */
     uart->len = 0;
     uart->current = 0;
 }

 static Property grlib_apbuart_properties[] = {
     DEFINE_PROP_CHR("chrdev", UART, chr),
     DEFINE_PROP_END_OF_LIST(),
 };

 static void grlib_apbuart_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);

     dc->realize = grlib_apbuart_realize;
     dc->reset = grlib_apbuart_reset;
     device_class_set_props(dc, grlib_apbuart_properties);
 }

 static const TypeInfo grlib_apbuart_info = {
     .name          = TYPE_GRLIB_APB_UART,
     .parent        = TYPE_SYS_BUS_DEVICE,
     .instance_size = sizeof(UART),
     .class_init    = grlib_apbuart_class_init,
 };

 static void grlib_apbuart_register_types(void)
 {
     type_register_static(&grlib_apbuart_info);
 }

 type_init(grlib_apbuart_register_types)
	/*
	* QEMU GRLIB APB UART Emulator
	*
	* SPDX-License-Identifier: MIT
	*
	* Copyright (c) 2010-2024 AdaCore
	*
	* 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.
	*/

	#include "qemu/osdep.h"
	#include "hw/irq.h"
	#include "hw/qdev-properties.h"
	#include "hw/qdev-properties-system.h"
	#include "hw/char/grlib_uart.h"
	#include "hw/sysbus.h"
	#include "qemu/module.h"
	#include "chardev/char-fe.h"

	#include "trace.h"
	#include "qom/object.h"

	#define UART_REG_SIZE 20 /* Size of memory mapped registers */

	/* UART status register fields */
	#define UART_DATA_READY (1 << 0)
	#define UART_TRANSMIT_SHIFT_EMPTY (1 << 1)
	#define UART_TRANSMIT_FIFO_EMPTY (1 << 2)
	#define UART_BREAK_RECEIVED (1 << 3)
	#define UART_OVERRUN (1 << 4)
	#define UART_PARITY_ERROR (1 << 5)
	#define UART_FRAMING_ERROR (1 << 6)
	#define UART_TRANSMIT_FIFO_HALF (1 << 7)
	#define UART_RECEIVE_FIFO_HALF (1 << 8)
	#define UART_TRANSMIT_FIFO_FULL (1 << 9)
	#define UART_RECEIVE_FIFO_FULL (1 << 10)

	/* UART control register fields */
	#define UART_RECEIVE_ENABLE (1 << 0)
	#define UART_TRANSMIT_ENABLE (1 << 1)
	#define UART_RECEIVE_INTERRUPT (1 << 2)
	#define UART_TRANSMIT_INTERRUPT (1 << 3)
	#define UART_PARITY_SELECT (1 << 4)
	#define UART_PARITY_ENABLE (1 << 5)
	#define UART_FLOW_CONTROL (1 << 6)
	#define UART_LOOPBACK (1 << 7)
	#define UART_EXTERNAL_CLOCK (1 << 8)
	#define UART_RECEIVE_FIFO_INTERRUPT (1 << 9)
	#define UART_TRANSMIT_FIFO_INTERRUPT (1 << 10)
	#define UART_FIFO_DEBUG_MODE (1 << 11)
	#define UART_OUTPUT_ENABLE (1 << 12)
	#define UART_FIFO_AVAILABLE (1 << 31)

	/* Memory mapped register offsets */
	#define DATA_OFFSET 0x00
	#define STATUS_OFFSET 0x04
	#define CONTROL_OFFSET 0x08
	#define SCALER_OFFSET 0x0C /* not supported */
	#define FIFO_DEBUG_OFFSET 0x10 /* not supported */

	#define FIFO_LENGTH 1024

	OBJECT_DECLARE_SIMPLE_TYPE(UART, GRLIB_APB_UART)

	struct UART {
	SysBusDevice parent_obj;

	MemoryRegion iomem;
	qemu_irq irq;

	CharBackend chr;

	/* registers */
	uint32_t status;
	uint32_t control;

	/* FIFO */
	char buffer[FIFO_LENGTH];
	int len;
	int current;
	};

	static int uart_data_to_read(UART *uart)
	{
	return uart->current < uart->len;
	}

	static char uart_pop(UART *uart)
	{
	char ret;

	if (uart->len == 0) {
	uart->status &= ~UART_DATA_READY;
	return 0;
	}

	ret = uart->buffer[uart->current++];

	if (uart->current >= uart->len) {
	/* Flush */
	uart->len = 0;
	uart->current = 0;
	}

	if (!uart_data_to_read(uart)) {
	uart->status &= ~UART_DATA_READY;
	}

	return ret;
	}

	static void uart_add_to_fifo(UART *uart,
	const uint8_t *buffer,
	int length)
	{
	if (uart->len + length > FIFO_LENGTH) {
	abort();
	}
	memcpy(uart->buffer + uart->len, buffer, length);
	uart->len += length;
	}

	static int grlib_apbuart_can_receive(void *opaque)
	{
	UART *uart = opaque;

	return FIFO_LENGTH - uart->len;
	}

	static void grlib_apbuart_receive(void opaque, const uint8_t buf, int size)
	{
	UART *uart = opaque;

	if (uart->control & UART_RECEIVE_ENABLE) {
	uart_add_to_fifo(uart, buf, size);

	uart->status \|= UART_DATA_READY;

	if (uart->control & UART_RECEIVE_INTERRUPT) {
	qemu_irq_pulse(uart->irq);
	}
	}
	}

	static void grlib_apbuart_event(void *opaque, QEMUChrEvent event)
	{
	trace_grlib_apbuart_event(event);
	}


	static uint64_t grlib_apbuart_read(void *opaque, hwaddr addr,
	unsigned size)
	{
	UART *uart = opaque;

	addr &= 0xff;

	/* Unit registers */
	switch (addr) {
	case DATA_OFFSET:
	case DATA_OFFSET + 3: /* when only one byte read */
	return uart_pop(uart);

	case STATUS_OFFSET:
	/* Read Only */
	return uart->status;

	case CONTROL_OFFSET:
	return uart->control;

	case SCALER_OFFSET:
	/* Not supported */
	return 0;

	default:
	trace_grlib_apbuart_readl_unknown(addr);
	return 0;
	}
	}

	static void grlib_apbuart_write(void *opaque, hwaddr addr,
	uint64_t value, unsigned size)
	{
	UART *uart = opaque;
	unsigned char c = 0;

	addr &= 0xff;

	/* Unit registers */
	switch (addr) {
	case DATA_OFFSET:
	case DATA_OFFSET + 3: /* When only one byte write */
	/* Transmit when character device available and transmitter enabled */
	if (qemu_chr_fe_backend_connected(&uart->chr) &&
	(uart->control & UART_TRANSMIT_ENABLE)) {
	c = value & 0xFF;
	/* XXX this blocks entire thread. Rewrite to use
	* qemu_chr_fe_write and background I/O callbacks */
	qemu_chr_fe_write_all(&uart->chr, &c, 1);
	/* Generate interrupt */
	if (uart->control & UART_TRANSMIT_INTERRUPT) {
	qemu_irq_pulse(uart->irq);
	}
	}
	return;

	case STATUS_OFFSET:
	/* Read Only */
	return;

	case CONTROL_OFFSET:
	uart->control = value;
	return;

	case SCALER_OFFSET:
	/* Not supported */
	return;

	default:
	break;
	}

	trace_grlib_apbuart_writel_unknown(addr, value);
	}

	static const MemoryRegionOps grlib_apbuart_ops = {
	.write = grlib_apbuart_write,
	.read = grlib_apbuart_read,
	.endianness = DEVICE_NATIVE_ENDIAN,
	};

	static void grlib_apbuart_realize(DeviceState dev, Error *errp)
	{
	UART *uart = GRLIB_APB_UART(dev);
	SysBusDevice *sbd = SYS_BUS_DEVICE(dev);

	qemu_chr_fe_set_handlers(&uart->chr,
	grlib_apbuart_can_receive,
	grlib_apbuart_receive,
	grlib_apbuart_event,
	NULL, uart, NULL, true);

	sysbus_init_irq(sbd, &uart->irq);

	memory_region_init_io(&uart->iomem, OBJECT(uart), &grlib_apbuart_ops, uart,
	"uart", UART_REG_SIZE);

	sysbus_init_mmio(sbd, &uart->iomem);
	}

	static void grlib_apbuart_reset(DeviceState *d)
	{
	UART *uart = GRLIB_APB_UART(d);

	/* Transmitter FIFO and shift registers are always empty in QEMU */
	uart->status = UART_TRANSMIT_FIFO_EMPTY \| UART_TRANSMIT_SHIFT_EMPTY;
	/* Everything is off */
	uart->control = 0;
	/* Flush receive FIFO */
	uart->len = 0;
	uart->current = 0;
	}

	static Property grlib_apbuart_properties[] = {
	DEFINE_PROP_CHR("chrdev", UART, chr),
	DEFINE_PROP_END_OF_LIST(),
	};

	static void grlib_apbuart_class_init(ObjectClass klass, void data)
	{
	DeviceClass *dc = DEVICE_CLASS(klass);

	dc->realize = grlib_apbuart_realize;
	dc->reset = grlib_apbuart_reset;
	device_class_set_props(dc, grlib_apbuart_properties);
	}

	static const TypeInfo grlib_apbuart_info = {
	.name = TYPE_GRLIB_APB_UART,
	.parent = TYPE_SYS_BUS_DEVICE,
	.instance_size = sizeof(UART),
	.class_init = grlib_apbuart_class_init,
	};

	static void grlib_apbuart_register_types(void)
	{
	type_register_static(&grlib_apbuart_info);
	}

	type_init(grlib_apbuart_register_types)