/* * 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; device_class_set_legacy_reset(dc, 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)