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qemu/hw/char/ibex_uart.c
Alexander Wagner 82a4ed8e50 hw/char: disable ibex uart receive if the buffer is full 
Not disabling the UART leads to QEMU overwriting the UART receive buffer with
the newest received byte. The rx_level variable is added to allow the use of
the existing OpenTitan driver libraries.

Signed-off-by: Alexander Wagner <alexander.wagner@ulal.de>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20210309152130.13038-1-alexander.wagner@ulal.de
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
2021-03-22 21:54:40 -04:00

531 lines
16 KiB
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/*
* QEMU lowRISC Ibex UART device
*
* Copyright (c) 2020 Western Digital
*
* For details check the documentation here:
* https://docs.opentitan.org/hw/ip/uart/doc/
*
* 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/char/ibex_uart.h"
#include "hw/irq.h"
#include "hw/qdev-clock.h"
#include "hw/qdev-properties.h"
#include "hw/qdev-properties-system.h"
#include "migration/vmstate.h"
#include "qemu/log.h"
#include "qemu/module.h"
static void ibex_uart_update_irqs(IbexUartState *s)
{
if (s->uart_intr_state & s->uart_intr_enable & R_INTR_STATE_TX_WATERMARK_MASK) {
qemu_set_irq(s->tx_watermark, 1);
} else {
qemu_set_irq(s->tx_watermark, 0);
}
if (s->uart_intr_state & s->uart_intr_enable & R_INTR_STATE_RX_WATERMARK_MASK) {
qemu_set_irq(s->rx_watermark, 1);
} else {
qemu_set_irq(s->rx_watermark, 0);
}
if (s->uart_intr_state & s->uart_intr_enable & R_INTR_STATE_TX_EMPTY_MASK) {
qemu_set_irq(s->tx_empty, 1);
} else {
qemu_set_irq(s->tx_empty, 0);
}
if (s->uart_intr_state & s->uart_intr_enable & R_INTR_STATE_RX_OVERFLOW_MASK) {
qemu_set_irq(s->rx_overflow, 1);
} else {
qemu_set_irq(s->rx_overflow, 0);
}
}
static int ibex_uart_can_receive(void *opaque)
{
IbexUartState *s = opaque;
if ((s->uart_ctrl & R_CTRL_RX_ENABLE_MASK)
&& !(s->uart_status & R_STATUS_RXFULL_MASK)) {
return 1;
}
return 0;
}
static void ibex_uart_receive(void *opaque, const uint8_t *buf, int size)
{
IbexUartState *s = opaque;
uint8_t rx_fifo_level = (s->uart_fifo_ctrl & R_FIFO_CTRL_RXILVL_MASK)
>> R_FIFO_CTRL_RXILVL_SHIFT;
s->uart_rdata = *buf;
s->uart_status &= ~R_STATUS_RXIDLE_MASK;
s->uart_status &= ~R_STATUS_RXEMPTY_MASK;
/* The RXFULL is set after receiving a single byte
* as the FIFO buffers are not yet implemented.
*/
s->uart_status |= R_STATUS_RXFULL_MASK;
s->rx_level += 1;
if (size > rx_fifo_level) {
s->uart_intr_state |= R_INTR_STATE_RX_WATERMARK_MASK;
}
ibex_uart_update_irqs(s);
}
static gboolean ibex_uart_xmit(GIOChannel *chan, GIOCondition cond,
void *opaque)
{
IbexUartState *s = opaque;
uint8_t tx_fifo_level = (s->uart_fifo_ctrl & R_FIFO_CTRL_TXILVL_MASK)
>> R_FIFO_CTRL_TXILVL_SHIFT;
int ret;
/* instant drain the fifo when there's no back-end */
if (!qemu_chr_fe_backend_connected(&s->chr)) {
s->tx_level = 0;
return FALSE;
}
if (!s->tx_level) {
s->uart_status &= ~R_STATUS_TXFULL_MASK;
s->uart_status |= R_STATUS_TXEMPTY_MASK;
s->uart_intr_state |= R_INTR_STATE_TX_EMPTY_MASK;
s->uart_intr_state &= ~R_INTR_STATE_TX_WATERMARK_MASK;
ibex_uart_update_irqs(s);
return FALSE;
}
ret = qemu_chr_fe_write(&s->chr, s->tx_fifo, s->tx_level);
if (ret >= 0) {
s->tx_level -= ret;
memmove(s->tx_fifo, s->tx_fifo + ret, s->tx_level);
}
if (s->tx_level) {
guint r = qemu_chr_fe_add_watch(&s->chr, G_IO_OUT | G_IO_HUP,
ibex_uart_xmit, s);
if (!r) {
s->tx_level = 0;
return FALSE;
}
}
/* Clear the TX Full bit */
if (s->tx_level != IBEX_UART_TX_FIFO_SIZE) {
s->uart_status &= ~R_STATUS_TXFULL_MASK;
}
/* Disable the TX_WATERMARK IRQ */
if (s->tx_level < tx_fifo_level) {
s->uart_intr_state &= ~R_INTR_STATE_TX_WATERMARK_MASK;
}
/* Set TX empty */
if (s->tx_level == 0) {
s->uart_status |= R_STATUS_TXEMPTY_MASK;
s->uart_intr_state |= R_INTR_STATE_TX_EMPTY_MASK;
}
ibex_uart_update_irqs(s);
return FALSE;
}
static void uart_write_tx_fifo(IbexUartState *s, const uint8_t *buf,
int size)
{
uint64_t current_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
uint8_t tx_fifo_level = (s->uart_fifo_ctrl & R_FIFO_CTRL_TXILVL_MASK)
>> R_FIFO_CTRL_TXILVL_SHIFT;
if (size > IBEX_UART_TX_FIFO_SIZE - s->tx_level) {
size = IBEX_UART_TX_FIFO_SIZE - s->tx_level;
qemu_log_mask(LOG_GUEST_ERROR, "ibex_uart: TX FIFO overflow");
}
memcpy(s->tx_fifo + s->tx_level, buf, size);
s->tx_level += size;
if (s->tx_level > 0) {
s->uart_status &= ~R_STATUS_TXEMPTY_MASK;
}
if (s->tx_level >= tx_fifo_level) {
s->uart_intr_state |= R_INTR_STATE_TX_WATERMARK_MASK;
ibex_uart_update_irqs(s);
}
if (s->tx_level == IBEX_UART_TX_FIFO_SIZE) {
s->uart_status |= R_STATUS_TXFULL_MASK;
}
timer_mod(s->fifo_trigger_handle, current_time +
(s->char_tx_time * 4));
}
static void ibex_uart_reset(DeviceState *dev)
{
IbexUartState *s = IBEX_UART(dev);
s->uart_intr_state = 0x00000000;
s->uart_intr_state = 0x00000000;
s->uart_intr_enable = 0x00000000;
s->uart_ctrl = 0x00000000;
s->uart_status = 0x0000003c;
s->uart_rdata = 0x00000000;
s->uart_fifo_ctrl = 0x00000000;
s->uart_fifo_status = 0x00000000;
s->uart_ovrd = 0x00000000;
s->uart_val = 0x00000000;
s->uart_timeout_ctrl = 0x00000000;
s->tx_level = 0;
s->rx_level = 0;
s->char_tx_time = (NANOSECONDS_PER_SECOND / 230400) * 10;
ibex_uart_update_irqs(s);
}
static uint64_t ibex_uart_get_baud(IbexUartState *s)
{
uint64_t baud;
baud = ((s->uart_ctrl & R_CTRL_NCO_MASK) >> 16);
baud *= clock_get_hz(s->f_clk);
baud >>= 20;
return baud;
}
static uint64_t ibex_uart_read(void *opaque, hwaddr addr,
unsigned int size)
{
IbexUartState *s = opaque;
uint64_t retvalue = 0;
switch (addr >> 2) {
case R_INTR_STATE:
retvalue = s->uart_intr_state;
break;
case R_INTR_ENABLE:
retvalue = s->uart_intr_enable;
break;
case R_INTR_TEST:
qemu_log_mask(LOG_GUEST_ERROR,
"%s: wdata is write only\n", __func__);
break;
case R_CTRL:
retvalue = s->uart_ctrl;
break;
case R_STATUS:
retvalue = s->uart_status;
break;
case R_RDATA:
retvalue = s->uart_rdata;
if ((s->uart_ctrl & R_CTRL_RX_ENABLE_MASK) && (s->rx_level > 0)) {
qemu_chr_fe_accept_input(&s->chr);
s->rx_level -= 1;
s->uart_status &= ~R_STATUS_RXFULL_MASK;
if (s->rx_level == 0) {
s->uart_status |= R_STATUS_RXIDLE_MASK;
s->uart_status |= R_STATUS_RXEMPTY_MASK;
}
}
break;
case R_WDATA:
qemu_log_mask(LOG_GUEST_ERROR,
"%s: wdata is write only\n", __func__);
break;
case R_FIFO_CTRL:
retvalue = s->uart_fifo_ctrl;
break;
case R_FIFO_STATUS:
retvalue = s->uart_fifo_status;
retvalue |= (s->rx_level & 0x1F) << R_FIFO_STATUS_RXLVL_SHIFT;
retvalue |= (s->tx_level & 0x1F) << R_FIFO_STATUS_TXLVL_SHIFT;
qemu_log_mask(LOG_UNIMP,
"%s: RX fifos are not supported\n", __func__);
break;
case R_OVRD:
retvalue = s->uart_ovrd;
qemu_log_mask(LOG_UNIMP,
"%s: ovrd is not supported\n", __func__);
break;
case R_VAL:
retvalue = s->uart_val;
qemu_log_mask(LOG_UNIMP,
"%s: val is not supported\n", __func__);
break;
case R_TIMEOUT_CTRL:
retvalue = s->uart_timeout_ctrl;
qemu_log_mask(LOG_UNIMP,
"%s: timeout_ctrl is not supported\n", __func__);
break;
default:
qemu_log_mask(LOG_GUEST_ERROR,
"%s: Bad offset 0x%"HWADDR_PRIx"\n", __func__, addr);
return 0;
}
return retvalue;
}
static void ibex_uart_write(void *opaque, hwaddr addr,
uint64_t val64, unsigned int size)
{
IbexUartState *s = opaque;
uint32_t value = val64;
switch (addr >> 2) {
case R_INTR_STATE:
/* Write 1 clear */
s->uart_intr_state &= ~value;
ibex_uart_update_irqs(s);
break;
case R_INTR_ENABLE:
s->uart_intr_enable = value;
ibex_uart_update_irqs(s);
break;
case R_INTR_TEST:
s->uart_intr_state |= value;
ibex_uart_update_irqs(s);
break;
case R_CTRL:
s->uart_ctrl = value;
if (value & R_CTRL_NF_MASK) {
qemu_log_mask(LOG_UNIMP,
"%s: UART_CTRL_NF is not supported\n", __func__);
}
if (value & R_CTRL_SLPBK_MASK) {
qemu_log_mask(LOG_UNIMP,
"%s: UART_CTRL_SLPBK is not supported\n", __func__);
}
if (value & R_CTRL_LLPBK_MASK) {
qemu_log_mask(LOG_UNIMP,
"%s: UART_CTRL_LLPBK is not supported\n", __func__);
}
if (value & R_CTRL_PARITY_EN_MASK) {
qemu_log_mask(LOG_UNIMP,
"%s: UART_CTRL_PARITY_EN is not supported\n",
__func__);
}
if (value & R_CTRL_PARITY_ODD_MASK) {
qemu_log_mask(LOG_UNIMP,
"%s: UART_CTRL_PARITY_ODD is not supported\n",
__func__);
}
if (value & R_CTRL_RXBLVL_MASK) {
qemu_log_mask(LOG_UNIMP,
"%s: UART_CTRL_RXBLVL is not supported\n", __func__);
}
if (value & R_CTRL_NCO_MASK) {
uint64_t baud = ibex_uart_get_baud(s);
s->char_tx_time = (NANOSECONDS_PER_SECOND / baud) * 10;
}
break;
case R_STATUS:
qemu_log_mask(LOG_GUEST_ERROR,
"%s: status is read only\n", __func__);
break;
case R_RDATA:
qemu_log_mask(LOG_GUEST_ERROR,
"%s: rdata is read only\n", __func__);
break;
case R_WDATA:
uart_write_tx_fifo(s, (uint8_t *) &value, 1);
break;
case R_FIFO_CTRL:
s->uart_fifo_ctrl = value;
if (value & R_FIFO_CTRL_RXRST_MASK) {
s->rx_level = 0;
qemu_log_mask(LOG_UNIMP,
"%s: RX fifos are not supported\n", __func__);
}
if (value & R_FIFO_CTRL_TXRST_MASK) {
s->tx_level = 0;
}
break;
case R_FIFO_STATUS:
qemu_log_mask(LOG_GUEST_ERROR,
"%s: fifo_status is read only\n", __func__);
break;
case R_OVRD:
s->uart_ovrd = value;
qemu_log_mask(LOG_UNIMP,
"%s: ovrd is not supported\n", __func__);
break;
case R_VAL:
qemu_log_mask(LOG_GUEST_ERROR,
"%s: val is read only\n", __func__);
break;
case R_TIMEOUT_CTRL:
s->uart_timeout_ctrl = value;
qemu_log_mask(LOG_UNIMP,
"%s: timeout_ctrl is not supported\n", __func__);
break;
default:
qemu_log_mask(LOG_GUEST_ERROR,
"%s: Bad offset 0x%"HWADDR_PRIx"\n", __func__, addr);
}
}
static void ibex_uart_clk_update(void *opaque, ClockEvent event)
{
IbexUartState *s = opaque;
/* recompute uart's speed on clock change */
uint64_t baud = ibex_uart_get_baud(s);
s->char_tx_time = (NANOSECONDS_PER_SECOND / baud) * 10;
}
static void fifo_trigger_update(void *opaque)
{
IbexUartState *s = opaque;
if (s->uart_ctrl & R_CTRL_TX_ENABLE_MASK) {
ibex_uart_xmit(NULL, G_IO_OUT, s);
}
}
static const MemoryRegionOps ibex_uart_ops = {
.read = ibex_uart_read,
.write = ibex_uart_write,
.endianness = DEVICE_NATIVE_ENDIAN,
.impl.min_access_size = 4,
.impl.max_access_size = 4,
};
static int ibex_uart_post_load(void *opaque, int version_id)
{
IbexUartState *s = opaque;
ibex_uart_update_irqs(s);
return 0;
}
static const VMStateDescription vmstate_ibex_uart = {
.name = TYPE_IBEX_UART,
.version_id = 1,
.minimum_version_id = 1,
.post_load = ibex_uart_post_load,
.fields = (VMStateField[]) {
VMSTATE_UINT8_ARRAY(tx_fifo, IbexUartState,
IBEX_UART_TX_FIFO_SIZE),
VMSTATE_UINT32(tx_level, IbexUartState),
VMSTATE_UINT64(char_tx_time, IbexUartState),
VMSTATE_TIMER_PTR(fifo_trigger_handle, IbexUartState),
VMSTATE_UINT32(uart_intr_state, IbexUartState),
VMSTATE_UINT32(uart_intr_enable, IbexUartState),
VMSTATE_UINT32(uart_ctrl, IbexUartState),
VMSTATE_UINT32(uart_status, IbexUartState),
VMSTATE_UINT32(uart_rdata, IbexUartState),
VMSTATE_UINT32(uart_fifo_ctrl, IbexUartState),
VMSTATE_UINT32(uart_fifo_status, IbexUartState),
VMSTATE_UINT32(uart_ovrd, IbexUartState),
VMSTATE_UINT32(uart_val, IbexUartState),
VMSTATE_UINT32(uart_timeout_ctrl, IbexUartState),
VMSTATE_END_OF_LIST()
}
};
static Property ibex_uart_properties[] = {
DEFINE_PROP_CHR("chardev", IbexUartState, chr),
DEFINE_PROP_END_OF_LIST(),
};
static void ibex_uart_init(Object *obj)
{
IbexUartState *s = IBEX_UART(obj);
s->f_clk = qdev_init_clock_in(DEVICE(obj), "f_clock",
ibex_uart_clk_update, s, ClockUpdate);
clock_set_hz(s->f_clk, IBEX_UART_CLOCK);
sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->tx_watermark);
sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->rx_watermark);
sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->tx_empty);
sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->rx_overflow);
memory_region_init_io(&s->mmio, obj, &ibex_uart_ops, s,
TYPE_IBEX_UART, 0x400);
sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->mmio);
}
static void ibex_uart_realize(DeviceState *dev, Error **errp)
{
IbexUartState *s = IBEX_UART(dev);
s->fifo_trigger_handle = timer_new_ns(QEMU_CLOCK_VIRTUAL,
fifo_trigger_update, s);
qemu_chr_fe_set_handlers(&s->chr, ibex_uart_can_receive,
ibex_uart_receive, NULL, NULL,
s, NULL, true);
}
static void ibex_uart_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
dc->reset = ibex_uart_reset;
dc->realize = ibex_uart_realize;
dc->vmsd = &vmstate_ibex_uart;
device_class_set_props(dc, ibex_uart_properties);
}
static const TypeInfo ibex_uart_info = {
.name = TYPE_IBEX_UART,
.parent = TYPE_SYS_BUS_DEVICE,
.instance_size = sizeof(IbexUartState),
.instance_init = ibex_uart_init,
.class_init = ibex_uart_class_init,
};
static void ibex_uart_register_types(void)
{
type_register_static(&ibex_uart_info);
}
type_init(ibex_uart_register_types)
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