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hw/char/exynos4210_uart: Implement Rx FIFO level triggers and timeouts
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The driver already implements a receive FIFO, but it does not
handle receive FIFO trigger levels and timeout. Implement the
missing functionality.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Message-id: 20200123052540.6132-7-linux@roeck-us.net
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
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@groeck @pm215
groeck authored and pm215 committed Jan 23, 2020
1 parent c9d3396 commit 3a5d3a6
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Showing 2 changed files with 94 additions and 26 deletions.
117 changes: 92 additions & 25 deletions hw/char/exynos4210_uart.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@
#include "migration/vmstate.h"
#include "qemu/error-report.h"
#include "qemu/module.h"
#include "qemu/timer.h"
#include "chardev/char-fe.h"
#include "chardev/char-serial.h"

Expand Down Expand Up @@ -118,6 +119,7 @@ static const Exynos4210UartReg exynos4210_uart_regs[] = {
#define ULCON_STOP_BIT_SHIFT 1

/* UART Tx/Rx Status */
#define UTRSTAT_Rx_TIMEOUT 0x8
#define UTRSTAT_TRANSMITTER_EMPTY 0x4
#define UTRSTAT_Tx_BUFFER_EMPTY 0x2
#define UTRSTAT_Rx_BUFFER_DATA_READY 0x1
Expand Down Expand Up @@ -147,6 +149,9 @@ typedef struct Exynos4210UartState {
Exynos4210UartFIFO rx;
Exynos4210UartFIFO tx;

QEMUTimer *fifo_timeout_timer;
uint64_t wordtime; /* word time in ns */

CharBackend chr;
qemu_irq irq;

Expand Down Expand Up @@ -209,15 +214,12 @@ static void fifo_reset(Exynos4210UartFIFO *q)
q->rp = 0;
}

static uint32_t exynos4210_uart_Tx_FIFO_trigger_level(const Exynos4210UartState *s)
static uint32_t exynos4210_uart_FIFO_trigger_level(uint32_t channel,
uint32_t reg)
{
uint32_t level = 0;
uint32_t reg;
uint32_t level;

reg = (s->reg[I_(UFCON)] & UFCON_Tx_FIFO_TRIGGER_LEVEL) >>
UFCON_Tx_FIFO_TRIGGER_LEVEL_SHIFT;

switch (s->channel) {
switch (channel) {
case 0:
level = reg * 32;
break;
Expand All @@ -231,26 +233,60 @@ static uint32_t exynos4210_uart_Tx_FIFO_trigger_level(const Exynos4210UartState
break;
default:
level = 0;
trace_exynos_uart_channel_error(s->channel);
trace_exynos_uart_channel_error(channel);
break;
}

return level;
}

static uint32_t
exynos4210_uart_Tx_FIFO_trigger_level(const Exynos4210UartState *s)
{
uint32_t reg;

reg = (s->reg[I_(UFCON)] & UFCON_Tx_FIFO_TRIGGER_LEVEL) >>
UFCON_Tx_FIFO_TRIGGER_LEVEL_SHIFT;

return exynos4210_uart_FIFO_trigger_level(s->channel, reg);
}

static uint32_t
exynos4210_uart_Rx_FIFO_trigger_level(const Exynos4210UartState *s)
{
uint32_t reg;

reg = ((s->reg[I_(UFCON)] & UFCON_Rx_FIFO_TRIGGER_LEVEL) >>
UFCON_Rx_FIFO_TRIGGER_LEVEL_SHIFT) + 1;

return exynos4210_uart_FIFO_trigger_level(s->channel, reg);
}

static void exynos4210_uart_update_irq(Exynos4210UartState *s)
{
/*
* The Tx interrupt is always requested if the number of data in the
* transmit FIFO is smaller than the trigger level.
*/
if (s->reg[I_(UFCON)] & UFCON_FIFO_ENABLE) {

uint32_t count = (s->reg[I_(UFSTAT)] & UFSTAT_Tx_FIFO_COUNT) >>
UFSTAT_Tx_FIFO_COUNT_SHIFT;

if (count <= exynos4210_uart_Tx_FIFO_trigger_level(s)) {
s->reg[I_(UINTSP)] |= UINTSP_TXD;
}

/*
* Rx interrupt if trigger level is reached or if rx timeout
* interrupt is disabled and there is data in the receive buffer
*/
count = fifo_elements_number(&s->rx);
if ((count && !(s->reg[I_(UCON)] & 0x80)) ||
count >= exynos4210_uart_Rx_FIFO_trigger_level(s)) {
s->reg[I_(UINTSP)] |= UINTSP_RXD;
timer_del(s->fifo_timeout_timer);
}
} else if (s->reg[I_(UTRSTAT)] & UTRSTAT_Rx_BUFFER_DATA_READY) {
s->reg[I_(UINTSP)] |= UINTSP_RXD;
}

s->reg[I_(UINTP)] = s->reg[I_(UINTSP)] & ~s->reg[I_(UINTM)];
Expand All @@ -264,6 +300,21 @@ static void exynos4210_uart_update_irq(Exynos4210UartState *s)
}
}

static void exynos4210_uart_timeout_int(void *opaque)
{
Exynos4210UartState *s = opaque;

trace_exynos_uart_rx_timeout(s->channel, s->reg[I_(UTRSTAT)],
s->reg[I_(UINTSP)]);

if ((s->reg[I_(UTRSTAT)] & UTRSTAT_Rx_BUFFER_DATA_READY) ||
(s->reg[I_(UCON)] & (1 << 11))) {
s->reg[I_(UINTSP)] |= UINTSP_RXD;
s->reg[I_(UTRSTAT)] |= UTRSTAT_Rx_TIMEOUT;
exynos4210_uart_update_irq(s);
}
}

static void exynos4210_uart_update_parameters(Exynos4210UartState *s)
{
int speed, parity, data_bits, stop_bits;
Expand Down Expand Up @@ -302,10 +353,24 @@ static void exynos4210_uart_update_parameters(Exynos4210UartState *s)
ssp.data_bits = data_bits;
ssp.stop_bits = stop_bits;

s->wordtime = NANOSECONDS_PER_SECOND * (data_bits + stop_bits + 1) / speed;

qemu_chr_fe_ioctl(&s->chr, CHR_IOCTL_SERIAL_SET_PARAMS, &ssp);

trace_exynos_uart_update_params(
s->channel, speed, parity, data_bits, stop_bits);
s->channel, speed, parity, data_bits, stop_bits, s->wordtime);
}

static void exynos4210_uart_rx_timeout_set(Exynos4210UartState *s)
{
if (s->reg[I_(UCON)] & 0x80) {
uint32_t timeout = ((s->reg[I_(UCON)] >> 12) & 0x0f) * s->wordtime;

timer_mod(s->fifo_timeout_timer,
qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + timeout);
} else {
timer_del(s->fifo_timeout_timer);
}
}

static void exynos4210_uart_write(void *opaque, hwaddr offset,
Expand Down Expand Up @@ -361,6 +426,10 @@ static void exynos4210_uart_write(void *opaque, hwaddr offset,
exynos4210_uart_update_irq(s);
break;
case UTRSTAT:
if (val & UTRSTAT_Rx_TIMEOUT) {
s->reg[I_(UTRSTAT)] &= ~UTRSTAT_Rx_TIMEOUT;
}
break;
case UERSTAT:
case UFSTAT:
case UMSTAT:
Expand All @@ -382,6 +451,7 @@ static void exynos4210_uart_write(void *opaque, hwaddr offset,
break;
}
}

static uint64_t exynos4210_uart_read(void *opaque, hwaddr offset,
unsigned size)
{
Expand Down Expand Up @@ -461,32 +531,24 @@ static int exynos4210_uart_can_receive(void *opaque)
return fifo_empty_elements_number(&s->rx);
}


static void exynos4210_uart_receive(void *opaque, const uint8_t *buf, int size)
{
Exynos4210UartState *s = (Exynos4210UartState *)opaque;
int i;

if (s->reg[I_(UFCON)] & UFCON_FIFO_ENABLE) {
if (fifo_empty_elements_number(&s->rx) < size) {
for (i = 0; i < fifo_empty_elements_number(&s->rx); i++) {
fifo_store(&s->rx, buf[i]);
}
size = fifo_empty_elements_number(&s->rx);
s->reg[I_(UINTSP)] |= UINTSP_ERROR;
s->reg[I_(UTRSTAT)] |= UTRSTAT_Rx_BUFFER_DATA_READY;
} else {
for (i = 0; i < size; i++) {
fifo_store(&s->rx, buf[i]);
}
s->reg[I_(UTRSTAT)] |= UTRSTAT_Rx_BUFFER_DATA_READY;
}
/* XXX: Around here we maybe should check Rx trigger level */
s->reg[I_(UINTSP)] |= UINTSP_RXD;
for (i = 0; i < size; i++) {
fifo_store(&s->rx, buf[i]);
}
exynos4210_uart_rx_timeout_set(s);
} else {
s->reg[I_(URXH)] = buf[0];
s->reg[I_(UINTSP)] |= UINTSP_RXD;
s->reg[I_(UTRSTAT)] |= UTRSTAT_Rx_BUFFER_DATA_READY;
}
s->reg[I_(UTRSTAT)] |= UTRSTAT_Rx_BUFFER_DATA_READY;

exynos4210_uart_update_irq(s);
}
Expand Down Expand Up @@ -527,6 +589,7 @@ static int exynos4210_uart_post_load(void *opaque, int version_id)
Exynos4210UartState *s = (Exynos4210UartState *)opaque;

exynos4210_uart_update_parameters(s);
exynos4210_uart_rx_timeout_set(s);

return 0;
}
Expand Down Expand Up @@ -588,6 +651,10 @@ static void exynos4210_uart_init(Object *obj)
SysBusDevice *dev = SYS_BUS_DEVICE(obj);
Exynos4210UartState *s = EXYNOS4210_UART(dev);

s->fifo_timeout_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
exynos4210_uart_timeout_int, s);
s->wordtime = NANOSECONDS_PER_SECOND * 10 / 9600;

/* memory mapping */
memory_region_init_io(&s->iomem, obj, &exynos4210_uart_ops, s,
"exynos4210.uart", EXYNOS4210_UART_REGS_MEM_SIZE);
Expand Down
3 changes: 2 additions & 1 deletion hw/char/trace-events
View file
Original file line number Diff line number Diff line change
Expand Up @@ -81,7 +81,7 @@ nrf51_uart_write(uint64_t addr, uint64_t value, unsigned int size) "addr 0x%" PR
# exynos4210_uart.c
exynos_uart_irq_raised(uint32_t channel, uint32_t reg) "UART%d: IRQ raised: 0x%08"PRIx32
exynos_uart_irq_lowered(uint32_t channel) "UART%d: IRQ lowered"
exynos_uart_update_params(uint32_t channel, int speed, uint8_t parity, int data, int stop) "UART%d: speed: %d, parity: %c, data bits: %d, stop bits: %d"
exynos_uart_update_params(uint32_t channel, int speed, uint8_t parity, int data, int stop, uint64_t wordtime) "UART%d: speed: %d, parity: %c, data bits: %d, stop bits: %d wordtime: %"PRId64"ns"
exynos_uart_write(uint32_t channel, uint32_t offset, const char *name, uint64_t val) "UART%d: <0x%04x> %s <- 0x%" PRIx64
exynos_uart_read(uint32_t channel, uint32_t offset, const char *name, uint64_t val) "UART%d: <0x%04x> %s -> 0x%" PRIx64
exynos_uart_rx_fifo_reset(uint32_t channel) "UART%d: Rx FIFO Reset"
Expand All @@ -94,3 +94,4 @@ exynos_uart_rx_error(uint32_t channel) "UART%d: Rx error"
exynos_uart_wo_read(uint32_t channel, const char *name, uint32_t reg) "UART%d: Trying to read from WO register: %s [0x%04"PRIx32"]"
exynos_uart_rxsize(uint32_t channel, uint32_t size) "UART%d: Rx FIFO size: %d"
exynos_uart_channel_error(uint32_t channel) "Wrong UART channel number: %d"
exynos_uart_rx_timeout(uint32_t channel, uint32_t stat, uint32_t intsp) "UART%d: Rx timeout stat=0x%x intsp=0x%x"

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