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xemu/hw/ssi/imx_spi.c
Trent Piepho 016d4b0127 imx_spi: Unset XCH when TX FIFO becomes empty 
The current emulation will clear the XCH bit when a burst finishes.
This is not quite correct.  According to the i.MX7d referemce manual,
Rev 0.1, §10.1.7.3:

    This bit [XCH] is cleared automatically when all data in the TXFIFO
    and the shift register has been shifted out.

So XCH should be cleared when the FIFO empties, not on completion of a
burst.  The FIFO is 64 x 32 bits = 2048 bits, while the max burst size
is larger at 4096 bits.  So it's possible that the burst is not finished
after the TXFIFO empties.

Sending a large block (> 2048 bits) with the Linux driver will use a
burst that is larger than the TXFIFO.  After the TXFIFO has emptied XCH
does not become unset, as the burst is not yet finished.

What should happen after the TXFIFO empties is the driver will refill it
and set XCH.  The rising edge of XCH will trigger another transfer to
begin.  However, since the emulation does not set XCH to 0, there is no
rising edge and the next trasfer never begins.

Signed-off-by: Trent Piepho <tpiepho@impinj.com>
Message-id: 20180731201056.29257-1-tpiepho@impinj.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2018-08-16 14:29:57 +01:00

460 lines
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/*
* IMX SPI Controller
*
* Copyright (c) 2016 Jean-Christophe Dubois <jcd@tribudubois.net>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
*/
#include "qemu/osdep.h"
#include "hw/ssi/imx_spi.h"
#include "sysemu/sysemu.h"
#include "qemu/log.h"
#ifndef DEBUG_IMX_SPI
#define DEBUG_IMX_SPI 0
#endif
#define DPRINTF(fmt, args...) \
do { \
if (DEBUG_IMX_SPI) { \
fprintf(stderr, "[%s]%s: " fmt , TYPE_IMX_SPI, \
__func__, ##args); \
} \
} while (0)
static const char *imx_spi_reg_name(uint32_t reg)
{
static char unknown[20];
switch (reg) {
case ECSPI_RXDATA:
return "ECSPI_RXDATA";
case ECSPI_TXDATA:
return "ECSPI_TXDATA";
case ECSPI_CONREG:
return "ECSPI_CONREG";
case ECSPI_CONFIGREG:
return "ECSPI_CONFIGREG";
case ECSPI_INTREG:
return "ECSPI_INTREG";
case ECSPI_DMAREG:
return "ECSPI_DMAREG";
case ECSPI_STATREG:
return "ECSPI_STATREG";
case ECSPI_PERIODREG:
return "ECSPI_PERIODREG";
case ECSPI_TESTREG:
return "ECSPI_TESTREG";
case ECSPI_MSGDATA:
return "ECSPI_MSGDATA";
default:
sprintf(unknown, "%d ?", reg);
return unknown;
}
}
static const VMStateDescription vmstate_imx_spi = {
.name = TYPE_IMX_SPI,
.version_id = 1,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_FIFO32(tx_fifo, IMXSPIState),
VMSTATE_FIFO32(rx_fifo, IMXSPIState),
VMSTATE_INT16(burst_length, IMXSPIState),
VMSTATE_UINT32_ARRAY(regs, IMXSPIState, ECSPI_MAX),
VMSTATE_END_OF_LIST()
},
};
static void imx_spi_txfifo_reset(IMXSPIState *s)
{
fifo32_reset(&s->tx_fifo);
s->regs[ECSPI_STATREG] |= ECSPI_STATREG_TE;
s->regs[ECSPI_STATREG] &= ~ECSPI_STATREG_TF;
}
static void imx_spi_rxfifo_reset(IMXSPIState *s)
{
fifo32_reset(&s->rx_fifo);
s->regs[ECSPI_STATREG] &= ~ECSPI_STATREG_RR;
s->regs[ECSPI_STATREG] &= ~ECSPI_STATREG_RF;
s->regs[ECSPI_STATREG] &= ~ECSPI_STATREG_RO;
}
static void imx_spi_update_irq(IMXSPIState *s)
{
int level;
if (fifo32_is_empty(&s->rx_fifo)) {
s->regs[ECSPI_STATREG] &= ~ECSPI_STATREG_RR;
} else {
s->regs[ECSPI_STATREG] |= ECSPI_STATREG_RR;
}
if (fifo32_is_full(&s->rx_fifo)) {
s->regs[ECSPI_STATREG] |= ECSPI_STATREG_RF;
} else {
s->regs[ECSPI_STATREG] &= ~ECSPI_STATREG_RF;
}
if (fifo32_is_empty(&s->tx_fifo)) {
s->regs[ECSPI_STATREG] |= ECSPI_STATREG_TE;
} else {
s->regs[ECSPI_STATREG] &= ~ECSPI_STATREG_TE;
}
if (fifo32_is_full(&s->tx_fifo)) {
s->regs[ECSPI_STATREG] |= ECSPI_STATREG_TF;
} else {
s->regs[ECSPI_STATREG] &= ~ECSPI_STATREG_TF;
}
level = s->regs[ECSPI_STATREG] & s->regs[ECSPI_INTREG] ? 1 : 0;
qemu_set_irq(s->irq, level);
DPRINTF("IRQ level is %d\n", level);
}
static uint8_t imx_spi_selected_channel(IMXSPIState *s)
{
return EXTRACT(s->regs[ECSPI_CONREG], ECSPI_CONREG_CHANNEL_SELECT);
}
static uint32_t imx_spi_burst_length(IMXSPIState *s)
{
return EXTRACT(s->regs[ECSPI_CONREG], ECSPI_CONREG_BURST_LENGTH) + 1;
}
static bool imx_spi_is_enabled(IMXSPIState *s)
{
return s->regs[ECSPI_CONREG] & ECSPI_CONREG_EN;
}
static bool imx_spi_channel_is_master(IMXSPIState *s)
{
uint8_t mode = EXTRACT(s->regs[ECSPI_CONREG], ECSPI_CONREG_CHANNEL_MODE);
return (mode & (1 << imx_spi_selected_channel(s))) ? true : false;
}
static bool imx_spi_is_multiple_master_burst(IMXSPIState *s)
{
uint8_t wave = EXTRACT(s->regs[ECSPI_CONFIGREG], ECSPI_CONFIGREG_SS_CTL);
return imx_spi_channel_is_master(s) &&
!(s->regs[ECSPI_CONREG] & ECSPI_CONREG_SMC) &&
((wave & (1 << imx_spi_selected_channel(s))) ? true : false);
}
static void imx_spi_flush_txfifo(IMXSPIState *s)
{
uint32_t tx;
uint32_t rx;
DPRINTF("Begin: TX Fifo Size = %d, RX Fifo Size = %d\n",
fifo32_num_used(&s->tx_fifo), fifo32_num_used(&s->rx_fifo));
while (!fifo32_is_empty(&s->tx_fifo)) {
int tx_burst = 0;
int index = 0;
if (s->burst_length <= 0) {
s->burst_length = imx_spi_burst_length(s);
DPRINTF("Burst length = %d\n", s->burst_length);
if (imx_spi_is_multiple_master_burst(s)) {
s->regs[ECSPI_CONREG] |= ECSPI_CONREG_XCH;
}
}
tx = fifo32_pop(&s->tx_fifo);
DPRINTF("data tx:0x%08x\n", tx);
tx_burst = MIN(s->burst_length, 32);
rx = 0;
while (tx_burst) {
uint8_t byte = tx & 0xff;
DPRINTF("writing 0x%02x\n", (uint32_t)byte);
/* We need to write one byte at a time */
byte = ssi_transfer(s->bus, byte);
DPRINTF("0x%02x read\n", (uint32_t)byte);
tx = tx >> 8;
rx |= (byte << (index * 8));
/* Remove 8 bits from the actual burst */
tx_burst -= 8;
s->burst_length -= 8;
index++;
}
DPRINTF("data rx:0x%08x\n", rx);
if (fifo32_is_full(&s->rx_fifo)) {
s->regs[ECSPI_STATREG] |= ECSPI_STATREG_RO;
} else {
fifo32_push(&s->rx_fifo, (uint8_t)rx);
}
if (s->burst_length <= 0) {
if (!imx_spi_is_multiple_master_burst(s)) {
s->regs[ECSPI_STATREG] |= ECSPI_STATREG_TC;
break;
}
}
}
if (fifo32_is_empty(&s->tx_fifo)) {
s->regs[ECSPI_STATREG] |= ECSPI_STATREG_TC;
s->regs[ECSPI_CONREG] &= ~ECSPI_CONREG_XCH;
}
/* TODO: We should also use TDR and RDR bits */
DPRINTF("End: TX Fifo Size = %d, RX Fifo Size = %d\n",
fifo32_num_used(&s->tx_fifo), fifo32_num_used(&s->rx_fifo));
}
static void imx_spi_reset(DeviceState *dev)
{
IMXSPIState *s = IMX_SPI(dev);
DPRINTF("\n");
memset(s->regs, 0, sizeof(s->regs));
s->regs[ECSPI_STATREG] = 0x00000003;
imx_spi_rxfifo_reset(s);
imx_spi_txfifo_reset(s);
imx_spi_update_irq(s);
s->burst_length = 0;
}
static uint64_t imx_spi_read(void *opaque, hwaddr offset, unsigned size)
{
uint32_t value = 0;
IMXSPIState *s = opaque;
uint32_t index = offset >> 2;
if (index >= ECSPI_MAX) {
qemu_log_mask(LOG_GUEST_ERROR, "[%s]%s: Bad register at offset 0x%"
HWADDR_PRIx "\n", TYPE_IMX_SPI, __func__, offset);
return 0;
}
switch (index) {
case ECSPI_RXDATA:
if (!imx_spi_is_enabled(s)) {
value = 0;
} else if (fifo32_is_empty(&s->rx_fifo)) {
/* value is undefined */
value = 0xdeadbeef;
} else {
/* read from the RX FIFO */
value = fifo32_pop(&s->rx_fifo);
}
break;
case ECSPI_TXDATA:
qemu_log_mask(LOG_GUEST_ERROR, "[%s]%s: Trying to read from TX FIFO\n",
TYPE_IMX_SPI, __func__);
/* Reading from TXDATA gives 0 */
break;
case ECSPI_MSGDATA:
qemu_log_mask(LOG_GUEST_ERROR, "[%s]%s: Trying to read from MSG FIFO\n",
TYPE_IMX_SPI, __func__);
/* Reading from MSGDATA gives 0 */
break;
default:
value = s->regs[index];
break;
}
DPRINTF("reg[%s] => 0x%" PRIx32 "\n", imx_spi_reg_name(index), value);
imx_spi_update_irq(s);
return (uint64_t)value;
}
static void imx_spi_write(void *opaque, hwaddr offset, uint64_t value,
unsigned size)
{
IMXSPIState *s = opaque;
uint32_t index = offset >> 2;
uint32_t change_mask;
if (index >= ECSPI_MAX) {
qemu_log_mask(LOG_GUEST_ERROR, "[%s]%s: Bad register at offset 0x%"
HWADDR_PRIx "\n", TYPE_IMX_SPI, __func__, offset);
return;
}
DPRINTF("reg[%s] <= 0x%" PRIx32 "\n", imx_spi_reg_name(index),
(uint32_t)value);
change_mask = s->regs[index] ^ value;
switch (index) {
case ECSPI_RXDATA:
qemu_log_mask(LOG_GUEST_ERROR, "[%s]%s: Trying to write to RX FIFO\n",
TYPE_IMX_SPI, __func__);
break;
case ECSPI_TXDATA:
if (!imx_spi_is_enabled(s)) {
/* Ignore writes if device is disabled */
break;
} else if (fifo32_is_full(&s->tx_fifo)) {
/* Ignore writes if queue is full */
break;
}
fifo32_push(&s->tx_fifo, (uint32_t)value);
if (imx_spi_channel_is_master(s) &&
(s->regs[ECSPI_CONREG] & ECSPI_CONREG_SMC)) {
/*
* Start emitting if current channel is master and SMC bit is
* set.
*/
imx_spi_flush_txfifo(s);
}
break;
case ECSPI_STATREG:
/* the RO and TC bits are write-one-to-clear */
value &= ECSPI_STATREG_RO | ECSPI_STATREG_TC;
s->regs[ECSPI_STATREG] &= ~value;
break;
case ECSPI_CONREG:
s->regs[ECSPI_CONREG] = value;
if (!imx_spi_is_enabled(s)) {
/* device is disabled, so this is a reset */
imx_spi_reset(DEVICE(s));
return;
}
if (imx_spi_channel_is_master(s)) {
int i;
/* We are in master mode */
for (i = 0; i < 4; i++) {
qemu_set_irq(s->cs_lines[i],
i == imx_spi_selected_channel(s) ? 0 : 1);
}
if ((value & change_mask & ECSPI_CONREG_SMC) &&
!fifo32_is_empty(&s->tx_fifo)) {
/* SMC bit is set and TX FIFO has some slots filled in */
imx_spi_flush_txfifo(s);
} else if ((value & change_mask & ECSPI_CONREG_XCH) &&
!(value & ECSPI_CONREG_SMC)) {
/* This is a request to start emitting */
imx_spi_flush_txfifo(s);
}
}
break;
case ECSPI_MSGDATA:
/* it is not clear from the spec what MSGDATA is for */
/* Anyway it is not used by Linux driver */
/* So for now we just ignore it */
qemu_log_mask(LOG_UNIMP,
"[%s]%s: Trying to write to MSGDATA, ignoring\n",
TYPE_IMX_SPI, __func__);
break;
default:
s->regs[index] = value;
break;
}
imx_spi_update_irq(s);
}
static const struct MemoryRegionOps imx_spi_ops = {
.read = imx_spi_read,
.write = imx_spi_write,
.endianness = DEVICE_NATIVE_ENDIAN,
.valid = {
/*
* Our device would not work correctly if the guest was doing
* unaligned access. This might not be a limitation on the real
* device but in practice there is no reason for a guest to access
* this device unaligned.
*/
.min_access_size = 4,
.max_access_size = 4,
.unaligned = false,
},
};
static void imx_spi_realize(DeviceState *dev, Error **errp)
{
IMXSPIState *s = IMX_SPI(dev);
int i;
s->bus = ssi_create_bus(dev, "spi");
memory_region_init_io(&s->iomem, OBJECT(dev), &imx_spi_ops, s,
TYPE_IMX_SPI, 0x1000);
sysbus_init_mmio(SYS_BUS_DEVICE(dev), &s->iomem);
sysbus_init_irq(SYS_BUS_DEVICE(dev), &s->irq);
ssi_auto_connect_slaves(dev, s->cs_lines, s->bus);
for (i = 0; i < 4; ++i) {
sysbus_init_irq(SYS_BUS_DEVICE(dev), &s->cs_lines[i]);
}
s->burst_length = 0;
fifo32_create(&s->tx_fifo, ECSPI_FIFO_SIZE);
fifo32_create(&s->rx_fifo, ECSPI_FIFO_SIZE);
}
static void imx_spi_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
dc->realize = imx_spi_realize;
dc->vmsd = &vmstate_imx_spi;
dc->reset = imx_spi_reset;
dc->desc = "i.MX SPI Controller";
}
static const TypeInfo imx_spi_info = {
.name = TYPE_IMX_SPI,
.parent = TYPE_SYS_BUS_DEVICE,
.instance_size = sizeof(IMXSPIState),
.class_init = imx_spi_class_init,
};
static void imx_spi_register_types(void)
{
type_register_static(&imx_spi_info);
}
type_init(imx_spi_register_types)
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