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qemu-e2k/hw/char/ipoctal232.c
Daniel P. Berrange 6ab3fc32ea hw: replace most use of qemu_chr_fe_write with qemu_chr_fe_write_all 
The qemu_chr_fe_write method will return -1 on EAGAIN if the
chardev backend write would block. Almost no callers of the
qemu_chr_fe_write() method check the return value, instead
blindly assuming data was successfully sent. In most cases
this will lead to silent data loss on interactive consoles,
but in some cases (eg RNG EGD) it'll just cause corruption
of the protocol being spoken.

We unfortunately can't fix the virtio-console code, due to
a bug in the Linux guest drivers, which would cause the
entire Linux kernel to hang if we delay processing of the
incoming data in any way. Fixing this requires first fixing
the guest driver to not hold spinlocks while writing to the
hvc device backend.

Fixes bug: https://bugs.launchpad.net/qemu/+bug/1586756

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1473170165-540-4-git-send-email-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-09-13 19:09:42 +02:00

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/*
* QEMU GE IP-Octal 232 IndustryPack emulation
*
* Copyright (C) 2012 Igalia, S.L.
* Author: Alberto Garcia <berto@igalia.com>
*
* This code is licensed under the GNU GPL v2 or (at your option) any
* later version.
*/
#include "qemu/osdep.h"
#include "hw/ipack/ipack.h"
#include "qemu/bitops.h"
#include "sysemu/char.h"
/* #define DEBUG_IPOCTAL */
#ifdef DEBUG_IPOCTAL
#define DPRINTF2(fmt, ...) \
do { fprintf(stderr, fmt, ## __VA_ARGS__); } while (0)
#else
#define DPRINTF2(fmt, ...) do { } while (0)
#endif
#define DPRINTF(fmt, ...) DPRINTF2("IP-Octal: " fmt, ## __VA_ARGS__)
#define RX_FIFO_SIZE 3
/* The IP-Octal has 8 channels (a-h)
divided into 4 blocks (A-D) */
#define N_CHANNELS 8
#define N_BLOCKS 4
#define REG_MRa 0x01
#define REG_MRb 0x11
#define REG_SRa 0x03
#define REG_SRb 0x13
#define REG_CSRa 0x03
#define REG_CSRb 0x13
#define REG_CRa 0x05
#define REG_CRb 0x15
#define REG_RHRa 0x07
#define REG_RHRb 0x17
#define REG_THRa 0x07
#define REG_THRb 0x17
#define REG_ACR 0x09
#define REG_ISR 0x0B
#define REG_IMR 0x0B
#define REG_OPCR 0x1B
#define CR_ENABLE_RX BIT(0)
#define CR_DISABLE_RX BIT(1)
#define CR_ENABLE_TX BIT(2)
#define CR_DISABLE_TX BIT(3)
#define CR_CMD(cr) ((cr) >> 4)
#define CR_NO_OP 0
#define CR_RESET_MR 1
#define CR_RESET_RX 2
#define CR_RESET_TX 3
#define CR_RESET_ERR 4
#define CR_RESET_BRKINT 5
#define CR_START_BRK 6
#define CR_STOP_BRK 7
#define CR_ASSERT_RTSN 8
#define CR_NEGATE_RTSN 9
#define CR_TIMEOUT_ON 10
#define CR_TIMEOUT_OFF 12
#define SR_RXRDY BIT(0)
#define SR_FFULL BIT(1)
#define SR_TXRDY BIT(2)
#define SR_TXEMT BIT(3)
#define SR_OVERRUN BIT(4)
#define SR_PARITY BIT(5)
#define SR_FRAMING BIT(6)
#define SR_BREAK BIT(7)
#define ISR_TXRDYA BIT(0)
#define ISR_RXRDYA BIT(1)
#define ISR_BREAKA BIT(2)
#define ISR_CNTRDY BIT(3)
#define ISR_TXRDYB BIT(4)
#define ISR_RXRDYB BIT(5)
#define ISR_BREAKB BIT(6)
#define ISR_MPICHG BIT(7)
#define ISR_TXRDY(CH) (((CH) & 1) ? BIT(4) : BIT(0))
#define ISR_RXRDY(CH) (((CH) & 1) ? BIT(5) : BIT(1))
#define ISR_BREAK(CH) (((CH) & 1) ? BIT(6) : BIT(2))
typedef struct IPOctalState IPOctalState;
typedef struct SCC2698Channel SCC2698Channel;
typedef struct SCC2698Block SCC2698Block;
struct SCC2698Channel {
IPOctalState *ipoctal;
CharDriverState *dev;
bool rx_enabled;
uint8_t mr[2];
uint8_t mr_idx;
uint8_t sr;
uint8_t rhr[RX_FIFO_SIZE];
uint8_t rhr_idx;
uint8_t rx_pending;
};
struct SCC2698Block {
uint8_t imr;
uint8_t isr;
};
struct IPOctalState {
IPackDevice parent_obj;
SCC2698Channel ch[N_CHANNELS];
SCC2698Block blk[N_BLOCKS];
uint8_t irq_vector;
};
#define TYPE_IPOCTAL "ipoctal232"
#define IPOCTAL(obj) \
OBJECT_CHECK(IPOctalState, (obj), TYPE_IPOCTAL)
static const VMStateDescription vmstate_scc2698_channel = {
.name = "scc2698_channel",
.version_id = 1,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_BOOL(rx_enabled, SCC2698Channel),
VMSTATE_UINT8_ARRAY(mr, SCC2698Channel, 2),
VMSTATE_UINT8(mr_idx, SCC2698Channel),
VMSTATE_UINT8(sr, SCC2698Channel),
VMSTATE_UINT8_ARRAY(rhr, SCC2698Channel, RX_FIFO_SIZE),
VMSTATE_UINT8(rhr_idx, SCC2698Channel),
VMSTATE_UINT8(rx_pending, SCC2698Channel),
VMSTATE_END_OF_LIST()
}
};
static const VMStateDescription vmstate_scc2698_block = {
.name = "scc2698_block",
.version_id = 1,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_UINT8(imr, SCC2698Block),
VMSTATE_UINT8(isr, SCC2698Block),
VMSTATE_END_OF_LIST()
}
};
static const VMStateDescription vmstate_ipoctal = {
.name = "ipoctal232",
.version_id = 1,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_IPACK_DEVICE(parent_obj, IPOctalState),
VMSTATE_STRUCT_ARRAY(ch, IPOctalState, N_CHANNELS, 1,
vmstate_scc2698_channel, SCC2698Channel),
VMSTATE_STRUCT_ARRAY(blk, IPOctalState, N_BLOCKS, 1,
vmstate_scc2698_block, SCC2698Block),
VMSTATE_UINT8(irq_vector, IPOctalState),
VMSTATE_END_OF_LIST()
}
};
/* data[10] is 0x0C, not 0x0B as the doc says */
static const uint8_t id_prom_data[] = {
0x49, 0x50, 0x41, 0x43, 0xF0, 0x22,
0xA1, 0x00, 0x00, 0x00, 0x0C, 0xCC
};
static void update_irq(IPOctalState *dev, unsigned block)
{
IPackDevice *idev = IPACK_DEVICE(dev);
/* Blocks A and B interrupt on INT0#, C and D on INT1#.
Thus, to get the status we have to check two blocks. */
SCC2698Block *blk0 = &dev->blk[block];
SCC2698Block *blk1 = &dev->blk[block^1];
unsigned intno = block / 2;
if ((blk0->isr & blk0->imr) || (blk1->isr & blk1->imr)) {
qemu_irq_raise(idev->irq[intno]);
} else {
qemu_irq_lower(idev->irq[intno]);
}
}
static void write_cr(IPOctalState *dev, unsigned channel, uint8_t val)
{
SCC2698Channel *ch = &dev->ch[channel];
SCC2698Block *blk = &dev->blk[channel / 2];
DPRINTF("Write CR%c %u: ", channel + 'a', val);
/* The lower 4 bits are used to enable and disable Tx and Rx */
if (val & CR_ENABLE_RX) {
DPRINTF2("Rx on, ");
ch->rx_enabled = true;
}
if (val & CR_DISABLE_RX) {
DPRINTF2("Rx off, ");
ch->rx_enabled = false;
}
if (val & CR_ENABLE_TX) {
DPRINTF2("Tx on, ");
ch->sr |= SR_TXRDY | SR_TXEMT;
blk->isr |= ISR_TXRDY(channel);
}
if (val & CR_DISABLE_TX) {
DPRINTF2("Tx off, ");
ch->sr &= ~(SR_TXRDY | SR_TXEMT);
blk->isr &= ~ISR_TXRDY(channel);
}
DPRINTF2("cmd: ");
/* The rest of the bits implement different commands */
switch (CR_CMD(val)) {
case CR_NO_OP:
DPRINTF2("none");
break;
case CR_RESET_MR:
DPRINTF2("reset MR");
ch->mr_idx = 0;
break;
case CR_RESET_RX:
DPRINTF2("reset Rx");
ch->rx_enabled = false;
ch->rx_pending = 0;
ch->sr &= ~SR_RXRDY;
blk->isr &= ~ISR_RXRDY(channel);
break;
case CR_RESET_TX:
DPRINTF2("reset Tx");
ch->sr &= ~(SR_TXRDY | SR_TXEMT);
blk->isr &= ~ISR_TXRDY(channel);
break;
case CR_RESET_ERR:
DPRINTF2("reset err");
ch->sr &= ~(SR_OVERRUN | SR_PARITY | SR_FRAMING | SR_BREAK);
break;
case CR_RESET_BRKINT:
DPRINTF2("reset brk ch int");
blk->isr &= ~(ISR_BREAKA | ISR_BREAKB);
break;
default:
DPRINTF2("unsupported 0x%x", CR_CMD(val));
}
DPRINTF2("\n");
}
static uint16_t io_read(IPackDevice *ip, uint8_t addr)
{
IPOctalState *dev = IPOCTAL(ip);
uint16_t ret = 0;
/* addr[7:6]: block (A-D)
addr[7:5]: channel (a-h)
addr[5:0]: register */
unsigned block = addr >> 5;
unsigned channel = addr >> 4;
/* Big endian, accessed using 8-bit bytes at odd locations */
unsigned offset = (addr & 0x1F) ^ 1;
SCC2698Channel *ch = &dev->ch[channel];
SCC2698Block *blk = &dev->blk[block];
uint8_t old_isr = blk->isr;
switch (offset) {
case REG_MRa:
case REG_MRb:
ret = ch->mr[ch->mr_idx];
DPRINTF("Read MR%u%c: 0x%x\n", ch->mr_idx + 1, channel + 'a', ret);
ch->mr_idx = 1;
break;
case REG_SRa:
case REG_SRb:
ret = ch->sr;
DPRINTF("Read SR%c: 0x%x\n", channel + 'a', ret);
break;
case REG_RHRa:
case REG_RHRb:
ret = ch->rhr[ch->rhr_idx];
if (ch->rx_pending > 0) {
ch->rx_pending--;
if (ch->rx_pending == 0) {
ch->sr &= ~SR_RXRDY;
blk->isr &= ~ISR_RXRDY(channel);
if (ch->dev) {
qemu_chr_accept_input(ch->dev);
}
} else {
ch->rhr_idx = (ch->rhr_idx + 1) % RX_FIFO_SIZE;
}
if (ch->sr & SR_BREAK) {
ch->sr &= ~SR_BREAK;
blk->isr |= ISR_BREAK(channel);
}
}
DPRINTF("Read RHR%c (0x%x)\n", channel + 'a', ret);
break;
case REG_ISR:
ret = blk->isr;
DPRINTF("Read ISR%c: 0x%x\n", block + 'A', ret);
break;
default:
DPRINTF("Read unknown/unsupported register 0x%02x\n", offset);
}
if (old_isr != blk->isr) {
update_irq(dev, block);
}
return ret;
}
static void io_write(IPackDevice *ip, uint8_t addr, uint16_t val)
{
IPOctalState *dev = IPOCTAL(ip);
unsigned reg = val & 0xFF;
/* addr[7:6]: block (A-D)
addr[7:5]: channel (a-h)
addr[5:0]: register */
unsigned block = addr >> 5;
unsigned channel = addr >> 4;
/* Big endian, accessed using 8-bit bytes at odd locations */
unsigned offset = (addr & 0x1F) ^ 1;
SCC2698Channel *ch = &dev->ch[channel];
SCC2698Block *blk = &dev->blk[block];
uint8_t old_isr = blk->isr;
uint8_t old_imr = blk->imr;
switch (offset) {
case REG_MRa:
case REG_MRb:
ch->mr[ch->mr_idx] = reg;
DPRINTF("Write MR%u%c 0x%x\n", ch->mr_idx + 1, channel + 'a', reg);
ch->mr_idx = 1;
break;
/* Not implemented */
case REG_CSRa:
case REG_CSRb:
DPRINTF("Write CSR%c: 0x%x\n", channel + 'a', reg);
break;
case REG_CRa:
case REG_CRb:
write_cr(dev, channel, reg);
break;
case REG_THRa:
case REG_THRb:
if (ch->sr & SR_TXRDY) {
DPRINTF("Write THR%c (0x%x)\n", channel + 'a', reg);
if (ch->dev) {
uint8_t thr = reg;
/* XXX this blocks entire thread. Rewrite to use
* qemu_chr_fe_write and background I/O callbacks */
qemu_chr_fe_write_all(ch->dev, &thr, 1);
}
} else {
DPRINTF("Write THR%c (0x%x), Tx disabled\n", channel + 'a', reg);
}
break;
/* Not implemented */
case REG_ACR:
DPRINTF("Write ACR%c 0x%x\n", block + 'A', val);
break;
case REG_IMR:
DPRINTF("Write IMR%c 0x%x\n", block + 'A', val);
blk->imr = reg;
break;
/* Not implemented */
case REG_OPCR:
DPRINTF("Write OPCR%c 0x%x\n", block + 'A', val);
break;
default:
DPRINTF("Write unknown/unsupported register 0x%02x %u\n", offset, val);
}
if (old_isr != blk->isr || old_imr != blk->imr) {
update_irq(dev, block);
}
}
static uint16_t id_read(IPackDevice *ip, uint8_t addr)
{
uint16_t ret = 0;
unsigned pos = addr / 2; /* The ID PROM data is stored every other byte */
if (pos < ARRAY_SIZE(id_prom_data)) {
ret = id_prom_data[pos];
} else {
DPRINTF("Attempt to read unavailable PROM data at 0x%x\n", addr);
}
return ret;
}
static void id_write(IPackDevice *ip, uint8_t addr, uint16_t val)
{
IPOctalState *dev = IPOCTAL(ip);
if (addr == 1) {
DPRINTF("Write IRQ vector: %u\n", (unsigned) val);
dev->irq_vector = val; /* Undocumented, but the hw works like that */
} else {
DPRINTF("Attempt to write 0x%x to 0x%x\n", val, addr);
}
}
static uint16_t int_read(IPackDevice *ip, uint8_t addr)
{
IPOctalState *dev = IPOCTAL(ip);
/* Read address 0 to ACK INT0# and address 2 to ACK INT1# */
if (addr != 0 && addr != 2) {
DPRINTF("Attempt to read from 0x%x\n", addr);
return 0;
} else {
/* Update interrupts if necessary */
update_irq(dev, addr);
return dev->irq_vector;
}
}
static void int_write(IPackDevice *ip, uint8_t addr, uint16_t val)
{
DPRINTF("Attempt to write 0x%x to 0x%x\n", val, addr);
}
static uint16_t mem_read16(IPackDevice *ip, uint32_t addr)
{
DPRINTF("Attempt to read from 0x%x\n", addr);
return 0;
}
static void mem_write16(IPackDevice *ip, uint32_t addr, uint16_t val)
{
DPRINTF("Attempt to write 0x%x to 0x%x\n", val, addr);
}
static uint8_t mem_read8(IPackDevice *ip, uint32_t addr)
{
DPRINTF("Attempt to read from 0x%x\n", addr);
return 0;
}
static void mem_write8(IPackDevice *ip, uint32_t addr, uint8_t val)
{
IPOctalState *dev = IPOCTAL(ip);
if (addr == 1) {
DPRINTF("Write IRQ vector: %u\n", (unsigned) val);
dev->irq_vector = val;
} else {
DPRINTF("Attempt to write 0x%x to 0x%x\n", val, addr);
}
}
static int hostdev_can_receive(void *opaque)
{
SCC2698Channel *ch = opaque;
int available_bytes = RX_FIFO_SIZE - ch->rx_pending;
return ch->rx_enabled ? available_bytes : 0;
}
static void hostdev_receive(void *opaque, const uint8_t *buf, int size)
{
SCC2698Channel *ch = opaque;
IPOctalState *dev = ch->ipoctal;
unsigned pos = ch->rhr_idx + ch->rx_pending;
int i;
assert(size + ch->rx_pending <= RX_FIFO_SIZE);
/* Copy data to the RxFIFO */
for (i = 0; i < size; i++) {
pos %= RX_FIFO_SIZE;
ch->rhr[pos++] = buf[i];
}
ch->rx_pending += size;
/* If the RxFIFO was empty raise an interrupt */
if (!(ch->sr & SR_RXRDY)) {
unsigned block, channel = 0;
/* Find channel number to update the ISR register */
while (&dev->ch[channel] != ch) {
channel++;
}
block = channel / 2;
dev->blk[block].isr |= ISR_RXRDY(channel);
ch->sr |= SR_RXRDY;
update_irq(dev, block);
}
}
static void hostdev_event(void *opaque, int event)
{
SCC2698Channel *ch = opaque;
switch (event) {
case CHR_EVENT_OPENED:
DPRINTF("Device %s opened\n", ch->dev->label);
break;
case CHR_EVENT_BREAK: {
uint8_t zero = 0;
DPRINTF("Device %s received break\n", ch->dev->label);
if (!(ch->sr & SR_BREAK)) {
IPOctalState *dev = ch->ipoctal;
unsigned block, channel = 0;
while (&dev->ch[channel] != ch) {
channel++;
}
block = channel / 2;
ch->sr |= SR_BREAK;
dev->blk[block].isr |= ISR_BREAK(channel);
}
/* Put a zero character in the buffer */
hostdev_receive(ch, &zero, 1);
}
break;
default:
DPRINTF("Device %s received event %d\n", ch->dev->label, event);
}
}
static void ipoctal_realize(DeviceState *dev, Error **errp)
{
IPOctalState *s = IPOCTAL(dev);
unsigned i;
for (i = 0; i < N_CHANNELS; i++) {
SCC2698Channel *ch = &s->ch[i];
ch->ipoctal = s;
/* Redirect IP-Octal channels to host character devices */
if (ch->dev) {
qemu_chr_add_handlers(ch->dev, hostdev_can_receive,
hostdev_receive, hostdev_event, ch);
DPRINTF("Redirecting channel %u to %s\n", i, ch->dev->label);
} else {
DPRINTF("Could not redirect channel %u, no chardev set\n", i);
}
}
}
static Property ipoctal_properties[] = {
DEFINE_PROP_CHR("chardev0", IPOctalState, ch[0].dev),
DEFINE_PROP_CHR("chardev1", IPOctalState, ch[1].dev),
DEFINE_PROP_CHR("chardev2", IPOctalState, ch[2].dev),
DEFINE_PROP_CHR("chardev3", IPOctalState, ch[3].dev),
DEFINE_PROP_CHR("chardev4", IPOctalState, ch[4].dev),
DEFINE_PROP_CHR("chardev5", IPOctalState, ch[5].dev),
DEFINE_PROP_CHR("chardev6", IPOctalState, ch[6].dev),
DEFINE_PROP_CHR("chardev7", IPOctalState, ch[7].dev),
DEFINE_PROP_END_OF_LIST(),
};
static void ipoctal_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
IPackDeviceClass *ic = IPACK_DEVICE_CLASS(klass);
ic->realize = ipoctal_realize;
ic->io_read = io_read;
ic->io_write = io_write;
ic->id_read = id_read;
ic->id_write = id_write;
ic->int_read = int_read;
ic->int_write = int_write;
ic->mem_read16 = mem_read16;
ic->mem_write16 = mem_write16;
ic->mem_read8 = mem_read8;
ic->mem_write8 = mem_write8;
set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
dc->desc = "GE IP-Octal 232 8-channel RS-232 IndustryPack";
dc->props = ipoctal_properties;
dc->vmsd = &vmstate_ipoctal;
}
static const TypeInfo ipoctal_info = {
.name = TYPE_IPOCTAL,
.parent = TYPE_IPACK_DEVICE,
.instance_size = sizeof(IPOctalState),
.class_init = ipoctal_class_init,
};
static void ipoctal_register_types(void)
{
type_register_static(&ipoctal_info);
}
type_init(ipoctal_register_types)
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