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qemu/hw/char/sh_serial.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 SCI/SCIF serial port emulation
*
* Copyright (c) 2007 Magnus Damm
*
* Based on serial.c - QEMU 16450 UART emulation
* Copyright (c) 2003-2004 Fabrice Bellard
*
* 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/hw.h"
#include "hw/sh4/sh.h"
#include "sysemu/char.h"
#include "exec/address-spaces.h"
//#define DEBUG_SERIAL
#define SH_SERIAL_FLAG_TEND (1 << 0)
#define SH_SERIAL_FLAG_TDE (1 << 1)
#define SH_SERIAL_FLAG_RDF (1 << 2)
#define SH_SERIAL_FLAG_BRK (1 << 3)
#define SH_SERIAL_FLAG_DR (1 << 4)
#define SH_RX_FIFO_LENGTH (16)
typedef struct {
MemoryRegion iomem;
MemoryRegion iomem_p4;
MemoryRegion iomem_a7;
uint8_t smr;
uint8_t brr;
uint8_t scr;
uint8_t dr; /* ftdr / tdr */
uint8_t sr; /* fsr / ssr */
uint16_t fcr;
uint8_t sptr;
uint8_t rx_fifo[SH_RX_FIFO_LENGTH]; /* frdr / rdr */
uint8_t rx_cnt;
uint8_t rx_tail;
uint8_t rx_head;
int freq;
int feat;
int flags;
int rtrg;
CharDriverState *chr;
qemu_irq eri;
qemu_irq rxi;
qemu_irq txi;
qemu_irq tei;
qemu_irq bri;
} sh_serial_state;
static void sh_serial_clear_fifo(sh_serial_state * s)
{
memset(s->rx_fifo, 0, SH_RX_FIFO_LENGTH);
s->rx_cnt = 0;
s->rx_head = 0;
s->rx_tail = 0;
}
static void sh_serial_write(void *opaque, hwaddr offs,
uint64_t val, unsigned size)
{
sh_serial_state *s = opaque;
unsigned char ch;
#ifdef DEBUG_SERIAL
printf("sh_serial: write offs=0x%02x val=0x%02x\n",
offs, val);
#endif
switch(offs) {
case 0x00: /* SMR */
s->smr = val & ((s->feat & SH_SERIAL_FEAT_SCIF) ? 0x7b : 0xff);
return;
case 0x04: /* BRR */
s->brr = val;
return;
case 0x08: /* SCR */
/* TODO : For SH7751, SCIF mask should be 0xfb. */
s->scr = val & ((s->feat & SH_SERIAL_FEAT_SCIF) ? 0xfa : 0xff);
if (!(val & (1 << 5)))
s->flags |= SH_SERIAL_FLAG_TEND;
if ((s->feat & SH_SERIAL_FEAT_SCIF) && s->txi) {
qemu_set_irq(s->txi, val & (1 << 7));
}
if (!(val & (1 << 6))) {
qemu_set_irq(s->rxi, 0);
}
return;
case 0x0c: /* FTDR / TDR */
if (s->chr) {
ch = val;
/* XXX this blocks entire thread. Rewrite to use
* qemu_chr_fe_write and background I/O callbacks */
qemu_chr_fe_write_all(s->chr, &ch, 1);
}
s->dr = val;
s->flags &= ~SH_SERIAL_FLAG_TDE;
return;
#if 0
case 0x14: /* FRDR / RDR */
ret = 0;
break;
#endif
}
if (s->feat & SH_SERIAL_FEAT_SCIF) {
switch(offs) {
case 0x10: /* FSR */
if (!(val & (1 << 6)))
s->flags &= ~SH_SERIAL_FLAG_TEND;
if (!(val & (1 << 5)))
s->flags &= ~SH_SERIAL_FLAG_TDE;
if (!(val & (1 << 4)))
s->flags &= ~SH_SERIAL_FLAG_BRK;
if (!(val & (1 << 1)))
s->flags &= ~SH_SERIAL_FLAG_RDF;
if (!(val & (1 << 0)))
s->flags &= ~SH_SERIAL_FLAG_DR;
if (!(val & (1 << 1)) || !(val & (1 << 0))) {
if (s->rxi) {
qemu_set_irq(s->rxi, 0);
}
}
return;
case 0x18: /* FCR */
s->fcr = val;
switch ((val >> 6) & 3) {
case 0:
s->rtrg = 1;
break;
case 1:
s->rtrg = 4;
break;
case 2:
s->rtrg = 8;
break;
case 3:
s->rtrg = 14;
break;
}
if (val & (1 << 1)) {
sh_serial_clear_fifo(s);
s->sr &= ~(1 << 1);
}
return;
case 0x20: /* SPTR */
s->sptr = val & 0xf3;
return;
case 0x24: /* LSR */
return;
}
}
else {
switch(offs) {
#if 0
case 0x0c:
ret = s->dr;
break;
case 0x10:
ret = 0;
break;
#endif
case 0x1c:
s->sptr = val & 0x8f;
return;
}
}
fprintf(stderr, "sh_serial: unsupported write to 0x%02"
HWADDR_PRIx "\n", offs);
abort();
}
static uint64_t sh_serial_read(void *opaque, hwaddr offs,
unsigned size)
{
sh_serial_state *s = opaque;
uint32_t ret = ~0;
#if 0
switch(offs) {
case 0x00:
ret = s->smr;
break;
case 0x04:
ret = s->brr;
break;
case 0x08:
ret = s->scr;
break;
case 0x14:
ret = 0;
break;
}
#endif
if (s->feat & SH_SERIAL_FEAT_SCIF) {
switch(offs) {
case 0x00: /* SMR */
ret = s->smr;
break;
case 0x08: /* SCR */
ret = s->scr;
break;
case 0x10: /* FSR */
ret = 0;
if (s->flags & SH_SERIAL_FLAG_TEND)
ret |= (1 << 6);
if (s->flags & SH_SERIAL_FLAG_TDE)
ret |= (1 << 5);
if (s->flags & SH_SERIAL_FLAG_BRK)
ret |= (1 << 4);
if (s->flags & SH_SERIAL_FLAG_RDF)
ret |= (1 << 1);
if (s->flags & SH_SERIAL_FLAG_DR)
ret |= (1 << 0);
if (s->scr & (1 << 5))
s->flags |= SH_SERIAL_FLAG_TDE | SH_SERIAL_FLAG_TEND;
break;
case 0x14:
if (s->rx_cnt > 0) {
ret = s->rx_fifo[s->rx_tail++];
s->rx_cnt--;
if (s->rx_tail == SH_RX_FIFO_LENGTH)
s->rx_tail = 0;
if (s->rx_cnt < s->rtrg)
s->flags &= ~SH_SERIAL_FLAG_RDF;
}
break;
case 0x18:
ret = s->fcr;
break;
case 0x1c:
ret = s->rx_cnt;
break;
case 0x20:
ret = s->sptr;
break;
case 0x24:
ret = 0;
break;
}
}
else {
switch(offs) {
#if 0
case 0x0c:
ret = s->dr;
break;
case 0x10:
ret = 0;
break;
case 0x14:
ret = s->rx_fifo[0];
break;
#endif
case 0x1c:
ret = s->sptr;
break;
}
}
#ifdef DEBUG_SERIAL
printf("sh_serial: read offs=0x%02x val=0x%x\n",
offs, ret);
#endif
if (ret & ~((1 << 16) - 1)) {
fprintf(stderr, "sh_serial: unsupported read from 0x%02"
HWADDR_PRIx "\n", offs);
abort();
}
return ret;
}
static int sh_serial_can_receive(sh_serial_state *s)
{
return s->scr & (1 << 4);
}
static void sh_serial_receive_break(sh_serial_state *s)
{
if (s->feat & SH_SERIAL_FEAT_SCIF)
s->sr |= (1 << 4);
}
static int sh_serial_can_receive1(void *opaque)
{
sh_serial_state *s = opaque;
return sh_serial_can_receive(s);
}
static void sh_serial_receive1(void *opaque, const uint8_t *buf, int size)
{
sh_serial_state *s = opaque;
if (s->feat & SH_SERIAL_FEAT_SCIF) {
int i;
for (i = 0; i < size; i++) {
if (s->rx_cnt < SH_RX_FIFO_LENGTH) {
s->rx_fifo[s->rx_head++] = buf[i];
if (s->rx_head == SH_RX_FIFO_LENGTH) {
s->rx_head = 0;
}
s->rx_cnt++;
if (s->rx_cnt >= s->rtrg) {
s->flags |= SH_SERIAL_FLAG_RDF;
if (s->scr & (1 << 6) && s->rxi) {
qemu_set_irq(s->rxi, 1);
}
}
}
}
} else {
s->rx_fifo[0] = buf[0];
}
}
static void sh_serial_event(void *opaque, int event)
{
sh_serial_state *s = opaque;
if (event == CHR_EVENT_BREAK)
sh_serial_receive_break(s);
}
static const MemoryRegionOps sh_serial_ops = {
.read = sh_serial_read,
.write = sh_serial_write,
.endianness = DEVICE_NATIVE_ENDIAN,
};
void sh_serial_init(MemoryRegion *sysmem,
hwaddr base, int feat,
uint32_t freq, CharDriverState *chr,
qemu_irq eri_source,
qemu_irq rxi_source,
qemu_irq txi_source,
qemu_irq tei_source,
qemu_irq bri_source)
{
sh_serial_state *s;
s = g_malloc0(sizeof(sh_serial_state));
s->feat = feat;
s->flags = SH_SERIAL_FLAG_TEND | SH_SERIAL_FLAG_TDE;
s->rtrg = 1;
s->smr = 0;
s->brr = 0xff;
s->scr = 1 << 5; /* pretend that TX is enabled so early printk works */
s->sptr = 0;
if (feat & SH_SERIAL_FEAT_SCIF) {
s->fcr = 0;
}
else {
s->dr = 0xff;
}
sh_serial_clear_fifo(s);
memory_region_init_io(&s->iomem, NULL, &sh_serial_ops, s,
"serial", 0x100000000ULL);
memory_region_init_alias(&s->iomem_p4, NULL, "serial-p4", &s->iomem,
0, 0x28);
memory_region_add_subregion(sysmem, P4ADDR(base), &s->iomem_p4);
memory_region_init_alias(&s->iomem_a7, NULL, "serial-a7", &s->iomem,
0, 0x28);
memory_region_add_subregion(sysmem, A7ADDR(base), &s->iomem_a7);
s->chr = chr;
if (chr) {
qemu_chr_fe_claim_no_fail(chr);
qemu_chr_add_handlers(chr, sh_serial_can_receive1, sh_serial_receive1,
sh_serial_event, s);
}
s->eri = eri_source;
s->rxi = rxi_source;
s->txi = txi_source;
s->tei = tei_source;
s->bri = bri_source;
}
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