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qemu-patch-raspberry4/hw/dma.c
aliguori 492c30af25 Make DMA bottom-half driven (v2) 
The current DMA routines are driven by a call in main_loop_wait() after every
select.

This patch converts the DMA code to be driven by a constantly rescheduled
bottom half.  The advantage of using a scheduled bottom half is that we can
stop scheduling the bottom half when there no DMA channels are runnable.  This
means we can potentially detect this case and sleep longer in the main loop.

The only two architectures implementing DMA_run() are cris and i386.  For cris,
I converted it to a simple repeating bottom half.  I've only compile tested
this as cris does not seem to work on a 64-bit host.  It should be functionally
identical to the previous implementation so I expect it to work.

For x86, I've made sure to only fire the DMA bottom half if there is a DMA
channel that is runnable.  The effect of this is that unless you're using sb16
or a floppy disk, the DMA bottom half never fires.

You probably should test this malc.  My own benchmarks actually show slight
improvement by it's possible the change in timing could affect your demos.

Since v1, I've changed the code to use a BH instead of a timer.  cris at least
seems to depend on faster than 10ms polling.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>



git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5573 c046a42c-6fe2-441c-8c8c-71466251a162
2008-10-31 17:25:56 +00:00

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/*
* QEMU DMA emulation
*
* Copyright (c) 2003-2004 Vassili Karpov (malc)
*
* 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 "hw.h"
#include "isa.h"
/* #define DEBUG_DMA */
#define dolog(...) fprintf (stderr, "dma: " __VA_ARGS__)
#ifdef DEBUG_DMA
#define lwarn(...) fprintf (stderr, "dma: " __VA_ARGS__)
#define linfo(...) fprintf (stderr, "dma: " __VA_ARGS__)
#define ldebug(...) fprintf (stderr, "dma: " __VA_ARGS__)
#else
#define lwarn(...)
#define linfo(...)
#define ldebug(...)
#endif
#define LENOFA(a) ((int) (sizeof(a)/sizeof(a[0])))
struct dma_regs {
int now[2];
uint16_t base[2];
uint8_t mode;
uint8_t page;
uint8_t pageh;
uint8_t dack;
uint8_t eop;
DMA_transfer_handler transfer_handler;
void *opaque;
};
#define ADDR 0
#define COUNT 1
static struct dma_cont {
uint8_t status;
uint8_t command;
uint8_t mask;
uint8_t flip_flop;
int dshift;
struct dma_regs regs[4];
} dma_controllers[2];
enum {
CMD_MEMORY_TO_MEMORY = 0x01,
CMD_FIXED_ADDRESS = 0x02,
CMD_BLOCK_CONTROLLER = 0x04,
CMD_COMPRESSED_TIME = 0x08,
CMD_CYCLIC_PRIORITY = 0x10,
CMD_EXTENDED_WRITE = 0x20,
CMD_LOW_DREQ = 0x40,
CMD_LOW_DACK = 0x80,
CMD_NOT_SUPPORTED = CMD_MEMORY_TO_MEMORY | CMD_FIXED_ADDRESS
| CMD_COMPRESSED_TIME | CMD_CYCLIC_PRIORITY | CMD_EXTENDED_WRITE
| CMD_LOW_DREQ | CMD_LOW_DACK
};
static void DMA_run (void);
static int channels[8] = {-1, 2, 3, 1, -1, -1, -1, 0};
static void write_page (void *opaque, uint32_t nport, uint32_t data)
{
struct dma_cont *d = opaque;
int ichan;
ichan = channels[nport & 7];
if (-1 == ichan) {
dolog ("invalid channel %#x %#x\n", nport, data);
return;
}
d->regs[ichan].page = data;
}
static void write_pageh (void *opaque, uint32_t nport, uint32_t data)
{
struct dma_cont *d = opaque;
int ichan;
ichan = channels[nport & 7];
if (-1 == ichan) {
dolog ("invalid channel %#x %#x\n", nport, data);
return;
}
d->regs[ichan].pageh = data;
}
static uint32_t read_page (void *opaque, uint32_t nport)
{
struct dma_cont *d = opaque;
int ichan;
ichan = channels[nport & 7];
if (-1 == ichan) {
dolog ("invalid channel read %#x\n", nport);
return 0;
}
return d->regs[ichan].page;
}
static uint32_t read_pageh (void *opaque, uint32_t nport)
{
struct dma_cont *d = opaque;
int ichan;
ichan = channels[nport & 7];
if (-1 == ichan) {
dolog ("invalid channel read %#x\n", nport);
return 0;
}
return d->regs[ichan].pageh;
}
static inline void init_chan (struct dma_cont *d, int ichan)
{
struct dma_regs *r;
r = d->regs + ichan;
r->now[ADDR] = r->base[ADDR] << d->dshift;
r->now[COUNT] = 0;
}
static inline int getff (struct dma_cont *d)
{
int ff;
ff = d->flip_flop;
d->flip_flop = !ff;
return ff;
}
static uint32_t read_chan (void *opaque, uint32_t nport)
{
struct dma_cont *d = opaque;
int ichan, nreg, iport, ff, val, dir;
struct dma_regs *r;
iport = (nport >> d->dshift) & 0x0f;
ichan = iport >> 1;
nreg = iport & 1;
r = d->regs + ichan;
dir = ((r->mode >> 5) & 1) ? -1 : 1;
ff = getff (d);
if (nreg)
val = (r->base[COUNT] << d->dshift) - r->now[COUNT];
else
val = r->now[ADDR] + r->now[COUNT] * dir;
ldebug ("read_chan %#x -> %d\n", iport, val);
return (val >> (d->dshift + (ff << 3))) & 0xff;
}
static void write_chan (void *opaque, uint32_t nport, uint32_t data)
{
struct dma_cont *d = opaque;
int iport, ichan, nreg;
struct dma_regs *r;
iport = (nport >> d->dshift) & 0x0f;
ichan = iport >> 1;
nreg = iport & 1;
r = d->regs + ichan;
if (getff (d)) {
r->base[nreg] = (r->base[nreg] & 0xff) | ((data << 8) & 0xff00);
init_chan (d, ichan);
} else {
r->base[nreg] = (r->base[nreg] & 0xff00) | (data & 0xff);
}
}
static void write_cont (void *opaque, uint32_t nport, uint32_t data)
{
struct dma_cont *d = opaque;
int iport, ichan = 0;
iport = (nport >> d->dshift) & 0x0f;
switch (iport) {
case 0x08: /* command */
if ((data != 0) && (data & CMD_NOT_SUPPORTED)) {
dolog ("command %#x not supported\n", data);
return;
}
d->command = data;
break;
case 0x09:
ichan = data & 3;
if (data & 4) {
d->status |= 1 << (ichan + 4);
}
else {
d->status &= ~(1 << (ichan + 4));
}
d->status &= ~(1 << ichan);
DMA_run();
break;
case 0x0a: /* single mask */
if (data & 4)
d->mask |= 1 << (data & 3);
else
d->mask &= ~(1 << (data & 3));
DMA_run();
break;
case 0x0b: /* mode */
{
ichan = data & 3;
#ifdef DEBUG_DMA
{
int op, ai, dir, opmode;
op = (data >> 2) & 3;
ai = (data >> 4) & 1;
dir = (data >> 5) & 1;
opmode = (data >> 6) & 3;
linfo ("ichan %d, op %d, ai %d, dir %d, opmode %d\n",
ichan, op, ai, dir, opmode);
}
#endif
d->regs[ichan].mode = data;
break;
}
case 0x0c: /* clear flip flop */
d->flip_flop = 0;
break;
case 0x0d: /* reset */
d->flip_flop = 0;
d->mask = ~0;
d->status = 0;
d->command = 0;
break;
case 0x0e: /* clear mask for all channels */
d->mask = 0;
DMA_run();
break;
case 0x0f: /* write mask for all channels */
d->mask = data;
DMA_run();
break;
default:
dolog ("unknown iport %#x\n", iport);
break;
}
#ifdef DEBUG_DMA
if (0xc != iport) {
linfo ("write_cont: nport %#06x, ichan % 2d, val %#06x\n",
nport, ichan, data);
}
#endif
}
static uint32_t read_cont (void *opaque, uint32_t nport)
{
struct dma_cont *d = opaque;
int iport, val;
iport = (nport >> d->dshift) & 0x0f;
switch (iport) {
case 0x08: /* status */
val = d->status;
d->status &= 0xf0;
break;
case 0x0f: /* mask */
val = d->mask;
break;
default:
val = 0;
break;
}
ldebug ("read_cont: nport %#06x, iport %#04x val %#x\n", nport, iport, val);
return val;
}
int DMA_get_channel_mode (int nchan)
{
return dma_controllers[nchan > 3].regs[nchan & 3].mode;
}
void DMA_hold_DREQ (int nchan)
{
int ncont, ichan;
ncont = nchan > 3;
ichan = nchan & 3;
linfo ("held cont=%d chan=%d\n", ncont, ichan);
dma_controllers[ncont].status |= 1 << (ichan + 4);
DMA_run();
}
void DMA_release_DREQ (int nchan)
{
int ncont, ichan;
ncont = nchan > 3;
ichan = nchan & 3;
linfo ("released cont=%d chan=%d\n", ncont, ichan);
dma_controllers[ncont].status &= ~(1 << (ichan + 4));
DMA_run();
}
static void channel_run (int ncont, int ichan)
{
int n;
struct dma_regs *r = &dma_controllers[ncont].regs[ichan];
#ifdef DEBUG_DMA
int dir, opmode;
dir = (r->mode >> 5) & 1;
opmode = (r->mode >> 6) & 3;
if (dir) {
dolog ("DMA in address decrement mode\n");
}
if (opmode != 1) {
dolog ("DMA not in single mode select %#x\n", opmode);
}
#endif
r = dma_controllers[ncont].regs + ichan;
n = r->transfer_handler (r->opaque, ichan + (ncont << 2),
r->now[COUNT], (r->base[COUNT] + 1) << ncont);
r->now[COUNT] = n;
ldebug ("dma_pos %d size %d\n", n, (r->base[COUNT] + 1) << ncont);
}
static QEMUBH *dma_bh;
static void DMA_run (void)
{
struct dma_cont *d;
int icont, ichan;
int rearm = 0;
d = dma_controllers;
for (icont = 0; icont < 2; icont++, d++) {
for (ichan = 0; ichan < 4; ichan++) {
int mask;
mask = 1 << ichan;
if ((0 == (d->mask & mask)) && (0 != (d->status & (mask << 4)))) {
channel_run (icont, ichan);
rearm = 1;
}
}
}
if (rearm)
qemu_bh_schedule_idle(dma_bh);
}
static void DMA_run_bh(void *unused)
{
DMA_run();
}
void DMA_register_channel (int nchan,
DMA_transfer_handler transfer_handler,
void *opaque)
{
struct dma_regs *r;
int ichan, ncont;
ncont = nchan > 3;
ichan = nchan & 3;
r = dma_controllers[ncont].regs + ichan;
r->transfer_handler = transfer_handler;
r->opaque = opaque;
}
int DMA_read_memory (int nchan, void *buf, int pos, int len)
{
struct dma_regs *r = &dma_controllers[nchan > 3].regs[nchan & 3];
target_phys_addr_t addr = ((r->pageh & 0x7f) << 24) | (r->page << 16) | r->now[ADDR];
if (r->mode & 0x20) {
int i;
uint8_t *p = buf;
cpu_physical_memory_read (addr - pos - len, buf, len);
/* What about 16bit transfers? */
for (i = 0; i < len >> 1; i++) {
uint8_t b = p[len - i - 1];
p[i] = b;
}
}
else
cpu_physical_memory_read (addr + pos, buf, len);
return len;
}
int DMA_write_memory (int nchan, void *buf, int pos, int len)
{
struct dma_regs *r = &dma_controllers[nchan > 3].regs[nchan & 3];
target_phys_addr_t addr = ((r->pageh & 0x7f) << 24) | (r->page << 16) | r->now[ADDR];
if (r->mode & 0x20) {
int i;
uint8_t *p = buf;
cpu_physical_memory_write (addr - pos - len, buf, len);
/* What about 16bit transfers? */
for (i = 0; i < len; i++) {
uint8_t b = p[len - i - 1];
p[i] = b;
}
}
else
cpu_physical_memory_write (addr + pos, buf, len);
return len;
}
/* request the emulator to transfer a new DMA memory block ASAP */
void DMA_schedule(int nchan)
{
CPUState *env = cpu_single_env;
if (env)
cpu_interrupt(env, CPU_INTERRUPT_EXIT);
}
static void dma_reset(void *opaque)
{
struct dma_cont *d = opaque;
write_cont (d, (0x0d << d->dshift), 0);
}
static int dma_phony_handler (void *opaque, int nchan, int dma_pos, int dma_len)
{
dolog ("unregistered DMA channel used nchan=%d dma_pos=%d dma_len=%d\n",
nchan, dma_pos, dma_len);
return dma_pos;
}
/* dshift = 0: 8 bit DMA, 1 = 16 bit DMA */
static void dma_init2(struct dma_cont *d, int base, int dshift,
int page_base, int pageh_base)
{
static const int page_port_list[] = { 0x1, 0x2, 0x3, 0x7 };
int i;
d->dshift = dshift;
for (i = 0; i < 8; i++) {
register_ioport_write (base + (i << dshift), 1, 1, write_chan, d);
register_ioport_read (base + (i << dshift), 1, 1, read_chan, d);
}
for (i = 0; i < LENOFA (page_port_list); i++) {
register_ioport_write (page_base + page_port_list[i], 1, 1,
write_page, d);
register_ioport_read (page_base + page_port_list[i], 1, 1,
read_page, d);
if (pageh_base >= 0) {
register_ioport_write (pageh_base + page_port_list[i], 1, 1,
write_pageh, d);
register_ioport_read (pageh_base + page_port_list[i], 1, 1,
read_pageh, d);
}
}
for (i = 0; i < 8; i++) {
register_ioport_write (base + ((i + 8) << dshift), 1, 1,
write_cont, d);
register_ioport_read (base + ((i + 8) << dshift), 1, 1,
read_cont, d);
}
qemu_register_reset(dma_reset, d);
dma_reset(d);
for (i = 0; i < LENOFA (d->regs); ++i) {
d->regs[i].transfer_handler = dma_phony_handler;
}
}
static void dma_save (QEMUFile *f, void *opaque)
{
struct dma_cont *d = opaque;
int i;
/* qemu_put_8s (f, &d->status); */
qemu_put_8s (f, &d->command);
qemu_put_8s (f, &d->mask);
qemu_put_8s (f, &d->flip_flop);
qemu_put_be32 (f, d->dshift);
for (i = 0; i < 4; ++i) {
struct dma_regs *r = &d->regs[i];
qemu_put_be32 (f, r->now[0]);
qemu_put_be32 (f, r->now[1]);
qemu_put_be16s (f, &r->base[0]);
qemu_put_be16s (f, &r->base[1]);
qemu_put_8s (f, &r->mode);
qemu_put_8s (f, &r->page);
qemu_put_8s (f, &r->pageh);
qemu_put_8s (f, &r->dack);
qemu_put_8s (f, &r->eop);
}
}
static int dma_load (QEMUFile *f, void *opaque, int version_id)
{
struct dma_cont *d = opaque;
int i;
if (version_id != 1)
return -EINVAL;
/* qemu_get_8s (f, &d->status); */
qemu_get_8s (f, &d->command);
qemu_get_8s (f, &d->mask);
qemu_get_8s (f, &d->flip_flop);
d->dshift=qemu_get_be32 (f);
for (i = 0; i < 4; ++i) {
struct dma_regs *r = &d->regs[i];
r->now[0]=qemu_get_be32 (f);
r->now[1]=qemu_get_be32 (f);
qemu_get_be16s (f, &r->base[0]);
qemu_get_be16s (f, &r->base[1]);
qemu_get_8s (f, &r->mode);
qemu_get_8s (f, &r->page);
qemu_get_8s (f, &r->pageh);
qemu_get_8s (f, &r->dack);
qemu_get_8s (f, &r->eop);
}
DMA_run();
return 0;
}
void DMA_init (int high_page_enable)
{
dma_init2(&dma_controllers[0], 0x00, 0, 0x80,
high_page_enable ? 0x480 : -1);
dma_init2(&dma_controllers[1], 0xc0, 1, 0x88,
high_page_enable ? 0x488 : -1);
register_savevm ("dma", 0, 1, dma_save, dma_load, &dma_controllers[0]);
register_savevm ("dma", 1, 1, dma_save, dma_load, &dma_controllers[1]);
dma_bh = qemu_bh_new(DMA_run_bh, NULL);
}
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