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hw/dma: sifive_pdma: Don't run DMA when channel is disclaimed

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If Control.run bit is set while not preserving the Control.claim
bit, the DMA transfer shall not be started.

The following result is PDMA tested in U-Boot on Unleashed board:

=> mw.l 0x3000000 0x0                      <= Disclaim channel 0
=> mw.l 0x3000000 0x1                      <= Claim channel 0
=> mw.l 0x3000004 0x55000000               <= wsize = rsize = 5 (2^5 = 32 bytes)
=> mw.q 0x3000008 0x2                      <= NextBytes = 2
=> mw.q 0x3000010 0x84000000               <= NextDestination = 0x84000000
=> mw.q 0x3000018 0x84001000               <= NextSource = 0x84001000
=> mw.l 0x84000000 0x87654321              <= Fill test data to dst
=> mw.l 0x84001000 0x12345678              <= Fill test data to src
=> md.l 0x84000000 1; md.l 0x84001000 1    <= Dump src/dst memory contents
84000000: 87654321                               !Ce.
84001000: 12345678                               xV4.
=> md.l 0x3000000 8                        <= Dump PDMA status
03000000: 00000001 55000000 00000002 00000000    .......U........
03000010: 84000000 00000000 84001000 00000000    ................
=> mw.l 0x3000000 0x2                      <= Set channel 0 run bit only
=> md.l 0x3000000 8                        <= Dump PDMA status
03000000: 00000000 55000000 00000002 00000000    .......U........
03000010: 84000000 00000000 84001000 00000000    ................
=> md.l 0x84000000 1; md.l 0x84001000 1    <= Dump src/dst memory contents
84000000: 87654321                               !Ce.
84001000: 12345678                               xV4.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20210927072124.1564129-2-bmeng.cn@gmail.com
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
This commit is contained in:
Bin Meng 2021-09-27 15:21:24 +08:00 committed by Alistair Francis
parent b7af62ae2c
commit 47b5fbf5a3
1 changed files with 9 additions and 2 deletions
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11
hw/dma/sifive_pdma.c
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@ -232,7 +232,7 @@ static void sifive_pdma_write(void *opaque, hwaddr offset,
{
SiFivePDMAState *s = opaque;
int ch = SIFIVE_PDMA_CHAN_NO(offset);
bool claimed;
bool claimed, run;
if (ch >= SIFIVE_PDMA_CHANS) {
qemu_log_mask(LOG_GUEST_ERROR, "%s: Invalid channel no %d\n",
@ -244,6 +244,7 @@ static void sifive_pdma_write(void *opaque, hwaddr offset,
switch (offset) {
case DMA_CONTROL:
claimed = !!(s->chan[ch].control & CONTROL_CLAIM);
run = !!(s->chan[ch].control & CONTROL_RUN);
if (!claimed && (value & CONTROL_CLAIM)) {
/* reset Next* registers */
@ -254,13 +255,19 @@ static void sifive_pdma_write(void *opaque, hwaddr offset,
s->chan[ch].next_src = 0;
}
/* claim bit can only be cleared when run is low */
if (run && !(value & CONTROL_CLAIM)) {
value |= CONTROL_CLAIM;
}
s->chan[ch].control = value;
/*
* If channel was not claimed before run bit is set,
* or if the channel is disclaimed when run was low,
* DMA won't run.
*/
if (!claimed) {
if (!claimed || (!run && !(value & CONTROL_CLAIM))) {
s->chan[ch].control &= ~CONTROL_RUN;
return;
}