[PATCH v2 03/14] hw/dma/zynq-devcfg: Handle bitstream loading via DMA to 0xffffffff

["Corvin Köhne" <corvin.koehne@gmail.com>]

From: YannickV <Y.Vossen@beckhoff.com>

A DMA transfer to destination address `0xffffffff` should trigger a
bitstream load via the PCAP interface. Currently, this case is not
intercepted, causing loaders to enter an infinite loop when polling
the status register.

This commit adds a check for `0xffffffff` as the destination address.
If detected, the relevant status register bits (`DMA_DONE`,
`DMA_P_DONE`, and `PCFG_DONE`) are set to indicate a successful
bitstream load. If the address is different, the DMA transfer proceeds
as usual. A successful load is indicated but nothing is actually
done. Guests relying on FPGA functions are still known to fail.

This feature is required for the integration of the Beckhoff
CX7200 model.

Signed-off-by: Yannick Voßen <y.vossen@beckhoff.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@amd.com>
---
 hw/dma/xlnx-zynq-devcfg.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/hw/dma/xlnx-zynq-devcfg.c b/hw/dma/xlnx-zynq-devcfg.c
index 0fd0d23f57..b838c1c0d0 100644
--- a/hw/dma/xlnx-zynq-devcfg.c
+++ b/hw/dma/xlnx-zynq-devcfg.c
@@ -247,7 +247,14 @@ static uint64_t r_lock_pre_write(RegisterInfo *reg, uint64_t val)
 static void r_dma_dst_len_post_write(RegisterInfo *reg, uint64_t val)
 {
     XlnxZynqDevcfg *s = XLNX_ZYNQ_DEVCFG(reg->opaque);
-
+    if ((s->regs[R_DMA_DST_ADDR]) == 0xffffffff) {
+        DB_PRINT("bitstream loading detected\n");
+        s->regs[R_INT_STS] |= R_INT_STS_DMA_DONE_MASK |
+                                R_INT_STS_DMA_P_DONE_MASK |
+                                R_INT_STS_PCFG_DONE_MASK;
+        xlnx_zynq_devcfg_update_ixr(s);
+        return;
+    }
     s->dma_cmd_fifo[s->dma_cmd_fifo_num] = (XlnxZynqDevcfgDMACmd) {
             .src_addr = s->regs[R_DMA_SRC_ADDR] & ~0x3UL,
             .dest_addr = s->regs[R_DMA_DST_ADDR] & ~0x3UL,
-- 
2.50.1