[PATCH v2 1/4] hw/dma: sifive_pdma: reset Next* registers when Control.claim is set

[frank . chang]

From: Frank Chang <frank.chang@sifive.com>

Setting Control.claim clears all of the chanel's Next registers.
This is effective only when Control.claim is set from 0 to 1.

Signed-off-by: Frank Chang <frank.chang@sifive.com>
Tested-by: Max Hsu <max.hsu@sifive.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
---
 hw/dma/sifive_pdma.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/hw/dma/sifive_pdma.c b/hw/dma/sifive_pdma.c
index 9b2ac2017d9..d92e27dfdc4 100644
--- a/hw/dma/sifive_pdma.c
+++ b/hw/dma/sifive_pdma.c
@@ -54,6 +54,13 @@
 #define DMA_EXEC_DST        0x110
 #define DMA_EXEC_SRC        0x118
 
+/*
+ * FU540/FU740 docs are incorrect with NextConfig.wsize/rsize reset values.
+ * The reset values tested on Unleashed/Unmatched boards are 6 instead of 0.
+ */
+#define CONFIG_WRSZ_DEFAULT 6
+#define CONFIG_RDSZ_DEFAULT 6
+
 enum dma_chan_state {
     DMA_CHAN_STATE_IDLE,
     DMA_CHAN_STATE_STARTED,
@@ -221,6 +228,7 @@ static void sifive_pdma_write(void *opaque, hwaddr offset,
 {
     SiFivePDMAState *s = opaque;
     int ch = SIFIVE_PDMA_CHAN_NO(offset);
+    bool claimed;
 
     if (ch >= SIFIVE_PDMA_CHANS) {
         qemu_log_mask(LOG_GUEST_ERROR, "%s: Invalid channel no %d\n",
@@ -231,6 +239,17 @@ static void sifive_pdma_write(void *opaque, hwaddr offset,
     offset &= 0xfff;
     switch (offset) {
     case DMA_CONTROL:
+        claimed = !!s->chan[ch].control & CONTROL_CLAIM;
+
+        if (!claimed && (value & CONTROL_CLAIM)) {
+            /* reset Next* registers */
+            s->chan[ch].next_config = (CONFIG_RDSZ_DEFAULT << 
CONFIG_RDSZ_SHIFT) |
+                                      (CONFIG_WRSZ_DEFAULT << 
CONFIG_WRSZ_SHIFT);
+            s->chan[ch].next_bytes = 0;
+            s->chan[ch].next_dst = 0;
+            s->chan[ch].next_src = 0;
+        }
+
         s->chan[ch].control = value;
 
         if (value & CONTROL_RUN) {
-- 
2.25.1