[PATCH 1/3] dmaengine: dw-axi-dmac: dump channel registers on error

[Ben Dooks <ben.dooks@sifive.com>]

On channel error, dump the channel register state before
the channel's LLI entries to see what the controller was
actually doing when the error happend.

Signed-off-by: Ben Dooks <ben.dooks@sifive.com>
---
 .../dma/dw-axi-dmac/dw-axi-dmac-platform.c    | 28 +++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
index e9c9bcb1f5c2..75c537153e92 100644
--- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
+++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
@@ -79,6 +79,20 @@ axi_chan_iowrite64(struct axi_dma_chan *chan, u32 reg, u64 val)
 	iowrite32(upper_32_bits(val), chan->chan_regs + reg + 4);
 }
 
+static inline u64
+axi_chan_ioread64(struct axi_dma_chan *chan, u32 reg)
+{
+	u32 high, low;
+	u64 result;
+
+	low = ioread32(chan->chan_regs + reg);
+	high = ioread32(chan->chan_regs + reg + 4);
+
+	result = low;
+	result |= (u64)high << 32;
+	return result;
+}
+
 static inline void axi_chan_config_write(struct axi_dma_chan *chan,
 					 struct axi_dma_chan_config *config)
 {
@@ -979,6 +993,18 @@ static int dw_axi_dma_chan_slave_config(struct dma_chan *dchan,
 	return 0;
 }
 
+static void axi_chan_dump_regs(struct axi_dma_chan *chan)
+{
+	dev_err(dchan2dev(&chan->vc.chan),
+		"R: SAR: 0x%llx DAR: 0x%llx LLP: 0x%llx BTS 0x%x CTL: 0x%x:%08x\n",
+		axi_chan_ioread64(chan, CH_SAR),
+		axi_chan_ioread64(chan, CH_DAR),
+		axi_chan_ioread64(chan, CH_LLP),
+		axi_chan_ioread32(chan, CH_BLOCK_TS),
+		axi_chan_ioread32(chan, CH_CTL_H),
+		axi_chan_ioread32(chan, CH_CTL_L));
+}
+
 static void axi_chan_dump_lli(struct axi_dma_chan *chan,
 			      struct axi_dma_hw_desc *desc)
 {
@@ -1020,6 +1046,8 @@ static noinline void axi_chan_handle_err(struct axi_dma_chan *chan, u32 status)
 	dev_err(chan2dev(chan),
 		"Bad descriptor submitted for %s, cookie: %d, irq: 0x%08x\n",
 		axi_chan_name(chan), vd->tx.cookie, status);
+
+	axi_chan_dump_regs(chan);
 	axi_chan_list_dump_lli(chan, vd_to_axi_desc(vd));
 
 	vchan_cookie_complete(vd);
-- 
2.35.1