dmaengine: Actions: get rid of bit fields from dma descriptor

At the moment, Driver uses bit fields to describe registers of the DMA
descriptor structure that makes it less portable and maintainable, and
Andre suugested(and even sketched important bits for it) to make use of
array to describe this DMA descriptors instead. It gives the flexibility
while extending support for other platform such as Actions S700.

This commit removes the "owl_dma_lli_hw" (that includes bit-fields) and
uses array to describe DMA descriptor.

Suggested-by: Andre Przywara <[email protected]>
Signed-off-by: Amit Singh Tomar <[email protected]>
Reviewed-by: Manivannan Sadhasivam <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Vinod Koul <[email protected]>

Author: Atomar25

drivers/dma/owl-dma.c

@@ -120,30 +120,33 @@
 #define BIT_FIELD(val, width, shift, newshift)	\
 		((((val) >> (shift)) & ((BIT(width)) - 1)) << (newshift))
 
+/* Frame count value is fixed as 1 */
+#define FCNT_VAL				0x1
+
 /**
- * struct owl_dma_lli_hw - Hardware link list for dma transfer
- * @next_lli: physical address of the next link list
- * @saddr: source physical address
- * @daddr: destination physical address
- * @flen: frame length
- * @fcnt: frame count
- * @src_stride: source stride
- * @dst_stride: destination stride
- * @ctrla: dma_mode and linklist ctrl config
- * @ctrlb: interrupt config
- * @const_num: data for constant fill
+ * owl_dmadesc_offsets - Describe DMA descriptor, hardware link
+ * list for dma transfer
+ * @OWL_DMADESC_NEXT_LLI: physical address of the next link list
+ * @OWL_DMADESC_SADDR: source physical address
+ * @OWL_DMADESC_DADDR: destination physical address
+ * @OWL_DMADESC_FLEN: frame length
+ * @OWL_DMADESC_SRC_STRIDE: source stride
+ * @OWL_DMADESC_DST_STRIDE: destination stride
+ * @OWL_DMADESC_CTRLA: dma_mode and linklist ctrl config
+ * @OWL_DMADESC_CTRLB: interrupt config
+ * @OWL_DMADESC_CONST_NUM: data for constant fill
  */
-struct owl_dma_lli_hw {
-	u32	next_lli;
-	u32	saddr;
-	u32	daddr;
-	u32	flen:20;
-	u32	fcnt:12;
-	u32	src_stride;
-	u32	dst_stride;
-	u32	ctrla;
-	u32	ctrlb;
-	u32	const_num;
+enum owl_dmadesc_offsets {
+	OWL_DMADESC_NEXT_LLI = 0,
+	OWL_DMADESC_SADDR,
+	OWL_DMADESC_DADDR,
+	OWL_DMADESC_FLEN,
+	OWL_DMADESC_SRC_STRIDE,
+	OWL_DMADESC_DST_STRIDE,
+	OWL_DMADESC_CTRLA,
+	OWL_DMADESC_CTRLB,
+	OWL_DMADESC_CONST_NUM,
+	OWL_DMADESC_SIZE
 };
 
 /**
@@ -153,7 +156,7 @@ struct owl_dma_lli_hw {
  * @node: node for txd's lli_list
  */
 struct owl_dma_lli {
-	struct  owl_dma_lli_hw	hw;
+	u32			hw[OWL_DMADESC_SIZE];
 	dma_addr_t		phys;
 	struct list_head	node;
 };
@@ -318,6 +321,11 @@ static inline u32 llc_hw_ctrlb(u32 int_ctl)
 	return ctl;
 }
 
+static u32 llc_hw_flen(struct owl_dma_lli *lli)
+{
+	return lli->hw[OWL_DMADESC_FLEN] & GENMASK(19, 0);
+}
+
 static void owl_dma_free_lli(struct owl_dma *od,
 			     struct owl_dma_lli *lli)
 {
@@ -349,8 +357,9 @@ static struct owl_dma_lli *owl_dma_add_lli(struct owl_dma_txd *txd,
 		list_add_tail(&next->node, &txd->lli_list);
 
 	if (prev) {
-		prev->hw.next_lli = next->phys;
-		prev->hw.ctrla |= llc_hw_ctrla(OWL_DMA_MODE_LME, 0);
+		prev->hw[OWL_DMADESC_NEXT_LLI] = next->phys;
+		prev->hw[OWL_DMADESC_CTRLA] |=
+					llc_hw_ctrla(OWL_DMA_MODE_LME, 0);
 	}
 
 	return next;
@@ -363,8 +372,7 @@ static inline int owl_dma_cfg_lli(struct owl_dma_vchan *vchan,
 				  struct dma_slave_config *sconfig,
 				  bool is_cyclic)
 {
-	struct owl_dma_lli_hw *hw = &lli->hw;
-	u32 mode;
+	u32 mode, ctrlb;
 
 	mode = OWL_DMA_MODE_PW(0);
 
@@ -405,22 +413,28 @@ static inline int owl_dma_cfg_lli(struct owl_dma_vchan *vchan,
 		return -EINVAL;
 	}
 
-	hw->next_lli = 0; /* One link list by default */
-	hw->saddr = src;
-	hw->daddr = dst;
-
-	hw->fcnt = 1; /* Frame count fixed as 1 */
-	hw->flen = len; /* Max frame length is 1MB */
-	hw->src_stride = 0;
-	hw->dst_stride = 0;
-	hw->ctrla = llc_hw_ctrla(mode,
-				 OWL_DMA_LLC_SAV_LOAD_NEXT |
-				 OWL_DMA_LLC_DAV_LOAD_NEXT);
+	lli->hw[OWL_DMADESC_CTRLA] = llc_hw_ctrla(mode,
+						  OWL_DMA_LLC_SAV_LOAD_NEXT |
+						  OWL_DMA_LLC_DAV_LOAD_NEXT);
 
 	if (is_cyclic)
-		hw->ctrlb = llc_hw_ctrlb(OWL_DMA_INTCTL_BLOCK);
+		ctrlb = llc_hw_ctrlb(OWL_DMA_INTCTL_BLOCK);
 	else
-		hw->ctrlb = llc_hw_ctrlb(OWL_DMA_INTCTL_SUPER_BLOCK);
+		ctrlb = llc_hw_ctrlb(OWL_DMA_INTCTL_SUPER_BLOCK);
+
+	lli->hw[OWL_DMADESC_NEXT_LLI] = 0; /* One link list by default */
+	lli->hw[OWL_DMADESC_SADDR] = src;
+	lli->hw[OWL_DMADESC_DADDR] = dst;
+	lli->hw[OWL_DMADESC_SRC_STRIDE] = 0;
+	lli->hw[OWL_DMADESC_DST_STRIDE] = 0;
+	/*
+	 * Word starts from offset 0xC is shared between frame length
+	 * (max frame length is 1MB) and frame count, where first 20
+	 * bits are for frame length and rest of 12 bits are for frame
+	 * count.
+	 */
+	lli->hw[OWL_DMADESC_FLEN] = len | FCNT_VAL << 20;
+	lli->hw[OWL_DMADESC_CTRLB] = ctrlb;
 
 	return 0;
 }
@@ -752,7 +766,7 @@ static u32 owl_dma_getbytes_chan(struct owl_dma_vchan *vchan)
 			/* Start from the next active node */
 			if (lli->phys == next_lli_phy) {
 				list_for_each_entry(lli, &txd->lli_list, node)
-					bytes += lli->hw.flen;
+					bytes += llc_hw_flen(lli);
 				break;
 			}
 		}
@@ -783,7 +797,7 @@ static enum dma_status owl_dma_tx_status(struct dma_chan *chan,
 	if (vd) {
 		txd = to_owl_txd(&vd->tx);
 		list_for_each_entry(lli, &txd->lli_list, node)
-			bytes += lli->hw.flen;
+			bytes += llc_hw_flen(lli);
 	} else {
 		bytes = owl_dma_getbytes_chan(vchan);
 	}