[PATCHv4] dmaengine: fsl-edma: fixup reg offset and hw S/G support in big-endian model

[Jingchang Lu]

The offset of all 8-/16-bit registers in big-endian eDMA model are
swapped in a 32-bit size opposite those in the little-endian model.

The hardware Scatter/Gather requires the subsequent TCDs stored in memory
in little endian independent of the register endian model, the eDMA engine
will do the swap if need.

This patch also use regular assignment for tcd variables r/w
instead of with io function previously that may not always be true.

Signed-off-by: Jingchang Lu <jingchang.lu@xxxxxxxxxxxxx>
---
changes in v4:
 use __le32/16 define little endian tcd struct explicitly.
 modify fsl_edma_set_tcd_regs() to simplify parameters.
 define fsl_edma_fill_tcd() as inline function.

changes in v3:
 use unsigned long instead of u32 in reg offset swap cast to avoid warning.

changes in v2:
 simplify register offset swap calculation.
 use regular assignment for tcd variables r/w instead of io function.

 drivers/dma/fsl-edma.c | 189 +++++++++++++++++++++++++------------------------
 1 file changed, 96 insertions(+), 93 deletions(-)

diff --git a/drivers/dma/fsl-edma.c b/drivers/dma/fsl-edma.c
index 3c5711d..2ce7076 100644
--- a/drivers/dma/fsl-edma.c
+++ b/drivers/dma/fsl-edma.c
@@ -118,17 +118,17 @@
 				BIT(DMA_SLAVE_BUSWIDTH_8_BYTES)
 
 struct fsl_edma_hw_tcd {
-	u32	saddr;
-	u16	soff;
-	u16	attr;
-	u32	nbytes;
-	u32	slast;
-	u32	daddr;
-	u16	doff;
-	u16	citer;
-	u32	dlast_sga;
-	u16	csr;
-	u16	biter;
+	__le32	saddr;
+	__le16	soff;
+	__le16	attr;
+	__le32	nbytes;
+	__le32	slast;
+	__le32	daddr;
+	__le16	doff;
+	__le16	citer;
+	__le32	dlast_sga;
+	__le16	csr;
+	__le16	biter;
 };
 
 struct fsl_edma_sw_tcd {
@@ -175,18 +175,12 @@ struct fsl_edma_engine {
 };
 
 /*
- * R/W functions for big- or little-endian registers
- * the eDMA controller's endian is independent of the CPU core's endian.
+ * R/W functions for big- or little-endian registers:
+ * The eDMA controller's endian is independent of the CPU core's endian.
+ * For the big-endian IP module, the offset for 8-bit or 16-bit registers
+ * should also be swapped opposite to that in little-endian IP.
  */
 
-static u16 edma_readw(struct fsl_edma_engine *edma, void __iomem *addr)
-{
-	if (edma->big_endian)
-		return ioread16be(addr);
-	else
-		return ioread16(addr);
-}
-
 static u32 edma_readl(struct fsl_edma_engine *edma, void __iomem *addr)
 {
 	if (edma->big_endian)
@@ -197,13 +191,18 @@ static u32 edma_readl(struct fsl_edma_engine *edma, void __iomem *addr)
 
 static void edma_writeb(struct fsl_edma_engine *edma, u8 val, void __iomem *addr)
 {
-	iowrite8(val, addr);
+	/* swap the reg offset for these in big-endian mode */
+	if (edma->big_endian)
+		iowrite8(val, (void __iomem *)((unsigned long)addr ^ 0x3));
+	else
+		iowrite8(val, addr);
 }
 
 static void edma_writew(struct fsl_edma_engine *edma, u16 val, void __iomem *addr)
 {
+	/* swap the reg offset for these in big-endian mode */
 	if (edma->big_endian)
-		iowrite16be(val, addr);
+		iowrite16be(val, (void __iomem *)((unsigned long)addr ^ 0x2));
 	else
 		iowrite16(val, addr);
 }
@@ -254,13 +253,12 @@ static void fsl_edma_chan_mux(struct fsl_edma_chan *fsl_chan,
 	chans_per_mux = fsl_chan->edma->n_chans / DMAMUX_NR;
 	ch_off = fsl_chan->vchan.chan.chan_id % chans_per_mux;
 	muxaddr = fsl_chan->edma->muxbase[ch / chans_per_mux];
+	slot = EDMAMUX_CHCFG_SOURCE(slot);
 
 	if (enable)
-		edma_writeb(fsl_chan->edma,
-				EDMAMUX_CHCFG_ENBL | EDMAMUX_CHCFG_SOURCE(slot),
-				muxaddr + ch_off);
+		iowrite8(EDMAMUX_CHCFG_ENBL | slot, muxaddr + ch_off);
 	else
-		edma_writeb(fsl_chan->edma, EDMAMUX_CHCFG_DIS, muxaddr + ch_off);
+		iowrite8(EDMAMUX_CHCFG_DIS, muxaddr + ch_off);
 }
 
 static unsigned int fsl_edma_get_tcd_attr(enum dma_slave_buswidth addr_width)
@@ -286,9 +284,8 @@ static void fsl_edma_free_desc(struct virt_dma_desc *vdesc)
 
 	fsl_desc = to_fsl_edma_desc(vdesc);
 	for (i = 0; i < fsl_desc->n_tcds; i++)
-			dma_pool_free(fsl_desc->echan->tcd_pool,
-					fsl_desc->tcd[i].vtcd,
-					fsl_desc->tcd[i].ptcd);
+		dma_pool_free(fsl_desc->echan->tcd_pool, fsl_desc->tcd[i].vtcd,
+			      fsl_desc->tcd[i].ptcd);
 	kfree(fsl_desc);
 }
 
@@ -363,8 +360,8 @@ static size_t fsl_edma_desc_residue(struct fsl_edma_chan *fsl_chan,
 
 	/* calculate the total size in this desc */
 	for (len = i = 0; i < fsl_chan->edesc->n_tcds; i++)
-		len += edma_readl(fsl_chan->edma, &(edesc->tcd[i].vtcd->nbytes))
-			* edma_readw(fsl_chan->edma, &(edesc->tcd[i].vtcd->biter));
+		len += le32_to_cpu(edesc->tcd[i].vtcd->nbytes)
+			* le16_to_cpu(edesc->tcd[i].vtcd->biter);
 
 	if (!in_progress)
 		return len;
@@ -376,14 +373,12 @@ static size_t fsl_edma_desc_residue(struct fsl_edma_chan *fsl_chan,
 
 	/* figure out the finished and calculate the residue */
 	for (i = 0; i < fsl_chan->edesc->n_tcds; i++) {
-		size = edma_readl(fsl_chan->edma, &(edesc->tcd[i].vtcd->nbytes))
-			* edma_readw(fsl_chan->edma, &(edesc->tcd[i].vtcd->biter));
+		size = le32_to_cpu(edesc->tcd[i].vtcd->nbytes)
+			* le16_to_cpu(edesc->tcd[i].vtcd->biter);
 		if (dir == DMA_MEM_TO_DEV)
-			dma_addr = edma_readl(fsl_chan->edma,
-					&(edesc->tcd[i].vtcd->saddr));
+			dma_addr = le32_to_cpu(edesc->tcd[i].vtcd->saddr);
 		else
-			dma_addr = edma_readl(fsl_chan->edma,
-					&(edesc->tcd[i].vtcd->daddr));
+			dma_addr = le32_to_cpu(edesc->tcd[i].vtcd->daddr);
 
 		len -= size;
 		if (cur_addr > dma_addr && cur_addr < dma_addr + size) {
@@ -424,55 +419,67 @@ static enum dma_status fsl_edma_tx_status(struct dma_chan *chan,
 	return fsl_chan->status;
 }
 
-static void fsl_edma_set_tcd_params(struct fsl_edma_chan *fsl_chan,
-		u32 src, u32 dst, u16 attr, u16 soff, u32 nbytes,
-		u32 slast, u16 citer, u16 biter, u32 doff, u32 dlast_sga,
-		u16 csr)
+static void fsl_edma_set_tcd_regs(struct fsl_edma_chan *fsl_chan,
+				  struct fsl_edma_hw_tcd *tcd)
 {
+	struct fsl_edma_engine *edma = fsl_chan->edma;
 	void __iomem *addr = fsl_chan->edma->membase;
 	u32 ch = fsl_chan->vchan.chan.chan_id;
 
 	/*
-	 * TCD parameters have been swapped in fill_tcd_params(),
-	 * so just write them to registers in the cpu endian here
+	 * TCD parameters are stored in struct fsl_edma_hw_tcd in little
+	 * endian format. However, we need to load the TCD registers in
+	 * big- or little-endian obeying the eDMA engine model endian.
 	 */
-	writew(0, addr + EDMA_TCD_CSR(ch));
-	writel(src, addr + EDMA_TCD_SADDR(ch));
-	writel(dst, addr + EDMA_TCD_DADDR(ch));
-	writew(attr, addr + EDMA_TCD_ATTR(ch));
-	writew(soff, addr + EDMA_TCD_SOFF(ch));
-	writel(nbytes, addr + EDMA_TCD_NBYTES(ch));
-	writel(slast, addr + EDMA_TCD_SLAST(ch));
-	writew(citer, addr + EDMA_TCD_CITER(ch));
-	writew(biter, addr + EDMA_TCD_BITER(ch));
-	writew(doff, addr + EDMA_TCD_DOFF(ch));
-	writel(dlast_sga, addr + EDMA_TCD_DLAST_SGA(ch));
-	writew(csr, addr + EDMA_TCD_CSR(ch));
-}
-
-static void fill_tcd_params(struct fsl_edma_engine *edma,
-		struct fsl_edma_hw_tcd *tcd, u32 src, u32 dst,
-		u16 attr, u16 soff, u32 nbytes, u32 slast, u16 citer,
-		u16 biter, u16 doff, u32 dlast_sga, bool major_int,
-		bool disable_req, bool enable_sg)
+	edma_writew(edma, 0, addr + EDMA_TCD_CSR(ch));
+	edma_writel(edma, le32_to_cpu(tcd->saddr), addr + EDMA_TCD_SADDR(ch));
+	edma_writel(edma, le32_to_cpu(tcd->daddr), addr + EDMA_TCD_DADDR(ch));
+
+	edma_writew(edma, le16_to_cpu(tcd->attr), addr + EDMA_TCD_ATTR(ch));
+	edma_writew(edma, le16_to_cpu(tcd->soff), addr + EDMA_TCD_SOFF(ch));
+
+	edma_writel(edma, le32_to_cpu(tcd->nbytes), addr + EDMA_TCD_NBYTES(ch));
+	edma_writel(edma, le32_to_cpu(tcd->slast), addr + EDMA_TCD_SLAST(ch));
+
+	edma_writew(edma, le16_to_cpu(tcd->citer), addr + EDMA_TCD_CITER(ch));
+	edma_writew(edma, le16_to_cpu(tcd->biter), addr + EDMA_TCD_BITER(ch));
+	edma_writew(edma, le16_to_cpu(tcd->doff), addr + EDMA_TCD_DOFF(ch));
+
+	edma_writel(edma, le32_to_cpu(tcd->dlast_sga), addr + EDMA_TCD_DLAST_SGA(ch));
+
+	edma_writew(edma, le16_to_cpu(tcd->csr), addr + EDMA_TCD_CSR(ch));
+}
+
+static inline
+void fsl_edma_fill_tcd(struct fsl_edma_hw_tcd *tcd, u32 src, u32 dst,
+		       u16 attr, u16 soff, u32 nbytes, u32 slast, u16 citer,
+		       u16 biter, u16 doff, u32 dlast_sga, bool major_int,
+		       bool disable_req, bool enable_sg)
 {
 	u16 csr = 0;
 
 	/*
-	 * eDMA hardware SGs require the TCD parameters stored in memory
-	 * the same endian as the eDMA module so that they can be loaded
-	 * automatically by the engine
+	 * eDMA hardware SGs require the TCDs to be stored in little
+	 * endian format irrespective of the register endian model.
+	 * So we put the value in little endian in memory, waiting
+	 * for fsl_edma_set_tcd_regs doing the swap.
 	 */
-	edma_writel(edma, src, &(tcd->saddr));
-	edma_writel(edma, dst, &(tcd->daddr));
-	edma_writew(edma, attr, &(tcd->attr));
-	edma_writew(edma, EDMA_TCD_SOFF_SOFF(soff), &(tcd->soff));
-	edma_writel(edma, EDMA_TCD_NBYTES_NBYTES(nbytes), &(tcd->nbytes));
-	edma_writel(edma, EDMA_TCD_SLAST_SLAST(slast), &(tcd->slast));
-	edma_writew(edma, EDMA_TCD_CITER_CITER(citer), &(tcd->citer));
-	edma_writew(edma, EDMA_TCD_DOFF_DOFF(doff), &(tcd->doff));
-	edma_writel(edma, EDMA_TCD_DLAST_SGA_DLAST_SGA(dlast_sga), &(tcd->dlast_sga));
-	edma_writew(edma, EDMA_TCD_BITER_BITER(biter), &(tcd->biter));
+	tcd->saddr = cpu_to_le32(src);
+	tcd->daddr = cpu_to_le32(dst);
+
+	tcd->attr = cpu_to_le16(attr);
+
+	tcd->soff = cpu_to_le16(EDMA_TCD_SOFF_SOFF(soff));
+
+	tcd->nbytes = cpu_to_le32(EDMA_TCD_NBYTES_NBYTES(nbytes));
+	tcd->slast = cpu_to_le32(EDMA_TCD_SLAST_SLAST(slast));
+
+	tcd->citer = cpu_to_le16(EDMA_TCD_CITER_CITER(citer));
+	tcd->doff = cpu_to_le16(EDMA_TCD_DOFF_DOFF(doff));
+
+	tcd->dlast_sga = cpu_to_le32(EDMA_TCD_DLAST_SGA_DLAST_SGA(dlast_sga));
+
+	tcd->biter = cpu_to_le16(EDMA_TCD_BITER_BITER(biter));
 	if (major_int)
 		csr |= EDMA_TCD_CSR_INT_MAJOR;
 
@@ -482,7 +489,7 @@ static void fill_tcd_params(struct fsl_edma_engine *edma,
 	if (enable_sg)
 		csr |= EDMA_TCD_CSR_E_SG;
 
-	edma_writew(edma, csr, &(tcd->csr));
+	tcd->csr = cpu_to_le16(csr);
 }
 
 static struct fsl_edma_desc *fsl_edma_alloc_desc(struct fsl_edma_chan *fsl_chan,
@@ -558,9 +565,9 @@ static struct dma_async_tx_descriptor *fsl_edma_prep_dma_cyclic(
 			doff = fsl_chan->fsc.addr_width;
 		}
 
-		fill_tcd_params(fsl_chan->edma, fsl_desc->tcd[i].vtcd, src_addr,
-				dst_addr, fsl_chan->fsc.attr, soff, nbytes, 0,
-				iter, iter, doff, last_sg, true, false, true);
+		fsl_edma_fill_tcd(fsl_desc->tcd[i].vtcd, src_addr, dst_addr,
+				  fsl_chan->fsc.attr, soff, nbytes, 0, iter,
+				  iter, doff, last_sg, true, false, true);
 		dma_buf_next += period_len;
 	}
 
@@ -607,16 +614,16 @@ static struct dma_async_tx_descriptor *fsl_edma_prep_slave_sg(
 		iter = sg_dma_len(sg) / nbytes;
 		if (i < sg_len - 1) {
 			last_sg = fsl_desc->tcd[(i + 1)].ptcd;
-			fill_tcd_params(fsl_chan->edma, fsl_desc->tcd[i].vtcd,
-					src_addr, dst_addr, fsl_chan->fsc.attr,
-					soff, nbytes, 0, iter, iter, doff, last_sg,
-					false, false, true);
+			fsl_edma_fill_tcd(fsl_desc->tcd[i].vtcd, src_addr,
+					  dst_addr, fsl_chan->fsc.attr, soff,
+					  nbytes, 0, iter, iter, doff, last_sg,
+					  false, false, true);
 		} else {
 			last_sg = 0;
-			fill_tcd_params(fsl_chan->edma, fsl_desc->tcd[i].vtcd,
-					src_addr, dst_addr, fsl_chan->fsc.attr,
-					soff, nbytes, 0, iter, iter, doff, last_sg,
-					true, true, false);
+			fsl_edma_fill_tcd(fsl_desc->tcd[i].vtcd, src_addr,
+					  dst_addr, fsl_chan->fsc.attr, soff,
+					  nbytes, 0, iter, iter, doff, last_sg,
+					  true, true, false);
 		}
 	}
 
@@ -625,17 +632,13 @@ static struct dma_async_tx_descriptor *fsl_edma_prep_slave_sg(
 
 static void fsl_edma_xfer_desc(struct fsl_edma_chan *fsl_chan)
 {
-	struct fsl_edma_hw_tcd *tcd;
 	struct virt_dma_desc *vdesc;
 
 	vdesc = vchan_next_desc(&fsl_chan->vchan);
 	if (!vdesc)
 		return;
 	fsl_chan->edesc = to_fsl_edma_desc(vdesc);
-	tcd = fsl_chan->edesc->tcd[0].vtcd;
-	fsl_edma_set_tcd_params(fsl_chan, tcd->saddr, tcd->daddr, tcd->attr,
-			tcd->soff, tcd->nbytes, tcd->slast, tcd->citer,
-			tcd->biter, tcd->doff, tcd->dlast_sga, tcd->csr);
+	fsl_edma_set_tcd_regs(fsl_chan, fsl_chan->edesc->tcd[0].vtcd);
 	fsl_edma_enable_request(fsl_chan);
 	fsl_chan->status = DMA_IN_PROGRESS;
 }
-- 
1.8.0

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