dmaengine: dw-edma: Join read/write channels into a single device

There is no point in splitting read/write channels.  First of all, eDMA
read and write channels belong to one physical controller. Secondly,
channel differentiation can be done by filtering and dma_get_slave_caps().
Finally, having these channels handled separately needlessly complicates
the code and causes this debugfs warning:

  debugfs: Directory '1f052000.pcie' with parent 'dmaengine' already present!

Join the read/write channels into a single DMA device.  Client drivers can
choose the correct channel via the DMA slave direction setting. The default
value is overridden by the dw_edma_device_caps() callback in accordance
with the channel type.

Link: https://lore.kernel.org/r/20230113171409.30470-18-Sergey.Semin@baikalelectronics.ru
Tested-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Acked-by: Vinod Koul <vkoul@kernel.org>

2 files changed, 61 insertions, 60 deletions

diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
index ecd3e8f7ac5d..c3ecae4287d0 100644
--- a/drivers/dma/dw-edma/dw-edma-core.c
+++ b/drivers/dma/dw-edma/dw-edma-core.c
@@ -208,6 +208,24 @@ static void dw_edma_start_transfer(struct dw_edma_chan *chan)
 	desc->chunks_alloc--;
 }
 
+static void dw_edma_device_caps(struct dma_chan *dchan,
+				struct dma_slave_caps *caps)
+{
+	struct dw_edma_chan *chan = dchan2dw_edma_chan(dchan);
+
+	if (chan->dw->chip->flags & DW_EDMA_CHIP_LOCAL) {
+		if (chan->dir == EDMA_DIR_READ)
+			caps->directions = BIT(DMA_DEV_TO_MEM);
+		else
+			caps->directions = BIT(DMA_MEM_TO_DEV);
+	} else {
+		if (chan->dir == EDMA_DIR_WRITE)
+			caps->directions = BIT(DMA_DEV_TO_MEM);
+		else
+			caps->directions = BIT(DMA_MEM_TO_DEV);
+	}
+}
+
 static int dw_edma_device_config(struct dma_chan *dchan,
 				 struct dma_slave_config *config)
 {
@@ -717,8 +735,7 @@ static void dw_edma_free_chan_resources(struct dma_chan *dchan)
 	}
 }
 
-static int dw_edma_channel_setup(struct dw_edma *dw, bool write,
-				 u32 wr_alloc, u32 rd_alloc)
+static int dw_edma_channel_setup(struct dw_edma *dw, u32 wr_alloc, u32 rd_alloc)
 {
 	struct dw_edma_chip *chip = dw->chip;
 	struct dw_edma_region *dt_region;
@@ -726,27 +743,15 @@ static int dw_edma_channel_setup(struct dw_edma *dw, bool write,
 	struct dw_edma_chan *chan;
 	struct dw_edma_irq *irq;
 	struct dma_device *dma;
-	u32 alloc, off_alloc;
-	u32 i, j, cnt;
-	int err = 0;
+	u32 i, ch_cnt;
 	u32 pos;
 
-	if (write) {
-		i = 0;
-		cnt = dw->wr_ch_cnt;
-		dma = &dw->wr_edma;
-		alloc = wr_alloc;
-		off_alloc = 0;
-	} else {
-		i = dw->wr_ch_cnt;
-		cnt = dw->rd_ch_cnt;
-		dma = &dw->rd_edma;
-		alloc = rd_alloc;
-		off_alloc = wr_alloc;
-	}
+	ch_cnt = dw->wr_ch_cnt + dw->rd_ch_cnt;
+	dma = &dw->dma;
 
 	INIT_LIST_HEAD(&dma->channels);
-	for (j = 0; (alloc || dw->nr_irqs == 1) && j < cnt; j++, i++) {
+
+	for (i = 0; i < ch_cnt; i++) {
 		chan = &dw->chan[i];
 
 		dt_region = devm_kzalloc(dev, sizeof(*dt_region), GFP_KERNEL);
@@ -756,52 +761,62 @@ static int dw_edma_channel_setup(struct dw_edma *dw, bool write,
 		chan->vc.chan.private = dt_region;
 
 		chan->dw = dw;
-		chan->id = j;
-		chan->dir = write ? EDMA_DIR_WRITE : EDMA_DIR_READ;
+
+		if (i < dw->wr_ch_cnt) {
+			chan->id = i;
+			chan->dir = EDMA_DIR_WRITE;
+		} else {
+			chan->id = i - dw->wr_ch_cnt;
+			chan->dir = EDMA_DIR_READ;
+		}
+
 		chan->configured = false;
 		chan->request = EDMA_REQ_NONE;
 		chan->status = EDMA_ST_IDLE;
 
-		if (write)
-			chan->ll_max = (chip->ll_region_wr[j].sz / EDMA_LL_SZ);
+		if (chan->dir == EDMA_DIR_WRITE)
+			chan->ll_max = (chip->ll_region_wr[chan->id].sz / EDMA_LL_SZ);
 		else
-			chan->ll_max = (chip->ll_region_rd[j].sz / EDMA_LL_SZ);
+			chan->ll_max = (chip->ll_region_rd[chan->id].sz / EDMA_LL_SZ);
 		chan->ll_max -= 1;
 
 		dev_vdbg(dev, "L. List:\tChannel %s[%u] max_cnt=%u\n",
-			 write ? "write" : "read", j, chan->ll_max);
+			 chan->dir == EDMA_DIR_WRITE ? "write" : "read",
+			 chan->id, chan->ll_max);
 
 		if (dw->nr_irqs == 1)
 			pos = 0;
+		else if (chan->dir == EDMA_DIR_WRITE)
+			pos = chan->id % wr_alloc;
 		else
-			pos = off_alloc + (j % alloc);
+			pos = wr_alloc + chan->id % rd_alloc;
 
 		irq = &dw->irq[pos];
 
-		if (write)
-			irq->wr_mask |= BIT(j);
+		if (chan->dir == EDMA_DIR_WRITE)
+			irq->wr_mask |= BIT(chan->id);
 		else
-			irq->rd_mask |= BIT(j);
+			irq->rd_mask |= BIT(chan->id);
 
 		irq->dw = dw;
 		memcpy(&chan->msi, &irq->msi, sizeof(chan->msi));
 
 		dev_vdbg(dev, "MSI:\t\tChannel %s[%u] addr=0x%.8x%.8x, data=0x%.8x\n",
-			 write ? "write" : "read", j,
+			 chan->dir == EDMA_DIR_WRITE  ? "write" : "read", chan->id,
 			 chan->msi.address_hi, chan->msi.address_lo,
 			 chan->msi.data);
 
 		chan->vc.desc_free = vchan_free_desc;
 		vchan_init(&chan->vc, dma);
 
-		if (write) {
-			dt_region->paddr = chip->dt_region_wr[j].paddr;
-			dt_region->vaddr = chip->dt_region_wr[j].vaddr;
-			dt_region->sz = chip->dt_region_wr[j].sz;
+		if (chan->dir == EDMA_DIR_WRITE) {
+			dt_region->paddr = chip->dt_region_wr[chan->id].paddr;
+			dt_region->vaddr = chip->dt_region_wr[chan->id].vaddr;
+			dt_region->sz = chip->dt_region_wr[chan->id].sz;
 		} else {
-			dt_region->paddr = chip->dt_region_rd[j].paddr;
-			dt_region->vaddr = chip->dt_region_rd[j].vaddr;
-			dt_region->sz = chip->dt_region_rd[j].sz;
+			dt_region->paddr = chip->dt_region_rd[chan->id].paddr;
+			dt_region->vaddr = chip->dt_region_rd[chan->id].vaddr;
+			dt_region->sz = chip->dt_region_rd[chan->id].sz;
 		}
 
 		dw_edma_v0_core_device_config(chan);
@@ -813,7 +828,7 @@ static int dw_edma_channel_setup(struct dw_edma *dw, bool write,
 	dma_cap_set(DMA_CYCLIC, dma->cap_mask);
 	dma_cap_set(DMA_PRIVATE, dma->cap_mask);
 	dma_cap_set(DMA_INTERLEAVE, dma->cap_mask);
-	dma->directions = BIT(write ? DMA_DEV_TO_MEM : DMA_MEM_TO_DEV);
+	dma->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
 	dma->src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
 	dma->dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
 	dma->residue_granularity = DMA_RESIDUE_GRANULARITY_DESCRIPTOR;
@@ -822,6 +837,7 @@ static int dw_edma_channel_setup(struct dw_edma *dw, bool write,
 	dma->dev = chip->dev;
 	dma->device_alloc_chan_resources = dw_edma_alloc_chan_resources;
 	dma->device_free_chan_resources = dw_edma_free_chan_resources;
+	dma->device_caps = dw_edma_device_caps;
 	dma->device_config = dw_edma_device_config;
 	dma->device_pause = dw_edma_device_pause;
 	dma->device_resume = dw_edma_device_resume;
@@ -835,9 +851,7 @@ static int dw_edma_channel_setup(struct dw_edma *dw, bool write,
 	dma_set_max_seg_size(dma->dev, U32_MAX);
 
 	/* Register DMA device */
-	err = dma_async_device_register(dma);
-
-	return err;
+	return dma_async_device_register(dma);
 }
 
 static inline void dw_edma_dec_irq_alloc(int *nr_irqs, u32 *alloc, u16 cnt)
@@ -982,13 +996,8 @@ int dw_edma_probe(struct dw_edma_chip *chip)
 	if (err)
 		return err;
 
-	/* Setup write channels */
-	err = dw_edma_channel_setup(dw, true, wr_alloc, rd_alloc);
-	if (err)
-		goto err_irq_free;
-
-	/* Setup read channels */
-	err = dw_edma_channel_setup(dw, false, wr_alloc, rd_alloc);
+	/* Setup write/read channels */
+	err = dw_edma_channel_setup(dw, wr_alloc, rd_alloc);
 	if (err)
 		goto err_irq_free;
 
@@ -1022,15 +1031,8 @@ int dw_edma_remove(struct dw_edma_chip *chip)
 		free_irq(chip->ops->irq_vector(dev, i), &dw->irq[i]);
 
 	/* Deregister eDMA device */
-	dma_async_device_unregister(&dw->wr_edma);
-	list_for_each_entry_safe(chan, _chan, &dw->wr_edma.channels,
-				 vc.chan.device_node) {
-		tasklet_kill(&chan->vc.task);
-		list_del(&chan->vc.chan.device_node);
-	}
-
-	dma_async_device_unregister(&dw->rd_edma);
-	list_for_each_entry_safe(chan, _chan, &dw->rd_edma.channels,
+	dma_async_device_unregister(&dw->dma);
+	list_for_each_entry_safe(chan, _chan, &dw->dma.channels,
 				 vc.chan.device_node) {
 		tasklet_kill(&chan->vc.task);
 		list_del(&chan->vc.chan.device_node);
diff --git a/drivers/dma/dw-edma/dw-edma-core.h b/drivers/dma/dw-edma/dw-edma-core.h
index 85df2d511907..b576a8fff45a 100644
--- a/drivers/dma/dw-edma/dw-edma-core.h
+++ b/drivers/dma/dw-edma/dw-edma-core.h
@@ -98,10 +98,9 @@ struct dw_edma_irq {
 struct dw_edma {
 	char				name[20];
 
-	struct dma_device		wr_edma;
-	u16				wr_ch_cnt;
+	struct dma_device		dma;
 
-	struct dma_device		rd_edma;
+	u16				wr_ch_cnt;
 	u16				rd_ch_cnt;
 
 	struct dw_edma_irq		*irq;