linux-kernel - [PATCH 1/5] dmaengine: xilinx: xdma: Add transfer termination callbacks

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Date:   Wed, 22 Nov 2023 23:09:17 +0100
From:   Jan Kuliga <jankul@...tek.krakow.pl>
To:     lizhi.hou@....com, brian.xu@....com, raj.kumar.rampelli@....com,
        vkoul@...nel.org, michal.simek@....com, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Jan Kuliga <jankul@...tek.krakow.pl>
Subject: [PATCH 1/5] dmaengine: xilinx: xdma: Add transfer termination callbacks

The xdma driver currently doesn't implement proper transfer termination
callbacks. Therefore, there is no way to gracefully terminate the
on-going DMA transactions. That is particularly useful for cyclic DMA
transfers. Implement these callbacks.

Signed-off-by: Jan Kuliga <jankul@...tek.krakow.pl>
---
 drivers/dma/xilinx/xdma-regs.h |  1 +
 drivers/dma/xilinx/xdma.c      | 55 ++++++++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+)

diff --git a/drivers/dma/xilinx/xdma-regs.h b/drivers/dma/xilinx/xdma-regs.h
index e641a5083e14..1f17ce165f92 100644
--- a/drivers/dma/xilinx/xdma-regs.h
+++ b/drivers/dma/xilinx/xdma-regs.h
@@ -76,6 +76,7 @@ struct xdma_hw_desc {
 #define XDMA_CHAN_CONTROL_W1S		0x8
 #define XDMA_CHAN_CONTROL_W1C		0xc
 #define XDMA_CHAN_STATUS		0x40
+#define XDMA_CHAN_STATUS_RC		0x44
 #define XDMA_CHAN_COMPLETED_DESC	0x48
 #define XDMA_CHAN_ALIGNMENTS		0x4c
 #define XDMA_CHAN_INTR_ENABLE		0x90
diff --git a/drivers/dma/xilinx/xdma.c b/drivers/dma/xilinx/xdma.c
index 84a88029226f..58539a093de2 100644
--- a/drivers/dma/xilinx/xdma.c
+++ b/drivers/dma/xilinx/xdma.c
@@ -632,6 +632,59 @@ xdma_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t address,
 	return NULL;
 }
 
+/**
+ * xdma_terminate_all - Halt the DMA channel
+ * @chan: DMA channel
+ */
+static int xdma_terminate_all(struct dma_chan *chan)
+{
+	int ret;
+	u32 val;
+	unsigned long flags;
+	struct xdma_chan *xchan = to_xdma_chan(chan);
+	struct xdma_device *xdev = xchan->xdev_hdl;
+	struct virt_dma_desc *vd;
+	LIST_HEAD(head);
+
+	/* Clear the RUN bit to stop the transfer */
+	ret = regmap_write(xdev->rmap, xchan->base + XDMA_CHAN_CONTROL_W1C,
+							CHAN_CTRL_RUN_STOP);
+	if (ret)
+		return ret;
+
+	/* Clear the channel status register */
+	ret = regmap_read(xdev->rmap, xchan->base + XDMA_CHAN_STATUS_RC, &val);
+	if (ret)
+		return ret;
+
+	spin_lock_irqsave(&xchan->vchan.lock, flags);
+
+	/* Don't care if there were no descriptors issued */
+	vd = vchan_next_desc(&xchan->vchan);
+	if (vd) {
+		list_del(&vd->node);
+		vchan_terminate_vdesc(vd);
+	}
+	vchan_get_all_descriptors(&xchan->vchan, &head);
+	list_splice_tail_init(&head, &xchan->vchan.desc_terminated);
+
+	xchan->busy = false;
+	spin_unlock_irqrestore(&xchan->vchan.lock, flags);
+
+	return 0;
+}
+
+/**
+ * xdma_synchronize - Synchronize current execution context to the DMA channel
+ * @chan: DMA channel
+ */
+static void xdma_synchronize(struct dma_chan *chan)
+{
+	struct xdma_chan *xchan = to_xdma_chan(chan);
+
+	vchan_synchronize(&xchan->vchan);
+}
+
 /**
  * xdma_device_config - Configure the DMA channel
  * @chan: DMA channel
@@ -1093,6 +1146,8 @@ static int xdma_probe(struct platform_device *pdev)
 	xdev->dma_dev.filter.mapcnt = pdata->device_map_cnt;
 	xdev->dma_dev.filter.fn = xdma_filter_fn;
 	xdev->dma_dev.device_prep_dma_cyclic = xdma_prep_dma_cyclic;
+	xdev->dma_dev.device_terminate_all = xdma_terminate_all;
+	xdev->dma_dev.device_synchronize = xdma_synchronize;
 
 	ret = dma_async_device_register(&xdev->dma_dev);
 	if (ret) {
-- 
2.34.1