[PATCH v2 0/2] dmaengine: add UniPhier MIO DMAC driver

[PATCH v2 0/2] dmaengine: add UniPhier MIO DMAC driver

[Masahiro Yamada]

1/2: DT-binding
2/2: driver


Masahiro Yamada (2):
  dt-bindings: dmaengine: add DT binding for UniPhier MIO DMAC
  dmaengine: uniphier-mdmac: add UniPhier MIO DMAC driver

 .../devicetree/bindings/dma/uniphier-mio-dmac.txt  |  25 ++
 MAINTAINERS                                        |   1 +
 drivers/dma/Kconfig                                |  11 +
 drivers/dma/Makefile                               |   1 +
 drivers/dma/uniphier-mdmac.c                       | 481 +++++++++++++++++++++
 5 files changed, 519 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/dma/uniphier-mio-dmac.txt
 create mode 100644 drivers/dma/uniphier-mdmac.c

-- 
2.7.4

[PATCH v2 1/2] dt-bindings: dmaengine: add DT binding for UniPhier MIO DMAC

[Masahiro Yamada]

The MIO DMAC (Media IO DMA Controller) is used in UniPhier LD4,
Pro4, and sLD8 SoCs.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

Changes in v2:
 - Rename the node "dmac" to "dma-controller"
 - Remove dma-channels property

 .../devicetree/bindings/dma/uniphier-mio-dmac.txt  | 25 ++++++++++++++++++++++
 1 file changed, 25 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/dma/uniphier-mio-dmac.txt

diff --git a/Documentation/devicetree/bindings/dma/uniphier-mio-dmac.txt b/Documentation/devicetree/bindings/dma/uniphier-mio-dmac.txt
new file mode 100644
index 0000000..b12388d
--- /dev/null
+++ b/Documentation/devicetree/bindings/dma/uniphier-mio-dmac.txt
@@ -0,0 +1,25 @@
+UniPhier Media IO DMA controller
+
+This works as an external DMA engine for SD/eMMC controllers etc.
+found in UniPhier LD4, Pro4, sLD8 SoCs.
+
+Required properties:
+- compatible: should be "socionext,uniphier-mio-dmac".
+- reg: offset and length of the register set for the device.
+- interrupts: a list of interrupt specifiers associated with the DMA channels.
+- clocks: a single clock specifier.
+- #dma-cells: should be <1>. The single cell represents the channel index.
+
+Example:
+	dmac: dma-controller@5a000000 {
+		compatible = "socionext,uniphier-mio-dmac";
+		reg = <0x5a000000 0x1000>;
+		interrupts = <0 68 4>, <0 68 4>, <0 69 4>, <0 70 4>,
+			     <0 71 4>, <0 72 4>, <0 73 4>, <0 74 4>;
+		clocks = <&mio_clk 7>;
+		#dma-cells = <1>;
+	};
+
+Note:
+In the example above, "interrupts = <0 68 4>, <0 68 4>, ..." is not a typo.
+The first two channels share a single interrupt line.
-- 
2.7.4

Re: [PATCH v2 1/2] dt-bindings: dmaengine: add DT binding for UniPhier MIO DMAC

[Rob Herring]

On Fri, 24 Aug 2018 10:41:12 +0900, Masahiro Yamada wrote:
> The MIO DMAC (Media IO DMA Controller) is used in UniPhier LD4,
> Pro4, and sLD8 SoCs.
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> ---
> 
> Changes in v2:
>  - Rename the node "dmac" to "dma-controller"
>  - Remove dma-channels property
> 
>  .../devicetree/bindings/dma/uniphier-mio-dmac.txt  | 25 ++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/dma/uniphier-mio-dmac.txt
> 

Reviewed-by: Rob Herring <robh@kernel.org>

[PATCH v2 2/2] dmaengine: uniphier-mdmac: add UniPhier MIO DMAC driver

[Masahiro Yamada]

The MIO DMAC (Media IO DMA Controller) is used in UniPhier LD4,
Pro4, and sLD8 SoCs.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

Changes in v2:
 - Use platform_irq_count() to get the number of channels

 MAINTAINERS                  |   1 +
 drivers/dma/Kconfig          |  11 +
 drivers/dma/Makefile         |   1 +
 drivers/dma/uniphier-mdmac.c | 481 +++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 494 insertions(+)
 create mode 100644 drivers/dma/uniphier-mdmac.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 994b157..83ba996 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2193,6 +2193,7 @@ F:	arch/arm/mm/cache-uniphier.c
 F:	arch/arm64/boot/dts/socionext/uniphier*
 F:	drivers/bus/uniphier-system-bus.c
 F:	drivers/clk/uniphier/
+F:	drivers/dmaengine/uniphier-mdmac.c
 F:	drivers/gpio/gpio-uniphier.c
 F:	drivers/i2c/busses/i2c-uniphier*
 F:	drivers/irqchip/irq-uniphier-aidet.c
diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index dacf3f4..8b8c7f0 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -576,6 +576,17 @@ config TIMB_DMA
 	help
 	  Enable support for the Timberdale FPGA DMA engine.
 
+config UNIPHIER_MDMAC
+	tristate "UniPhier MIO DMAC"
+	depends on ARCH_UNIPHIER || COMPILE_TEST
+	depends on OF
+	select DMA_ENGINE
+	select DMA_VIRTUAL_CHANNELS
+	help
+	  Enable support for the MIO DMAC (Media I/O DMA controller) on the
+	  UniPhier platform.  This DMA controller is used as the external
+	  DMA engine of the SD/eMMC controllers of the LD4, Pro4, sLD8 SoCs.
+
 config XGENE_DMA
 	tristate "APM X-Gene DMA support"
 	depends on ARCH_XGENE || COMPILE_TEST
diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
index c91702d..973a170 100644
--- a/drivers/dma/Makefile
+++ b/drivers/dma/Makefile
@@ -69,6 +69,7 @@ obj-$(CONFIG_TXX9_DMAC) += txx9dmac.o
 obj-$(CONFIG_TEGRA20_APB_DMA) += tegra20-apb-dma.o
 obj-$(CONFIG_TEGRA210_ADMA) += tegra210-adma.o
 obj-$(CONFIG_TIMB_DMA) += timb_dma.o
+obj-$(CONFIG_UNIPHIER_MDMAC) += uniphier-mdmac.o
 obj-$(CONFIG_XGENE_DMA) += xgene-dma.o
 obj-$(CONFIG_ZX_DMA) += zx_dma.o
 obj-$(CONFIG_ST_FDMA) += st_fdma.o
diff --git a/drivers/dma/uniphier-mdmac.c b/drivers/dma/uniphier-mdmac.c
new file mode 100644
index 0000000..e4db0a7
--- /dev/null
+++ b/drivers/dma/uniphier-mdmac.c
@@ -0,0 +1,481 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright (C) 2018 Socionext Inc.
+//   Author: Masahiro Yamada <yamada.masahiro@socionext.com>
+
+#include <linux/clk.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/interrupt.h>
+#include <linux/iopoll.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_dma.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#include "virt-dma.h"
+
+/* registers common for all channels */
+#define UNIPHIER_MDMAC_CMD		0x000	// issue DMA start/abort
+#define   UNIPHIER_MDMAC_CMD_ABORT		BIT(31) // 1: abort, 0: start
+
+/* per-channel registers */
+#define UNIPHIER_MDMAC_CH_OFFSET	0x100
+#define UNIPHIER_MDMAC_CH_STRIDE	0x040
+
+#define UNIPHIER_MDMAC_CH_IRQ_STAT	0x010	// current hw status (RO)
+#define UNIPHIER_MDMAC_CH_IRQ_REQ	0x014	// latched STAT (WOC)
+#define UNIPHIER_MDMAC_CH_IRQ_EN	0x018	// IRQ enable mask
+#define UNIPHIER_MDMAC_CH_IRQ_DET	0x01c	// REQ & EN (RO)
+#define   UNIPHIER_MDMAC_CH_IRQ__ABORT		BIT(13)
+#define   UNIPHIER_MDMAC_CH_IRQ__DONE		BIT(1)
+#define UNIPHIER_MDMAC_CH_SRC_MODE	0x020	// mode of source
+#define UNIPHIER_MDMAC_CH_DEST_MODE	0x024	// mode of destination
+#define   UNIPHIER_MDMAC_CH_MODE__ADDR_INC	(0 << 4)
+#define   UNIPHIER_MDMAC_CH_MODE__ADDR_DEC	(1 << 4)
+#define   UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED	(2 << 4)
+#define UNIPHIER_MDMAC_CH_SRC_ADDR	0x028	// source address
+#define UNIPHIER_MDMAC_CH_DEST_ADDR	0x02c	// destination address
+#define UNIPHIER_MDMAC_CH_SIZE		0x030	// transfer bytes
+
+struct uniphier_mdmac_desc {
+	struct virt_dma_desc vd;
+	struct scatterlist *sgl;
+	unsigned int sg_len;
+	unsigned int sg_cur;
+	enum dma_transfer_direction dir;
+};
+
+struct uniphier_mdmac_chan {
+	struct virt_dma_chan vc;
+	struct uniphier_mdmac_device *mdev;
+	struct uniphier_mdmac_desc *md;
+	void __iomem *reg_ch_base;
+	unsigned int chan_id;
+};
+
+struct uniphier_mdmac_device {
+	struct dma_device ddev;
+	struct clk *clk;
+	void __iomem *reg_base;
+	struct uniphier_mdmac_chan channels[0];
+};
+
+static struct uniphier_mdmac_chan *to_uniphier_mdmac_chan(
+						struct virt_dma_chan *vc)
+{
+	return container_of(vc, struct uniphier_mdmac_chan, vc);
+}
+
+static struct uniphier_mdmac_desc *to_uniphier_mdmac_desc(
+						struct virt_dma_desc *vd)
+{
+	return container_of(vd, struct uniphier_mdmac_desc, vd);
+}
+
+/* mc->vc.lock must be held by caller */
+static struct uniphier_mdmac_desc *__uniphier_mdmac_next_desc(
+						struct uniphier_mdmac_chan *mc)
+{
+	struct virt_dma_desc *vd;
+
+	vd = vchan_next_desc(&mc->vc);
+	if (!vd) {
+		mc->md = NULL;
+		return NULL;
+	}
+
+	list_del(&vd->node);
+
+	mc->md = to_uniphier_mdmac_desc(vd);
+
+	return mc->md;
+}
+
+/* mc->vc.lock must be held by caller */
+static void __uniphier_mdmac_handle(struct uniphier_mdmac_chan *mc,
+				    struct uniphier_mdmac_desc *md)
+{
+	struct uniphier_mdmac_device *mdev = mc->mdev;
+	struct scatterlist *sg;
+	u32 irq_flag = UNIPHIER_MDMAC_CH_IRQ__DONE;
+	u32 src_mode, src_addr, dest_mode, dest_addr, chunk_size;
+
+	sg = &md->sgl[md->sg_cur];
+
+	if (md->dir == DMA_MEM_TO_DEV) {
+		src_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_INC;
+		src_addr = sg_dma_address(sg);
+		dest_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED;
+		dest_addr = 0;
+	} else {
+		src_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED;
+		src_addr = 0;
+		dest_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_INC;
+		dest_addr = sg_dma_address(sg);
+	}
+
+	chunk_size = sg_dma_len(sg);
+
+	writel(src_mode, mc->reg_ch_base + UNIPHIER_MDMAC_CH_SRC_MODE);
+	writel(dest_mode, mc->reg_ch_base + UNIPHIER_MDMAC_CH_DEST_MODE);
+	writel(src_addr, mc->reg_ch_base + UNIPHIER_MDMAC_CH_SRC_ADDR);
+	writel(dest_addr, mc->reg_ch_base + UNIPHIER_MDMAC_CH_DEST_ADDR);
+	writel(chunk_size, mc->reg_ch_base + UNIPHIER_MDMAC_CH_SIZE);
+
+	/* write 1 to clear */
+	writel(irq_flag, mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_REQ);
+
+	writel(irq_flag, mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_EN);
+
+	writel(BIT(mc->chan_id), mdev->reg_base + UNIPHIER_MDMAC_CMD);
+}
+
+/* mc->vc.lock must be held by caller */
+static void __uniphier_mdmac_start(struct uniphier_mdmac_chan *mc)
+{
+	struct uniphier_mdmac_desc *md;
+
+	md = __uniphier_mdmac_next_desc(mc);
+	if (md)
+		__uniphier_mdmac_handle(mc, md);
+}
+
+/* mc->vc.lock must be held by caller */
+static int __uniphier_mdmac_abort(struct uniphier_mdmac_chan *mc)
+{
+	struct uniphier_mdmac_device *mdev = mc->mdev;
+	u32 irq_flag = UNIPHIER_MDMAC_CH_IRQ__ABORT;
+	u32 val;
+
+	/* write 1 to clear */
+	writel(irq_flag, mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_REQ);
+
+	writel(UNIPHIER_MDMAC_CMD_ABORT | BIT(mc->chan_id),
+	       mdev->reg_base + UNIPHIER_MDMAC_CMD);
+
+	/*
+	 * Abort should be accepted soon. We poll the bit here instead of
+	 * waiting for the interrupt.
+	 */
+	return readl_poll_timeout(mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_REQ,
+				  val, val & irq_flag, 0, 20);
+}
+
+/* mc->vc.lock must be held by caller */
+static u32 __uniphier_mdmac_get_residue(struct uniphier_mdmac_desc *md)
+{
+	u32 residue = 0;
+	int i;
+
+	for (i = md->sg_cur; i < md->sg_len; i++)
+		residue += sg_dma_len(&md->sgl[i]);
+
+	return residue;
+}
+
+static irqreturn_t uniphier_mdmac_interrupt(int irq, void *dev_id)
+{
+	struct uniphier_mdmac_chan *mc = dev_id;
+	struct uniphier_mdmac_desc *md;
+	irqreturn_t ret = IRQ_HANDLED;
+	u32 irq_stat;
+
+	spin_lock(&mc->vc.lock);
+
+	irq_stat = readl(mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_DET);
+
+	/*
+	 * Some channels share a single interrupt line. If the IRQ status is 0,
+	 * this is probably triggered by a different channel.
+	 */
+	if (!irq_stat) {
+		ret = IRQ_NONE;
+		goto out;
+	}
+
+	/* write 1 to clear */
+	writel(irq_stat, mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_REQ);
+
+	/*
+	 * UNIPHIER_MDMAC_CH_IRQ__DONE interrupt is asserted even when the DMA
+	 * is aborted.  To distinguish the normal completion and the abort,
+	 * check mc->md.  If it is NULL, we are aborting.
+	 */
+	md = mc->md;
+	if (!md)
+		goto out;
+
+	md->sg_cur++;
+
+	if (md->sg_cur >= md->sg_len) {
+		vchan_cookie_complete(&md->vd);
+		md = __uniphier_mdmac_next_desc(mc);
+		if (!md)
+			goto out;
+	}
+
+	__uniphier_mdmac_handle(mc, md);
+
+out:
+	spin_unlock(&mc->vc.lock);
+
+	return ret;
+}
+
+static struct dma_async_tx_descriptor *uniphier_mdmac_prep_slave_sg(
+					struct dma_chan *chan,
+					struct scatterlist *sgl,
+					unsigned int sg_len,
+					enum dma_transfer_direction direction,
+					unsigned long flags, void *context)
+{
+	struct virt_dma_chan *vc = to_virt_chan(chan);
+	struct uniphier_mdmac_desc *md;
+
+	if (!is_slave_direction(direction))
+		return NULL;
+
+	md = kzalloc(sizeof(*md), GFP_KERNEL);
+	if (!md)
+		return NULL;
+
+	md->sgl = sgl;
+	md->sg_len = sg_len;
+	md->dir = direction;
+
+	return vchan_tx_prep(vc, &md->vd, flags);
+}
+
+static int uniphier_mdmac_terminate_all(struct dma_chan *chan)
+{
+	struct virt_dma_chan *vc = to_virt_chan(chan);
+	struct uniphier_mdmac_chan *mc = to_uniphier_mdmac_chan(vc);
+	unsigned long flags;
+	int ret = 0;
+	LIST_HEAD(head);
+
+	spin_lock_irqsave(&vc->lock, flags);
+
+	if (mc->md) {
+		vchan_terminate_vdesc(&mc->md->vd);
+		mc->md = NULL;
+		ret = __uniphier_mdmac_abort(mc);
+	}
+	vchan_get_all_descriptors(vc, &head);
+
+	spin_unlock_irqrestore(&vc->lock, flags);
+
+	vchan_dma_desc_free_list(vc, &head);
+
+	return ret;
+}
+
+static void uniphier_mdmac_synchronize(struct dma_chan *chan)
+{
+	vchan_synchronize(to_virt_chan(chan));
+}
+
+static enum dma_status uniphier_mdmac_tx_status(struct dma_chan *chan,
+						dma_cookie_t cookie,
+						struct dma_tx_state *txstate)
+{
+	struct virt_dma_chan *vc;
+	struct virt_dma_desc *vd;
+	struct uniphier_mdmac_chan *mc;
+	struct uniphier_mdmac_desc *md = NULL;
+	enum dma_status stat;
+	unsigned long flags;
+
+	stat = dma_cookie_status(chan, cookie, txstate);
+	if (stat == DMA_COMPLETE)
+		return stat;
+
+	vc = to_virt_chan(chan);
+
+	spin_lock_irqsave(&vc->lock, flags);
+
+	mc = to_uniphier_mdmac_chan(vc);
+
+	if (mc->md && mc->md->vd.tx.cookie == cookie)
+		md = mc->md;
+
+	if (!md) {
+		vd = vchan_find_desc(vc, cookie);
+		if (vd)
+			md = to_uniphier_mdmac_desc(vd);
+	}
+
+	if (md)
+		txstate->residue = __uniphier_mdmac_get_residue(md);
+
+	spin_unlock_irqrestore(&vc->lock, flags);
+
+	return stat;
+}
+
+static void uniphier_mdmac_issue_pending(struct dma_chan *chan)
+{
+	struct virt_dma_chan *vc = to_virt_chan(chan);
+	struct uniphier_mdmac_chan *mc = to_uniphier_mdmac_chan(vc);
+	unsigned long flags;
+
+	spin_lock_irqsave(&vc->lock, flags);
+
+	if (vchan_issue_pending(vc) && !mc->md)
+		__uniphier_mdmac_start(mc);
+
+	spin_unlock_irqrestore(&vc->lock, flags);
+}
+
+static void uniphier_mdmac_desc_free(struct virt_dma_desc *vd)
+{
+	kfree(to_uniphier_mdmac_desc(vd));
+}
+
+static int uniphier_mdmac_chan_init(struct platform_device *pdev,
+				    struct uniphier_mdmac_device *mdev,
+				    int chan_id)
+{
+	struct device *dev = &pdev->dev;
+	struct uniphier_mdmac_chan *mc = &mdev->channels[chan_id];
+	char *irq_name;
+	int irq, ret;
+
+	irq = platform_get_irq(pdev, chan_id);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "failed to get IRQ number for ch%d\n",
+			chan_id);
+		return irq;
+	}
+
+	irq_name = devm_kasprintf(dev, GFP_KERNEL, "uniphier-mio-dmac-ch%d",
+				  chan_id);
+	if (!irq_name)
+		return -ENOMEM;
+
+	ret = devm_request_irq(dev, irq, uniphier_mdmac_interrupt,
+			       IRQF_SHARED, irq_name, mc);
+	if (ret)
+		return ret;
+
+	mc->mdev = mdev;
+	mc->reg_ch_base = mdev->reg_base + UNIPHIER_MDMAC_CH_OFFSET +
+					UNIPHIER_MDMAC_CH_STRIDE * chan_id;
+	mc->chan_id = chan_id;
+	mc->vc.desc_free = uniphier_mdmac_desc_free;
+	vchan_init(&mc->vc, &mdev->ddev);
+
+	return 0;
+}
+
+static int uniphier_mdmac_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct uniphier_mdmac_device *mdev;
+	struct dma_device *ddev;
+	struct resource *res;
+	int nr_chans, ret, i;
+
+	nr_chans = platform_irq_count(pdev);
+	if (nr_chans < 0)
+		return nr_chans;
+
+	ret = dma_set_mask(dev, DMA_BIT_MASK(32));
+	if (ret)
+		return ret;
+
+	mdev = devm_kzalloc(dev, struct_size(mdev, channels, nr_chans),
+			    GFP_KERNEL);
+	if (!mdev)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	mdev->reg_base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(mdev->reg_base))
+		return PTR_ERR(mdev->reg_base);
+
+	mdev->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(mdev->clk)) {
+		dev_err(dev, "failed to get clock\n");
+		return PTR_ERR(mdev->clk);
+	}
+
+	ret = clk_prepare_enable(mdev->clk);
+	if (ret)
+		return ret;
+
+	ddev = &mdev->ddev;
+	ddev->dev = dev;
+	dma_cap_set(DMA_PRIVATE, ddev->cap_mask);
+	ddev->src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_UNDEFINED);
+	ddev->dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_UNDEFINED);
+	ddev->directions = BIT(DMA_MEM_TO_DEV) | BIT(DMA_DEV_TO_MEM);
+	ddev->residue_granularity = DMA_RESIDUE_GRANULARITY_SEGMENT;
+	ddev->device_prep_slave_sg = uniphier_mdmac_prep_slave_sg;
+	ddev->device_terminate_all = uniphier_mdmac_terminate_all;
+	ddev->device_synchronize = uniphier_mdmac_synchronize;
+	ddev->device_tx_status = uniphier_mdmac_tx_status;
+	ddev->device_issue_pending = uniphier_mdmac_issue_pending;
+	INIT_LIST_HEAD(&ddev->channels);
+
+	for (i = 0; i < nr_chans; i++) {
+		ret = uniphier_mdmac_chan_init(pdev, mdev, i);
+		if (ret)
+			goto disable_clk;
+	}
+
+	ret = dma_async_device_register(ddev);
+	if (ret)
+		goto disable_clk;
+
+	ret = of_dma_controller_register(dev->of_node, of_dma_xlate_by_chan_id,
+					 ddev);
+	if (ret)
+		goto unregister_dmac;
+
+	platform_set_drvdata(pdev, mdev);
+
+	return 0;
+
+unregister_dmac:
+	dma_async_device_unregister(ddev);
+disable_clk:
+	clk_disable_unprepare(mdev->clk);
+
+	return ret;
+}
+
+static int uniphier_mdmac_remove(struct platform_device *pdev)
+{
+	struct uniphier_mdmac_device *mdev = platform_get_drvdata(pdev);
+
+	of_dma_controller_free(pdev->dev.of_node);
+	dma_async_device_unregister(&mdev->ddev);
+	clk_disable_unprepare(mdev->clk);
+
+	return 0;
+}
+
+static const struct of_device_id uniphier_mdmac_match[] = {
+	{ .compatible = "socionext,uniphier-mio-dmac" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, uniphier_mdmac_match);
+
+static struct platform_driver uniphier_mdmac_driver = {
+	.probe = uniphier_mdmac_probe,
+	.remove = uniphier_mdmac_remove,
+	.driver = {
+		.name = "uniphier-mio-dmac",
+		.of_match_table = uniphier_mdmac_match,
+	},
+};
+module_platform_driver(uniphier_mdmac_driver);
+
+MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
+MODULE_DESCRIPTION("UniPhier MIO DMAC driver");
+MODULE_LICENSE("GPL v2");
-- 
2.7.4

Re: [PATCH v2 2/2] dmaengine: uniphier-mdmac: add UniPhier MIO DMAC driver

[Vinod]

On 24-08-18, 10:41, Masahiro Yamada wrote:

> +/* mc->vc.lock must be held by caller */
> +static u32 __uniphier_mdmac_get_residue(struct uniphier_mdmac_desc *md)
> +{
> +	u32 residue = 0;
> +	int i;
> +
> +	for (i = md->sg_cur; i < md->sg_len; i++)
> +		residue += sg_dma_len(&md->sgl[i]);

so if the descriptor is submitted to hardware, we return the descriptor
length, which is not correct.

Two cases are required to be handled:
1. Descriptor is in queue (IMO above logic is fine for that, but it can
be calculated at descriptor submit and looked up here)

2. Descriptor is running (interesting case), you need to read current
register and offset that from descriptor length and return

> +static struct dma_async_tx_descriptor *uniphier_mdmac_prep_slave_sg(
> +					struct dma_chan *chan,
> +					struct scatterlist *sgl,
> +					unsigned int sg_len,
> +					enum dma_transfer_direction direction,
> +					unsigned long flags, void *context)
> +{
> +	struct virt_dma_chan *vc = to_virt_chan(chan);
> +	struct uniphier_mdmac_desc *md;
> +
> +	if (!is_slave_direction(direction))
> +		return NULL;
> +
> +	md = kzalloc(sizeof(*md), GFP_KERNEL);

_prep calls can be invoked from atomic context, so this should be
GFP_NOWAIT, see Documentation/driver-api/dmaengine/provider.rst

> +	if (!md)
> +		return NULL;
> +
> +	md->sgl = sgl;
> +	md->sg_len = sg_len;
> +	md->dir = direction;
> +
> +	return vchan_tx_prep(vc, &md->vd, flags);

this seems missing stuff. Where do you do register calculation for the
descriptor and where is slave_config here, how do you know where to
send/receive data form/to (peripheral)

> +static enum dma_status uniphier_mdmac_tx_status(struct dma_chan *chan,
> +						dma_cookie_t cookie,
> +						struct dma_tx_state *txstate)
> +{
> +	struct virt_dma_chan *vc;
> +	struct virt_dma_desc *vd;
> +	struct uniphier_mdmac_chan *mc;
> +	struct uniphier_mdmac_desc *md = NULL;
> +	enum dma_status stat;
> +	unsigned long flags;
> +
> +	stat = dma_cookie_status(chan, cookie, txstate);
> +	if (stat == DMA_COMPLETE)
> +		return stat;
> +
> +	vc = to_virt_chan(chan);
> +
> +	spin_lock_irqsave(&vc->lock, flags);
> +
> +	mc = to_uniphier_mdmac_chan(vc);
> +
> +	if (mc->md && mc->md->vd.tx.cookie == cookie)
> +		md = mc->md;
> +
> +	if (!md) {
> +		vd = vchan_find_desc(vc, cookie);
> +		if (vd)
> +			md = to_uniphier_mdmac_desc(vd);
> +	}
> +
> +	if (md)
> +		txstate->residue = __uniphier_mdmac_get_residue(md);

txstate can be NULL and should be checked...

> +static int uniphier_mdmac_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct uniphier_mdmac_device *mdev;
> +	struct dma_device *ddev;
> +	struct resource *res;
> +	int nr_chans, ret, i;
> +
> +	nr_chans = platform_irq_count(pdev);
> +	if (nr_chans < 0)
> +		return nr_chans;
> +
> +	ret = dma_set_mask(dev, DMA_BIT_MASK(32));
> +	if (ret)
> +		return ret;
> +
> +	mdev = devm_kzalloc(dev, struct_size(mdev, channels, nr_chans),
> +			    GFP_KERNEL);

kcalloc variant?

> +	if (!mdev)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	mdev->reg_base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(mdev->reg_base))
> +		return PTR_ERR(mdev->reg_base);
> +
> +	mdev->clk = devm_clk_get(dev, NULL);
> +	if (IS_ERR(mdev->clk)) {
> +		dev_err(dev, "failed to get clock\n");
> +		return PTR_ERR(mdev->clk);
> +	}
> +
> +	ret = clk_prepare_enable(mdev->clk);
> +	if (ret)
> +		return ret;
> +
> +	ddev = &mdev->ddev;
> +	ddev->dev = dev;
> +	dma_cap_set(DMA_PRIVATE, ddev->cap_mask);
> +	ddev->src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_UNDEFINED);
> +	ddev->dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_UNDEFINED);
> +	ddev->directions = BIT(DMA_MEM_TO_DEV) | BIT(DMA_DEV_TO_MEM);
> +	ddev->residue_granularity = DMA_RESIDUE_GRANULARITY_SEGMENT;
> +	ddev->device_prep_slave_sg = uniphier_mdmac_prep_slave_sg;
> +	ddev->device_terminate_all = uniphier_mdmac_terminate_all;
> +	ddev->device_synchronize = uniphier_mdmac_synchronize;
> +	ddev->device_tx_status = uniphier_mdmac_tx_status;
> +	ddev->device_issue_pending = uniphier_mdmac_issue_pending;

No device_config?
-- 
~Vinod

Re: [PATCH v2 2/2] dmaengine: uniphier-mdmac: add UniPhier MIO DMAC driver

[Masahiro Yamada]

Hi Vinod,


2018-09-11 16:00 GMT+09:00 Vinod <vkoul@kernel.org>:
> On 24-08-18, 10:41, Masahiro Yamada wrote:
>
>> +/* mc->vc.lock must be held by caller */
>> +static u32 __uniphier_mdmac_get_residue(struct uniphier_mdmac_desc *md)
>> +{
>> +     u32 residue = 0;
>> +     int i;
>> +
>> +     for (i = md->sg_cur; i < md->sg_len; i++)
>> +             residue += sg_dma_len(&md->sgl[i]);
>
> so if the descriptor is submitted to hardware, we return the descriptor
> length, which is not correct.
>
> Two cases are required to be handled:
> 1. Descriptor is in queue (IMO above logic is fine for that, but it can
> be calculated at descriptor submit and looked up here)

Where do you want it to be calculated?

This hardware provides only simple registers (address and size)
for one-shot transfer instead of descriptors.

So, I used sgl as-is because I did not see a good reason
to transform sgl to another data structure.




> 2. Descriptor is running (interesting case), you need to read current
> register and offset that from descriptor length and return


OK, I will read out the register value
to retrieve the residue from the on-flight transfer.


>> +static struct dma_async_tx_descriptor *uniphier_mdmac_prep_slave_sg(
>> +                                     struct dma_chan *chan,
>> +                                     struct scatterlist *sgl,
>> +                                     unsigned int sg_len,
>> +                                     enum dma_transfer_direction direction,
>> +                                     unsigned long flags, void *context)
>> +{
>> +     struct virt_dma_chan *vc = to_virt_chan(chan);
>> +     struct uniphier_mdmac_desc *md;
>> +
>> +     if (!is_slave_direction(direction))
>> +             return NULL;
>> +
>> +     md = kzalloc(sizeof(*md), GFP_KERNEL);
>
> _prep calls can be invoked from atomic context, so this should be
> GFP_NOWAIT, see Documentation/driver-api/dmaengine/provider.rst

Will fix.


>> +     if (!md)
>> +             return NULL;
>> +
>> +     md->sgl = sgl;
>> +     md->sg_len = sg_len;
>> +     md->dir = direction;
>> +
>> +     return vchan_tx_prep(vc, &md->vd, flags);
>
> this seems missing stuff. Where do you do register calculation for the
> descriptor and where is slave_config here, how do you know where to
> send/receive data form/to (peripheral)


This dmac is really simple, and un-flexible.

The peripheral address to send/receive data from/to is hard-weird.
cfg->{src_addr,dst_addr} is not configurable.

Look at __uniphier_mdmac_handle().
'dest_addr' and 'src_addr' must be set to 0 for the peripheral.




>> +static enum dma_status uniphier_mdmac_tx_status(struct dma_chan *chan,
>> +                                             dma_cookie_t cookie,
>> +                                             struct dma_tx_state *txstate)
>> +{
>> +     struct virt_dma_chan *vc;
>> +     struct virt_dma_desc *vd;
>> +     struct uniphier_mdmac_chan *mc;
>> +     struct uniphier_mdmac_desc *md = NULL;
>> +     enum dma_status stat;
>> +     unsigned long flags;
>> +
>> +     stat = dma_cookie_status(chan, cookie, txstate);
>> +     if (stat == DMA_COMPLETE)
>> +             return stat;
>> +
>> +     vc = to_virt_chan(chan);
>> +
>> +     spin_lock_irqsave(&vc->lock, flags);
>> +
>> +     mc = to_uniphier_mdmac_chan(vc);
>> +
>> +     if (mc->md && mc->md->vd.tx.cookie == cookie)
>> +             md = mc->md;
>> +
>> +     if (!md) {
>> +             vd = vchan_find_desc(vc, cookie);
>> +             if (vd)
>> +                     md = to_uniphier_mdmac_desc(vd);
>> +     }
>> +
>> +     if (md)
>> +             txstate->residue = __uniphier_mdmac_get_residue(md);
>
> txstate can be NULL and should be checked...

Will fix.


>> +static int uniphier_mdmac_probe(struct platform_device *pdev)
>> +{
>> +     struct device *dev = &pdev->dev;
>> +     struct uniphier_mdmac_device *mdev;
>> +     struct dma_device *ddev;
>> +     struct resource *res;
>> +     int nr_chans, ret, i;
>> +
>> +     nr_chans = platform_irq_count(pdev);
>> +     if (nr_chans < 0)
>> +             return nr_chans;
>> +
>> +     ret = dma_set_mask(dev, DMA_BIT_MASK(32));
>> +     if (ret)
>> +             return ret;
>> +
>> +     mdev = devm_kzalloc(dev, struct_size(mdev, channels, nr_chans),
>> +                         GFP_KERNEL);
>
> kcalloc variant?


No.

I allocate here
sizeof(*mdev) + nr_chans * sizeof(struct uniphier_mdmac_chan)

kcalloc does not cater to it.

You should check struct_size() helper macro.




>> +     if (!mdev)
>> +             return -ENOMEM;
>> +
>> +     res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +     mdev->reg_base = devm_ioremap_resource(dev, res);
>> +     if (IS_ERR(mdev->reg_base))
>> +             return PTR_ERR(mdev->reg_base);
>> +
>> +     mdev->clk = devm_clk_get(dev, NULL);
>> +     if (IS_ERR(mdev->clk)) {
>> +             dev_err(dev, "failed to get clock\n");
>> +             return PTR_ERR(mdev->clk);
>> +     }
>> +
>> +     ret = clk_prepare_enable(mdev->clk);
>> +     if (ret)
>> +             return ret;
>> +
>> +     ddev = &mdev->ddev;
>> +     ddev->dev = dev;
>> +     dma_cap_set(DMA_PRIVATE, ddev->cap_mask);
>> +     ddev->src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_UNDEFINED);
>> +     ddev->dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_UNDEFINED);
>> +     ddev->directions = BIT(DMA_MEM_TO_DEV) | BIT(DMA_DEV_TO_MEM);
>> +     ddev->residue_granularity = DMA_RESIDUE_GRANULARITY_SEGMENT;
>> +     ddev->device_prep_slave_sg = uniphier_mdmac_prep_slave_sg;
>> +     ddev->device_terminate_all = uniphier_mdmac_terminate_all;
>> +     ddev->device_synchronize = uniphier_mdmac_synchronize;
>> +     ddev->device_tx_status = uniphier_mdmac_tx_status;
>> +     ddev->device_issue_pending = uniphier_mdmac_issue_pending;
>
> No device_config?


As I mentioned above, this hardware has no room for configuration.
Nothing in struct dma_slave_config except 'direction' is configurable
for this hardware.

The 'direction' is deprecated.


If an empty device_config hook is OK,
I will add it.


-- 
Best Regards
Masahiro Yamada

Re: [PATCH v2 2/2] dmaengine: uniphier-mdmac: add UniPhier MIO DMAC driver

[Vinod]

On 12-09-18, 12:01, Masahiro Yamada wrote:
> Hi Vinod,
> 
> 
> 2018-09-11 16:00 GMT+09:00 Vinod <vkoul@kernel.org>:
> > On 24-08-18, 10:41, Masahiro Yamada wrote:
> >
> >> +/* mc->vc.lock must be held by caller */
> >> +static u32 __uniphier_mdmac_get_residue(struct uniphier_mdmac_desc *md)
> >> +{
> >> +     u32 residue = 0;
> >> +     int i;
> >> +
> >> +     for (i = md->sg_cur; i < md->sg_len; i++)
> >> +             residue += sg_dma_len(&md->sgl[i]);
> >
> > so if the descriptor is submitted to hardware, we return the descriptor
> > length, which is not correct.
> >
> > Two cases are required to be handled:
> > 1. Descriptor is in queue (IMO above logic is fine for that, but it can
> > be calculated at descriptor submit and looked up here)
> 
> Where do you want it to be calculated?

where is it calculated now?

> This hardware provides only simple registers (address and size)
> for one-shot transfer instead of descriptors.
> 
> So, I used sgl as-is because I did not see a good reason
> to transform sgl to another data structure.


> > this seems missing stuff. Where do you do register calculation for the
> > descriptor and where is slave_config here, how do you know where to
> > send/receive data form/to (peripheral)
> 
> 
> This dmac is really simple, and un-flexible.
> 
> The peripheral address to send/receive data from/to is hard-weird.
> cfg->{src_addr,dst_addr} is not configurable.
> 
> Look at __uniphier_mdmac_handle().
> 'dest_addr' and 'src_addr' must be set to 0 for the peripheral.

Fair enough, what about other values like addr_width and maxburst?
-- 
~Vinod

Re: [PATCH v2 2/2] dmaengine: uniphier-mdmac: add UniPhier MIO DMAC driver

[Masahiro Yamada]

2018-09-12 13:35 GMT+09:00 Vinod <vkoul@kernel.org>:
> On 12-09-18, 12:01, Masahiro Yamada wrote:
>> Hi Vinod,
>>
>>
>> 2018-09-11 16:00 GMT+09:00 Vinod <vkoul@kernel.org>:
>> > On 24-08-18, 10:41, Masahiro Yamada wrote:
>> >
>> >> +/* mc->vc.lock must be held by caller */
>> >> +static u32 __uniphier_mdmac_get_residue(struct uniphier_mdmac_desc *md)
>> >> +{
>> >> +     u32 residue = 0;
>> >> +     int i;
>> >> +
>> >> +     for (i = md->sg_cur; i < md->sg_len; i++)
>> >> +             residue += sg_dma_len(&md->sgl[i]);
>> >
>> > so if the descriptor is submitted to hardware, we return the descriptor
>> > length, which is not correct.
>> >
>> > Two cases are required to be handled:
>> > 1. Descriptor is in queue (IMO above logic is fine for that, but it can
>> > be calculated at descriptor submit and looked up here)
>>
>> Where do you want it to be calculated?
>
> where is it calculated now?


Please see __uniphier_mdmac_handle().


It gets the address and size by sg_dma_address(), sg_dma_len()
just before setting them to the hardware registers.


       sg = &md->sgl[md->sg_cur];

       if (md->dir == DMA_MEM_TO_DEV) {
               src_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_INC;
               src_addr = sg_dma_address(sg);
               dest_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED;
               dest_addr = 0;
       } else {
               src_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED;
               src_addr = 0;
               dest_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_INC;
               dest_addr = sg_dma_address(sg);
       }







>> This hardware provides only simple registers (address and size)
>> for one-shot transfer instead of descriptors.
>>
>> So, I used sgl as-is because I did not see a good reason
>> to transform sgl to another data structure.
>
>
>> > this seems missing stuff. Where do you do register calculation for the
>> > descriptor and where is slave_config here, how do you know where to
>> > send/receive data form/to (peripheral)
>>
>>
>> This dmac is really simple, and un-flexible.
>>
>> The peripheral address to send/receive data from/to is hard-weird.
>> cfg->{src_addr,dst_addr} is not configurable.
>>
>> Look at __uniphier_mdmac_handle().
>> 'dest_addr' and 'src_addr' must be set to 0 for the peripheral.
>
> Fair enough, what about other values like addr_width and maxburst?


None of them is configurable.



-- 
Best Regards
Masahiro Yamada

Re: [PATCH v2 2/2] dmaengine: uniphier-mdmac: add UniPhier MIO DMAC driver

[Vinod]

On 12-09-18, 14:25, Masahiro Yamada wrote:
> 2018-09-12 13:35 GMT+09:00 Vinod <vkoul@kernel.org>:
> > On 12-09-18, 12:01, Masahiro Yamada wrote:
> >> Hi Vinod,
> >>
> >>
> >> 2018-09-11 16:00 GMT+09:00 Vinod <vkoul@kernel.org>:
> >> > On 24-08-18, 10:41, Masahiro Yamada wrote:
> >> >
> >> >> +/* mc->vc.lock must be held by caller */
> >> >> +static u32 __uniphier_mdmac_get_residue(struct uniphier_mdmac_desc *md)
> >> >> +{
> >> >> +     u32 residue = 0;
> >> >> +     int i;
> >> >> +
> >> >> +     for (i = md->sg_cur; i < md->sg_len; i++)
> >> >> +             residue += sg_dma_len(&md->sgl[i]);
> >> >
> >> > so if the descriptor is submitted to hardware, we return the descriptor
> >> > length, which is not correct.
> >> >
> >> > Two cases are required to be handled:
> >> > 1. Descriptor is in queue (IMO above logic is fine for that, but it can
> >> > be calculated at descriptor submit and looked up here)
> >>
> >> Where do you want it to be calculated?
> >
> > where is it calculated now?
> 
> 
> Please see __uniphier_mdmac_handle().
> 
> 
> It gets the address and size by sg_dma_address(), sg_dma_len()
> just before setting them to the hardware registers.
> 
> 
>        sg = &md->sgl[md->sg_cur];
> 
>        if (md->dir == DMA_MEM_TO_DEV) {
>                src_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_INC;
>                src_addr = sg_dma_address(sg);
>                dest_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED;
>                dest_addr = 0;
>        } else {
>                src_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED;
>                src_addr = 0;
>                dest_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_INC;
>                dest_addr = sg_dma_address(sg);
>        }
> 
> 
> 
> 
> 
> 
> 
> >> This hardware provides only simple registers (address and size)
> >> for one-shot transfer instead of descriptors.
> >>
> >> So, I used sgl as-is because I did not see a good reason
> >> to transform sgl to another data structure.
> >
> >
> >> > this seems missing stuff. Where do you do register calculation for the
> >> > descriptor and where is slave_config here, how do you know where to
> >> > send/receive data form/to (peripheral)
> >>
> >>
> >> This dmac is really simple, and un-flexible.
> >>
> >> The peripheral address to send/receive data from/to is hard-weird.
> >> cfg->{src_addr,dst_addr} is not configurable.
> >>
> >> Look at __uniphier_mdmac_handle().
> >> 'dest_addr' and 'src_addr' must be set to 0 for the peripheral.
> >
> > Fair enough, what about other values like addr_width and maxburst?
> 
> 
> None of them is configurable.

what is configurable here :-)

Who are the users of this DMA?

-- 
~Vinod

Re: [PATCH v2 2/2] dmaengine: uniphier-mdmac: add UniPhier MIO DMAC driver

[Masahiro Yamada]

2018-09-12 16:26 GMT+09:00 Vinod <vkoul@kernel.org>:
> On 12-09-18, 14:25, Masahiro Yamada wrote:
>> 2018-09-12 13:35 GMT+09:00 Vinod <vkoul@kernel.org>:
>> > On 12-09-18, 12:01, Masahiro Yamada wrote:
>> >> Hi Vinod,
>> >>
>> >>
>> >> 2018-09-11 16:00 GMT+09:00 Vinod <vkoul@kernel.org>:
>> >> > On 24-08-18, 10:41, Masahiro Yamada wrote:
>> >> >
>> >> >> +/* mc->vc.lock must be held by caller */
>> >> >> +static u32 __uniphier_mdmac_get_residue(struct uniphier_mdmac_desc *md)
>> >> >> +{
>> >> >> +     u32 residue = 0;
>> >> >> +     int i;
>> >> >> +
>> >> >> +     for (i = md->sg_cur; i < md->sg_len; i++)
>> >> >> +             residue += sg_dma_len(&md->sgl[i]);
>> >> >
>> >> > so if the descriptor is submitted to hardware, we return the descriptor
>> >> > length, which is not correct.
>> >> >
>> >> > Two cases are required to be handled:
>> >> > 1. Descriptor is in queue (IMO above logic is fine for that, but it can
>> >> > be calculated at descriptor submit and looked up here)
>> >>
>> >> Where do you want it to be calculated?
>> >
>> > where is it calculated now?
>>
>>
>> Please see __uniphier_mdmac_handle().
>>
>>
>> It gets the address and size by sg_dma_address(), sg_dma_len()
>> just before setting them to the hardware registers.
>>
>>
>>        sg = &md->sgl[md->sg_cur];
>>
>>        if (md->dir == DMA_MEM_TO_DEV) {
>>                src_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_INC;
>>                src_addr = sg_dma_address(sg);
>>                dest_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED;
>>                dest_addr = 0;
>>        } else {
>>                src_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED;
>>                src_addr = 0;
>>                dest_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_INC;
>>                dest_addr = sg_dma_address(sg);
>>        }
>>
>>
>>
>>
>>
>>
>>
>> >> This hardware provides only simple registers (address and size)
>> >> for one-shot transfer instead of descriptors.
>> >>
>> >> So, I used sgl as-is because I did not see a good reason
>> >> to transform sgl to another data structure.
>> >
>> >
>> >> > this seems missing stuff. Where do you do register calculation for the
>> >> > descriptor and where is slave_config here, how do you know where to
>> >> > send/receive data form/to (peripheral)
>> >>
>> >>
>> >> This dmac is really simple, and un-flexible.
>> >>
>> >> The peripheral address to send/receive data from/to is hard-weird.
>> >> cfg->{src_addr,dst_addr} is not configurable.
>> >>
>> >> Look at __uniphier_mdmac_handle().
>> >> 'dest_addr' and 'src_addr' must be set to 0 for the peripheral.
>> >
>> > Fair enough, what about other values like addr_width and maxburst?
>>
>>
>> None of them is configurable.
>
> what is configurable here :-)

The physical address of the memory, transfer size, direction
are configurable, of course.
But, they are out of scope of device_config hook.


> Who are the users of this DMA?

SD/eMMC controllers.



-- 
Best Regards
Masahiro Yamada