[v4] dmaengine, PCI: endpoint: Enable remote use of integrated DesignWare eDMA

[PATCH v4 6/9] PCI: dwc: ep: Report integrated eDMA resources via EPC remote-resource API

Posted by Koichiro Den 3 days, 2 hours ago

Implement pci_epc_ops.get_remote_resources() for DesignWare PCIe
endpoint controllers with integrated eDMA.

Report:
  - the eDMA controller MMIO window (physical base + size),
  - each non-empty per-channel linked-list region, along with
    per-channel metadata such as the Linux IRQ number and the
    interrupt-emulation doorbell register offset.

This allows endpoint function drivers (e.g. pci-epf-test) to discover
the eDMA resources and map a suitable doorbell target into BAR space.

Signed-off-by: Koichiro Den <den@valinux.co.jp>
---
 .../pci/controller/dwc/pcie-designware-ep.c   | 85 +++++++++++++++++++
 1 file changed, 85 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index 7e7844ff0f7e..29dedac86190 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -8,6 +8,7 @@
 
 #include <linux/align.h>
 #include <linux/bitfield.h>
+#include <linux/dma/edma.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 
@@ -808,6 +809,89 @@ dw_pcie_ep_get_features(struct pci_epc *epc, u8 func_no, u8 vfunc_no)
 	return ep->ops->get_features(ep);
 }
 
+static int
+dw_pcie_ep_get_remote_resources(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
+				struct pci_epc_remote_resource *resources,
+				int num_resources)
+{
+	struct dw_pcie_ep *ep = epc_get_drvdata(epc);
+	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
+	struct dw_edma_chip *edma = &pci->edma;
+	struct dw_edma_chan_info info;
+	int ll_cnt = 0, needed, idx = 0;
+	resource_size_t dma_size;
+	phys_addr_t dma_phys;
+	unsigned int i;
+	int ret;
+
+	if (!pci->edma_reg_size)
+		return 0;
+
+	dma_phys = pci->edma_reg_phys;
+	dma_size = pci->edma_reg_size;
+
+	for (i = 0; i < edma->ll_wr_cnt; i++)
+		if (edma->ll_region_wr[i].sz)
+			ll_cnt++;
+
+	for (i = 0; i < edma->ll_rd_cnt; i++)
+		if (edma->ll_region_rd[i].sz)
+			ll_cnt++;
+
+	needed = 1 + ll_cnt;
+
+	/* Count query mode */
+	if (!resources || !num_resources)
+		return needed;
+
+	if (num_resources < needed)
+		return -ENOSPC;
+
+	resources[idx++] = (struct pci_epc_remote_resource) {
+		.type = PCI_EPC_RR_DMA_CTRL_MMIO,
+		.phys_addr = dma_phys,
+		.size = dma_size,
+	};
+
+	/* One LL region per write channel */
+	for (i = 0; i < edma->ll_wr_cnt; i++) {
+		if (!edma->ll_region_wr[i].sz)
+			continue;
+
+		ret = dw_edma_chan_info(edma, i, &info);
+		if (ret)
+			return ret;
+
+		resources[idx++] = (struct pci_epc_remote_resource) {
+			.type = PCI_EPC_RR_DMA_CHAN_DESC,
+			.phys_addr = edma->ll_region_wr[i].paddr,
+			.size = edma->ll_region_wr[i].sz,
+			.u.dma_chan_desc.irq = info.irq,
+			.u.dma_chan_desc.db_offset = info.db_offset,
+		};
+	}
+
+	/* One LL region per read channel */
+	for (i = 0; i < edma->ll_rd_cnt; i++) {
+		if (!edma->ll_region_rd[i].sz)
+			continue;
+
+		ret = dw_edma_chan_info(edma, i + edma->ll_wr_cnt, &info);
+		if (ret)
+			return ret;
+
+		resources[idx++] = (struct pci_epc_remote_resource) {
+			.type = PCI_EPC_RR_DMA_CHAN_DESC,
+			.phys_addr = edma->ll_region_rd[i].paddr,
+			.size = edma->ll_region_rd[i].sz,
+			.u.dma_chan_desc.irq = info.irq,
+			.u.dma_chan_desc.db_offset = info.db_offset,
+		};
+	}
+
+	return idx;
+}
+
 static const struct pci_epc_ops epc_ops = {
 	.write_header		= dw_pcie_ep_write_header,
 	.set_bar		= dw_pcie_ep_set_bar,
@@ -823,6 +907,7 @@ static const struct pci_epc_ops epc_ops = {
 	.start			= dw_pcie_ep_start,
 	.stop			= dw_pcie_ep_stop,
 	.get_features		= dw_pcie_ep_get_features,
+	.get_remote_resources	= dw_pcie_ep_get_remote_resources,
 };
 
 /**
-- 
2.51.0

Re: [PATCH v4 6/9] PCI: dwc: ep: Report integrated eDMA resources via EPC remote-resource API

Posted by Frank Li 3 days, 1 hour ago

On Sat, Feb 07, 2026 at 02:26:43AM +0900, Koichiro Den wrote:
> Implement pci_epc_ops.get_remote_resources() for DesignWare PCIe
> endpoint controllers with integrated eDMA.
>
> Report:
>   - the eDMA controller MMIO window (physical base + size),
>   - each non-empty per-channel linked-list region, along with
>     per-channel metadata such as the Linux IRQ number and the
>     interrupt-emulation doorbell register offset.
>
> This allows endpoint function drivers (e.g. pci-epf-test) to discover
> the eDMA resources and map a suitable doorbell target into BAR space.
>
> Signed-off-by: Koichiro Den <den@valinux.co.jp>
> ---
>  .../pci/controller/dwc/pcie-designware-ep.c   | 85 +++++++++++++++++++
>  1 file changed, 85 insertions(+)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
> index 7e7844ff0f7e..29dedac86190 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> @@ -8,6 +8,7 @@
>
>  #include <linux/align.h>
>  #include <linux/bitfield.h>
> +#include <linux/dma/edma.h>
>  #include <linux/of.h>
>  #include <linux/platform_device.h>
>
> @@ -808,6 +809,89 @@ dw_pcie_ep_get_features(struct pci_epc *epc, u8 func_no, u8 vfunc_no)
>  	return ep->ops->get_features(ep);
>  }
>
> +static int
> +dw_pcie_ep_get_remote_resources(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
> +				struct pci_epc_remote_resource *resources,
> +				int num_resources)
> +{
> +	struct dw_pcie_ep *ep = epc_get_drvdata(epc);
> +	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
> +	struct dw_edma_chip *edma = &pci->edma;
> +	struct dw_edma_chan_info info;
> +	int ll_cnt = 0, needed, idx = 0;
> +	resource_size_t dma_size;
> +	phys_addr_t dma_phys;
> +	unsigned int i;
> +	int ret;
> +
> +	if (!pci->edma_reg_size)
> +		return 0;
> +
> +	dma_phys = pci->edma_reg_phys;
> +	dma_size = pci->edma_reg_size;
> +
> +	for (i = 0; i < edma->ll_wr_cnt; i++)
> +		if (edma->ll_region_wr[i].sz)
> +			ll_cnt++;
> +
> +	for (i = 0; i < edma->ll_rd_cnt; i++)
> +		if (edma->ll_region_rd[i].sz)
> +			ll_cnt++;
> +
> +	needed = 1 + ll_cnt;
> +
> +	/* Count query mode */
> +	if (!resources || !num_resources)
> +		return needed;
> +
> +	if (num_resources < needed)
> +		return -ENOSPC;
> +
> +	resources[idx++] = (struct pci_epc_remote_resource) {
> +		.type = PCI_EPC_RR_DMA_CTRL_MMIO,
> +		.phys_addr = dma_phys,
> +		.size = dma_size,
> +	};
> +
> +	/* One LL region per write channel */
> +	for (i = 0; i < edma->ll_wr_cnt; i++) {
> +		if (!edma->ll_region_wr[i].sz)
> +			continue;
> +
> +		ret = dw_edma_chan_info(edma, i, &info);
> +		if (ret)
> +			return ret;
> +
> +		resources[idx++] = (struct pci_epc_remote_resource) {
> +			.type = PCI_EPC_RR_DMA_CHAN_DESC,
> +			.phys_addr = edma->ll_region_wr[i].paddr,
> +			.size = edma->ll_region_wr[i].sz,
> +			.u.dma_chan_desc.irq = info.irq,
> +			.u.dma_chan_desc.db_offset = info.db_offset,
> +		};
> +	}
> +
> +	/* One LL region per read channel */
> +	for (i = 0; i < edma->ll_rd_cnt; i++) {
> +		if (!edma->ll_region_rd[i].sz)
> +			continue;
> +
> +		ret = dw_edma_chan_info(edma, i + edma->ll_wr_cnt, &info);

edma's information is what dw-EP pass to edma driver, supposed dw-ep know
irq and HDMI or EDMA's information, I think needn't go around to EDMA again
to fetch this information back.

Frank
> +		if (ret)
> +			return ret;
> +
> +		resources[idx++] = (struct pci_epc_remote_resource) {
> +			.type = PCI_EPC_RR_DMA_CHAN_DESC,
> +			.phys_addr = edma->ll_region_rd[i].paddr,
> +			.size = edma->ll_region_rd[i].sz,
> +			.u.dma_chan_desc.irq = info.irq,
> +			.u.dma_chan_desc.db_offset = info.db_offset,
> +		};
> +	}
> +
> +	return idx;
> +}
> +
>  static const struct pci_epc_ops epc_ops = {
>  	.write_header		= dw_pcie_ep_write_header,
>  	.set_bar		= dw_pcie_ep_set_bar,
> @@ -823,6 +907,7 @@ static const struct pci_epc_ops epc_ops = {
>  	.start			= dw_pcie_ep_start,
>  	.stop			= dw_pcie_ep_stop,
>  	.get_features		= dw_pcie_ep_get_features,
> +	.get_remote_resources	= dw_pcie_ep_get_remote_resources,
>  };
>
>  /**
> --
> 2.51.0
>

Re: [PATCH v4 6/9] PCI: dwc: ep: Report integrated eDMA resources via EPC remote-resource API

Posted by Koichiro Den 2 days, 3 hours ago

On Fri, Feb 06, 2026 at 01:06:46PM -0500, Frank Li wrote:
> On Sat, Feb 07, 2026 at 02:26:43AM +0900, Koichiro Den wrote:
> > Implement pci_epc_ops.get_remote_resources() for DesignWare PCIe
> > endpoint controllers with integrated eDMA.
> >
> > Report:
> >   - the eDMA controller MMIO window (physical base + size),
> >   - each non-empty per-channel linked-list region, along with
> >     per-channel metadata such as the Linux IRQ number and the
> >     interrupt-emulation doorbell register offset.
> >
> > This allows endpoint function drivers (e.g. pci-epf-test) to discover
> > the eDMA resources and map a suitable doorbell target into BAR space.
> >
> > Signed-off-by: Koichiro Den <den@valinux.co.jp>
> > ---
> >  .../pci/controller/dwc/pcie-designware-ep.c   | 85 +++++++++++++++++++
> >  1 file changed, 85 insertions(+)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
> > index 7e7844ff0f7e..29dedac86190 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> > @@ -8,6 +8,7 @@
> >
> >  #include <linux/align.h>
> >  #include <linux/bitfield.h>
> > +#include <linux/dma/edma.h>
> >  #include <linux/of.h>
> >  #include <linux/platform_device.h>
> >
> > @@ -808,6 +809,89 @@ dw_pcie_ep_get_features(struct pci_epc *epc, u8 func_no, u8 vfunc_no)
> >  	return ep->ops->get_features(ep);
> >  }
> >
> > +static int
> > +dw_pcie_ep_get_remote_resources(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
> > +				struct pci_epc_remote_resource *resources,
> > +				int num_resources)
> > +{
> > +	struct dw_pcie_ep *ep = epc_get_drvdata(epc);
> > +	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
> > +	struct dw_edma_chip *edma = &pci->edma;
> > +	struct dw_edma_chan_info info;
> > +	int ll_cnt = 0, needed, idx = 0;
> > +	resource_size_t dma_size;
> > +	phys_addr_t dma_phys;
> > +	unsigned int i;
> > +	int ret;
> > +
> > +	if (!pci->edma_reg_size)
> > +		return 0;
> > +
> > +	dma_phys = pci->edma_reg_phys;
> > +	dma_size = pci->edma_reg_size;
> > +
> > +	for (i = 0; i < edma->ll_wr_cnt; i++)
> > +		if (edma->ll_region_wr[i].sz)
> > +			ll_cnt++;
> > +
> > +	for (i = 0; i < edma->ll_rd_cnt; i++)
> > +		if (edma->ll_region_rd[i].sz)
> > +			ll_cnt++;
> > +
> > +	needed = 1 + ll_cnt;
> > +
> > +	/* Count query mode */
> > +	if (!resources || !num_resources)
> > +		return needed;
> > +
> > +	if (num_resources < needed)
> > +		return -ENOSPC;
> > +
> > +	resources[idx++] = (struct pci_epc_remote_resource) {
> > +		.type = PCI_EPC_RR_DMA_CTRL_MMIO,
> > +		.phys_addr = dma_phys,
> > +		.size = dma_size,
> > +	};
> > +
> > +	/* One LL region per write channel */
> > +	for (i = 0; i < edma->ll_wr_cnt; i++) {
> > +		if (!edma->ll_region_wr[i].sz)
> > +			continue;
> > +
> > +		ret = dw_edma_chan_info(edma, i, &info);
> > +		if (ret)
> > +			return ret;
> > +
> > +		resources[idx++] = (struct pci_epc_remote_resource) {
> > +			.type = PCI_EPC_RR_DMA_CHAN_DESC,
> > +			.phys_addr = edma->ll_region_wr[i].paddr,
> > +			.size = edma->ll_region_wr[i].sz,
> > +			.u.dma_chan_desc.irq = info.irq,
> > +			.u.dma_chan_desc.db_offset = info.db_offset,
> > +		};
> > +	}
> > +
> > +	/* One LL region per read channel */
> > +	for (i = 0; i < edma->ll_rd_cnt; i++) {
> > +		if (!edma->ll_region_rd[i].sz)
> > +			continue;
> > +
> > +		ret = dw_edma_chan_info(edma, i + edma->ll_wr_cnt, &info);
> 
> edma's information is what dw-EP pass to edma driver, supposed dw-ep know
> irq and HDMI or EDMA's information, I think needn't go around to EDMA again
> to fetch this information back.

Thanks for the feedback. As I understand it, yes, dw-EP passes information
such as nr_irqs/ll_wr_cnt/ll_rd_cnt to dw-edma, but the per-channel
chan-to-irq mapping is decided inside dw-edma. The doorbell offset is also
derived from the dw-(e|h)dma v0 core registers.

To avoid having dw-EP call back into dw-edma just to fetch the mapping
(i.e. get rid of dw_edma_chan_info()), we could cache the per-channel
metadata in struct dw_edma_chip and have dw-edma fill it at probe time.
Then get_remote_resources() can just read the cached values.

Something like:

diff --git a/include/linux/dma/edma.h b/include/linux/dma/edma.h
index 53b31a974331..83503aacaf5f 100644
--- a/include/linux/dma/edma.h
+++ b/include/linux/dma/edma.h
@@ -88,6 +88,17 @@ struct dw_edma_peripheral_config {
        enum dw_edma_ch_irq_mode irq_mode;
 };

+/**
+ * struct dw_edma_ch_info - DW eDMA channel metadata
+ * @irq:       Linux IRQ number used by this channel's interrupt vector
+ * @db_offset: offset within the eDMA register window that can be used as
+ *             an interrupt-emulation doorbell for this channel
+ */
+struct dw_edma_ch_info {
+       int                     irq;
+       resource_size_t         db_offset;
+};
+
 /**
  * struct dw_edma_chip - representation of DesignWare eDMA controller hardware
  * @dev:                struct device of the eDMA controller
@@ -124,6 +135,10 @@ struct dw_edma_chip {
        struct dw_edma_region   dt_region_wr[EDMA_MAX_WR_CH];
        struct dw_edma_region   dt_region_rd[EDMA_MAX_RD_CH];

+       /* cached channel info */
+       struct dw_edma_ch_info  ch_info_wr[EDMA_MAX_WR_CH];
+       struct dw_edma_ch_info  ch_info_rd[EDMA_MAX_RD_CH];
+
        enum dw_edma_map_format mf;

        struct dw_edma          *dw;

Best regards,
Koichiro

> 
> Frank
> > +		if (ret)
> > +			return ret;
> > +
> > +		resources[idx++] = (struct pci_epc_remote_resource) {
> > +			.type = PCI_EPC_RR_DMA_CHAN_DESC,
> > +			.phys_addr = edma->ll_region_rd[i].paddr,
> > +			.size = edma->ll_region_rd[i].sz,
> > +			.u.dma_chan_desc.irq = info.irq,
> > +			.u.dma_chan_desc.db_offset = info.db_offset,
> > +		};
> > +	}
> > +
> > +	return idx;
> > +}
> > +
> >  static const struct pci_epc_ops epc_ops = {
> >  	.write_header		= dw_pcie_ep_write_header,
> >  	.set_bar		= dw_pcie_ep_set_bar,
> > @@ -823,6 +907,7 @@ static const struct pci_epc_ops epc_ops = {
> >  	.start			= dw_pcie_ep_start,
> >  	.stop			= dw_pcie_ep_stop,
> >  	.get_features		= dw_pcie_ep_get_features,
> > +	.get_remote_resources	= dw_pcie_ep_get_remote_resources,
> >  };
> >
> >  /**
> > --
> > 2.51.0
> >

[PATCH v4 1/9] dmaengine: dw-edma: Add per-channel interrupt routing control
[PATCH v4 2/9] dmaengine: dw-edma: Deassert emulated interrupts in the IRQ handler
[PATCH v4 3/9] dmaengine: dw-edma: Export per-channel IRQ and doorbell register offset
[PATCH v4 4/9] PCI: endpoint: Add remote resource query API
[PATCH v4 5/9] PCI: dwc: Record integrated eDMA register window
[PATCH v4 6/9] PCI: dwc: ep: Report integrated eDMA resources via EPC remote-resource API
[PATCH v4 7/9] PCI: endpoint: pci-epf-test: Add embedded doorbell variant
[PATCH v4 8/9] misc: pci_endpoint_test: Allow selecting embedded doorbell
[PATCH v4 9/9] selftests: pci_endpoint: Exercise MSI and embedded doorbell