Re: [PATCH v2 03/23] dmaengine: sdxi: Add PCI initialization

[Frank Li]

On Mon, May 11, 2026 at 02:16:15PM -0500, Nathan Lynch wrote:
> Add enough code to bind a SDXI device via the class code and map its
> control registers and doorbell region. All device resources are
> managed with devres at this point, so there is no explicit teardown
> path.
>
> While the SDXI specification includes a PCIe binding, the standard is
> intended to be independent of the underlying I/O interconnect. So the
> driver confines PCI-specific code to pci.c, and the rest (such as
> device.c, introduced here) is bus-agnostic. Hence there is some
> indirection: during probe, the bus code registers any matched device
> with the generic SDXI core, supplying the device and a sdxi_bus_ops
> vector. After the core associates a new sdxi_dev with the device,
> bus-specific initialization proceeds via the sdxi_bus_ops->init()
> callback.
>
> Co-developed-by: Wei Huang <wei.huang2@xxxxxxx>
> Signed-off-by: Wei Huang <wei.huang2@xxxxxxx>
> Signed-off-by: Nathan Lynch <nathan.lynch@xxxxxxx>
> ---

Reviewed-by: Frank Li <Frank.Li@xxxxxxx>

>  drivers/dma/Kconfig       |  2 ++
>  drivers/dma/Makefile      |  1 +
>  drivers/dma/sdxi/Kconfig  |  8 +++++
>  drivers/dma/sdxi/Makefile |  6 ++++
>  drivers/dma/sdxi/device.c | 26 +++++++++++++++
>  drivers/dma/sdxi/pci.c    | 83 +++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/dma/sdxi/sdxi.h   | 38 ++++++++++++++++++++++
>  7 files changed, 164 insertions(+)
>
> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
> index ae6a682c9f76..3d89284e7cf8 100644
> --- a/drivers/dma/Kconfig
> +++ b/drivers/dma/Kconfig
> @@ -762,6 +762,8 @@ source "drivers/dma/lgm/Kconfig"
>
>  source "drivers/dma/loongson/Kconfig"
>
> +source "drivers/dma/sdxi/Kconfig"
> +
>  source "drivers/dma/stm32/Kconfig"
>
>  # clients
> diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
> index 14aa086629d5..371927615c4a 100644
> --- a/drivers/dma/Makefile
> +++ b/drivers/dma/Makefile
> @@ -84,6 +84,7 @@ obj-$(CONFIG_XGENE_DMA) += xgene-dma.o
>  obj-$(CONFIG_ST_FDMA) += st_fdma.o
>  obj-$(CONFIG_FSL_DPAA2_QDMA) += fsl-dpaa2-qdma/
>  obj-$(CONFIG_INTEL_LDMA) += lgm/
> +obj-$(CONFIG_SDXI) += sdxi/
>
>  obj-y += amd/
>  obj-y += loongson/
> diff --git a/drivers/dma/sdxi/Kconfig b/drivers/dma/sdxi/Kconfig
> new file mode 100644
> index 000000000000..a568284cd583
> --- /dev/null
> +++ b/drivers/dma/sdxi/Kconfig
> @@ -0,0 +1,8 @@
> +config SDXI
> +	tristate "SDXI support"
> +	select DMA_ENGINE
> +	help
> +	  Enable support for Smart Data Accelerator Interface (SDXI)
> +	  Platform Data Mover devices. SDXI is a vendor-neutral
> +	  standard for a memory-to-memory data mover and acceleration
> +	  interface.
> diff --git a/drivers/dma/sdxi/Makefile b/drivers/dma/sdxi/Makefile
> new file mode 100644
> index 000000000000..f84b87d53e27
> --- /dev/null
> +++ b/drivers/dma/sdxi/Makefile
> @@ -0,0 +1,6 @@
> +# SPDX-License-Identifier: GPL-2.0
> +obj-$(CONFIG_SDXI) += sdxi.o
> +
> +sdxi-objs += device.o
> +
> +sdxi-$(CONFIG_PCI_MSI) += pci.o
> diff --git a/drivers/dma/sdxi/device.c b/drivers/dma/sdxi/device.c
> new file mode 100644
> index 000000000000..b718ce04afa0
> --- /dev/null
> +++ b/drivers/dma/sdxi/device.c
> @@ -0,0 +1,26 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * SDXI hardware device driver
> + *
> + * Copyright Advanced Micro Devices, Inc.
> + */
> +
> +#include <linux/device.h>
> +#include <linux/slab.h>
> +
> +#include "sdxi.h"
> +
> +int sdxi_register(struct device *dev, const struct sdxi_bus_ops *ops)
> +{
> +	struct sdxi_dev *sdxi;
> +
> +	sdxi = devm_kzalloc(dev, sizeof(*sdxi), GFP_KERNEL);
> +	if (!sdxi)
> +		return -ENOMEM;
> +
> +	sdxi->dev = dev;
> +	sdxi->bus_ops = ops;
> +	dev_set_drvdata(dev, sdxi);
> +
> +	return sdxi->bus_ops->init(sdxi);
> +}
> diff --git a/drivers/dma/sdxi/pci.c b/drivers/dma/sdxi/pci.c
> new file mode 100644
> index 000000000000..9ac94d6f8b96
> --- /dev/null
> +++ b/drivers/dma/sdxi/pci.c
> @@ -0,0 +1,83 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * SDXI PCI device code
> + *
> + * Copyright Advanced Micro Devices, Inc.
> + */
> +
> +#include <linux/dev_printk.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/iomap.h>
> +#include <linux/module.h>
> +#include <linux/pci.h>
> +
> +#include "sdxi.h"
> +
> +enum sdxi_mmio_bars {
> +	SDXI_PCI_BAR_CTL_REGS = 0,
> +	SDXI_PCI_BAR_DOORBELL = 2,
> +};
> +
> +static struct pci_dev *sdxi_to_pci_dev(const struct sdxi_dev *sdxi)
> +{
> +	return to_pci_dev(sdxi->dev);
> +}
> +
> +static int sdxi_pci_init(struct sdxi_dev *sdxi)
> +{
> +	struct pci_dev *pdev = sdxi_to_pci_dev(sdxi);
> +	struct device *dev = &pdev->dev;
> +	int ret;
> +
> +	ret = pcim_enable_device(pdev);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to enable device\n");
> +
> +	dma_set_mask_and_coherent(dev, DMA_BIT_MASK(64));
> +
> +	sdxi->ctrl_regs = pcim_iomap_region(pdev, SDXI_PCI_BAR_CTL_REGS,
> +					    KBUILD_MODNAME);
> +	if (IS_ERR(sdxi->ctrl_regs))
> +		return dev_err_probe(dev, PTR_ERR(sdxi->ctrl_regs),
> +				     "failed to map control registers\n");
> +
> +	sdxi->dbs = pcim_iomap_region(pdev, SDXI_PCI_BAR_DOORBELL,
> +				      KBUILD_MODNAME);
> +	if (IS_ERR(sdxi->dbs))
> +		return dev_err_probe(dev, PTR_ERR(sdxi->dbs),
> +				     "failed to map doorbell region\n");
> +
> +	pci_set_master(pdev);
> +	return 0;
> +}
> +
> +static const struct sdxi_bus_ops sdxi_pci_ops = {
> +	.init = sdxi_pci_init,
> +};
> +
> +static int sdxi_pci_probe(struct pci_dev *pdev,
> +			  const struct pci_device_id *id)
> +{
> +	return sdxi_register(&pdev->dev, &sdxi_pci_ops);
> +}
> +
> +static const struct pci_device_id sdxi_id_table[] = {
> +	{ PCI_DEVICE_CLASS(PCI_CLASS_ACCELERATOR_SDXI, 0xffffff) },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(pci, sdxi_id_table);
> +
> +static struct pci_driver sdxi_driver = {
> +	.name = "sdxi",
> +	.id_table = sdxi_id_table,
> +	.probe = sdxi_pci_probe,
> +	.sriov_configure = pci_sriov_configure_simple,
> +};
> +
> +MODULE_AUTHOR("Wei Huang");
> +MODULE_AUTHOR("Nathan Lynch");
> +MODULE_DESCRIPTION("SDXI PCIe interface driver");
> +MODULE_LICENSE("GPL");
> +module_pci_driver(sdxi_driver);
> diff --git a/drivers/dma/sdxi/sdxi.h b/drivers/dma/sdxi/sdxi.h
> new file mode 100644
> index 000000000000..d4c61ca2f875
> --- /dev/null
> +++ b/drivers/dma/sdxi/sdxi.h
> @@ -0,0 +1,38 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * SDXI device driver header
> + *
> + * Copyright Advanced Micro Devices, Inc.
> + */
> +
> +#ifndef DMA_SDXI_H
> +#define DMA_SDXI_H
> +
> +#include <linux/compiler_types.h>
> +#include <linux/types.h>
> +
> +struct sdxi_dev;
> +
> +/**
> + * struct sdxi_bus_ops - Bus-specific methods for SDXI devices.
> + */
> +struct sdxi_bus_ops {
> +	/**
> +	 * @init: Map control registers and doorbell region, allocate
> +	 *        IRQ ranges. Invoked before bus-agnostic SDXI
> +	 *        function initialization.
> +	 */
> +	int (*init)(struct sdxi_dev *sdxi);
> +};
> +
> +struct sdxi_dev {
> +	struct device *dev;
> +	void __iomem *ctrl_regs;	/* virt addr of ctrl registers */
> +	void __iomem *dbs;		/* virt addr of doorbells */
> +
> +	const struct sdxi_bus_ops *bus_ops;
> +};
> +
> +int sdxi_register(struct device *dev, const struct sdxi_bus_ops *ops);
> +
> +#endif /* DMA_SDXI_H */
>
> --
> 2.54.0
>