Re: [PATCH 07/23] dmaengine: sdxi: Allocate administrative context

[Frank Li]

On Fri, Apr 10, 2026 at 08:07:17AM -0500, Nathan Lynch wrote:
> Create the control structure hierarchy in memory for the per-function
> administrative context. Use devres to queue the corresponding cleanup
> since the admin context is a device-scope resource. The context is
> inert for now; changes to follow will make it functional.
>
> 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/sdxi/Makefile  |   4 +-
>  drivers/dma/sdxi/context.c | 128 +++++++++++++++++++++++++++++++++++++++++++++
>  drivers/dma/sdxi/context.h |  54 +++++++++++++++++++
>  drivers/dma/sdxi/device.c  |  11 ++++
>  drivers/dma/sdxi/hw.h      |  43 +++++++++++++++
>  drivers/dma/sdxi/sdxi.h    |   2 +
>  6 files changed, 241 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dma/sdxi/Makefile b/drivers/dma/sdxi/Makefile
> index f84b87d53e27..2178f274831c 100644
> --- a/drivers/dma/sdxi/Makefile
> +++ b/drivers/dma/sdxi/Makefile
> @@ -1,6 +1,8 @@
>  # SPDX-License-Identifier: GPL-2.0
>  obj-$(CONFIG_SDXI) += sdxi.o
>
> -sdxi-objs += device.o
> +sdxi-objs += \
> +	context.o     \
> +	device.o
>
>  sdxi-$(CONFIG_PCI_MSI) += pci.o
> diff --git a/drivers/dma/sdxi/context.c b/drivers/dma/sdxi/context.c
> new file mode 100644
> index 000000000000..0a6821992776
> --- /dev/null
> +++ b/drivers/dma/sdxi/context.c
> @@ -0,0 +1,128 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * SDXI context management
> + *
> + * Copyright Advanced Micro Devices, Inc.
> + */
> +
> +#define pr_fmt(fmt)     "SDXI: " fmt
> +
> +#include <linux/bug.h>
> +#include <linux/cleanup.h>
> +#include <linux/device/devres.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/dmapool.h>
> +#include <linux/errno.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +
> +#include "context.h"
> +#include "sdxi.h"
> +
> +#define DEFAULT_DESC_RING_ENTRIES 1024
> +
> +enum {
> +	/*
> +	 * The admin context always has ID 0. See SDXI 1.0 3.5
> +	 * Administrative Context (Context 0).
> +	 */
> +	SDXI_ADMIN_CXT_ID = 0,
> +};
> +
> +/*
> + * Free context and its resources. @cxt may be partially allocated but
> + * must have ->sdxi set.
> + */
> +static void sdxi_free_cxt(struct sdxi_cxt *cxt)
> +{
> +	struct sdxi_dev *sdxi = cxt->sdxi;
> +	struct sdxi_sq *sq = cxt->sq;
> +
> +	if (cxt->cxt_ctl)
> +		dma_pool_free(sdxi->cxt_ctl_pool, cxt->cxt_ctl,
> +			      cxt->cxt_ctl_dma);
> +	if (cxt->akey_table)
> +		dma_free_coherent(sdxi_to_dev(sdxi), sizeof(*cxt->akey_table),
> +				  cxt->akey_table, cxt->akey_table_dma);
> +	if (sq && sq->write_index)
> +		dma_pool_free(sdxi->write_index_pool, sq->write_index,
> +			      sq->write_index_dma);
> +	if (sq && sq->cxt_sts)
> +		dma_pool_free(sdxi->cxt_sts_pool, sq->cxt_sts, sq->cxt_sts_dma);
> +	if (sq && sq->desc_ring)
> +		dma_free_coherent(sdxi_to_dev(sdxi), sq->ring_size,
> +				  sq->desc_ring, sq->ring_dma);
> +	kfree(cxt->sq);
> +	kfree(cxt);
> +}
> +
> +DEFINE_FREE(sdxi_cxt, struct sdxi_cxt *, if (_T) sdxi_free_cxt(_T))
> +
> +/* Allocate a context and its control structure hierarchy in memory. */
> +static struct sdxi_cxt *sdxi_alloc_cxt(struct sdxi_dev *sdxi)
> +{
> +	struct device *dev = sdxi_to_dev(sdxi);
> +	struct sdxi_sq *sq;
> +	struct sdxi_cxt *cxt __free(sdxi_cxt) = kzalloc(sizeof(*cxt), GFP_KERNEL);
> +
> +	if (!cxt)
> +		return NULL;
> +
> +	cxt->sdxi = sdxi;
> +
> +	cxt->sq = kzalloc_obj(*cxt->sq, GFP_KERNEL);
> +	if (!cxt->sq)
> +		return NULL;
> +
> +	cxt->akey_table = dma_alloc_coherent(dev, sizeof(*cxt->akey_table),
> +					     &cxt->akey_table_dma, GFP_KERNEL);
> +	if (!cxt->akey_table)
> +		return NULL;
> +
> +	cxt->cxt_ctl = dma_pool_zalloc(sdxi->cxt_ctl_pool, GFP_KERNEL,
> +				       &cxt->cxt_ctl_dma);
> +	if (!cxt->cxt_ctl_dma)
> +		return NULL;
> +
> +	sq = cxt->sq;
> +
> +	sq->ring_entries = DEFAULT_DESC_RING_ENTRIES;
> +	sq->ring_size = sq->ring_entries * sizeof(sq->desc_ring[0]);
> +	sq->desc_ring = dma_alloc_coherent(dev, sq->ring_size, &sq->ring_dma,
> +					   GFP_KERNEL);
> +	if (!sq->desc_ring)
> +		return NULL;
> +
> +	sq->cxt_sts = dma_pool_zalloc(sdxi->cxt_sts_pool, GFP_KERNEL,
> +				      &sq->cxt_sts_dma);
> +	if (!sq->cxt_sts)
> +		return NULL;
> +
> +	sq->write_index = dma_pool_zalloc(sdxi->write_index_pool, GFP_KERNEL,
> +					  &sq->write_index_dma);
> +	if (!sq->write_index)
> +		return NULL;
> +
> +	return_ptr(cxt);
> +}
> +
> +static void free_admin_cxt(void *ptr)
> +{
> +	struct sdxi_dev *sdxi = ptr;
> +
> +	sdxi_free_cxt(sdxi->admin_cxt);
> +}
> +
> +int sdxi_admin_cxt_init(struct sdxi_dev *sdxi)
> +{
> +	struct sdxi_cxt *cxt __free(sdxi_cxt) = sdxi_alloc_cxt(sdxi);
> +	if (!cxt)
> +		return -ENOMEM;
> +
> +	cxt->id = SDXI_ADMIN_CXT_ID;
> +	cxt->db = sdxi->dbs + cxt->id * sdxi->db_stride;
> +
> +	sdxi->admin_cxt = no_free_ptr(cxt);
> +
> +	return devm_add_action_or_reset(sdxi_to_dev(sdxi), free_admin_cxt, sdxi);
> +}
> diff --git a/drivers/dma/sdxi/context.h b/drivers/dma/sdxi/context.h
> new file mode 100644
> index 000000000000..800b4ead1dd9
> --- /dev/null
> +++ b/drivers/dma/sdxi/context.h
> @@ -0,0 +1,54 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright Advanced Micro Devices, Inc.
> + */
> +
> +#ifndef DMA_SDXI_CONTEXT_H
> +#define DMA_SDXI_CONTEXT_H
> +
> +#include <linux/dma-mapping.h>
> +#include <linux/types.h>
> +
> +#include "hw.h"
> +#include "sdxi.h"
> +
> +/*
> + * The size of the AKey table is flexible, from 4KB to 1MB. Always use
> + * the minimum size for now.
> + */
> +struct sdxi_akey_table {
> +	struct sdxi_akey_ent entry[SZ_4K / sizeof(struct sdxi_akey_ent)];
> +};
> +
> +/* Submission Queue */
> +struct sdxi_sq {
> +	u32 ring_entries;
> +	u32 ring_size;
> +	struct sdxi_desc *desc_ring;
> +	dma_addr_t ring_dma;
> +
> +	__le64 *write_index;
> +	dma_addr_t write_index_dma;
> +
> +	struct sdxi_cxt_sts *cxt_sts;
> +	dma_addr_t cxt_sts_dma;
> +};
> +
> +struct sdxi_cxt {
> +	struct sdxi_dev *sdxi;
> +	unsigned int id;
> +
> +	__le64 __iomem *db;
> +
> +	struct sdxi_cxt_ctl *cxt_ctl;
> +	dma_addr_t cxt_ctl_dma;
> +
> +	struct sdxi_akey_table *akey_table;
> +	dma_addr_t akey_table_dma;
> +
> +	struct sdxi_sq *sq;
> +};
> +
> +int sdxi_admin_cxt_init(struct sdxi_dev *sdxi);
> +
> +#endif /* DMA_SDXI_CONTEXT_H */
> diff --git a/drivers/dma/sdxi/device.c b/drivers/dma/sdxi/device.c
> index 80bd1bbd9c7c..636abc410dcd 100644
> --- a/drivers/dma/sdxi/device.c
> +++ b/drivers/dma/sdxi/device.c
> @@ -13,6 +13,7 @@
>  #include <linux/log2.h>
>  #include <linux/slab.h>
>
> +#include "context.h"
>  #include "hw.h"
>  #include "mmio.h"
>  #include "sdxi.h"
> @@ -186,6 +187,16 @@ static int sdxi_fn_activate(struct sdxi_dev *sdxi)
>  			       sdxi->L1_dma >> ilog2(SZ_4K));
>  	L2_ent->lv01_ptr = cpu_to_le64(lv01_ptr);
>
> +	/*
> +	 * SDXI 1.0 4.1.8.4 Administrative Context
> +	 *
> +	 * The admin context will not consume descriptors until we
> +	 * write its doorbell later.
> +	 */
> +	err = sdxi_admin_cxt_init(sdxi);
> +	if (err)
> +		return err;
> +
>  	return 0;
>  }
>
> diff --git a/drivers/dma/sdxi/hw.h b/drivers/dma/sdxi/hw.h
> index 846c671c423f..b66eb22f7f90 100644
> --- a/drivers/dma/sdxi/hw.h
> +++ b/drivers/dma/sdxi/hw.h
> @@ -23,6 +23,7 @@
>
>  #include <linux/bits.h>
>  #include <linux/build_bug.h>
> +#include <linux/stddef.h>
>  #include <linux/types.h>
>  #include <asm/byteorder.h>
>
> @@ -72,12 +73,39 @@ static_assert(sizeof(struct sdxi_cxt_ctl) == 64);
>  /* SDXI 1.0 Table 3-5: Context Status (CXT_STS) */
>  struct sdxi_cxt_sts {
>  	__u8 state;
> +#define SDXI_CXT_STS_STATE GENMASK(3, 0)
>  	__u8 misc0;
>  	__u8 rsvd_0[6];
>  	__le64 read_index;
>  } __packed;
>  static_assert(sizeof(struct sdxi_cxt_sts) == 16);
>
> +/* SDXI 1.0 Table 3-6: CXT_STS.state Encoding */
> +/* Valid values for FIELD_GET(SDXI_CXT_STS_STATE, sdxi_cxt_sts.state). */
> +enum cxt_sts_state {
> +	CXTV_STOP_SW  = 0x0,
> +	CXTV_RUN      = 0x1,
> +	CXTV_STOPG_SW = 0x2,
> +	CXTV_STOP_FN  = 0x4,
> +	CXTV_STOPG_FN = 0x6,
> +	CXTV_ERR_FN   = 0xf,
> +};
> +
> +/* SDXI 1.0 Table 3-7: AKey Table Entry (AKEY_ENT) */
> +struct sdxi_akey_ent {
> +	__le16 intr_num;
> +#define SDXI_AKEY_ENT_VL BIT(0)
> +#define SDXI_AKEY_ENT_IV BIT(1)
> +#define SDXI_AKEY_ENT_INTR_NUM GENMASK(14, 4)
> +	__le16 tgt_sfunc;
> +	__le32 pasid;
> +	__le16 stag;
> +	__u8   rsvd_0[2];
> +	__le16 rkey;
> +	__u8   rsvd_1[2];
> +} __packed;
> +static_assert(sizeof(struct sdxi_akey_ent) == 16);
> +
>  /* SDXI 1.0 Table 6-4: CST_BLK (Completion Status Block) */
>  struct sdxi_cst_blk {
>  	__le64 signal;
> @@ -86,4 +114,19 @@ struct sdxi_cst_blk {
>  } __packed;
>  static_assert(sizeof(struct sdxi_cst_blk) == 32);
>
> +struct sdxi_desc {
> +	union {
> +		/*
> +		 * SDXI 1.0 Table 6-3: DSC_GENERIC SDXI Descriptor
> +		 * Common Header and Footer Format
> +		 */
> +		struct_group_tagged(sdxi_dsc_generic, generic,
> +			__le32 opcode;
> +			__u8 operation[52];
> +			__le64 csb_ptr;
> +		);
> +	};
> +} __packed;
> +static_assert(sizeof(struct sdxi_desc) == 64);
> +
>  #endif /* DMA_SDXI_HW_H */
> diff --git a/drivers/dma/sdxi/sdxi.h b/drivers/dma/sdxi/sdxi.h
> index 6cda60bb33c4..4ef893ae15f3 100644
> --- a/drivers/dma/sdxi/sdxi.h
> +++ b/drivers/dma/sdxi/sdxi.h
> @@ -51,6 +51,8 @@ struct sdxi_dev {
>  	struct dma_pool *cxt_ctl_pool;
>  	struct dma_pool *cst_blk_pool;
>
> +	struct sdxi_cxt *admin_cxt;
> +
>  	const struct sdxi_bus_ops *bus_ops;
>  };
>
>
> --
> 2.53.0
>