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

Nathan Lynch via B4 Relay
2026-04-10T13:07:50Z

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@amd.com>
Signed-off-by: Wei Huang <wei.huang2@amd.com>
Signed-off-by: Nathan Lynch <nathan.lynch@amd.com>
---
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