[PATCH v4 06/25] dmaengine: sdxi: Configure context tables
From: Nathan Lynch via B4 Relay
Date: Tue Nov 03 2026 - 21:52:52 EST
From: Nathan Lynch <nathan.lynch@xxxxxxx>
SDXI uses a two-level table hierarchy to track contexts. There is a
single level 2 table per function which enumerates up to 512 level 1
tables. Each level 1 table enumerates up to 128 contexts.
Allocate and install the L2 table and a single L1 table, enough for
context IDs 0-127 (i.e. the admin context with reserved id 0, plus 127
client contexts). For now, to avoid dynamic management of additional
L1 tables, cap ctl2.max_cxt to 127.
Since the table allocations are devres-managed, there is no
corresponding cleanup code required.
Co-developed-by: Wei Huang <wei.huang2@xxxxxxx>
Signed-off-by: Wei Huang <wei.huang2@xxxxxxx>
Signed-off-by: Nathan Lynch <nathan.lynch@xxxxxxx>
---
drivers/dma/sdxi/device.c | 39 ++++++++++++++++++++++++++++++++++--
drivers/dma/sdxi/hw.h | 50 +++++++++++++++++++++++++++++++++++++++++++++++
drivers/dma/sdxi/mmio.h | 3 +++
drivers/dma/sdxi/sdxi.h | 5 +++++
4 files changed, 95 insertions(+), 2 deletions(-)
diff --git a/drivers/dma/sdxi/device.c b/drivers/dma/sdxi/device.c
index c03af5833414..baf55f6b6826 100644
--- a/drivers/dma/sdxi/device.c
+++ b/drivers/dma/sdxi/device.c
@@ -13,11 +13,13 @@
#include <linux/iopoll.h>
#include <linux/jiffies.h>
#include <linux/limits.h>
+#include <linux/log2.h>
#include <linux/minmax.h>
#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/time.h>
+#include "hw.h"
#include "mmio.h"
#include "sdxi.h"
@@ -284,7 +286,8 @@ static int sdxi_fn_prepare(struct sdxi_dev *sdxi)
*/
static int sdxi_fn_activate(struct sdxi_dev *sdxi)
{
- u64 version, cap0, cap1, ctl2;
+ u64 version, cap0, cap1, ctl2, cxt_l2, lv01_ptr;
+ struct sdxi_cxt_L2_ent *L2_ent;
version = sdxi_read64(sdxi, SDXI_MMIO_VERSION);
dev_info(sdxi->dev, "SDXI %llu.%llu device found\n",
@@ -301,7 +304,13 @@ static int sdxi_fn_activate(struct sdxi_dev *sdxi)
sdxi->max_buffer = FIELD_GET(SDXI_MMIO_CAP1_MAX_BUFFER, cap1);
dma_set_max_seg_size(sdxi->dev,
min((u64)SZ_2M << sdxi->max_buffer, U32_MAX));
- sdxi->max_cxtid = FIELD_GET(SDXI_MMIO_CAP1_MAX_CXT, cap1);
+
+ /*
+ * Constrain the number of client contexts supported by the
+ * driver to what fits in a single L1 table.
+ */
+ sdxi->max_cxtid = min(SDXI_L1_TABLE_ENTRIES - 1,
+ FIELD_GET(SDXI_MMIO_CAP1_MAX_CXT, cap1));
/* Apply our configuration. */
ctl2 = FIELD_PREP(SDXI_MMIO_CTL2_MAX_CXT, sdxi->max_cxtid);
@@ -313,6 +322,32 @@ static int sdxi_fn_activate(struct sdxi_dev *sdxi)
FIELD_GET(SDXI_MMIO_CAP1_OPB_000_CAP, cap1));
sdxi_write64(sdxi, SDXI_MMIO_CTL2, ctl2);
+ /* SDXI 1.0 4.1.8.2 Context Level 2 Table Setup */
+ sdxi->L2_table = dmam_alloc_coherent(sdxi->dev,
+ sizeof(*sdxi->L2_table),
+ &sdxi->L2_dma, GFP_KERNEL);
+ if (!sdxi->L2_table)
+ return -ENOMEM;
+
+ cxt_l2 = FIELD_PREP(SDXI_MMIO_CXT_L2_PTR, sdxi->L2_dma >> ilog2(SZ_4K));
+ sdxi_write64(sdxi, SDXI_MMIO_CXT_L2, cxt_l2);
+
+ /* SDXI 1.0 4.1.8.3 Context Level 1 Table Setup */
+ sdxi->L1_table = dmam_alloc_coherent(sdxi->dev,
+ sizeof(*sdxi->L1_table),
+ &sdxi->L1_dma, GFP_KERNEL);
+ if (!sdxi->L1_table)
+ return -ENOMEM;
+ /*
+ * SDXI 1.0 4.1.8.3.c: Initialize the Context level 2 table to
+ * point to the Context Level 1 [table].
+ */
+ L2_ent = &sdxi->L2_table->entry[0];
+ lv01_ptr = FIELD_PREP(SDXI_CXT_L2_ENT_VL, 1) |
+ FIELD_PREP(SDXI_CXT_L2_ENT_LV01_PTR,
+ sdxi->L1_dma >> ilog2(SZ_4K));
+ L2_ent->lv01_ptr = cpu_to_le64(lv01_ptr);
+
return 0;
}
diff --git a/drivers/dma/sdxi/hw.h b/drivers/dma/sdxi/hw.h
new file mode 100644
index 000000000000..0551c2b52980
--- /dev/null
+++ b/drivers/dma/sdxi/hw.h
@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright Advanced Micro Devices, Inc. */
+
+/*
+ * Hardware layouts and constants follow SDXI specification names and
+ * definition order. Reserved fields and bits must be zero unless specified
+ * otherwise.
+ */
+
+#ifndef DMA_SDXI_HW_H
+#define DMA_SDXI_HW_H
+
+#include <linux/bits.h>
+#include <linux/build_bug.h>
+#include <linux/types.h>
+#include <asm/byteorder.h>
+
+/* SDXI 1.0 Table 3-2: Context Level 2 Table Entry (CXT_L2_ENT) */
+struct sdxi_cxt_L2_ent {
+ __le64 lv01_ptr;
+#define SDXI_CXT_L2_ENT_VL BIT_ULL(0)
+#define SDXI_CXT_L2_ENT_LV01_PTR GENMASK_ULL(63, 12)
+} __packed __aligned(8);
+static_assert(sizeof(struct sdxi_cxt_L2_ent) == 8);
+
+/* SDXI 1.0 3.2.1 Context Level 2 Table */
+#define SDXI_L2_TABLE_ENTRIES 512
+struct sdxi_cxt_L2_table {
+ struct sdxi_cxt_L2_ent entry[SDXI_L2_TABLE_ENTRIES];
+};
+static_assert(sizeof(struct sdxi_cxt_L2_table) == 4096);
+
+/* SDXI 1.0 Table 3-3: Context Level 1 Table Entry (CXT_L1_ENT) */
+struct sdxi_cxt_L1_ent {
+ __le64 cxt_ctl_ptr;
+ __le64 akey_ptr;
+ __le32 misc0;
+ __le32 opb_000_enb;
+ __u8 rsvd_0[8];
+} __packed __aligned(32);
+static_assert(sizeof(struct sdxi_cxt_L1_ent) == 32);
+
+/* SDXI 1.0 3.2.2 Context Level 1 Table */
+#define SDXI_L1_TABLE_ENTRIES 128
+struct sdxi_cxt_L1_table {
+ struct sdxi_cxt_L1_ent entry[SDXI_L1_TABLE_ENTRIES];
+};
+static_assert(sizeof(struct sdxi_cxt_L1_table) == 4096);
+
+#endif /* DMA_SDXI_HW_H */
diff --git a/drivers/dma/sdxi/mmio.h b/drivers/dma/sdxi/mmio.h
index 7c416de9f874..b040d2283fb2 100644
--- a/drivers/dma/sdxi/mmio.h
+++ b/drivers/dma/sdxi/mmio.h
@@ -68,6 +68,9 @@ enum sdxi_reg {
#define SDXI_MMIO_VERSION_MINOR GENMASK_ULL(7, 0)
#define SDXI_MMIO_VERSION_MAJOR GENMASK_ULL(23, 16)
+/* SDXI 1.0 Table 9-9: MMIO_CXT_L2 */
+#define SDXI_MMIO_CXT_L2_PTR GENMASK_ULL(63, 12)
+
/* SDXI 1.0 Table 9-10: MMIO_RKEY */
#define SDXI_MMIO_RKEY_EN BIT_ULL(0)
diff --git a/drivers/dma/sdxi/sdxi.h b/drivers/dma/sdxi/sdxi.h
index 7569b8395ce1..856a3838eec3 100644
--- a/drivers/dma/sdxi/sdxi.h
+++ b/drivers/dma/sdxi/sdxi.h
@@ -44,6 +44,11 @@ struct sdxi_dev {
u8 max_buffer; /* Configured log2 buffer size minus 21. */
u32 op_grp_cap; /* supported operation group cap */
+ struct sdxi_cxt_L2_table *L2_table;
+ dma_addr_t L2_dma;
+ struct sdxi_cxt_L1_table *L1_table;
+ dma_addr_t L1_dma;
+
bool has_mailbox;
const struct sdxi_bus_ops *bus_ops;
--
2.56.0