[PATCH v4 05/25] dmaengine: sdxi: Feature discovery and initial configuration
From: Nathan Lynch via B4 Relay
Date: Tue Nov 03 2026 - 21:51:01 EST
From: Nathan Lynch <nathan.lynch@xxxxxxx>
Discover the stopped function's version, doorbell stride, supported
operation groups, and context and buffer limits. Apply the driver
configuration to MMIO_CTL2 after function preparation has removed
inherited state.
Add capability fields and device bookkeeping. Report the SDXI version implemented by the function.
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 | 47 ++++++++++++++++++++++++++++++++++++++++++++++-
drivers/dma/sdxi/mmio.h | 13 +++++++++++++
drivers/dma/sdxi/sdxi.h | 6 ++++++
3 files changed, 65 insertions(+), 1 deletion(-)
diff --git a/drivers/dma/sdxi/device.c b/drivers/dma/sdxi/device.c
index 23a75beb6912..c03af5833414 100644
--- a/drivers/dma/sdxi/device.c
+++ b/drivers/dma/sdxi/device.c
@@ -8,9 +8,13 @@
#include <linux/bitfield.h>
#include <linux/delay.h>
#include <linux/device.h>
+#include <linux/dma-mapping.h>
#include <linux/export.h>
#include <linux/iopoll.h>
#include <linux/jiffies.h>
+#include <linux/limits.h>
+#include <linux/minmax.h>
+#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/time.h>
@@ -275,6 +279,43 @@ static int sdxi_fn_prepare(struct sdxi_dev *sdxi)
return 0;
}
+/*
+ * See SDXI 1.0 4.1.8 Activation of the SDXI Function by Software.
+ */
+static int sdxi_fn_activate(struct sdxi_dev *sdxi)
+{
+ u64 version, cap0, cap1, ctl2;
+
+ version = sdxi_read64(sdxi, SDXI_MMIO_VERSION);
+ dev_info(sdxi->dev, "SDXI %llu.%llu device found\n",
+ FIELD_GET(SDXI_MMIO_VERSION_MAJOR, version),
+ FIELD_GET(SDXI_MMIO_VERSION_MINOR, version));
+
+ /* Read capabilities and features. */
+ cap0 = sdxi_read64(sdxi, SDXI_MMIO_CAP0);
+ sdxi->db_stride = SZ_4K;
+ sdxi->db_stride *= 1U << FIELD_GET(SDXI_MMIO_CAP0_DB_STRIDE, cap0);
+
+ cap1 = sdxi_read64(sdxi, SDXI_MMIO_CAP1);
+ sdxi->op_grp_cap = FIELD_GET(SDXI_MMIO_CAP1_OPB_000_CAP, cap1);
+ 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);
+
+ /* Apply our configuration. */
+ ctl2 = FIELD_PREP(SDXI_MMIO_CTL2_MAX_CXT, sdxi->max_cxtid);
+ ctl2 |= FIELD_PREP(SDXI_MMIO_CTL2_MAX_BUFFER,
+ sdxi->max_buffer);
+ ctl2 |= FIELD_PREP(SDXI_MMIO_CTL2_MAX_AKEY_SZ,
+ FIELD_GET(SDXI_MMIO_CAP1_MAX_AKEY_SZ, cap1));
+ ctl2 |= FIELD_PREP(SDXI_MMIO_CTL2_OPB_000_AVL,
+ FIELD_GET(SDXI_MMIO_CAP1_OPB_000_CAP, cap1));
+ sdxi_write64(sdxi, SDXI_MMIO_CTL2, ctl2);
+
+ return 0;
+}
+
int sdxi_register(struct device *dev, const struct sdxi_bus_ops *ops)
{
struct sdxi_dev *sdxi;
@@ -292,7 +333,11 @@ int sdxi_register(struct device *dev, const struct sdxi_bus_ops *ops)
if (err)
return err;
- return sdxi_fn_prepare(sdxi);
+ err = sdxi_fn_prepare(sdxi);
+ if (err)
+ return err;
+
+ return sdxi_fn_activate(sdxi);
}
EXPORT_SYMBOL_NS_GPL(sdxi_register, "SDXI");
diff --git a/drivers/dma/sdxi/mmio.h b/drivers/dma/sdxi/mmio.h
index a9c1fbb404d5..7c416de9f874 100644
--- a/drivers/dma/sdxi/mmio.h
+++ b/drivers/dma/sdxi/mmio.h
@@ -16,7 +16,9 @@ enum sdxi_reg {
SDXI_MMIO_CTL0 = 0x00000,
SDXI_MMIO_CTL2 = 0x00010,
SDXI_MMIO_STS0 = 0x00100,
+ SDXI_MMIO_CAP0 = 0x00200,
SDXI_MMIO_CAP1 = 0x00208,
+ SDXI_MMIO_VERSION = 0x00210,
/* SDXI 1.0 9.2 Context and RKey Table Registers */
SDXI_MMIO_CXT_L2 = 0x10000,
@@ -48,6 +50,11 @@ enum sdxi_reg {
/* SDXI 1.0 Table 9-5: MMIO_STS0 */
#define SDXI_MMIO_STS0_FN_GSV GENMASK_ULL(2, 0)
+/* SDXI 1.0 Table 9-6: MMIO_CAP0 */
+#define SDXI_MMIO_CAP0_SFUNC GENMASK_ULL(15, 0)
+#define SDXI_MMIO_CAP0_DB_STRIDE GENMASK_ULL(22, 20)
+#define SDXI_MMIO_CAP0_MAX_DS_RING_SZ GENMASK_ULL(28, 24)
+
/* SDXI 1.0 Table 9-7: MMIO_CAP1 */
#define SDXI_MMIO_CAP1_MAX_BUFFER GENMASK_ULL(3, 0)
#define SDXI_MMIO_CAP1_RKEY_CAP BIT_ULL(4)
@@ -55,6 +62,12 @@ enum sdxi_reg {
#define SDXI_MMIO_CAP1_MAX_AKEY_SZ GENMASK_ULL(15, 12)
#define SDXI_MMIO_CAP1_MAX_CXT GENMASK_ULL(31, 16)
+#define SDXI_MMIO_CAP1_OPB_000_CAP GENMASK_ULL(63, 32)
+
+/* SDXI 1.0 Table 9-8: MMIO_VERSION */
+#define SDXI_MMIO_VERSION_MINOR GENMASK_ULL(7, 0)
+#define SDXI_MMIO_VERSION_MAJOR GENMASK_ULL(23, 16)
+
/* 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 bb0d2165d495..7569b8395ce1 100644
--- a/drivers/dma/sdxi/sdxi.h
+++ b/drivers/dma/sdxi/sdxi.h
@@ -38,6 +38,12 @@ struct sdxi_dev {
void __iomem *ctrl_regs; /* virt addr of ctrl registers */
void __iomem *dbs; /* virt addr of doorbells */
+ /* hardware capabilities (from cap0 & cap1) */
+ u32 db_stride; /* doorbell stride in bytes */
+ u16 max_cxtid; /* Maximum context ID allowed. */
+ u8 max_buffer; /* Configured log2 buffer size minus 21. */
+ u32 op_grp_cap; /* supported operation group cap */
+
bool has_mailbox;
const struct sdxi_bus_ops *bus_ops;
--
2.56.0