[PATCH v4 24/25] dmaengine: sdxi: MSI/MSI-X vector allocation and mapping
From: Nathan Lynch via B4 Relay
Date: Tue Nov 03 2026 - 21:59:17 EST
From: Nathan Lynch <nathan.lynch@xxxxxxx>
Request MSI/MSI-X vectors for the error log interrupt and up to one
interrupt per supported client context. Reserve vector 0 for the error log
and track the remaining allocated vectors with an IDA.
Introduce sdxi_alloc_vector() and sdxi_free_vector() which are thin
wrappers around the IDA that tracks the allocated vector range.
Introduce sdxi_vector_to_irq() which invokes a new get_irq() bus op to
translate the device-relative index to the Linux IRQ number for use
with request_irq() etc. For PCI this dispatches to pci_irq_vector().
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 | 3 +++
drivers/dma/sdxi/pci.c | 30 ++++++++++++++++++++++++++-
drivers/dma/sdxi/sdxi.h | 53 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 85 insertions(+), 1 deletion(-)
diff --git a/drivers/dma/sdxi/device.c b/drivers/dma/sdxi/device.c
index 8786be71d3e3..30c4e687cedf 100644
--- a/drivers/dma/sdxi/device.c
+++ b/drivers/dma/sdxi/device.c
@@ -11,6 +11,7 @@
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
#include <linux/export.h>
+#include <linux/idr.h>
#include <linux/iopoll.h>
#include <linux/jiffies.h>
#include <linux/limits.h>
@@ -437,6 +438,7 @@ int sdxi_register(struct device *dev, const struct sdxi_bus_ops *ops)
sdxi->dev = dev;
sdxi->bus_ops = ops;
+ ida_init(&sdxi->vectors);
xa_init_flags(&sdxi->client_cxts, XA_FLAGS_ALLOC1);
dev_set_drvdata(dev, sdxi);
@@ -459,6 +461,7 @@ void sdxi_unregister(struct device *dev)
/* Stop/reset is best effort if the hardware cannot be quiesced. */
sdxi_dev_stop(sdxi);
sdxi_client_cxts_exit(sdxi);
+ ida_destroy(&sdxi->vectors);
}
EXPORT_SYMBOL_NS_GPL(sdxi_unregister, "SDXI");
diff --git a/drivers/dma/sdxi/pci.c b/drivers/dma/sdxi/pci.c
index d196ab5cf6f1..ef978ca22db1 100644
--- a/drivers/dma/sdxi/pci.c
+++ b/drivers/dma/sdxi/pci.c
@@ -31,8 +31,9 @@ static int sdxi_pci_init(struct sdxi_dev *sdxi)
{
struct pci_dev *pdev = sdxi_to_pci_dev(sdxi);
struct device *dev = &pdev->dev;
+ u32 cap1_max_cxt;
u64 cap1;
- int ret;
+ int vecs, ret;
ret = pcim_enable_device(pdev);
if (ret)
@@ -63,6 +64,27 @@ static int sdxi_pci_init(struct sdxi_dev *sdxi)
sdxi->has_mailbox = pdev->is_virtfn ||
pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_SRIOV);
+ /*
+ * Allocate the minimum required set of vectors plus one for
+ * each client context supported by the function.
+ *
+ * pci_alloc_irq_vectors() handles calling pci_free_irq_vectors()
+ * automatically despite not being called pcim_*. See
+ * pci_setup_msi_context().
+ */
+ cap1_max_cxt = FIELD_GET(SDXI_MMIO_CAP1_MAX_CXT,
+ sdxi_read64(sdxi, SDXI_MMIO_CAP1));
+ vecs = pci_alloc_irq_vectors(pdev, SDXI_MIN_VECTORS,
+ SDXI_MIN_VECTORS + cap1_max_cxt,
+ PCI_IRQ_MSI | PCI_IRQ_MSIX);
+ if (vecs < 0)
+ return dev_err_probe(dev, vecs,
+ "failed to allocate MSIs (max_cxt=%u)\n",
+ cap1_max_cxt);
+
+ sdxi->nr_vectors = vecs;
+ dev_dbg(sdxi->dev, "allocated %u vectors\n", sdxi->nr_vectors);
+
pci_set_master(pdev);
return 0;
}
@@ -86,9 +108,15 @@ static int sdxi_pci_reset(struct sdxi_dev *sdxi)
return err;
}
+static int sdxi_pci_get_irq(struct sdxi_dev *sdxi, unsigned int nr)
+{
+ return pci_irq_vector(sdxi_to_pci_dev(sdxi), nr);
+}
+
static const struct sdxi_bus_ops sdxi_pci_ops = {
.init = sdxi_pci_init,
.reset = sdxi_pci_reset,
+ .get_irq = sdxi_pci_get_irq,
};
static int sdxi_pci_probe(struct pci_dev *pdev,
diff --git a/drivers/dma/sdxi/sdxi.h b/drivers/dma/sdxi/sdxi.h
index aaa43eab00b3..07044d837d9a 100644
--- a/drivers/dma/sdxi/sdxi.h
+++ b/drivers/dma/sdxi/sdxi.h
@@ -8,8 +8,10 @@
#ifndef DMA_SDXI_H
#define DMA_SDXI_H
+#include <linux/bug.h>
#include <linux/compiler_types.h>
#include <linux/dev_printk.h>
+#include <linux/idr.h>
#include <linux/io.h>
#include <linux/types.h>
#include <linux/xarray.h>
@@ -25,6 +27,18 @@
#define L1_CXT_CTRL_PTR_SHIFT 6
#define L1_CXT_AKEY_PTR_SHIFT 12
+enum {
+ /* Reserve vector 0 for the error log interrupt. */
+ SDXI_ERROR_VECTOR = 0,
+
+ /*
+ * Request at least one vector to account for the error log
+ * interrupt. Increment this if the driver gains more
+ * dedicated interrupts (e.g. one for the admin context).
+ */
+ SDXI_MIN_VECTORS = 1,
+};
+
struct sdxi_dev;
/**
@@ -41,6 +55,10 @@ struct sdxi_bus_ops {
* @reset: Bus-specific recovery when the native stop sequence fails.
*/
int (*reset)(struct sdxi_dev *sdxi);
+ /**
+ * @get_irq: Map device interrupt index to Linux IRQ number.
+ */
+ int (*get_irq)(struct sdxi_dev *sdxi, unsigned int index);
};
struct sdxi_dev {
@@ -61,6 +79,9 @@ struct sdxi_dev {
struct dma_pool *cxt_ctl_pool;
+ unsigned int nr_vectors;
+ struct ida vectors;
+
struct sdxi_cxt *admin_cxt;
struct xarray client_cxts; /* context id -> (struct sdxi_cxt *) */
@@ -69,6 +90,38 @@ struct sdxi_dev {
const struct sdxi_bus_ops *bus_ops;
};
+/**
+ * sdxi_alloc_vector() - Allocate an interrupt vector.
+ *
+ * A vector that will have the same lifetime as the device does not
+ * need to be released explicitly. Otherwise the vector must be
+ * released with sdxi_free_vector().
+ */
+static inline int sdxi_alloc_vector(struct sdxi_dev *sdxi)
+{
+ return ida_alloc_range(&sdxi->vectors, SDXI_MIN_VECTORS,
+ sdxi->nr_vectors - 1, GFP_KERNEL);
+}
+
+/**
+ * sdxi_free_vector() - Release a previously allocated index.
+ */
+static inline void sdxi_free_vector(struct sdxi_dev *sdxi, unsigned int nr)
+{
+ ida_free(&sdxi->vectors, nr);
+}
+
+/**
+ * sdxi_vector_to_irq() - Translate an allocated interrupt vector to
+ * Linux IRQ number suitable for passing to
+ * request_irq() et al.
+ */
+static inline int sdxi_vector_to_irq(struct sdxi_dev *sdxi, unsigned int nr)
+{
+ WARN_ON_ONCE(!ida_exists(&sdxi->vectors, nr));
+ return sdxi->bus_ops->get_irq(sdxi, nr);
+}
+
int sdxi_register(struct device *dev, const struct sdxi_bus_ops *ops);
void sdxi_unregister(struct device *dev);
--
2.56.0