[PATCH v4 24/25] dmaengine: sdxi: MSI/MSI-X vector allocation and mapping

[Nathan Lynch via B4 Relay <devnull+nathan.lynch.amd.com@kernel.org>]

From: Nathan Lynch <nathan.lynch@amd.com>

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