[PATCH v1 4/5] fpga: dfl: add generic support for MSIX interrupts

[matthew . gerlach]

From: Matthew Gerlach <matthew.gerlach@xxxxxxxxxxxxxxx>

Define and use a DFHv1 parameter to add generic support for MSIX
interrupts for DFL devices.

Signed-off-by: Matthew Gerlach <matthew.gerlach@xxxxxxxxxxxxxxx>
---
 drivers/fpga/dfl.c  | 59 +++++++++++++++++++++++++++++++++------------
 include/linux/dfl.h | 13 ++++++++++
 2 files changed, 57 insertions(+), 15 deletions(-)

diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
index b9aae85ba930..17f704dc8483 100644
--- a/drivers/fpga/dfl.c
+++ b/drivers/fpga/dfl.c
@@ -941,25 +941,11 @@ static int parse_feature_irqs(struct build_feature_devs_info *binfo,
 	void __iomem *base = binfo->ioaddr + ofst;
 	unsigned int i, ibase, inr = 0;
 	enum dfl_id_type type;
-	int virq;
+	int virq, off;
 	u64 v;
 
 	type = feature_dev_id_type(binfo->feature_dev);
 
-	/*
-	 * Ideally DFL framework should only read info from DFL header, but
-	 * current version DFL only provides mmio resources information for
-	 * each feature in DFL Header, no field for interrupt resources.
-	 * Interrupt resource information is provided by specific mmio
-	 * registers of each private feature which supports interrupt. So in
-	 * order to parse and assign irq resources, DFL framework has to look
-	 * into specific capability registers of these private features.
-	 *
-	 * Once future DFL version supports generic interrupt resource
-	 * information in common DFL headers, the generic interrupt parsing
-	 * code will be added. But in order to be compatible to old version
-	 * DFL, the driver may still fall back to these quirks.
-	 */
 	if (type == PORT_ID) {
 		switch (fid) {
 		case PORT_FEATURE_ID_UINT:
@@ -981,6 +967,28 @@ static int parse_feature_irqs(struct build_feature_devs_info *binfo,
 		}
 	}
 
+	if (fid != FEATURE_ID_AFU && fid != PORT_FEATURE_ID_ERROR &&
+	    fid != PORT_FEATURE_ID_UINT && fid != FME_FEATURE_ID_GLOBAL_ERR) {
+		v = readq(base);
+		v = FIELD_GET(DFH_VERSION, v);
+
+		if (v == 1) {
+			v =  readq(base + DFHv1_CSR_SIZE_GRP);
+			if (FIELD_GET(DFHv1_CSR_SIZE_GRP_HAS_PARAMS, v)) {
+				off = dfl_find_param(base + DFHv1_PARAM_HDR, ofst,
+						     DFHv1_PARAM_ID_MSIX);
+				if (off >= 0) {
+					ibase = readl(base + DFHv1_PARAM_HDR +
+						      off + DFHv1_PARAM_MSIX_STARTV);
+					inr = readl(base + DFHv1_PARAM_HDR +
+						    off + DFHv1_PARAM_MSIX_NUMV);
+					dev_dbg(binfo->dev, "%s start %d num %d fid 0x%x\n",
+						__func__, ibase, inr, fid);
+				}
+			}
+		}
+	}
+
 	if (!inr) {
 		*irq_base = 0;
 		*nr_irqs = 0;
@@ -1879,6 +1887,27 @@ long dfl_feature_ioctl_set_irq(struct platform_device *pdev,
 }
 EXPORT_SYMBOL_GPL(dfl_feature_ioctl_set_irq);
 
+int dfl_find_param(void __iomem *base, resource_size_t max, int param)
+{
+	int off = 0;
+	u64 v, next;
+
+	while (off < max) {
+		v = readq(base + off);
+		if (param == FIELD_GET(DFHv1_PARAM_HDR_ID, v))
+			return off;
+
+		next = FIELD_GET(DFHv1_PARAM_HDR_NEXT_OFFSET, v);
+		if (!next)
+			break;
+
+		off += next;
+	}
+
+	return -ENOENT;
+}
+EXPORT_SYMBOL_GPL(dfl_find_param);
+
 static void __exit dfl_fpga_exit(void)
 {
 	dfl_chardev_uinit();
diff --git a/include/linux/dfl.h b/include/linux/dfl.h
index 61bcf20c1bc8..5652879ab48e 100644
--- a/include/linux/dfl.h
+++ b/include/linux/dfl.h
@@ -69,6 +69,10 @@
 #define DFHv1_PARAM_HDR_VERSION		GENMASK_ULL(31, 16) /* Version Param */
 #define DFHv1_PARAM_HDR_NEXT_OFFSET	GENMASK_ULL(63, 32) /* Offset of next Param */
 
+#define DFHv1_PARAM_ID_MSIX	0x1
+#define DFHv1_PARAM_MSIX_STARTV	0x8
+#define DFHv1_PARAM_MSIX_NUMV	0xc
+
 /**
  * enum dfl_id_type - define the DFL FIU types
  */
@@ -142,4 +146,13 @@ void dfl_driver_unregister(struct dfl_driver *dfl_drv);
 	module_driver(__dfl_driver, dfl_driver_register, \
 		      dfl_driver_unregister)
 
+/*
+ * dfl_find_param() - find the offset of the given parameter
+ * @base: base pointer to start of dfl parameters in DFH
+ * @max: maximum offset to search
+ * @param: id of dfl parameter
+ *
+ * Return: positive offset on success, negative error code otherwise.
+ */
+int dfl_find_param(void __iomem *base, resource_size_t max, int param);
 #endif /* __LINUX_DFL_H */
-- 
2.25.1