[PATCH v2 2/5] fpga: dfl: expose feature revision from struct dfl_device

["Martin Hundebøll" <martin@geanix.com>]

From: Martin Hundebøll <mhu@silicom.dk>

Drivers can make use of the feature field from the DFL header, but
shouldn't know about the header structure. To avoid exposing such info,
and to reduce the number of reads from the io-mem, the revision is added
to struct dfl_device.

Signed-off-by: Martin Hundebøll <mhu@silicom.dk>
---

Changes since v1:
 * This patch replaces the previous patch 2 and exposes the feature
   revision through struct dfl_device instead of a helper reading from
   io-mem

 drivers/fpga/dfl.c  | 27 +++++++++++++++++----------
 drivers/fpga/dfl.h  |  1 +
 include/linux/dfl.h |  1 +
 3 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
index 511b20ff35a3..9381c579d1cd 100644
--- a/drivers/fpga/dfl.c
+++ b/drivers/fpga/dfl.c
@@ -381,6 +381,7 @@ dfl_dev_add(struct dfl_feature_platform_data *pdata,
 
 	ddev->type = feature_dev_id_type(pdev);
 	ddev->feature_id = feature->id;
+	ddev->revision = feature->revision;
 	ddev->cdev = pdata->dfl_cdev;
 
 	/* add mmio resource */
@@ -717,6 +718,7 @@ struct build_feature_devs_info {
  */
 struct dfl_feature_info {
 	u16 fid;
+	u8 rev;
 	struct resource mmio_res;
 	void __iomem *ioaddr;
 	struct list_head node;
@@ -796,6 +798,7 @@ static int build_info_commit_dev(struct build_feature_devs_info *binfo)
 		/* save resource information for each feature */
 		feature->dev = fdev;
 		feature->id = finfo->fid;
+		feature->revision = finfo->rev;
 
 		/*
 		 * the FIU header feature has some fundamental functions (sriov
@@ -910,19 +913,17 @@ static void build_info_free(struct build_feature_devs_info *binfo)
 	devm_kfree(binfo->dev, binfo);
 }
 
-static inline u32 feature_size(void __iomem *start)
+static inline u32 feature_size(u64 value)
 {
-	u64 v = readq(start + DFH);
-	u32 ofst = FIELD_GET(DFH_NEXT_HDR_OFST, v);
+	u32 ofst = FIELD_GET(DFH_NEXT_HDR_OFST, value);
 	/* workaround for private features with invalid size, use 4K instead */
 	return ofst ? ofst : 4096;
 }
 
-static u16 feature_id(void __iomem *start)
+static u16 feature_id(u64 value)
 {
-	u64 v = readq(start + DFH);
-	u16 id = FIELD_GET(DFH_ID, v);
-	u8 type = FIELD_GET(DFH_TYPE, v);
+	u16 id = FIELD_GET(DFH_ID, value);
+	u8 type = FIELD_GET(DFH_TYPE, value);
 
 	if (type == DFH_TYPE_FIU)
 		return FEATURE_ID_FIU_HEADER;
@@ -1021,10 +1022,15 @@ create_feature_instance(struct build_feature_devs_info *binfo,
 	unsigned int irq_base, nr_irqs;
 	struct dfl_feature_info *finfo;
 	int ret;
+	u8 rev;
+	u64 v;
+
+	v = readq(binfo->ioaddr + ofst);
+	rev = FIELD_GET(DFH_REVISION, v);
 
 	/* read feature size and id if inputs are invalid */
-	size = size ? size : feature_size(binfo->ioaddr + ofst);
-	fid = fid ? fid : feature_id(binfo->ioaddr + ofst);
+	size = size ? size : feature_size(v);
+	fid = fid ? fid : feature_id(v);
 
 	if (binfo->len - ofst < size)
 		return -EINVAL;
@@ -1038,6 +1044,7 @@ create_feature_instance(struct build_feature_devs_info *binfo,
 		return -ENOMEM;
 
 	finfo->fid = fid;
+	finfo->rev = rev;
 	finfo->mmio_res.start = binfo->start + ofst;
 	finfo->mmio_res.end = finfo->mmio_res.start + size - 1;
 	finfo->mmio_res.flags = IORESOURCE_MEM;
@@ -1166,7 +1173,7 @@ static int parse_feature_private(struct build_feature_devs_info *binfo,
 {
 	if (!is_feature_dev_detected(binfo)) {
 		dev_err(binfo->dev, "the private feature 0x%x does not belong to any AFU.\n",
-			feature_id(binfo->ioaddr + ofst));
+			feature_id(readq(binfo->ioaddr + ofst)));
 		return -EINVAL;
 	}
 
diff --git a/drivers/fpga/dfl.h b/drivers/fpga/dfl.h
index 2b82c96ba56c..422157cfd742 100644
--- a/drivers/fpga/dfl.h
+++ b/drivers/fpga/dfl.h
@@ -243,6 +243,7 @@ struct dfl_feature_irq_ctx {
 struct dfl_feature {
 	struct platform_device *dev;
 	u16 id;
+	u8 revision;
 	int resource_index;
 	void __iomem *ioaddr;
 	struct dfl_feature_irq_ctx *irq_ctx;
diff --git a/include/linux/dfl.h b/include/linux/dfl.h
index 6cc10982351a..431636a0dc78 100644
--- a/include/linux/dfl.h
+++ b/include/linux/dfl.h
@@ -38,6 +38,7 @@ struct dfl_device {
 	int id;
 	u16 type;
 	u16 feature_id;
+	u8 revision;
 	struct resource mmio_res;
 	int *irqs;
 	unsigned int num_irqs;
-- 
2.31.0