cxl: Move hpa_to_spa callback to a new root decoder ops structure

The root decoder's HPA to SPA translation logic was implemented using
a single function pointer. In preparation for additional per-decoder
callbacks, convert this into a struct cxl_rd_ops and move the
hpa_to_spa pointer into it.

To avoid maintaining a static ops instance populated with mostly NULL
pointers, allocate the ops structure dynamically only when a platform
requires overrides (e.g. XOR interleave decoding).

The setup can be extended as additional callbacks are added.

Co-developed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Link: https://patch.msgid.link/818530c82c351a9c0d3a204f593068dd2126a5a9.1754290144.git.alison.schofield@intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

drivers/cxl/acpi.c

@@ -20,7 +20,6 @@ static const guid_t acpi_cxl_qtg_id_guid =
 	GUID_INIT(0xF365F9A6, 0xA7DE, 0x4071,
 		  0xA6, 0x6A, 0xB4, 0x0C, 0x0B, 0x4F, 0x8E, 0x52);
 
-
 static u64 cxl_xor_hpa_to_spa(struct cxl_root_decoder *cxlrd, u64 hpa)
 {
 	struct cxl_cxims_data *cximsd = cxlrd->platform_data;
@@ -472,8 +471,13 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 
 	cxlrd->qos_class = cfmws->qtg_id;
 
-	if (cfmws->interleave_arithmetic == ACPI_CEDT_CFMWS_ARITHMETIC_XOR)
+	if (cfmws->interleave_arithmetic == ACPI_CEDT_CFMWS_ARITHMETIC_XOR) {
-		cxlrd->hpa_to_spa = cxl_xor_hpa_to_spa;
+		cxlrd->ops = kzalloc(sizeof(*cxlrd->ops), GFP_KERNEL);
+		if (!cxlrd->ops)
+			return -ENOMEM;
+
+		cxlrd->ops->hpa_to_spa = cxl_xor_hpa_to_spa;
+	}
 
 	rc = cxl_decoder_add(cxld, target_map);
 	if (rc)

drivers/cxl/core/port.c

@@ -450,6 +450,7 @@ static void cxl_root_decoder_release(struct device *dev)
 	if (atomic_read(&cxlrd->region_id) >= 0)
 		memregion_free(atomic_read(&cxlrd->region_id));
 	__cxl_decoder_release(&cxlrd->cxlsd.cxld);
+	kfree(cxlrd->ops);
 	kfree(cxlrd);
 }
 

drivers/cxl/core/region.c

@@ -2918,6 +2918,11 @@ static bool cxl_is_hpa_in_chunk(u64 hpa, struct cxl_region *cxlr, int pos)
 	return false;
 }
 
+static bool has_hpa_to_spa(struct cxl_root_decoder *cxlrd)
+{
+	return cxlrd->ops && cxlrd->ops->hpa_to_spa;
+}
+
 u64 cxl_dpa_to_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd,
 		   u64 dpa)
 {
@@ -2972,8 +2977,8 @@ u64 cxl_dpa_to_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd,
 	hpa = hpa_offset + p->res->start + p->cache_size;
 
 	/* Root decoder translation overrides typical modulo decode */
-	if (cxlrd->hpa_to_spa)
+	if (has_hpa_to_spa(cxlrd))
-		hpa = cxlrd->hpa_to_spa(cxlrd, hpa);
+		hpa = cxlrd->ops->hpa_to_spa(cxlrd, hpa);
 
 	if (!cxl_resource_contains_addr(p->res, hpa)) {
 		dev_dbg(&cxlr->dev,
@@ -2982,7 +2987,7 @@ u64 cxl_dpa_to_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd,
 	}
 
 	/* Simple chunk check, by pos & gran, only applies to modulo decodes */
-	if (!cxlrd->hpa_to_spa && (!cxl_is_hpa_in_chunk(hpa, cxlr, pos)))
+	if (!has_hpa_to_spa(cxlrd) && (!cxl_is_hpa_in_chunk(hpa, cxlr, pos)))
 		return ULLONG_MAX;
 
 	return hpa;

drivers/cxl/cxl.h

@@ -419,27 +419,33 @@ struct cxl_switch_decoder {
 };
 
 struct cxl_root_decoder;
-typedef u64 (*cxl_hpa_to_spa_fn)(struct cxl_root_decoder *cxlrd, u64 hpa);
+/**
+ * struct cxl_rd_ops - CXL root decoder callback operations
+ * @hpa_to_spa: Convert host physical address to system physical address
+ */
+struct cxl_rd_ops {
+	u64 (*hpa_to_spa)(struct cxl_root_decoder *cxlrd, u64 hpa);
+};
 
 /**
  * struct cxl_root_decoder - Static platform CXL address decoder
  * @res: host / parent resource for region allocations
  * @cache_size: extended linear cache size if exists, otherwise zero.
  * @region_id: region id for next region provisioning event
- * @hpa_to_spa: translate CXL host-physical-address to Platform system-physical-address
  * @platform_data: platform specific configuration data
  * @range_lock: sync region autodiscovery by address range
  * @qos_class: QoS performance class cookie
+ * @ops: CXL root decoder operations
  * @cxlsd: base cxl switch decoder
  */
 struct cxl_root_decoder {
 	struct resource *res;
 	resource_size_t cache_size;
 	atomic_t region_id;
-	cxl_hpa_to_spa_fn hpa_to_spa;
 	void *platform_data;
 	struct mutex range_lock;
 	int qos_class;
+	struct cxl_rd_ops *ops;
 	struct cxl_switch_decoder cxlsd;
 };