cxl: Introduce cxl_to_{ways,granularity}

Interleave granularity and ways have CXL specification defined encodings.
Promote the conversion helpers to a common header, and use them to
replace other open-coded instances.

Force caller to consider the error case of the conversion similarly to
other conversion helpers like kstrto*().

Co-developed-by: Ben Widawsky <bwidawsk@kernel.org>
Signed-off-by: Ben Widawsky <bwidawsk@kernel.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/165603875016.551046.17236943065932132355.stgit@dwillia2-xfh
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/cxl/acpi.c

@@ -9,10 +9,6 @@
 #include "cxlpci.h"
 #include "cxl.h"
 
-/* Encode defined in CXL 2.0 8.2.5.12.7 HDM Decoder Control Register */
-#define CFMWS_INTERLEAVE_WAYS(x)	(1 << (x)->interleave_ways)
-#define CFMWS_INTERLEAVE_GRANULARITY(x)	((x)->granularity + 8)
-
 static unsigned long cfmws_to_decoder_flags(int restrictions)
 {
 	unsigned long flags = CXL_DECODER_F_ENABLE;
@@ -34,7 +30,8 @@ static unsigned long cfmws_to_decoder_flags(int restrictions)
 static int cxl_acpi_cfmws_verify(struct device *dev,
 				 struct acpi_cedt_cfmws *cfmws)
 {
-	int expected_len;
+	int rc, expected_len;
+	unsigned int ways;
 
 	if (cfmws->interleave_arithmetic != ACPI_CEDT_CFMWS_ARITHMETIC_MODULO) {
 		dev_err(dev, "CFMWS Unsupported Interleave Arithmetic\n");
@@ -51,14 +48,14 @@ static int cxl_acpi_cfmws_verify(struct device *dev,
 		return -EINVAL;
 	}
 
-	if (CFMWS_INTERLEAVE_WAYS(cfmws) > CXL_DECODER_MAX_INTERLEAVE) {
-		dev_err(dev, "CFMWS Interleave Ways (%d) too large\n",
-			CFMWS_INTERLEAVE_WAYS(cfmws));
+	rc = cxl_to_ways(cfmws->interleave_ways, &ways);
+	if (rc) {
+		dev_err(dev, "CFMWS Interleave Ways (%d) invalid\n",
+			cfmws->interleave_ways);
 		return -EINVAL;
 	}
 
-	expected_len = struct_size((cfmws), interleave_targets,
-				   CFMWS_INTERLEAVE_WAYS(cfmws));
+	expected_len = struct_size(cfmws, interleave_targets, ways);
 
 	if (cfmws->header.length < expected_len) {
 		dev_err(dev, "CFMWS length %d less than expected %d\n",
@@ -87,7 +84,8 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
 	struct device *dev = ctx->dev;
 	struct acpi_cedt_cfmws *cfmws;
 	struct cxl_decoder *cxld;
-	int rc, i;
+	unsigned int ways, i, ig;
+	int rc;
 
 	cfmws = (struct acpi_cedt_cfmws *) header;
 
@@ -99,10 +97,16 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
 		return 0;
 	}
 
-	for (i = 0; i < CFMWS_INTERLEAVE_WAYS(cfmws); i++)
+	rc = cxl_to_ways(cfmws->interleave_ways, &ways);
+	if (rc)
+		return rc;
+	rc = cxl_to_granularity(cfmws->granularity, &ig);
+	if (rc)
+		return rc;
+	for (i = 0; i < ways; i++)
 		target_map[i] = cfmws->interleave_targets[i];
 
-	cxld = cxl_root_decoder_alloc(root_port, CFMWS_INTERLEAVE_WAYS(cfmws));
+	cxld = cxl_root_decoder_alloc(root_port, ways);
 	if (IS_ERR(cxld))
 		return 0;
 
@@ -112,8 +116,8 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
 		.start = cfmws->base_hpa,
 		.end = cfmws->base_hpa + cfmws->window_size - 1,
 	};
-	cxld->interleave_ways = CFMWS_INTERLEAVE_WAYS(cfmws);
-	cxld->interleave_granularity = CFMWS_INTERLEAVE_GRANULARITY(cfmws);
+	cxld->interleave_ways = ways;
+	cxld->interleave_granularity = ig;
 
 	rc = cxl_decoder_add(cxld, target_map);
 	if (rc)

drivers/cxl/core/hdm.c

@@ -128,33 +128,12 @@ struct cxl_hdm *devm_cxl_setup_hdm(struct cxl_port *port)
 }
 EXPORT_SYMBOL_NS_GPL(devm_cxl_setup_hdm, CXL);
 
-static int to_interleave_granularity(u32 ctrl)
-{
-	int val = FIELD_GET(CXL_HDM_DECODER0_CTRL_IG_MASK, ctrl);
-
-	return 256 << val;
-}
-
-static int to_interleave_ways(u32 ctrl)
-{
-	int val = FIELD_GET(CXL_HDM_DECODER0_CTRL_IW_MASK, ctrl);
-
-	switch (val) {
-	case 0 ... 4:
-		return 1 << val;
-	case 8 ... 10:
-		return 3 << (val - 8);
-	default:
-		return 0;
-	}
-}
-
 static int init_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld,
 			    int *target_map, void __iomem *hdm, int which)
 {
 	u64 size, base;
+	int i, rc;
 	u32 ctrl;
-	int i;
 	union {
 		u64 value;
 		unsigned char target_id[8];
@@ -183,14 +162,18 @@ static int init_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld,
 		if (ctrl & CXL_HDM_DECODER0_CTRL_LOCK)
 			cxld->flags |= CXL_DECODER_F_LOCK;
 	}
-	cxld->interleave_ways = to_interleave_ways(ctrl);
-	if (!cxld->interleave_ways) {
+	rc = cxl_to_ways(FIELD_GET(CXL_HDM_DECODER0_CTRL_IW_MASK, ctrl),
+			 &cxld->interleave_ways);
+	if (rc) {
 		dev_warn(&port->dev,
 			 "decoder%d.%d: Invalid interleave ways (ctrl: %#x)\n",
 			 port->id, cxld->id, ctrl);
-		return -ENXIO;
+		return rc;
 	}
-	cxld->interleave_granularity = to_interleave_granularity(ctrl);
+	rc = cxl_to_granularity(FIELD_GET(CXL_HDM_DECODER0_CTRL_IG_MASK, ctrl),
+				&cxld->interleave_granularity);
+	if (rc)
+		return rc;
 
 	if (FIELD_GET(CXL_HDM_DECODER0_CTRL_TYPE, ctrl))
 		cxld->target_type = CXL_DECODER_EXPANDER;

drivers/cxl/cxl.h

@@ -64,6 +64,32 @@ static inline int cxl_hdm_decoder_count(u32 cap_hdr)
 	return val ? val * 2 : 1;
 }
 
+/* Encode defined in CXL 2.0 8.2.5.12.7 HDM Decoder Control Register */
+static inline int cxl_to_granularity(u16 ig, unsigned int *val)
+{
+	if (ig > 6)
+		return -EINVAL;
+	*val = 256 << ig;
+	return 0;
+}
+
+/* Encode defined in CXL ECN "3, 6, 12 and 16-way memory Interleaving" */
+static inline int cxl_to_ways(u8 eniw, unsigned int *val)
+{
+	switch (eniw) {
+	case 0 ... 4:
+		*val = 1 << eniw;
+		break;
+	case 8 ... 10:
+		*val = 3 << (eniw - 8);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 /* CXL 2.0 8.2.8.1 Device Capabilities Array Register */
 #define CXLDEV_CAP_ARRAY_OFFSET 0x0
 #define   CXLDEV_CAP_ARRAY_CAP_ID 0