[PATCH v8 08/21] cxl/port: Add endpoint decoder DC mode support to sysfs

[Ira Weiny <ira.weiny@intel.com>]

Endpoint decoder mode is used to represent the partition the decoder
points to such as ram or pmem.

Expand the mode to allow a decoder to point to a specific DC partition
(Region).

Based on an original patch by Navneet Singh.

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>

---
Changes:
[Carpenter/smatch: fix cxl_decoder_mode_names array]
---
 Documentation/ABI/testing/sysfs-bus-cxl | 25 ++++++++++++------------
 drivers/cxl/core/hdm.c                  | 16 ++++++++++++++++
 drivers/cxl/core/port.c                 | 16 +++++++++++-----
 drivers/cxl/cxl.h                       | 34 +++++++++++++++++----------------
 4 files changed, 58 insertions(+), 33 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
index ff3ae83477f0876c0ee2d3955d27a11fa9d16d83..8d990d702f63363879150cf523c0be6229f315e0 100644
--- a/Documentation/ABI/testing/sysfs-bus-cxl
+++ b/Documentation/ABI/testing/sysfs-bus-cxl
@@ -361,23 +361,24 @@ Description:
 
 
 What:		/sys/bus/cxl/devices/decoderX.Y/mode
-Date:		May, 2022
-KernelVersion:	v6.0
+Date:		May, 2022, October 2024
+KernelVersion:	v6.0, v6.13 (dcY)
 Contact:	linux-cxl@vger.kernel.org
 Description:
 		(RW) When a CXL decoder is of devtype "cxl_decoder_endpoint" it
-		translates from a host physical address range, to a device local
-		address range. Device-local address ranges are further split
-		into a 'ram' (volatile memory) range and 'pmem' (persistent
-		memory) range. The 'mode' attribute emits one of 'ram', 'pmem',
-		'mixed', or 'none'. The 'mixed' indication is for error cases
-		when a decoder straddles the volatile/persistent partition
-		boundary, and 'none' indicates the decoder is not actively
-		decoding, or no DPA allocation policy has been set.
+		translates from a host physical address range, to a device
+		local address range. Device-local address ranges are further
+		split into a 'ram' (volatile memory) range, 'pmem' (persistent
+		memory) range, and Dynamic Capacity (DC) ranges. The 'mode'
+		attribute emits one of 'ram', 'pmem', 'dcY', 'mixed', or
+		'none'. The 'mixed' indication is for error cases when a
+		decoder straddles partition boundaries, and 'none' indicates
+		the decoder is not actively decoding, or no DPA allocation
+		policy has been set.
 
 		'mode' can be written, when the decoder is in the 'disabled'
-		state, with either 'ram' or 'pmem' to set the boundaries for the
-		next allocation.
+		state, with 'ram', 'pmem', or 'dcY' to set the boundaries for
+		the next allocation.
 
 
 What:		/sys/bus/cxl/devices/decoderX.Y/dpa_resource
diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
index e15241f94d17b774aa5befb37fb453af637a17ce..d0c32c3c6564df869d41030144c6d2a7c063747d 100644
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -548,6 +548,7 @@ int cxl_dpa_set_mode(struct cxl_endpoint_decoder *cxled,
 	switch (mode) {
 	case CXL_DECODER_RAM:
 	case CXL_DECODER_PMEM:
+	case CXL_DECODER_DC0 ... CXL_DECODER_DC7:
 		break;
 	default:
 		dev_dbg(dev, "unsupported mode: %d\n", mode);
@@ -571,6 +572,21 @@ int cxl_dpa_set_mode(struct cxl_endpoint_decoder *cxled,
 		return -ENXIO;
 	}
 
+	if (mode >= CXL_DECODER_DC0 && mode <= CXL_DECODER_DC7) {
+		struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlds);
+		int index;
+
+		index = dc_mode_to_region_index(mode);
+		if (!resource_size(&cxlds->dc_res[index])) {
+			dev_dbg(dev, "no available dynamic capacity\n");
+			return -ENXIO;
+		}
+		if (mds->dc_region[index].shareable) {
+			dev_err(dev, "DC region %d is shareable\n", index);
+			return -EINVAL;
+		}
+	}
+
 	cxled->mode = mode;
 	return 0;
 }
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 5c0b8ead315f41c4df14918ad4dcdb269990c5dd..7459ca8eae002727405bf1077d0187bcfb579144 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -205,11 +205,17 @@ static ssize_t mode_store(struct device *dev, struct device_attribute *attr,
 	enum cxl_decoder_mode mode;
 	ssize_t rc;
 
-	if (sysfs_streq(buf, "pmem"))
-		mode = CXL_DECODER_PMEM;
-	else if (sysfs_streq(buf, "ram"))
-		mode = CXL_DECODER_RAM;
-	else
+	for (mode = 0; mode < CXL_DECODER_MODE_MAX; mode++)
+		if (sysfs_streq(buf, cxl_decoder_mode_names[mode]))
+			break;
+
+	if (mode == CXL_DECODER_NONE ||
+	    mode == CXL_DECODER_DEAD ||
+	    mode == CXL_DECODER_MODE_MAX)
+		return -EINVAL;
+
+	/* Not yet supported */
+	if (mode >= CXL_DECODER_MIXED)
 		return -EINVAL;
 
 	rc = cxl_dpa_set_mode(cxled, mode);
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 055c840b6c2856ec77162c3c5f87293f00f8d8ec..79660c87e6be533a1d55311896f9a3c5514648f8 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -389,27 +389,29 @@ enum cxl_decoder_mode {
 	CXL_DECODER_DC7,
 	CXL_DECODER_MIXED,
 	CXL_DECODER_DEAD,
+	CXL_DECODER_MODE_MAX,
+};
+
+static const char * const cxl_decoder_mode_names[] = {
+	[CXL_DECODER_NONE] = "none",
+	[CXL_DECODER_RAM] = "ram",
+	[CXL_DECODER_PMEM] = "pmem",
+	[CXL_DECODER_DC0] = "dc0",
+	[CXL_DECODER_DC1] = "dc1",
+	[CXL_DECODER_DC2] = "dc2",
+	[CXL_DECODER_DC3] = "dc3",
+	[CXL_DECODER_DC4] = "dc4",
+	[CXL_DECODER_DC5] = "dc5",
+	[CXL_DECODER_DC6] = "dc6",
+	[CXL_DECODER_DC7] = "dc7",
+	[CXL_DECODER_MIXED] = "mixed",
+	[CXL_DECODER_DEAD] = "dead",
 };
 
 static inline const char *cxl_decoder_mode_name(enum cxl_decoder_mode mode)
 {
-	static const char * const names[] = {
-		[CXL_DECODER_NONE] = "none",
-		[CXL_DECODER_RAM] = "ram",
-		[CXL_DECODER_PMEM] = "pmem",
-		[CXL_DECODER_DC0] = "dc0",
-		[CXL_DECODER_DC1] = "dc1",
-		[CXL_DECODER_DC2] = "dc2",
-		[CXL_DECODER_DC3] = "dc3",
-		[CXL_DECODER_DC4] = "dc4",
-		[CXL_DECODER_DC5] = "dc5",
-		[CXL_DECODER_DC6] = "dc6",
-		[CXL_DECODER_DC7] = "dc7",
-		[CXL_DECODER_MIXED] = "mixed",
-	};
-
 	if (mode >= CXL_DECODER_NONE && mode <= CXL_DECODER_MIXED)
-		return names[mode];
+		return cxl_decoder_mode_names[mode];
 	return "mixed";
 }
 

-- 
2.47.1