linux-kernel - [PATCH 06/26] cxl/port: Add Dynamic Capacity mode support to endpoint decoders

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Date: Sun, 24 Mar 2024 16:18:09 -0700
From: ira.weiny@...el.com
To: Dave Jiang <dave.jiang@...el.com>, Fan Ni <fan.ni@...sung.com>, 
 Jonathan Cameron <Jonathan.Cameron@...wei.com>, 
 Navneet Singh <navneet.singh@...el.com>
Cc: Dan Williams <dan.j.williams@...el.com>, 
 Davidlohr Bueso <dave@...olabs.net>, 
 Alison Schofield <alison.schofield@...el.com>, 
 Vishal Verma <vishal.l.verma@...el.com>, Ira Weiny <ira.weiny@...el.com>, 
 linux-btrfs@...r.kernel.org, linux-cxl@...r.kernel.org, 
 linux-kernel@...r.kernel.org
Subject: [PATCH 06/26] cxl/port: Add Dynamic Capacity mode support to
 endpoint decoders

From: Navneet Singh <navneet.singh@...el.com>

Endpoint decoders which are used to map Dynamic Capacity must be
configured to point to the correct Dynamic Capacity (DC) Region.  The
decoder mode currently represents the partition the decoder points to
such as ram or pmem.

Expand the mode to include DC regions [partitions].

Signed-off-by: Navneet Singh <navneet.singh@...el.com>
Co-developed-by: Ira Weiny <ira.weiny@...el.com>
Signed-off-by: Ira Weiny <ira.weiny@...el.com>

---
Changes for v1:
[iweiny: eliminate added gotos]
[iweiny: Mark DC support for 6.10 kernel]
---
 Documentation/ABI/testing/sysfs-bus-cxl | 21 +++++++++++----------
 drivers/cxl/core/hdm.c                  | 19 +++++++++++++++++++
 drivers/cxl/core/port.c                 | 16 ++++++++++++++++
 3 files changed, 46 insertions(+), 10 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
index fff2581b8033..8b3efaf6563c 100644
--- a/Documentation/ABI/testing/sysfs-bus-cxl
+++ b/Documentation/ABI/testing/sysfs-bus-cxl
@@ -316,23 +316,24 @@ Description:
 
 
 What:		/sys/bus/cxl/devices/decoderX.Y/mode
-Date:		May, 2022
-KernelVersion:	v6.0
+Date:		May, 2022, June 2024
+KernelVersion:	v6.0, v6.10 (dcY)
 Contact:	linux-cxl@...r.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.
+		into a 'ram' (volatile memory) range, 'pmem' (persistent
+		memory) range, or Dynamic Capacity (DC) range. The 'mode'
+		attribute emits one of 'ram', 'pmem', 'dcY', '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.
 
 		'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 66b8419fd0c3..e22b6f4f7145 100644
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -255,6 +255,14 @@ static void devm_cxl_dpa_release(struct cxl_endpoint_decoder *cxled)
 	__cxl_dpa_release(cxled);
 }
 
+static int dc_mode_to_region_index(enum cxl_decoder_mode mode)
+{
+	if (mode < CXL_DECODER_DC0 || CXL_DECODER_DC7 < mode)
+		return -EINVAL;
+
+	return mode - CXL_DECODER_DC0;
+}
+
 static int __cxl_dpa_reserve(struct cxl_endpoint_decoder *cxled,
 			     resource_size_t base, resource_size_t len,
 			     resource_size_t skipped)
@@ -411,6 +419,7 @@ int cxl_dpa_set_mode(struct cxl_endpoint_decoder *cxled,
 	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
 	struct cxl_dev_state *cxlds = cxlmd->cxlds;
 	struct device *dev = &cxled->cxld.dev;
+	int rc;
 
 	guard(rwsem_write)(&cxl_dpa_rwsem);
 	if (cxled->cxld.flags & CXL_DECODER_F_ENABLE)
@@ -433,6 +442,16 @@ int cxl_dpa_set_mode(struct cxl_endpoint_decoder *cxled,
 			return -ENXIO;
 		}
 		break;
+	case CXL_DECODER_DC0 ... CXL_DECODER_DC7:
+		rc = dc_mode_to_region_index(mode);
+		if (rc < 0)
+			return rc;
+
+		if (resource_size(&cxlds->dc_res[rc]) == 0) {
+			dev_dbg(dev, "no available dynamic capacity\n");
+			return -ENXIO;
+		}
+		break;
 	default:
 		dev_dbg(dev, "unsupported mode: %d\n", mode);
 		return -EINVAL;
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index e59d9d37aa65..80c0651794eb 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -208,6 +208,22 @@ static ssize_t mode_store(struct device *dev, struct device_attribute *attr,
 		mode = CXL_DECODER_PMEM;
 	else if (sysfs_streq(buf, "ram"))
 		mode = CXL_DECODER_RAM;
+	else if (sysfs_streq(buf, "dc0"))
+		mode = CXL_DECODER_DC0;
+	else if (sysfs_streq(buf, "dc1"))
+		mode = CXL_DECODER_DC1;
+	else if (sysfs_streq(buf, "dc2"))
+		mode = CXL_DECODER_DC2;
+	else if (sysfs_streq(buf, "dc3"))
+		mode = CXL_DECODER_DC3;
+	else if (sysfs_streq(buf, "dc4"))
+		mode = CXL_DECODER_DC4;
+	else if (sysfs_streq(buf, "dc5"))
+		mode = CXL_DECODER_DC5;
+	else if (sysfs_streq(buf, "dc6"))
+		mode = CXL_DECODER_DC6;
+	else if (sysfs_streq(buf, "dc7"))
+		mode = CXL_DECODER_DC7;
 	else
 		return -EINVAL;
 

-- 
2.44.0