From: Ben Widawsky <bwidawsk@xxxxxxxxxx>
The region provisioning flow involves selecting interleave ways +
granularity settings for a region, and then programming the decoder
topology to meet those constraints, if possible. For example, root
decoders set the minimum interleave ways + granularity for any hosted
regions.
Given decoder programming is not atomic and collisions can occur between
multiple requesting regions userpace will be resonsible for conflict
resolution and it needs these attributes to make those decisions.
Signed-off-by: Ben Widawsky <bwidawsk@xxxxxxxxxx>
[djbw: reword changelog, make read-only, add sysfs ABI documentaion]
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
Documentation/ABI/testing/sysfs-bus-cxl | 23 +++++++++++++++++++++++
drivers/cxl/core/port.c | 23 +++++++++++++++++++++++
2 files changed, 46 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
index 85844f9bc00b..2a4e4163879f 100644
--- a/Documentation/ABI/testing/sysfs-bus-cxl
+++ b/Documentation/ABI/testing/sysfs-bus-cxl
@@ -215,3 +215,26 @@ Description:
allocations are enforced to occur in increasing 'decoderX.Y/id'
order and frees are enforced to occur in decreasing
'decoderX.Y/id' order.
+
+
+What: /sys/bus/cxl/devices/decoderX.Y/interleave_ways
+Date: May, 2022
+KernelVersion: v5.20
+Contact: linux-cxl@xxxxxxxxxxxxxxx
+Description:
+ (RO) The number of targets across which this decoder's host
+ physical address (HPA) memory range is interleaved. The device
+ maps every Nth block of HPA (of size ==
+ 'interleave_granularity') to consecutive DPA addresses. The
+ decoder's position in the interleave is determined by the
+ device's (endpoint or switch) switch ancestry.
+
+
+What: /sys/bus/cxl/devices/decoderX.Y/interleave_granularity
+Date: May, 2022
+KernelVersion: v5.20
+Contact: linux-cxl@xxxxxxxxxxxxxxx
+Description:
+ (RO) The number of consecutive bytes of host physical address
+ space this decoder claims at address N before awaint the next
+ address (N + interleave_granularity * intereleave_ways).
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index c48f217e689a..08a380d20cf1 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -260,10 +260,33 @@ static ssize_t dpa_size_store(struct device *dev, struct device_attribute *attr,
}
static DEVICE_ATTR_RW(dpa_size);
+static ssize_t interleave_granularity_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct cxl_decoder *cxld = to_cxl_decoder(dev);
+
+ return sysfs_emit(buf, "%d\n", cxld->interleave_granularity);
+}
+
+static DEVICE_ATTR_RO(interleave_granularity);
+
+static ssize_t interleave_ways_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct cxl_decoder *cxld = to_cxl_decoder(dev);
+
+ return sysfs_emit(buf, "%d\n", cxld->interleave_ways);
+}
+
+static DEVICE_ATTR_RO(interleave_ways);
+
static struct attribute *cxl_decoder_base_attrs[] = {
&dev_attr_start.attr,
&dev_attr_size.attr,
&dev_attr_locked.attr,
+ &dev_attr_interleave_granularity.attr,
+ &dev_attr_interleave_ways.attr,
NULL,
};
--
2.36.1
