From 538831f1beb818c93e5879bf19de37d89ec88ed6 Mon Sep 17 00:00:00 2001 From: Ben Widawsky Date: Sun, 10 Apr 2022 15:26:13 -0700 Subject: [PATCH] cxl/hdm: Add sysfs attributes for interleave ways + granularity 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 userspace will be responsible for conflict resolution and it needs these attributes to make those decisions. Signed-off-by: Ben Widawsky Reviewed-by: Jonathan Cameron Link: https://lore.kernel.org/r/165784332235.1758207.7185062713652694607.stgit@dwillia2-xfh.jf.intel.com [djbw: reword changelog, make read-only, add sysfs ABI documentaion] Signed-off-by: Dan Williams --- Documentation/ABI/testing/sysfs-bus-cxl | 27 +++++++++++++++++++++++++ drivers/cxl/core/port.c | 23 +++++++++++++++++++++ 2 files changed, 50 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl index 1ab69aca61521..223b8762d037c 100644 --- a/Documentation/ABI/testing/sysfs-bus-cxl +++ b/Documentation/ABI/testing/sysfs-bus-cxl @@ -241,3 +241,30 @@ 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@vger.kernel.org +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. For root + decoders their interleave is specified by platform firmware and + they only specify a downstream target order for host bridges. + + +What: /sys/bus/cxl/devices/decoderX.Y/interleave_granularity +Date: May, 2022 +KernelVersion: v5.20 +Contact: linux-cxl@vger.kernel.org +Description: + (RO) The number of consecutive bytes of host physical address + space this decoder claims at address N before the decode rotates + to the next target in the interleave at address N + + interleave_granularity (assuming N is aligned to + interleave_granularity). diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c index c7f1844d58deb..719563d85ce16 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, }; -- 2.30.2