Regions are carved out of an addresses space which is claimed by top
level decoders, and subsequently their children decoders. Regions are
created with a size and therefore must fit, with proper alignment, in
that address space. The support for doing this fitting is handled by the
driver automatically.
As an example, a platform might configure a top level decoder to claim
1TB of address space @ 0x800000000 -> 0x10800000000; it would be
possible to create M regions with appropriate alignment to occupy that
address space. Each of those regions would have a host physical address
somewhere in the range between 32G and 1.3TB, and the location will be
determined by the logic added here.
The request_region() usage is not strictly mandatory at this point as
the actual handling of the address space is done with genpools. It is
highly likely however that the resource/region APIs will become useful
in the not too distant future.
All decoders manage a host physical address space while active. Only the
root decoder has constraints on location and size. As a result, it makes
most sense for the root decoder to be responsible for managing the
entire address space, and mid-level decoders and endpoints can ask the
root decoder for suballocations.
Signed-off-by: Ben Widawsky <ben.widawsky@xxxxxxxxx>
---
drivers/cxl/acpi.c | 30 ++++++++++++++++++++++++++++++
drivers/cxl/cxl.h | 2 ++
2 files changed, 32 insertions(+)
diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index d6dcb2b6af48..74681bfbf53c 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0-only
/* Copyright(c) 2021 Intel Corporation. All rights reserved. */
#include <linux/platform_device.h>
+#include <linux/genalloc.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/kernel.h>
@@ -73,6 +74,27 @@ static int cxl_acpi_cfmws_verify(struct device *dev,
return 0;
}
+/*
+ * Every decoder while active has an address space that it is decoding. However,
+ * only the root level decoders have fixed host physical address space ranges.
+ */
+static int cxl_create_cfmws_address_space(struct cxl_decoder *cxld,
+ struct acpi_cedt_cfmws *cfmws)
+{
+ const int order = ilog2(SZ_256M * cxld->interleave_ways);
+ struct device *dev = &cxld->dev;
+ struct gen_pool *pool;
+
+ pool = devm_gen_pool_create(dev, order, NUMA_NO_NODE, dev_name(dev));
+ if (IS_ERR(pool))
+ return PTR_ERR(pool);
+
+ cxld->address_space = pool;
+
+ return gen_pool_add(cxld->address_space, cfmws->base_hpa,
+ cfmws->window_size, NUMA_NO_NODE);
+}
+
struct cxl_cfmws_context {
struct device *dev;
struct cxl_port *root_port;
@@ -113,6 +135,14 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
cxld->interleave_ways = CFMWS_INTERLEAVE_WAYS(cfmws);
cxld->interleave_granularity = CFMWS_INTERLEAVE_GRANULARITY(cfmws);
+ rc = cxl_create_cfmws_address_space(cxld, cfmws);
+ if (rc) {
+ dev_err(dev,
+ "Failed to create CFMWS address space for decoder\n");
+ put_device(&cxld->dev);
+ return 0;
+ }
+
rc = cxl_decoder_add(cxld, target_map);
if (rc)
put_device(&cxld->dev);
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index d1a8ca19c9ea..b300673072f5 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -251,6 +251,7 @@ enum cxl_decoder_type {
* @flags: memory type capabilities and locking
* @target_lock: coordinate coherent reads of the target list
* @region_ida: allocator for region ids.
+ * @address_space: Used/free address space for regions.
* @nr_targets: number of elements in @target
* @target: active ordered target list in current decoder configuration
*/
@@ -267,6 +268,7 @@ struct cxl_decoder {
unsigned long flags;
seqlock_t target_lock;
struct ida region_ida;
+ struct gen_pool *address_space;
int nr_targets;
struct cxl_dport *target[];
};
--
2.35.0
