[PATCH v2 08/15] cxl/region: Address space allocation

[Ben Widawsky <ben.widawsky@xxxxxxxxx>]

When a region is not assigned a host physical address, one is picked by
the driver. As the address will determine which CFMWS contains the
region, it's usually a better idea to let the driver make this
determination.

Signed-off-by: Ben Widawsky <ben.widawsky@xxxxxxxxx>
---
 drivers/cxl/region.c | 40 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/drivers/cxl/region.c b/drivers/cxl/region.c
index 53046da2e131..c12d9bd22705 100644
--- a/drivers/cxl/region.c
+++ b/drivers/cxl/region.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/device.h>
 #include <linux/module.h>
 #include <linux/pci.h>
@@ -62,6 +63,20 @@ static struct cxl_port *get_root_decoder(const struct cxl_memdev *endpoint)
 	return NULL;
 }
 
+static void release_cxl_region(void *r)
+{
+	struct cxl_region *region = (struct cxl_region *)r;
+	struct cxl_decoder *rootd = rootd_from_region(region);
+	struct resource *res = &rootd->platform_res;
+	resource_size_t start, size;
+
+	start = region->res->start;
+	size = resource_size(region->res);
+
+	__release_region(res, start, size);
+	gen_pool_free(rootd->address_space, start, size);
+}
+
 /**
  * sanitize_region() - Check is region is reasonably configured
  * @region: The region to check
@@ -111,8 +126,29 @@ static int sanitize_region(const struct cxl_region *region)
  */
 static int allocate_address_space(struct cxl_region *region)
 {
-	/* TODO */
-	return 0;
+	struct cxl_decoder *rootd = rootd_from_region(region);
+	unsigned long start;
+
+	start = gen_pool_alloc(rootd->address_space, region->config.size);
+	if (!start) {
+		dev_dbg(&region->dev,
+			"Couldn't allocate %lluM of address space",
+			region->config.size >> 20);
+		return -ENOMEM;
+	}
+
+	region->res = __request_region(&rootd->platform_res, start,
+				       region->config.size,
+				       dev_name(&region->dev), IORESOURCE_MEM);
+	if (!region->res) {
+		dev_dbg(&region->dev, "Couldn't obtain region from %s (%pR)\n",
+			dev_name(&rootd->dev), &rootd->platform_res);
+		gen_pool_free(rootd->address_space, start, region->config.size);
+		return -ENOMEM;
+	}
+
+	return devm_add_action_or_reset(&region->dev, release_cxl_region,
+					region);
 }
 
 /**
-- 
2.34.1