linux-kernel - [PATCH v11 05/20] cxl/port: Pre-initialize component register mappings

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Date:   Wed, 27 Sep 2023 17:43:24 +0200
From:   Robert Richter <rrichter@....com>
To:     Alison Schofield <alison.schofield@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Ben Widawsky <bwidawsk@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        "Davidlohr Bueso" <dave@...olabs.net>,
        Jonathan Cameron <jonathan.cameron@...wei.com>,
        Dave Jiang <dave.jiang@...el.com>
CC:     <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Terry Bowman <terry.bowman@....com>,
        Robert Richter <rrichter@....com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>
Subject: [PATCH v11 05/20] cxl/port: Pre-initialize component register mappings

The component registers of a component may not exist and
cxl_setup_comp_regs() will fail for that reason. In another case,
Software may not use and set those registers up. cxl_setup_comp_regs()
is then called with a base address of CXL_RESOURCE_NONE. Both are
valid cases, but the function returns without initializing the
register map.

Now, a missing component register block is not necessarily a reason to
fail (feature is optional or its existence checked later). Change
cxl_setup_comp_regs() to also use components with the component
register block missing. Thus, always initialize struct
cxl_register_map with valid values, set @dev and make @resource
CXL_RESOURCE_NONE.

The change is in preparation of follow-on patches.

Signed-off-by: Terry Bowman <terry.bowman@....com>
Signed-off-by: Robert Richter <rrichter@....com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
---
 drivers/cxl/core/port.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index b993dea61436..28ba8922d0a4 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -694,16 +694,18 @@ static struct cxl_port *cxl_port_alloc(struct device *uport_dev,
 static int cxl_setup_comp_regs(struct device *host, struct cxl_register_map *map,
 			       resource_size_t component_reg_phys)
 {
-	if (component_reg_phys == CXL_RESOURCE_NONE)
-		return 0;
-
 	*map = (struct cxl_register_map) {
 		.host = host,
-		.reg_type = CXL_REGLOC_RBI_COMPONENT,
+		.reg_type = CXL_REGLOC_RBI_EMPTY,
 		.resource = component_reg_phys,
-		.max_size = CXL_COMPONENT_REG_BLOCK_SIZE,
 	};
 
+	if (component_reg_phys == CXL_RESOURCE_NONE)
+		return 0;
+
+	map->reg_type = CXL_REGLOC_RBI_COMPONENT;
+	map->max_size = CXL_COMPONENT_REG_BLOCK_SIZE;
+
 	return cxl_setup_regs(map);
 }
 
-- 
2.30.2