linux-kernel - [PATCH v6 08/17] cxl/pci: Map CXL PCIe Upstream Switch Port RAS registers

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Message-ID: <20250208002941.4135321-9-terry.bowman@amd.com>
Date: Fri, 7 Feb 2025 18:29:32 -0600
From: Terry Bowman <terry.bowman@....com>
To: <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-pci@...r.kernel.org>, <nifan.cxl@...il.com>, <dave@...olabs.net>,
	<jonathan.cameron@...wei.com>, <dave.jiang@...el.com>,
	<alison.schofield@...el.com>, <vishal.l.verma@...el.com>,
	<dan.j.williams@...el.com>, <bhelgaas@...gle.com>, <mahesh@...ux.ibm.com>,
	<ira.weiny@...el.com>, <oohall@...il.com>, <Benjamin.Cheatham@....com>,
	<rrichter@....com>, <nathan.fontenot@....com>, <terry.bowman@....com>,
	<Smita.KoralahalliChannabasappa@....com>, <lukas@...ner.de>,
	<ming.li@...omail.com>, <PradeepVineshReddy.Kodamati@....com>
Subject: [PATCH v6 08/17] cxl/pci: Map CXL PCIe Upstream Switch Port RAS registers

Add logic to map CXL PCIe Upstream Switch Port (USP) RAS registers.

Introduce 'struct cxl_regs' member into 'struct cxl_port' to cache a
pointer to the CXL Upstream Port's mapped RAS registers.

Also, introduce cxl_uport_init_ras_reporting() to perform the USP RAS
register mapping. This is similar to the existing
cxl_dport_init_ras_reporting() but for USP devices.

The USP may have multiple downstream endpoints. Before mapping RAS
registers check if the registers are already mapped.

Introduce a mutex for synchronizing accesses to the cached RAS
mapping.

Signed-off-by: Terry Bowman <terry.bowman@....com>
Reviewed-by: Gregory Price <gourry@...rry.net>
---
 drivers/cxl/core/pci.c | 19 ++++++++++++++++++-
 drivers/cxl/cxl.h      |  4 ++++
 drivers/cxl/mem.c      |  8 ++++++++
 3 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
index c142d7890bfa..4af39abbfab3 100644
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c
@@ -781,6 +781,24 @@ static void cxl_disable_rch_root_ints(struct cxl_dport *dport)
 	writel(aer_cmd, aer_base + PCI_ERR_ROOT_COMMAND);
 }
 
+void cxl_uport_init_ras_reporting(struct cxl_port *port)
+{
+
+	/* uport may have more than 1 downstream EP. Check if already mapped. */
+	mutex_lock(&ras_init_mutex);
+	if (port->uport_regs.ras) {
+		mutex_unlock(&ras_init_mutex);
+		return;
+	}
+
+	port->reg_map.host = &port->dev;
+	if (cxl_map_component_regs(&port->reg_map, &port->uport_regs,
+				   BIT(CXL_CM_CAP_CAP_ID_RAS)))
+		dev_err(&port->dev, "Failed to map RAS capability\n");
+	mutex_unlock(&ras_init_mutex);
+}
+EXPORT_SYMBOL_NS_GPL(cxl_uport_init_ras_reporting, "CXL");
+
 /**
  * cxl_dport_init_ras_reporting - Setup CXL RAS report on this dport
  * @dport: the cxl_dport that needs to be initialized
@@ -807,7 +825,6 @@ void cxl_dport_init_ras_reporting(struct cxl_dport *dport)
 				   BIT(CXL_CM_CAP_CAP_ID_RAS)))
 		dev_err(dport_dev, "Failed to map RAS capability\n");
 	mutex_unlock(&ras_init_mutex);
-
 }
 EXPORT_SYMBOL_NS_GPL(cxl_dport_init_ras_reporting, "CXL");
 
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 82d0a8555a11..49f29a3ef68e 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -581,6 +581,7 @@ struct cxl_dax_region {
  * @parent_dport: dport that points to this port in the parent
  * @decoder_ida: allocator for decoder ids
  * @reg_map: component and ras register mapping parameters
+ * @uport_regs: mapped component registers
  * @nr_dports: number of entries in @dports
  * @hdm_end: track last allocated HDM decoder instance for allocation ordering
  * @commit_end: cursor to track highest committed decoder for commit ordering
@@ -602,6 +603,7 @@ struct cxl_port {
 	struct cxl_dport *parent_dport;
 	struct ida decoder_ida;
 	struct cxl_register_map reg_map;
+	struct cxl_component_regs uport_regs;
 	int nr_dports;
 	int hdm_end;
 	int commit_end;
@@ -755,8 +757,10 @@ struct cxl_dport *devm_cxl_add_rch_dport(struct cxl_port *port,
 
 #ifdef CONFIG_PCIEAER_CXL
 void cxl_dport_init_ras_reporting(struct cxl_dport *dport);
+void cxl_uport_init_ras_reporting(struct cxl_port *port);
 #else
 static inline void cxl_dport_init_ras_reporting(struct cxl_dport *dport) { }
+static inline void cxl_uport_init_ras_reporting(struct cxl_port *port) { }
 #endif
 
 struct cxl_decoder *to_cxl_decoder(struct device *dev);
diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index 8c1144bbc058..541cabca434e 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -60,6 +60,7 @@ static bool dev_is_cxl_pci(struct device *dev, u32 pcie_type)
 static void cxl_init_ep_ports_aer(struct cxl_ep *ep)
 {
 	struct cxl_dport *dport = ep->dport;
+	struct cxl_port *port = ep->next;
 
 	if (dport) {
 		struct device *dport_dev = dport->dport_dev;
@@ -68,6 +69,13 @@ static void cxl_init_ep_ports_aer(struct cxl_ep *ep)
 		    dev_is_cxl_pci(dport_dev, PCI_EXP_TYPE_ROOT_PORT))
 			cxl_dport_init_ras_reporting(dport);
 	}
+
+	if (port) {
+		struct device *uport_dev = port->uport_dev;
+
+		if (dev_is_cxl_pci(uport_dev, PCI_EXP_TYPE_UPSTREAM))
+			cxl_uport_init_ras_reporting(port);
+	}
 }
 
 static int devm_cxl_add_endpoint(struct device *host, struct cxl_memdev *cxlmd,
-- 
2.34.1