linux-kernel - [PATCH v10 12/15] cxl/pci: Disable root port interrupts in RCH mode

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Message-ID: <20230831170248.185078-5-terry.bowman@amd.com>
Date:   Thu, 31 Aug 2023 12:02:45 -0500
From:   Terry Bowman <terry.bowman@....com>
To:     <alison.schofield@...el.com>, <vishal.l.verma@...el.com>,
        <ira.weiny@...el.com>, <bwidawsk@...nel.org>,
        <dan.j.williams@...el.com>, <dave.jiang@...el.com>,
        <Jonathan.Cameron@...wei.com>, <linux-cxl@...r.kernel.org>
CC:     <terry.bowman@....com>, <rrichter@....com>,
        <linux-kernel@...r.kernel.org>, <bhelgaas@...gle.com>
Subject: [PATCH v10 12/15] cxl/pci: Disable root port interrupts in RCH mode

The RCH root port contains root command AER registers that should not be
enabled.[1] Disable these to prevent root port interrupts.

[1] CXL 3.0 - 12.2.1.1 RCH Downstream Port-detected Errors

Signed-off-by: Terry Bowman <terry.bowman@....com>
Signed-off-by: Robert Richter <rrichter@....com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Reviewed-by: Dave Jiang <dave.jiang@...el.com>
---
 drivers/cxl/core/core.h |  6 ++++++
 drivers/cxl/core/pci.c  | 29 +++++++++++++++++++++++++++++
 drivers/cxl/core/port.c |  3 +++
 3 files changed, 38 insertions(+)

diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index f470ef5c0a6a..6b037030b936 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -87,4 +87,10 @@ enum cxl_poison_trace_type {
 	CXL_POISON_TRACE_CLEAR,
 };
 
+#ifdef CONFIG_PCIEAER_CXL
+void cxl_disable_rch_root_ints(struct cxl_dport *dport);
+#else
+static inline void cxl_disable_rch_root_ints(struct cxl_dport *dport) { };
+#endif
+
 #endif /* __CXL_CORE_H__ */
diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
index 1c40270968b6..e306d3c9638b 100644
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c
@@ -819,6 +819,35 @@ static void cxl_handle_rdport_errors(struct cxl_dev_state *cxlds)
 		cxl_handle_rdport_ras(cxlds, dport);
 }
 
+void cxl_disable_rch_root_ints(struct cxl_dport *dport)
+{
+	void __iomem *aer_base = dport->regs.dport_aer;
+	struct pci_host_bridge *bridge;
+	u32 aer_cmd_mask, aer_cmd;
+
+	if (!aer_base)
+		return;
+
+	bridge = to_pci_host_bridge(dport->dport_dev);
+
+	/*
+	 * Disable RCH root port command interrupts.
+	 * CXL 3.0 12.2.1.1 - RCH Downstream Port-detected Errors
+	 *
+	 * This sequence may not be necessary. CXL spec states disabling
+	 * the root cmd register's interrupts is required. But, PCI spec
+	 * shows these are disabled by default on reset.
+	 */
+	if (bridge->native_cxl_error) {
+		aer_cmd_mask = (PCI_ERR_ROOT_CMD_COR_EN |
+				PCI_ERR_ROOT_CMD_NONFATAL_EN |
+				PCI_ERR_ROOT_CMD_FATAL_EN);
+		aer_cmd = readl(aer_base + PCI_ERR_ROOT_COMMAND);
+		aer_cmd &= ~aer_cmd_mask;
+		writel(aer_cmd, aer_base + PCI_ERR_ROOT_COMMAND);
+	}
+}
+
 #else
 static void cxl_handle_rdport_errors(struct cxl_dev_state *cxlds) { }
 #endif
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 2a22a7ed4704..d195af72ed65 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -1042,6 +1042,9 @@ __devm_cxl_add_dport(struct cxl_port *port, struct device *dport_dev,
 
 	cxl_dport_map_regs(dport);
 
+	if (dport->rch)
+		cxl_disable_rch_root_ints(dport);
+
 	cond_cxl_root_lock(port);
 	rc = add_dport(port, dport);
 	cond_cxl_root_unlock(port);
-- 
2.34.1