[PATCH v11 16/20] cxl/pci: Disable root port interrupts in RCH mode

Robert Richter
2023-09-27T15:48:20Z

From: Terry Bowman <terry.bowman@amd.com>

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@amd.com>
Signed-off-by: Robert Richter <rrichter@amd.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
---
drivers/cxl/core/pci.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)

diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
index 8d849c8bf8fb..61e443aff0eb 100644
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c
@@ -763,6 +763,35 @@ static void cxl_dport_map_regs(struct cxl_dport *dport)
cxl_dport_map_rch_aer(dport);
}

+static 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);
+ }
+}
+
void devm_cxl_setup_parent_dport(struct device *host, struct cxl_dport *dport)
{
struct device *dport_dev = dport->dport_dev;
@@ -774,6 +803,9 @@ void devm_cxl_setup_parent_dport(struct device *host, struct cxl_dport *dport)

dport->reg_map.host = host;
cxl_dport_map_regs(dport);
+
+ if (dport->rch)
+ cxl_disable_rch_root_ints(dport);
}
EXPORT_SYMBOL_NS_GPL(devm_cxl_setup_parent_dport, CXL);

--
2.30.2