linux-kernel - [PATCH 07/15] cxl/acpi: Check RCH's PCIe Host Bridge ACPI ID

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Message-ID: <20220831081603.3415-8-rrichter@amd.com>
Date:   Wed, 31 Aug 2022 10:15:55 +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>
CC:     <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>, Robert Richter <rrichter@....com>
Subject: [PATCH 07/15] cxl/acpi: Check RCH's PCIe Host Bridge ACPI ID

An RCH is a root bridge and has "PNP0A08" or "ACPI0016" ACPI ID set.
Check this.

Signed-off-by: Robert Richter <rrichter@....com>
---
 drivers/cxl/acpi.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index a19e3154dd44..ffdf439adb87 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -312,9 +312,16 @@ static int add_root_nvdimm_bridge(struct device *match, void *data)
 	return 1;
 }
 
+static const struct acpi_device_id cxl_host_ids[] = {
+	{ "ACPI0016", 0 },
+	{ "PNP0A08", 0 },
+	{ },
+};
+
 struct pci_host_bridge *cxl_find_next_rch(struct pci_host_bridge *host)
 {
 	struct pci_bus *bus = host ? host->bus : NULL;
+	struct acpi_device *adev;
 
 	while ((bus = pci_find_next_bus(bus)) != NULL) {
 		host = bus ? to_pci_host_bridge(bus->bridge) : NULL;
@@ -323,6 +330,19 @@ struct pci_host_bridge *cxl_find_next_rch(struct pci_host_bridge *host)
 
 		dev_dbg(&host->dev, "PCI bridge found\n");
 
+		/* Must be a root bridge */
+		if (host->bus->parent)
+			continue;
+
+		dev_dbg(&host->dev, "PCI bridge is root bridge\n");
+
+		adev = ACPI_COMPANION(&host->dev);
+		if (acpi_match_device_ids(adev, cxl_host_ids))
+			continue;
+
+		dev_dbg(&host->dev, "PCI ACPI host found: %s\n",
+			acpi_dev_name(adev));
+
 		return host;
 	}
 
-- 
2.30.2