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From:   Robert Richter <rrichter@amd.com>
To:     Alison Schofield <alison.schofield@intel.com>,
        Vishal Verma <vishal.l.verma@intel.com>,
        Ira Weiny <ira.weiny@intel.com>,
        Ben Widawsky <bwidawsk@kernel.org>,
        Dan Williams <dan.j.williams@intel.com>
CC:     <linux-cxl@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Len Brown <lenb@kernel.org>, Robert Richter <rrichter@amd.com>
Subject: [PATCH 09/15] cxl/acpi: Determine PCI host bridge's ACPI UID
Date:   Wed, 31 Aug 2022 10:15:57 +0200
Message-ID: <20220831081603.3415-10-rrichter@amd.com>
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The UID is needed to read the RCH's CEDT entry with the RCRB base
address. Determine the host's UID from its ACPI fw node.

Signed-off-by: Robert Richter <rrichter@amd.com>
---
 drivers/cxl/acpi.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index f9cdf23a91a8..b3146b7ae922 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -368,8 +368,20 @@ struct pci_host_bridge *cxl_find_next_rch(struct pci_host_bridge *host)
 static int __init cxl_restricted_host_probe(struct platform_device *pdev)
 {
 	struct pci_host_bridge *host = NULL;
+	struct acpi_device *adev;
+	unsigned long long uid = ~0;
 
 	while ((host = cxl_find_next_rch(host)) != NULL) {
+		adev = ACPI_COMPANION(&host->dev);
+		if (!adev || !adev->pnp.unique_id ||
+			(kstrtoull(adev->pnp.unique_id, 10, &uid) < 0))
+			continue;
+
+		dev_dbg(&adev->dev, "host uid: %llu\n", uid);
+
+		if (uid > U32_MAX)
+			continue;
+
 		dev_info(&host->dev, "host supports CXL\n");
 	}
 
-- 
2.30.2