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From:   Jason Baron <jbaron@akamai.com>
To:     bp@suse.de
Cc:     linux-kernel@vger.kernel.org,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Tony Luck <tony.luck@intel.com>,
        linux-edac <linux-edac@vger.kernel.org>
Subject: [PATCH] EDAC/ie31200: fallback if host bridge device is already initialized
Date:   Thu, 16 Jul 2020 14:25:11 -0400
Message-Id: <1594923911-10885-1-git-send-email-jbaron@akamai.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

The Intel uncore driver may claim some of the pci ids from ie31200 which
means that the ie31200 edac driver will not initialize them as part of
pci_register_driver().

Let's add a fallback for this case to 'pci_get_device()' to get a
reference on the device such that it can still be configured. This is
similar in approach to other edac drivers.

Signed-off-by: Jason Baron <jbaron@akamai.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
---
 drivers/edac/ie31200_edac.c | 50 ++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 47 insertions(+), 3 deletions(-)

diff --git a/drivers/edac/ie31200_edac.c b/drivers/edac/ie31200_edac.c
index d68346a..ebe5099 100644
--- a/drivers/edac/ie31200_edac.c
+++ b/drivers/edac/ie31200_edac.c
@@ -170,6 +170,8 @@
 	(n << (28 + (2 * skl) - PAGE_SHIFT))
 
 static int nr_channels;
+static struct pci_dev *mci_pdev;
+static int ie31200_registered = 1;
 
 struct ie31200_priv {
 	void __iomem *window;
@@ -538,12 +540,16 @@ static int ie31200_probe1(struct pci_dev *pdev, int dev_idx)
 static int ie31200_init_one(struct pci_dev *pdev,
 			    const struct pci_device_id *ent)
 {
-	edac_dbg(0, "MC:\n");
+	int rc;
 
+	edac_dbg(0, "MC:\n");
 	if (pci_enable_device(pdev) < 0)
 		return -EIO;
+	rc = ie31200_probe1(pdev, ent->driver_data);
+	if (rc == 0 && !mci_pdev)
+		mci_pdev = pci_dev_get(pdev);
 
-	return ie31200_probe1(pdev, ent->driver_data);
+	return rc;
 }
 
 static void ie31200_remove_one(struct pci_dev *pdev)
@@ -552,6 +558,8 @@ static void ie31200_remove_one(struct pci_dev *pdev)
 	struct ie31200_priv *priv;
 
 	edac_dbg(0, "\n");
+	pci_dev_put(mci_pdev);
+	mci_pdev = NULL;
 	mci = edac_mc_del_mc(&pdev->dev);
 	if (!mci)
 		return;
@@ -593,17 +601,53 @@ static struct pci_driver ie31200_driver = {
 
 static int __init ie31200_init(void)
 {
+	int pci_rc, i;
+
 	edac_dbg(3, "MC:\n");
 	/* Ensure that the OPSTATE is set correctly for POLL or NMI */
 	opstate_init();
 
-	return pci_register_driver(&ie31200_driver);
+	pci_rc = pci_register_driver(&ie31200_driver);
+	if (pci_rc < 0)
+		goto fail0;
+
+	if (!mci_pdev) {
+		ie31200_registered = 0;
+		for (i = 0; ie31200_pci_tbl[i].vendor != 0; i++) {
+			mci_pdev = pci_get_device(ie31200_pci_tbl[i].vendor,
+						  ie31200_pci_tbl[i].device,
+						  NULL);
+			if (mci_pdev)
+				break;
+		}
+		if (!mci_pdev) {
+			edac_dbg(0, "ie31200 pci_get_device fail\n");
+			pci_rc = -ENODEV;
+			goto fail1;
+		}
+		pci_rc = ie31200_init_one(mci_pdev, &ie31200_pci_tbl[i]);
+		if (pci_rc < 0) {
+			edac_dbg(0, "ie31200 init fail\n");
+			pci_rc = -ENODEV;
+			goto fail1;
+		}
+	}
+	return 0;
+
+fail1:
+	pci_unregister_driver(&ie31200_driver);
+fail0:
+	pci_dev_put(mci_pdev);
+
+	return pci_rc;
 }
 
 static void __exit ie31200_exit(void)
 {
 	edac_dbg(3, "MC:\n");
 	pci_unregister_driver(&ie31200_driver);
+	if (!ie31200_registered)
+		ie31200_remove_one(mci_pdev);
 }
 
 module_init(ie31200_init);
-- 
2.7.4