EDAC/igen6: Add polling support

Some PCs with Intel N100 (with PCI device 8086:461c, DID_ADL_N_SKU4)
experienced issues with error interrupts not working, even with the
following configuration in the BIOS.

    In-Band ECC Support: Enabled
    In-Band ECC Operation Mode: 2 (make all requests protected and
                                   ignore range checks)
    IBECC Error Injection Control: Inject Correctable Error on insertion
                                   counter
    Error Injection Insertion Count: 251658240 (0xf000000)

Add polling mode support for these machines to ensure that memory error
events are handled.

Signed-off-by: Orange Kao <orange@aiven.io>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Link: https://lore.kernel.org/all/20241106114024.941659-3-orange@aiven.io

Author: orange-kao

drivers/edac/igen6_edac.c

@@ -1170,6 +1170,20 @@ static int igen6_pci_setup(struct pci_dev *pdev, u64 *mchbar)
 	return -ENODEV;
 }
 
+static void igen6_check(struct mem_ctl_info *mci)
+{
+	struct igen6_imc *imc = mci->pvt_info;
+	u64 ecclog;
+
+	/* errsts_clear() isn't NMI-safe. Delay it in the IRQ context */
+	ecclog = ecclog_read_and_clear(imc);
+	if (!ecclog)
+		return;
+
+	if (!ecclog_gen_pool_add(imc->mc, ecclog))
+		irq_work_queue(&ecclog_irq_work);
+}
+
 static int igen6_register_mci(int mc, u64 mchbar, struct pci_dev *pdev)
 {
 	struct edac_mc_layer layers[2];
@@ -1211,6 +1225,8 @@ static int igen6_register_mci(int mc, u64 mchbar, struct pci_dev *pdev)
 	mci->edac_cap = EDAC_FLAG_SECDED;
 	mci->mod_name = EDAC_MOD_STR;
 	mci->dev_name = pci_name(pdev);
+	if (edac_op_state == EDAC_OPSTATE_POLL)
+		mci->edac_check = igen6_check;
 	mci->pvt_info = &igen6_pvt->imc[mc];
 
 	imc = mci->pvt_info;
@@ -1350,8 +1366,18 @@ static void unregister_err_handler(void)
 	unregister_nmi_handler(NMI_SERR, IGEN6_NMI_NAME);
 }
 
-static void opstate_set(struct res_config *cfg)
+static void opstate_set(struct res_config *cfg, const struct pci_device_id *ent)
 {
+	/*
+	 * Quirk: Certain SoCs' error reporting interrupts don't work.
+	 *        Force polling mode for them to ensure that memory error
+	 *        events can be handled.
+	 */
+	if (ent->device == DID_ADL_N_SKU4) {
+		edac_op_state = EDAC_OPSTATE_POLL;
+		return;
+	}
+
 	/* Set the mode according to the configuration data. */
 	if (cfg->machine_check)
 		edac_op_state = EDAC_OPSTATE_INT;
@@ -1376,7 +1402,7 @@ static int igen6_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (rc)
 		goto fail;
 
-	opstate_set(res_cfg);
+	opstate_set(res_cfg, ent);
 
 	for (i = 0; i < res_cfg->num_imc; i++) {
 		rc = igen6_register_mci(i, mchbar, pdev);