powerpc/eeh: I/O chip EEH enable option

The patch adds the backend to enable or disable EEH functionality
for the specified PE. The backend is also used to enable MMIO or
DMA path for the problematic PE. It's notable that all PEs on
PowerNV platform support EEH functionality by default, and we
disallow to disable EEH for the specific PE.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/platforms/powernv/eeh-ioda.c

@@ -53,9 +53,72 @@ static int ioda_eeh_post_init(struct pci_controller *hose)
 	return 0;
 }
 
+/**
+ * ioda_eeh_set_option - Set EEH operation or I/O setting
+ * @pe: EEH PE
+ * @option: options
+ *
+ * Enable or disable EEH option for the indicated PE. The
+ * function also can be used to enable I/O or DMA for the
+ * PE.
+ */
+static int ioda_eeh_set_option(struct eeh_pe *pe, int option)
+{
+	s64 ret;
+	u32 pe_no;
+	struct pci_controller *hose = pe->phb;
+	struct pnv_phb *phb = hose->private_data;
+
+	/* Check on PE number */
+	if (pe->addr < 0 || pe->addr >= phb->ioda.total_pe) {
+		pr_err("%s: PE address %x out of range [0, %x] "
+		       "on PHB#%x\n",
+			__func__, pe->addr, phb->ioda.total_pe,
+			hose->global_number);
+		return -EINVAL;
+	}
+
+	pe_no = pe->addr;
+	switch (option) {
+	case EEH_OPT_DISABLE:
+		ret = -EEXIST;
+		break;
+	case EEH_OPT_ENABLE:
+		ret = 0;
+		break;
+	case EEH_OPT_THAW_MMIO:
+		ret = opal_pci_eeh_freeze_clear(phb->opal_id, pe_no,
+				OPAL_EEH_ACTION_CLEAR_FREEZE_MMIO);
+		if (ret) {
+			pr_warning("%s: Failed to enable MMIO for "
+				   "PHB#%x-PE#%x, err=%lld\n",
+				__func__, hose->global_number, pe_no, ret);
+			return -EIO;
+		}
+
+		break;
+	case EEH_OPT_THAW_DMA:
+		ret = opal_pci_eeh_freeze_clear(phb->opal_id, pe_no,
+				OPAL_EEH_ACTION_CLEAR_FREEZE_DMA);
+		if (ret) {
+			pr_warning("%s: Failed to enable DMA for "
+				   "PHB#%x-PE#%x, err=%lld\n",
+				__func__, hose->global_number, pe_no, ret);
+			return -EIO;
+		}
+
+		break;
+	default:
+		pr_warning("%s: Invalid option %d\n", __func__, option);
+		return -EINVAL;
+	}
+
+	return ret;
+}
+
 struct pnv_eeh_ops ioda_eeh_ops = {
 	.post_init		= ioda_eeh_post_init,
-	.set_option		= NULL,
+	.set_option		= ioda_eeh_set_option,
 	.get_state		= NULL,
 	.reset			= NULL,
 	.get_log		= NULL,