powerpc/eeh: Add eeh_pe_state sysfs entry

The patch adds sysfs entry "eeh_pe_state". Reading on it returns
the PE's state while writing to it clears the frozen state. It's
used to check or clear the PE frozen state from userland for
debugging purpose.

The patch also replaces printk(KERN_WARNING ...) with pr_warn() in
eeh_sysfs.c

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/eeh_sysfs.c

@@ -54,6 +54,62 @@ EEH_SHOW_ATTR(eeh_mode,            mode,            "0x%x");
 EEH_SHOW_ATTR(eeh_config_addr,     config_addr,     "0x%x");
 EEH_SHOW_ATTR(eeh_pe_config_addr,  pe_config_addr,  "0x%x");
 
+static ssize_t eeh_pe_state_show(struct device *dev,
+				 struct device_attribute *attr, char *buf)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct eeh_dev *edev = pci_dev_to_eeh_dev(pdev);
+	int state;
+
+	if (!edev || !edev->pe)
+		return -ENODEV;
+
+	state = eeh_ops->get_state(edev->pe, NULL);
+	return sprintf(buf, "%08x %08x\n",
+		       state, edev->pe->state);
+}
+
+static ssize_t eeh_pe_state_store(struct device *dev,
+				  struct device_attribute *attr,
+				  const char *buf, size_t count)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct eeh_dev *edev = pci_dev_to_eeh_dev(pdev);
+	int ret;
+
+	if (!edev || !edev->pe)
+		return -ENODEV;
+
+	/* Nothing to do if it's not frozen */
+	if (!(edev->pe->state & EEH_PE_ISOLATED))
+		return count;
+
+	/* Enable MMIO */
+	ret = eeh_pci_enable(edev->pe, EEH_OPT_THAW_MMIO);
+	if (ret) {
+		pr_warn("%s: Failure %d enabling MMIO for PHB#%d-PE#%d\n",
+			__func__, ret, edev->pe->phb->global_number,
+			edev->pe->addr);
+		return -EIO;
+	}
+
+	/* Enable DMA */
+	ret = eeh_pci_enable(edev->pe, EEH_OPT_THAW_DMA);
+	if (ret) {
+		pr_warn("%s: Failure %d enabling DMA for PHB#%d-PE#%d\n",
+			__func__, ret, edev->pe->phb->global_number,
+			edev->pe->addr);
+		return -EIO;
+	}
+
+	/* Clear software state */
+	eeh_pe_state_clear(edev->pe, EEH_PE_ISOLATED);
+
+	return count;
+}
+
+static DEVICE_ATTR_RW(eeh_pe_state);
+
 void eeh_sysfs_add_device(struct pci_dev *pdev)
 {
 	struct eeh_dev *edev = pci_dev_to_eeh_dev(pdev);
@@ -68,9 +124,10 @@ void eeh_sysfs_add_device(struct pci_dev *pdev)
 	rc += device_create_file(&pdev->dev, &dev_attr_eeh_mode);
 	rc += device_create_file(&pdev->dev, &dev_attr_eeh_config_addr);
 	rc += device_create_file(&pdev->dev, &dev_attr_eeh_pe_config_addr);
+	rc += device_create_file(&pdev->dev, &dev_attr_eeh_pe_state);
 
 	if (rc)
-		printk(KERN_WARNING "EEH: Unable to create sysfs entries\n");
+		pr_warn("EEH: Unable to create sysfs entries\n");
 	else if (edev)
 		edev->mode |= EEH_DEV_SYSFS;
 }
@@ -92,6 +149,7 @@ void eeh_sysfs_remove_device(struct pci_dev *pdev)
 	device_remove_file(&pdev->dev, &dev_attr_eeh_mode);
 	device_remove_file(&pdev->dev, &dev_attr_eeh_config_addr);
 	device_remove_file(&pdev->dev, &dev_attr_eeh_pe_config_addr);
+	device_remove_file(&pdev->dev, &dev_attr_eeh_pe_state);
 
 	if (edev)
 		edev->mode &= ~EEH_DEV_SYSFS;