PCI: show dma_mask bits in /sys

So we can catch if the driver sets an incorrect dma_mask.

Reviewed-by: Grant Grundler <grundler@google.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/pci-sysfs.c

@@ -183,6 +183,21 @@ numa_node_show(struct device *dev, struct device_attribute *attr, char *buf)
 }
 #endif
 
+static ssize_t
+dma_mask_bits_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+
+	return sprintf (buf, "%d\n", fls64(pdev->dma_mask));
+}
+
+static ssize_t
+consistent_dma_mask_bits_show(struct device *dev, struct device_attribute *attr,
+				 char *buf)
+{
+	return sprintf (buf, "%d\n", fls64(dev->coherent_dma_mask));
+}
+
 static ssize_t
 msi_bus_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
@@ -314,6 +329,8 @@ struct device_attribute pci_dev_attrs[] = {
 #ifdef CONFIG_NUMA
 	__ATTR_RO(numa_node),
 #endif
+	__ATTR_RO(dma_mask_bits),
+	__ATTR_RO(consistent_dma_mask_bits),
 	__ATTR(enable, 0600, is_enabled_show, is_enabled_store),
 	__ATTR(broken_parity_status,(S_IRUGO|S_IWUSR),
 		broken_parity_status_show,broken_parity_status_store),