edac: Add debufs nodes to allow doing fake error inject

Sometimes, it is useful to have a mechanism that generates fake
errors, in order to test the EDAC core code, and the userspace
tools.

Provide such mechanism by adding a few debugfs nodes.

Reviewed-by: Aristeu Rozanski <arozansk@redhat.com>
Cc: Doug Thompson <norsk5@yahoo.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 87 insertions, 0 deletions

diff --git a/drivers/edac/edac_mc_sysfs.c b/drivers/edac/edac_mc_sysfs.c
index 87fb396bc550..daa418b61525 100644
--- a/drivers/edac/edac_mc_sysfs.c
+++ b/drivers/edac/edac_mc_sysfs.c
@@ -17,6 +17,7 @@
 #include <linux/edac.h>
 #include <linux/bug.h>
 #include <linux/pm_runtime.h>
+#include <linux/uaccess.h>
 
 #include "edac_core.h"
 #include "edac_module.h"
@@ -783,6 +784,47 @@ static ssize_t mci_max_location_show(struct device *dev,
         return p - data;
 }
 
+#ifdef CONFIG_EDAC_DEBUG
+static ssize_t edac_fake_inject_write(struct file *file,
+                                      const char __user *data,
+                                      size_t count, loff_t *ppos)
+{
+        struct device *dev = file->private_data;
+        struct mem_ctl_info *mci = to_mci(dev);
+        static enum hw_event_mc_err_type type;
+
+        type = mci->fake_inject_ue ? HW_EVENT_ERR_UNCORRECTED
+                                   : HW_EVENT_ERR_CORRECTED;
+
+        printk(KERN_DEBUG
+               "Generating a %s fake error to %d.%d.%d to test core handling. NOTE: this won't test the driver-specific decoding logic.\n",
+                (type == HW_EVENT_ERR_UNCORRECTED) ? "UE" : "CE",
+                mci->fake_inject_layer[0],
+                mci->fake_inject_layer[1],
+                mci->fake_inject_layer[2]
+               );
+        edac_mc_handle_error(type, mci, 0, 0, 0,
+                             mci->fake_inject_layer[0],
+                             mci->fake_inject_layer[1],
+                             mci->fake_inject_layer[2],
+                             "FAKE ERROR", "for EDAC testing only", NULL);
+
+        return count;
+}
+
+static int debugfs_open(struct inode *inode, struct file *file)
+{
+        file->private_data = inode->i_private;
+        return 0;
+}
+
+static const struct file_operations debug_fake_inject_fops = {
+        .open = debugfs_open,
+        .write = edac_fake_inject_write,
+        .llseek = generic_file_llseek,
+};
+#endif
+
 /* default Control file */
 DEVICE_ATTR(reset_counters, S_IWUSR, NULL, mci_reset_counters_store);
 
@@ -833,6 +875,45 @@ static struct device_type mci_attr_type = {
         .release        = mci_attr_release,
 };
 
+#ifdef CONFIG_EDAC_DEBUG
+int edac_create_debug_nodes(struct mem_ctl_info *mci)
+{
+        struct dentry *d, *parent;
+        char name[80];
+        int i;
+
+        d = debugfs_create_dir(mci->dev.kobj.name, mci->debugfs);
+        if (!d)
+                return -ENOMEM;
+        parent = d;
+
+        for (i = 0; i < mci->n_layers; i++) {
+                sprintf(name, "fake_inject_%s",
+                             edac_layer_name[mci->layers[i].type]);
+                d = debugfs_create_u8(name, S_IRUGO | S_IWUSR, parent,
+                                      &mci->fake_inject_layer[i]);
+                if (!d)
+                        goto nomem;
+        }
+
+        d = debugfs_create_bool("fake_inject_ue", S_IRUGO | S_IWUSR, parent,
+                                &mci->fake_inject_ue);
+        if (!d)
+                goto nomem;
+
+        d = debugfs_create_file("fake_inject", S_IWUSR, parent,
+                                &mci->dev,
+                                &debug_fake_inject_fops);
+        if (!d)
+                goto nomem;
+
+        return 0;
+nomem:
+        debugfs_remove(mci->debugfs);
+        return -ENOMEM;
+}
+#endif
+
 /*
  * Create a new Memory Controller kobject instance,
  *      mc<id> under the 'mc' directory
@@ -911,6 +992,9 @@ int edac_create_sysfs_mci_device(struct mem_ctl_info *mci)
                 goto fail;
 #endif
 
+#ifdef CONFIG_EDAC_DEBUG
+        edac_create_debug_nodes(mci);
+#endif
         return 0;
 
 fail:
@@ -937,6 +1021,9 @@ void edac_remove_sysfs_mci_device(struct mem_ctl_info *mci)
 
         debugf0("%s()\n", __func__);
 
+#ifdef CONFIG_EDAC_DEBUG
+        debugfs_remove(mci->debugfs);
+#endif
 #ifdef CONFIG_EDAC_LEGACY_SYSFS
         edac_delete_csrow_objects(mci);
 #endif