[PATCH net-next v2 02/10] net: dsa: debugfs: add tree

[Vivien Didelot]

This commit adds the boiler plate to create a DSA related debug
filesystem entry as well as a "tree" file, containing the tree index.

    # cat switch1/tree
    0

Signed-off-by: Vivien Didelot <vivien.dide...@savoirfairelinux.com>
Reviewed-by: Florian Fainelli <f.faine...@gmail.com>
Reviewed-by: Andrew Lunn <and...@lunn.ch>
---
 net/dsa/debugfs.c | 107 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 107 insertions(+)

diff --git a/net/dsa/debugfs.c b/net/dsa/debugfs.c
index b6b5e5c97389..54e97e05a9d7 100644
--- a/net/dsa/debugfs.c
+++ b/net/dsa/debugfs.c
@@ -10,6 +10,7 @@
  */
 
 #include <linux/debugfs.h>
+#include <linux/seq_file.h>
 
 #include "dsa_priv.h"
 
@@ -19,6 +20,107 @@
 /* DSA module debugfs directory */
 static struct dentry *dsa_debugfs_dir;
 
+struct dsa_debugfs_ops {
+       int (*read)(struct dsa_switch *ds, int id, struct seq_file *seq);
+       int (*write)(struct dsa_switch *ds, int id, char *buf);
+};
+
+struct dsa_debugfs_priv {
+       const struct dsa_debugfs_ops *ops;
+       struct dsa_switch *ds;
+       int id;
+};
+
+static int dsa_debugfs_show(struct seq_file *seq, void *p)
+{
+       struct dsa_debugfs_priv *priv = seq->private;
+       struct dsa_switch *ds = priv->ds;
+
+       /* Somehow file mode is bypassed... Double check here */
+       if (!priv->ops->read)
+               return -EOPNOTSUPP;
+
+       return priv->ops->read(ds, priv->id, seq);
+}
+
+static ssize_t dsa_debugfs_write(struct file *file, const char __user 
*user_buf,
+                                size_t count, loff_t *ppos)
+{
+       struct seq_file *seq = file->private_data;
+       struct dsa_debugfs_priv *priv = seq->private;
+       struct dsa_switch *ds = priv->ds;
+       char buf[count + 1];
+       int err;
+
+       /* Somehow file mode is bypassed... Double check here */
+       if (!priv->ops->write)
+               return -EOPNOTSUPP;
+
+       if (copy_from_user(buf, user_buf, count))
+               return -EFAULT;
+
+       buf[count] = '\0';
+
+       err = priv->ops->write(ds, priv->id, buf);
+
+       return err ? err : count;
+}
+
+static int dsa_debugfs_open(struct inode *inode, struct file *file)
+{
+       return single_open(file, dsa_debugfs_show, inode->i_private);
+}
+
+static const struct file_operations dsa_debugfs_fops = {
+       .open = dsa_debugfs_open,
+       .read = seq_read,
+       .write = dsa_debugfs_write,
+       .llseek = no_llseek,
+       .release = single_release,
+       .owner = THIS_MODULE,
+};
+
+static int dsa_debugfs_create_file(struct dsa_switch *ds, struct dentry *dir,
+                                  char *name, int id,
+                                  const struct dsa_debugfs_ops *ops)
+{
+       struct dsa_debugfs_priv *priv;
+       struct dentry *entry;
+       umode_t mode;
+
+       priv = devm_kzalloc(ds->dev, sizeof(*priv), GFP_KERNEL);
+       if (!priv)
+               return -ENOMEM;
+
+       priv->ops = ops;
+       priv->ds = ds;
+       priv->id = id;
+
+       mode = 0;
+       if (ops->read)
+               mode |= 0444;
+       if (ops->write)
+               mode |= 0200;
+
+       entry = debugfs_create_file(name, mode, dir, priv, &dsa_debugfs_fops);
+       if (IS_ERR_OR_NULL(entry))
+               return -EFAULT;
+
+       return 0;
+}
+
+static int dsa_debugfs_tree_read(struct dsa_switch *ds, int id,
+                                struct seq_file *seq)
+{
+       seq_printf(seq, "%d\n", ds->dst->tree);
+
+       return 0;
+}
+
+static const struct dsa_debugfs_ops dsa_debugfs_tree_ops = {
+       .read = dsa_debugfs_tree_read,
+};
+
 static int dsa_debugfs_create_port(struct dsa_switch *ds, int port)
 {
        struct dentry *dir;
@@ -48,6 +150,11 @@ static int dsa_debugfs_create_switch(struct dsa_switch *ds)
        if (IS_ERR_OR_NULL(ds->debugfs_dir))
                return -EFAULT;
 
+       err = dsa_debugfs_create_file(ds, ds->debugfs_dir, "tree", -1,
+                                     &dsa_debugfs_tree_ops);
+       if (err)
+               return err;
+
        for (i = 0; i < ds->num_ports; i++) {
                if (ds->enabled_port_mask & BIT(i)) {
                        err = dsa_debugfs_create_port(ds, i);
-- 
2.14.1