regmap: debugfs: Factor out initial seek

In preparation for doing things a bit more quickly than a linear scan
factor out the initial seek from the debugfs register dump.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

1 files changed, 36 insertions, 3 deletions

diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index 3df274e06062..749a1dc5bbfb 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -56,16 +56,46 @@ static const struct file_operations regmap_name_fops = {
         .llseek = default_llseek,
 };
 
+/*
+ * Work out where the start offset maps into register numbers, bearing
+ * in mind that we suppress hidden registers.
+ */
+static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
+                                                  unsigned int base,
+                                                  loff_t from,
+                                                  loff_t *pos)
+{
+        loff_t p = *pos;
+        unsigned int i;
+
+        for (i = base; i <= map->max_register; i += map->reg_stride) {
+                if (!regmap_readable(map, i))
+                        continue;
+
+                if (regmap_precious(map, i))
+                        continue;
+
+                if (i >= from) {
+                        *pos = p;
+                        return i;
+                }
+
+                p += map->debugfs_tot_len;
+        }
+
+        return base;
+}
+
 static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
                                    unsigned int to, char __user *user_buf,
                                    size_t count, loff_t *ppos)
 {
         size_t buf_pos = 0;
-        loff_t p = 0;
+        loff_t p = *ppos;
         ssize_t ret;
         int i;
         char *buf;
-        unsigned int val;
+        unsigned int val, start_reg;
 
         if (*ppos < 0 || !count)
                 return -EINVAL;
@@ -83,7 +113,10 @@ static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
                         map->debugfs_val_len + 3;      /* : \n */
         }
 
-        for (i = from; i <= to; i += map->reg_stride) {
+        /* Work out which register we're starting at */
+        start_reg = regmap_debugfs_get_dump_start(map, from, *ppos, &p);
+
+        for (i = start_reg; i <= to; i += map->reg_stride) {
                 if (!regmap_readable(map, i))
                         continue;