net: dsa: ksz9477: create regmap cdev for switch registers

Now that we use regmap for the KSZ9477 driver, we can make the register
map available for introspection as a device file. As the KSZ driver has
a separate regmap for each of the three access sizes, we add a new
regmap_multi_register_cdev abstraction that multiplexes device file
access to the regmap with the best matching alignment.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.barebox.org/20230111132956.1153359-7-a.fatoum@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 21 insertions, 0 deletions

diff --git a/include/regmap.h b/include/regmap.h
index 986ed391ab..98ac90523b 100644
--- a/include/regmap.h
+++ b/include/regmap.h
@@ -175,6 +175,27 @@ struct device *regmap_get_device(struct regmap *map);
 
 int regmap_register_cdev(struct regmap *map, const char *name);
 
+/**
+ * regmap_multi_register_cdev() - Initialize cdev backed by multiple regmaps
+ *
+ * @map8:  regmap for  8-bit wide accesses. NULL if such access
+ *         should fail with -EINVAL
+ * @map16: regmap for 16-bit wide accesses. NULL if such access
+ *         should fail with -EINVAL
+ * @map32: regmap for 32-bit wide accesses. NULL if such access
+ *         should fail with -EINVAL
+ * @map64: regmap for 64-bit wide accesses. NULL if such access
+ *         should fail with -EINVAL
+ *
+ * Registers a cdev that demultiplexes cdev accesses to one
+ * of the underlying regmaps according to the access size
+ * (e.g. mw -b => map8, mw -l => map32)
+ */
+int regmap_multi_register_cdev(struct regmap *map8,
+			       struct regmap *map16,
+			       struct regmap *map32,
+			       struct regmap *map64);
+
 int regmap_write(struct regmap *map, unsigned int reg, unsigned int val);
 int regmap_read(struct regmap *map, unsigned int reg, unsigned int *val);