regmap: add SCCB support

This adds Serial Camera Control Bus (SCCB) support for regmap API that
is intended to be used by some of Omnivision sensor drivers.

The ov772x and ov9650 drivers are going to use this SCCB regmap API.

The ov772x driver was previously only worked with the i2c controller
drivers that support I2C_FUNC_PROTOCOL_MANGLING, because the ov772x
device doesn't support repeated starts.  After commit 0b964d183cbf
("media: ov772x: allow i2c controllers without
I2C_FUNC_PROTOCOL_MANGLING"), reading ov772x register is replaced with
issuing two separated i2c messages in order to avoid repeated start.
Using this SCCB regmap hides the implementation detail.

The ov9650 driver also issues two separated i2c messages to read the
registers as the device doesn't support repeated start.  So it can
make use of this SCCB regmap.

Cc: Mark Brown <broonie@kernel.org>
Cc: Peter Rosin <peda@axentia.se>
Cc: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Cc: Wolfram Sang <wsa@the-dreams.de>
Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
Cc: Jacopo Mondi <jacopo+renesas@jmondi.org>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Hans Verkuil <hans.verkuil@cisco.com>
Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 35 insertions, 0 deletions

diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 4f38068ffb71..52bf358e2c73 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -514,6 +514,10 @@ struct regmap *__regmap_init_i2c(struct i2c_client *i2c,
 				 const struct regmap_config *config,
 				 struct lock_class_key *lock_key,
 				 const char *lock_name);
+struct regmap *__regmap_init_sccb(struct i2c_client *i2c,
+				  const struct regmap_config *config,
+				  struct lock_class_key *lock_key,
+				  const char *lock_name);
 struct regmap *__regmap_init_slimbus(struct slim_device *slimbus,
 				 const struct regmap_config *config,
 				 struct lock_class_key *lock_key,
@@ -558,6 +562,10 @@ struct regmap *__devm_regmap_init_i2c(struct i2c_client *i2c,
 				      const struct regmap_config *config,
 				      struct lock_class_key *lock_key,
 				      const char *lock_name);
+struct regmap *__devm_regmap_init_sccb(struct i2c_client *i2c,
+				       const struct regmap_config *config,
+				       struct lock_class_key *lock_key,
+				       const char *lock_name);
 struct regmap *__devm_regmap_init_spi(struct spi_device *dev,
 				      const struct regmap_config *config,
 				      struct lock_class_key *lock_key,
@@ -646,6 +654,19 @@ int regmap_attach_dev(struct device *dev, struct regmap *map,
 				i2c, config)
 
 /**
+ * regmap_init_sccb() - Initialise register map
+ *
+ * @i2c: Device that will be interacted with
+ * @config: Configuration for register map
+ *
+ * The return value will be an ERR_PTR() on error or a valid pointer to
+ * a struct regmap.
+ */
+#define regmap_init_sccb(i2c, config)					\
+	__regmap_lockdep_wrapper(__regmap_init_sccb, #config,		\
+				i2c, config)
+
+/**
  * regmap_init_slimbus() - Initialise register map
  *
  * @slimbus: Device that will be interacted with
@@ -798,6 +819,20 @@ bool regmap_ac97_default_volatile(struct device *dev, unsigned int reg);
 				i2c, config)
 
 /**
+ * devm_regmap_init_sccb() - Initialise managed register map
+ *
+ * @i2c: Device that will be interacted with
+ * @config: Configuration for register map
+ *
+ * The return value will be an ERR_PTR() on error or a valid pointer
+ * to a struct regmap.  The regmap will be automatically freed by the
+ * device management code.
+ */
+#define devm_regmap_init_sccb(i2c, config)				\
+	__regmap_lockdep_wrapper(__devm_regmap_init_sccb, #config,	\
+				i2c, config)
+
+/**
  * devm_regmap_init_spi() - Initialise register map
  *
  * @dev: Device that will be interacted with