regmap: sdw-mbq: Add support for further MBQ register sizes

SoundWire MBQ register maps typically contain a variety of register
sizes, which doesn't map ideally to the regmap abstraction which
expects register maps to have a consistent size. Currently the MBQ
register map only allows 16-bit registers to be defined, however
this leads to complex CODEC driver implementations with an 8-bit
register map and a 16-bit MBQ, every control will then have a custom
get and put handler that allows them to access different register
maps. Further more 32-bit MBQ quantities are not currently supported.

Add support for additional MBQ sizes and to avoid the complexity
of multiple register maps treat the val_size as a maximum size for
the register map. Within the regmap use an ancillary callback to
determine how many bytes to actually read/write to the hardware for
a specific register. In the case that no callback is defined the
behaviour defaults back to the existing behaviour of a fixed size
register map.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://patch.msgid.link/20250107154408.814455-4-ckeepax@opensource.cirrus.com
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.dev>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 45 insertions, 2 deletions

diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index fd41baccbf3e..dd96a22f5657 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -506,6 +506,17 @@ struct regmap_range_cfg {
 	unsigned int window_len;
 };
 
+/**
+ * struct regmap_sdw_mbq_cfg - Configuration for Multi-Byte Quantities
+ *
+ * @mbq_size: Callback returning the actual size of the given register.
+ *
+ * Provides additional configuration required for SoundWire MBQ register maps.
+ */
+struct regmap_sdw_mbq_cfg {
+	int (*mbq_size)(struct device *dev, unsigned int reg);
+};
+
 struct regmap_async;
 
 typedef int (*regmap_hw_write)(void *context, const void *data,
@@ -652,6 +663,7 @@ struct regmap *__regmap_init_sdw(struct sdw_slave *sdw,
 				 const char *lock_name);
 struct regmap *__regmap_init_sdw_mbq(struct sdw_slave *sdw,
 				     const struct regmap_config *config,
+				     const struct regmap_sdw_mbq_cfg *mbq_config,
 				     struct lock_class_key *lock_key,
 				     const char *lock_name);
 struct regmap *__regmap_init_spi_avmm(struct spi_device *spi,
@@ -713,6 +725,7 @@ struct regmap *__devm_regmap_init_sdw(struct sdw_slave *sdw,
 				 const char *lock_name);
 struct regmap *__devm_regmap_init_sdw_mbq(struct sdw_slave *sdw,
 					  const struct regmap_config *config,
+					  const struct regmap_sdw_mbq_cfg *mbq_config,
 					  struct lock_class_key *lock_key,
 					  const char *lock_name);
 struct regmap *__devm_regmap_init_slimbus(struct slim_device *slimbus,
@@ -942,7 +955,22 @@ bool regmap_ac97_default_volatile(struct device *dev, unsigned int reg);
  */
 #define regmap_init_sdw_mbq(sdw, config)					\
 	__regmap_lockdep_wrapper(__regmap_init_sdw_mbq, #config,		\
-				sdw, config)
+				sdw, config, NULL)
+
+/**
+ * regmap_init_sdw_mbq_cfg() - Initialise MBQ SDW register map with config
+ *
+ * @sdw: Device that will be interacted with
+ * @config: Configuration for register map
+ * @mbq_config: Properties for the MBQ registers
+ *
+ * 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 regmap_init_sdw_mbq_cfg(sdw, config, mbq_config)		\
+	__regmap_lockdep_wrapper(__regmap_init_sdw_mbq, #config,	\
+				sdw, config, mbq_config)
 
 /**
  * regmap_init_spi_avmm() - Initialize register map for Intel SPI Slave
@@ -1155,7 +1183,22 @@ bool regmap_ac97_default_volatile(struct device *dev, unsigned int reg);
  */
 #define devm_regmap_init_sdw_mbq(sdw, config)			\
 	__regmap_lockdep_wrapper(__devm_regmap_init_sdw_mbq, #config,   \
-				sdw, config)
+				sdw, config, NULL)
+
+/**
+ * devm_regmap_init_sdw_mbq_cfg() - Initialise managed MBQ SDW register map with config
+ *
+ * @sdw: Device that will be interacted with
+ * @config: Configuration for register map
+ * @mbq_config: Properties for the MBQ registers
+ *
+ * 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_sdw_mbq_cfg(sdw, config, mbq_config)	\
+	__regmap_lockdep_wrapper(__devm_regmap_init_sdw_mbq,	\
+				#config, sdw, config, mbq_config)
 
 /**
  * devm_regmap_init_slimbus() - Initialise managed register map