[PATCH 1/2] media: v4l2-cci: Add support for custom regmap configuration

[Richard Leitner <richard.leitner@linux.dev>]

Some sensors, e.g. OV9282, require custom regmap configuration like setting
use_single_read. Therefore introduce a new custom cci configuration
struct, which exposes optional transport-specific regmap configuration for
I2C devices using the cci_*() register access helpers.

The existing devm_cci_regmap_init_i2c function is changed to use the
newly introduced devm_cci_regmap_init_i2c_cfg and its return value
documentation is fixed.

Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
---
 drivers/media/v4l2-core/v4l2-cci.c | 23 +++++++++++++++++++----
 include/media/v4l2-cci.h           | 37 ++++++++++++++++++++++++++++++++++++-
 2 files changed, 55 insertions(+), 5 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-cci.c b/drivers/media/v4l2-core/v4l2-cci.c
index e9ecf47859465..584ca080bc6e5 100644
--- a/drivers/media/v4l2-core/v4l2-cci.c
+++ b/drivers/media/v4l2-core/v4l2-cci.c
@@ -183,18 +183,33 @@ int cci_multi_reg_write(struct regmap *map, const struct cci_reg_sequence *regs,
 EXPORT_SYMBOL_GPL(cci_multi_reg_write);
 
 #if IS_ENABLED(CONFIG_V4L2_CCI_I2C)
-struct regmap *devm_cci_regmap_init_i2c(struct i2c_client *client,
-					int reg_addr_bits)
+struct regmap *devm_cci_regmap_init_i2c_cfg(struct i2c_client *client,
+					    const struct cci_regmap_config *cci_cfg)
 {
-	struct regmap_config config = {
-		.reg_bits = reg_addr_bits,
+	const struct regmap_config config = {
+		.reg_bits = cci_cfg->reg_addr_bits,
 		.val_bits = 8,
 		.reg_format_endian = REGMAP_ENDIAN_BIG,
 		.disable_locking = true,
+		.use_single_read = cci_cfg->use_single_read,
+		.use_single_write = cci_cfg->use_single_write,
 	};
 
 	return devm_regmap_init_i2c(client, &config);
 }
+EXPORT_SYMBOL_GPL(devm_cci_regmap_init_i2c_cfg);
+
+struct regmap *devm_cci_regmap_init_i2c(struct i2c_client *client,
+					int reg_addr_bits)
+{
+	const struct cci_regmap_config cci_cfg = {
+		.reg_addr_bits = reg_addr_bits,
+		.use_single_read = false,
+		.use_single_write = false,
+	};
+
+	return devm_cci_regmap_init_i2c_cfg(client, &cci_cfg);
+}
 EXPORT_SYMBOL_GPL(devm_cci_regmap_init_i2c);
 #endif
 
diff --git a/include/media/v4l2-cci.h b/include/media/v4l2-cci.h
index 4e96e90ee6369..8296a8c122b4d 100644
--- a/include/media/v4l2-cci.h
+++ b/include/media/v4l2-cci.h
@@ -27,6 +27,27 @@ struct cci_reg_sequence {
 	u64 val;
 };
 
+/**
+ * struct cci_regmap_config - Optional configuration for CCI I2C regmap creation
+ *
+ * @reg_addr_bits: Number of bits in the register address.
+ * @use_single_read: Force single-register read transactions.
+ * @use_single_write: Force single-register write transactions.
+ *
+ * This structure describes optional transport-specific regmap configuration for
+ * I2C devices using the cci_*() register access helpers.
+ *
+ * The CCI helper initializes the underlying regmap with the CCI defaults:
+ * 16-bit or 8-bit register addresses as selected by @reg_addr_bits, 8-bit
+ * register values, big-endian register address formatting, and disabled
+ * regmap locking.
+ */
+struct cci_regmap_config {
+	int reg_addr_bits;
+	bool use_single_read;
+	bool use_single_write;
+};
+
 /*
  * Macros to define register address with the register width encoded
  * into the higher bits.
@@ -123,6 +144,20 @@ int cci_multi_reg_write(struct regmap *map, const struct cci_reg_sequence *regs,
 			unsigned int num_regs, int *err);
 
 #if IS_ENABLED(CONFIG_V4L2_CCI_I2C)
+/**
+ * devm_cci_regmap_init_i2c_cfg() - Create regmap with a custom config to use
+ *                                  with cci_*() register access functions
+ *
+ * @client: i2c_client to create the regmap for
+ * @config: Configuration for CCI register map.
+ *
+ * Note the memory for the created regmap is devm() managed, tied to the client.
+ *
+ * Return: a pointer to the regmap on success, or an ERR_PTR() encoded error on failure.
+ */
+struct regmap *devm_cci_regmap_init_i2c_cfg(struct i2c_client *client,
+					    const struct cci_regmap_config *config);
+
 /**
  * devm_cci_regmap_init_i2c() - Create regmap to use with cci_*() register
  *                              access functions
@@ -132,7 +167,7 @@ int cci_multi_reg_write(struct regmap *map, const struct cci_reg_sequence *regs,
  *
  * Note the memory for the created regmap is devm() managed, tied to the client.
  *
- * Return: %0 on success or a negative error code on failure.
+ * Return: a pointer to the regmap on success, or an ERR_PTR() encoded error on failure.
  */
 struct regmap *devm_cci_regmap_init_i2c(struct i2c_client *client,
 					int reg_addr_bits);

-- 
2.53.0