From 613cbb91e9cee7cf5a61f0816d2acab7bc117407 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Tue, 27 Jun 2023 14:51:04 +0200 Subject: media: Add MIPI CCI register access helper functions The CSI2 specification specifies a standard method to access camera sensor registers called "Camera Control Interface (CCI)". This uses either 8 or 16 bit (big-endian wire order) register addresses and supports 8, 16, 24 or 32 bit (big-endian wire order) register widths. Currently a lot of Linux camera sensor drivers all have their own custom helpers for this, often copy and pasted from other drivers. Add a set of generic helpers for this so that all sensor drivers can switch to a single common implementation. These helpers take an extra optional "int *err" function parameter, this can be used to chain a bunch of register accesses together with only a single error check at the end, rather than needing to error check each individual register access. The first failing call will set the contents of err to a non 0 value and all other calls will then become no-ops. Link: https://lore.kernel.org/linux-media/59aefa7f-7bf9-6736-6040-39551329cd0a@redhat.com/ Reviewed-by: Andy Shevchenko Tested-by: Tommaso Merciai Reviewed-by: Tommaso Merciai Signed-off-by: Hans de Goede Signed-off-by: Sakari Ailus Signed-off-by: Mauro Carvalho Chehab --- include/media/v4l2-cci.h | 125 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 125 insertions(+) create mode 100644 include/media/v4l2-cci.h (limited to 'include/media') diff --git a/include/media/v4l2-cci.h b/include/media/v4l2-cci.h new file mode 100644 index 000000000000..0f6803e4b17e --- /dev/null +++ b/include/media/v4l2-cci.h @@ -0,0 +1,125 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * MIPI Camera Control Interface (CCI) register access helpers. + * + * Copyright (C) 2023 Hans de Goede + */ +#ifndef _V4L2_CCI_H +#define _V4L2_CCI_H + +#include + +struct i2c_client; +struct regmap; + +/** + * struct cci_reg_sequence - An individual write from a sequence of CCI writes + * + * @reg: Register address, use CCI_REG#() macros to encode reg width + * @val: Register value + * + * Register/value pairs for sequences of writes. + */ +struct cci_reg_sequence { + u32 reg; + u64 val; +}; + +/* + * Macros to define register address with the register width encoded + * into the higher bits. + */ +#define CCI_REG_ADDR_MASK GENMASK(15, 0) +#define CCI_REG_WIDTH_SHIFT 16 +#define CCI_REG_WIDTH_MASK GENMASK(19, 16) + +#define CCI_REG8(x) ((1 << CCI_REG_WIDTH_SHIFT) | (x)) +#define CCI_REG16(x) ((2 << CCI_REG_WIDTH_SHIFT) | (x)) +#define CCI_REG24(x) ((3 << CCI_REG_WIDTH_SHIFT) | (x)) +#define CCI_REG32(x) ((4 << CCI_REG_WIDTH_SHIFT) | (x)) +#define CCI_REG64(x) ((8 << CCI_REG_WIDTH_SHIFT) | (x)) + +/** + * cci_read() - Read a value from a single CCI register + * + * @map: Register map to read from + * @reg: Register address to read, use CCI_REG#() macros to encode reg width + * @val: Pointer to store read value + * @err: Optional pointer to store errors, if a previous error is set + * then the read will be skipped + * + * Return: %0 on success or a negative error code on failure. + */ +int cci_read(struct regmap *map, u32 reg, u64 *val, int *err); + +/** + * cci_write() - Write a value to a single CCI register + * + * @map: Register map to write to + * @reg: Register address to write, use CCI_REG#() macros to encode reg width + * @val: Value to be written + * @err: Optional pointer to store errors, if a previous error is set + * then the write will be skipped + * + * Return: %0 on success or a negative error code on failure. + */ +int cci_write(struct regmap *map, u32 reg, u64 val, int *err); + +/** + * cci_update_bits() - Perform a read/modify/write cycle on + * a single CCI register + * + * @map: Register map to update + * @reg: Register address to update, use CCI_REG#() macros to encode reg width + * @mask: Bitmask to change + * @val: New value for bitmask + * @err: Optional pointer to store errors, if a previous error is set + * then the update will be skipped + * + * Note this uses read-modify-write to update the bits, atomicity with regards + * to other cci_*() register access functions is NOT guaranteed. + * + * Return: %0 on success or a negative error code on failure. + */ +int cci_update_bits(struct regmap *map, u32 reg, u64 mask, u64 val, int *err); + +/** + * cci_multi_reg_write() - Write multiple registers to the device + * + * @map: Register map to write to + * @regs: Array of structures containing register-address, -value pairs to be + * written, register-addresses use CCI_REG#() macros to encode reg width + * @num_regs: Number of registers to write + * @err: Optional pointer to store errors, if a previous error is set + * then the write will be skipped + * + * Write multiple registers to the device where the set of register, value + * pairs are supplied in any order, possibly not all in a single range. + * + * Use of the CCI_REG#() macros to encode reg width is mandatory. + * + * For raw lists of register-address, -value pairs with only 8 bit + * wide writes regmap_multi_reg_write() can be used instead. + * + * Return: %0 on success or a negative error code on failure. + */ +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() - Create regmap to use with cci_*() register + * access functions + * + * @client: i2c_client to create the regmap for + * @reg_addr_bits: register address width to use (8 or 16) + * + * 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. + */ +struct regmap *devm_cci_regmap_init_i2c(struct i2c_client *client, + int reg_addr_bits); +#endif + +#endif -- cgit v1.2.3