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author | Hans de Goede <hdegoede@redhat.com> | 2023-06-27 15:51:04 +0300 |
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committer | Mauro Carvalho Chehab <mchehab@kernel.org> | 2023-08-10 08:58:38 +0300 |
commit | 613cbb91e9cee7cf5a61f0816d2acab7bc117407 (patch) | |
tree | de481e364ad1423b739965e2deca0b3c97491ad5 /include/media/v4l2-cci.h | |
parent | 35a2991856ec3035ea3bd5dac3b199bb5a0ec9cb (diff) | |
download | linux-613cbb91e9cee7cf5a61f0816d2acab7bc117407.tar.xz |
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 <andy.shevchenko@gmail.com>
Tested-by: Tommaso Merciai <tomm.merciai@gmail.com>
Reviewed-by: Tommaso Merciai <tomm.merciai@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Diffstat (limited to 'include/media/v4l2-cci.h')
-rw-r--r-- | include/media/v4l2-cci.h | 125 |
1 files changed, 125 insertions, 0 deletions
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 <hansg@kernel.org> + */ +#ifndef _V4L2_CCI_H +#define _V4L2_CCI_H + +#include <linux/types.h> + +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 |