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@xxxxxxxxxx/ Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> --- Changes in v3 - Use unsigned int instead of int in a couple of places - Run + fix checkpatch.pl --strict --max-line-length=80 - Rename cci_regmap_init_i2c() to devm_cci_regmap_init_i2c() - Some small kerneldoc text tweaks Changes in v2: - Drop cci_reg_type enum - Make having an encoded reg-width mandatory rather then using 0 to encode 8 bit width making reg-addresses without an encoded width default to a width of 8 - Add support for 64 bit wide registers - Introduce a new cci_reg_sequence struct with 64 bit reg values for 64 bit support and without the delay_us field - Various kerneldoc updates - Stop supporting delays in cci_multi_reg_write() - Some includes cleanups - Disable regmap locking --- Documentation/driver-api/media/v4l2-cci.rst | 5 + Documentation/driver-api/media/v4l2-core.rst | 1 + drivers/media/v4l2-core/Kconfig | 5 + drivers/media/v4l2-core/Makefile | 1 + drivers/media/v4l2-core/v4l2-cci.c | 163 +++++++++++++++++++ include/media/v4l2-cci.h | 123 ++++++++++++++ 6 files changed, 298 insertions(+) create mode 100644 Documentation/driver-api/media/v4l2-cci.rst create mode 100644 drivers/media/v4l2-core/v4l2-cci.c create mode 100644 include/media/v4l2-cci.h diff --git a/Documentation/driver-api/media/v4l2-cci.rst b/Documentation/driver-api/media/v4l2-cci.rst new file mode 100644 index 000000000000..dd297a40ed20 --- /dev/null +++ b/Documentation/driver-api/media/v4l2-cci.rst @@ -0,0 +1,5 @@ +.. SPDX-License-Identifier: GPL-2.0 + +V4L2 CCI kAPI +^^^^^^^^^^^^^ +.. kernel-doc:: include/media/v4l2-cci.h diff --git a/Documentation/driver-api/media/v4l2-core.rst b/Documentation/driver-api/media/v4l2-core.rst index 1a8c4a5f256b..239045ecc8f4 100644 --- a/Documentation/driver-api/media/v4l2-core.rst +++ b/Documentation/driver-api/media/v4l2-core.rst @@ -22,6 +22,7 @@ Video4Linux devices v4l2-mem2mem v4l2-async v4l2-fwnode + v4l2-cci v4l2-rect v4l2-tuner v4l2-common diff --git a/drivers/media/v4l2-core/Kconfig b/drivers/media/v4l2-core/Kconfig index 348559bc2468..523ba243261d 100644 --- a/drivers/media/v4l2-core/Kconfig +++ b/drivers/media/v4l2-core/Kconfig @@ -74,6 +74,11 @@ config V4L2_FWNODE config V4L2_ASYNC tristate +config V4L2_CCI + tristate + depends on I2C + select REGMAP_I2C + # Used by drivers that need Videobuf modules config VIDEOBUF_GEN tristate diff --git a/drivers/media/v4l2-core/Makefile b/drivers/media/v4l2-core/Makefile index 41d91bd10cf2..be2551705755 100644 --- a/drivers/media/v4l2-core/Makefile +++ b/drivers/media/v4l2-core/Makefile @@ -25,6 +25,7 @@ videodev-$(CONFIG_VIDEO_V4L2_I2C) += v4l2-i2c.o # (e. g. LC_ALL=C sort Makefile) obj-$(CONFIG_V4L2_ASYNC) += v4l2-async.o +obj-$(CONFIG_V4L2_CCI) += v4l2-cci.o obj-$(CONFIG_V4L2_FLASH_LED_CLASS) += v4l2-flash-led-class.o obj-$(CONFIG_V4L2_FWNODE) += v4l2-fwnode.o obj-$(CONFIG_V4L2_H264) += v4l2-h264.o diff --git a/drivers/media/v4l2-core/v4l2-cci.c b/drivers/media/v4l2-core/v4l2-cci.c new file mode 100644 index 000000000000..de1e59b2ebde --- /dev/null +++ b/drivers/media/v4l2-core/v4l2-cci.c @@ -0,0 +1,163 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * MIPI Camera Control Interface (CCI) register access helpers. + * + * Copyright (C) 2023 Hans de Goede <hansg@xxxxxxxxxx> + */ + +#include <linux/bitfield.h> +#include <linux/delay.h> +#include <linux/dev_printk.h> +#include <linux/module.h> +#include <linux/regmap.h> +#include <linux/types.h> + +#include <asm/unaligned.h> + +#include <media/v4l2-cci.h> + +int cci_read(struct regmap *map, u32 reg, u64 *val, int *err) +{ + unsigned int len; + u8 buf[8]; + int ret; + + if (err && *err) + return *err; + + len = FIELD_GET(CCI_REG_WIDTH_MASK, reg); + reg = FIELD_GET(CCI_REG_ADDR_MASK, reg); + + ret = regmap_bulk_read(map, reg, buf, len); + if (ret) { + dev_err(regmap_get_device(map), "Error reading reg 0x%4x: %d\n", + reg, ret); + goto out; + } + + switch (len) { + case 1: + *val = buf[0]; + break; + case 2: + *val = get_unaligned_be16(buf); + break; + case 3: + *val = get_unaligned_be24(buf); + break; + case 4: + *val = get_unaligned_be32(buf); + break; + case 8: + *val = get_unaligned_be64(buf); + break; + default: + dev_err(regmap_get_device(map), "Error invalid reg-width %u for reg 0x%04x\n", + len, reg); + ret = -EINVAL; + break; + } + +out: + if (ret && err) + *err = ret; + + return ret; +} +EXPORT_SYMBOL_GPL(cci_read); + +int cci_write(struct regmap *map, u32 reg, u64 val, int *err) +{ + unsigned int len; + u8 buf[8]; + int ret; + + if (err && *err) + return *err; + + len = FIELD_GET(CCI_REG_WIDTH_MASK, reg); + reg = FIELD_GET(CCI_REG_ADDR_MASK, reg); + + switch (len) { + case 1: + buf[0] = val; + break; + case 2: + put_unaligned_be16(val, buf); + break; + case 3: + put_unaligned_be24(val, buf); + break; + case 4: + put_unaligned_be32(val, buf); + break; + case 8: + put_unaligned_be64(val, buf); + break; + default: + dev_err(regmap_get_device(map), "Error invalid reg-width %u for reg 0x%04x\n", + len, reg); + ret = -EINVAL; + goto out; + } + + ret = regmap_bulk_write(map, reg, buf, len); + if (ret) + dev_err(regmap_get_device(map), "Error writing reg 0x%4x: %d\n", + reg, ret); + +out: + if (ret && err) + *err = ret; + + return ret; +} +EXPORT_SYMBOL_GPL(cci_write); + +int cci_update_bits(struct regmap *map, u32 reg, u64 mask, u64 val, int *err) +{ + u64 readval; + int ret; + + ret = cci_read(map, reg, &readval, err); + if (ret) + return ret; + + val = (readval & ~mask) | (val & mask); + + return cci_write(map, reg, val, err); +} +EXPORT_SYMBOL_GPL(cci_update_bits); + +int cci_multi_reg_write(struct regmap *map, const struct cci_reg_sequence *regs, + unsigned int num_regs, int *err) +{ + unsigned int i; + int ret; + + for (i = 0; i < num_regs; i++) { + ret = cci_write(map, regs[i].reg, regs[i].val, err); + if (ret) + return ret; + } + + return 0; +} +EXPORT_SYMBOL_GPL(cci_multi_reg_write); + +struct regmap *devm_cci_regmap_init_i2c(struct i2c_client *client, + int reg_addr_bits) +{ + struct regmap_config config = { + .reg_bits = reg_addr_bits, + .val_bits = 8, + .reg_format_endian = REGMAP_ENDIAN_BIG, + .disable_locking = true, + }; + + return devm_regmap_init_i2c(client, &config); +} +EXPORT_SYMBOL_GPL(devm_cci_regmap_init_i2c); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Hans de Goede <hansg@xxxxxxxxxx>"); diff --git a/include/media/v4l2-cci.h b/include/media/v4l2-cci.h new file mode 100644 index 000000000000..de5eb8c2a575 --- /dev/null +++ b/include/media/v4l2-cci.h @@ -0,0 +1,123 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * MIPI Camera Control Interface (CCI) register access helpers. + * + * Copyright (C) 2023 Hans de Goede <hansg@xxxxxxxxxx> + */ +#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); + +/** + * 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 -- 2.40.1
