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 then 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/ Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> --- 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 | 142 +++++++++++++++++++ include/media/v4l2-cci.h | 109 ++++++++++++++ 6 files changed, 263 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..21207d137dbe --- /dev/null +++ b/drivers/media/v4l2-core/v4l2-cci.c @@ -0,0 +1,142 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * MIPI Camera Control Interface (CCI) register access helpers. + * + * Copyright (C) 2023 Hans de Goede <hansg@xxxxxxxxxx> + */ + +#include <linux/delay.h> +#include <linux/dev_printk.h> +#include <linux/module.h> +#include <linux/regmap.h> + +#include <media/v4l2-cci.h> + +int cci_read(struct regmap *map, u32 reg, u32 *val, int *err) +{ + int i, len, ret; + u8 buf[4]; + + if (err && *err) + return *err; + + /* Set len to register width in bytes */ + len = ((reg & CCI_REG_WIDTH_MASK) >> CCI_REG_WIDTH_SHIFT) + 1; + reg &= CCI_REG_ADDR_MASK; + + 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); + if (err) + *err = ret; + + return ret; + } + + *val = 0; + for (i = 0; i < len; i++) { + *val <<= 8; + *val |= buf[i]; + } + + return 0; +} +EXPORT_SYMBOL_GPL(cci_read); + +int cci_write(struct regmap *map, u32 reg, u32 val, int *err) +{ + int i, len, ret; + u8 buf[4]; + + if (err && *err) + return *err; + + /* Set len to register width in bytes */ + len = ((reg & CCI_REG_WIDTH_MASK) >> CCI_REG_WIDTH_SHIFT) + 1; + reg &= CCI_REG_ADDR_MASK; + + for (i = 0; i < len; i++) { + buf[len - i - 1] = val & 0xff; + val >>= 8; + } + + 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); + if (err) + *err = ret; + } + + return ret; +} +EXPORT_SYMBOL_GPL(cci_write); + +int cci_update_bits(struct regmap *map, u32 reg, u32 mask, u32 val, int *err) +{ + int width, ret; + u32 readval; + + if (err && *err) + return *err; + + /* + * For single byte updates use regmap_update_bits(), this uses + * the regmap-lock to protect against other read-modify-writes racing. + */ + width = (reg & CCI_REG_WIDTH_MASK) >> CCI_REG_WIDTH_SHIFT; + if (width == cci_reg_8) { + reg &= CCI_REG_ADDR_MASK; + ret = regmap_update_bits(map, reg, mask, val); + if (ret) { + dev_err(regmap_get_device(map), "Error updating reg 0x%4x: %d\n", reg, ret); + if (err) + *err = ret; + } + + return 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 reg_sequence *regs, int num_regs, int *err) +{ + int i, ret; + + if (err && *err) + return *err; + + for (i = 0; i < num_regs; i++) { + ret = cci_write(map, regs[i].reg, regs[i].def, err); + if (ret) + return ret; + + if (regs[i].delay_us) + fsleep(regs[i].delay_us); + } + + return 0; +} +EXPORT_SYMBOL_GPL(cci_multi_reg_write); + +struct regmap *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, + }; + + return devm_regmap_init_i2c(client, &config); +} +EXPORT_SYMBOL_GPL(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..69b8a7c4a013 --- /dev/null +++ b/include/media/v4l2-cci.h @@ -0,0 +1,109 @@ +/* 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/regmap.h> +#include <linux/types.h> + +/* + * Note cci_reg_8 deliberately is 0, not 1, so that raw + * (not wrapped in a CCI_REG*() macro) register addresses + * do 8 bit wide accesses. This allows unchanged use of register + * initialization lists of raw address, value pairs which only + * do 8 bit width accesses. Which makes porting drivers easier. + */ +enum cci_reg_type { + cci_reg_8 = 0, + cci_reg_16, + cci_reg_24, + cci_reg_32, +}; + +/* + * Macros to define register address with the register width encoded + * into the higher bits. CCI_REG8() is a no-op so its use is optional. + */ +#define CCI_REG_ADDR_MASK GENMASK(15, 0) +#define CCI_REG_WIDTH_SHIFT 16 +#define CCI_REG_WIDTH_MASK GENMASK(17, 16) + +#define CCI_REG8(x) ((cci_reg_8 << CCI_REG_WIDTH_SHIFT) | (x)) +#define CCI_REG16(x) ((cci_reg_16 << CCI_REG_WIDTH_SHIFT) | (x)) +#define CCI_REG24(x) ((cci_reg_24 << CCI_REG_WIDTH_SHIFT) | (x)) +#define CCI_REG32(x) ((cci_reg_32 << CCI_REG_WIDTH_SHIFT) | (x)) + +/** + * cci_read() - Read a value from a single CCI register + * + * @map: Register map to write to + * @reg: Register address to write, 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 the write will be skipped + * + * Return: %0 on success or a negative error code on failure. + */ +int cci_read(struct regmap *map, u32 reg, u32 *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 the write will be skipped + * + * Return: %0 on success or a negative error code on failure. + */ +int cci_write(struct regmap *map, u32 reg, u32 val, int *err); + +/** + * cci_update_bits() - Perform a read/modify/write cycle on a single CCI register + * + * @map: Register map to write to + * @reg: Register address to write, 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 the update will be skipped + * + * For 8 bit width registers this is guaranteed to be atomic wrt other + * cci_*() register access functions. For multi-byte width registers + * atomicity is NOT guaranteed. + * + * Return: %0 on success or a negative error code on failure. + */ +int cci_update_bits(struct regmap *map, u32 reg, u32 mask, u32 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 the update 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. + * + * Return: %0 on success or a negative error code on failure. + */ +int cci_multi_reg_write(struct regmap *map, const struct reg_sequence *regs, int num_regs, int *err); + +/** + * 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 *cci_regmap_init_i2c(struct i2c_client *client, int reg_addr_bits); + +#endif -- 2.40.1
