Commit 613cbb91 authored by Hans de Goede's avatar Hans de Goede Committed by Mauro Carvalho Chehab
Browse files

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: default avatarAndy Shevchenko <andy.shevchenko@gmail.com>
Tested-by: default avatarTommaso Merciai <tomm.merciai@gmail.com>
Reviewed-by: default avatarTommaso Merciai <tomm.merciai@gmail.com>
Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
Signed-off-by: default avatarSakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@kernel.org>
parent 35a29918

Documentation/driver-api/media/v4l2-cci.rst

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+5 −0
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.. SPDX-License-Identifier: GPL-2.0



V4L2 CCI kAPI

^^^^^^^^^^^^^

.. kernel-doc:: include/media/v4l2-cci.h

Documentation/driver-api/media/v4l2-core.rst

+1 −0
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@@ -22,6 +22,7 @@ Video4Linux devices 
    v4l2-mem2mem

    v4l2-async

    v4l2-fwnode

    v4l2-cci

    v4l2-rect

    v4l2-tuner

    v4l2-common

drivers/media/v4l2-core/Kconfig

+9 −0
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@@ -74,6 +74,15 @@ config V4L2_FWNODE 
config V4L2_ASYNC

	tristate



config V4L2_CCI

	tristate



config V4L2_CCI_I2C

	tristate

	depends on I2C

	select REGMAP_I2C

	select V4L2_CCI



# Used by drivers that need Videobuf modules

config VIDEOBUF_GEN

	tristate

drivers/media/v4l2-core/Makefile

+1 −0
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@@ -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

drivers/media/v4l2-core/v4l2-cci.c

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// SPDX-License-Identifier: GPL-2.0

/*

 * MIPI Camera Control Interface (CCI) register access helpers.

 *

 * Copyright (C) 2023 Hans de Goede <hansg@kernel.org>

 */



#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);



#if IS_ENABLED(CONFIG_V4L2_CCI_I2C)

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);

#endif



MODULE_LICENSE("GPL");

MODULE_AUTHOR("Hans de Goede <hansg@kernel.org>");

MODULE_DESCRIPTION("MIPI Camera Control Interface (CCI) support");