Date:   Mon, 6 Feb 2017 11:38:28 +0000
From:   Ramiro Oliveira <Ramiro.Oliveira@...opsys.com>
To:     Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Ramiro Oliveira <Ramiro.Oliveira@...opsys.com>
CC:     <linux-media@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <CARLOS.PALMINHA@...opsys.com>,
        "David S. Miller" <davem@...emloft.net>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Hans Verkuil <hans.verkuil@...co.com>,
        Mark Rutland <mark.rutland@....com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        "Pavel Machek" <pavel@....cz>,
        Robert Jarzmik <robert.jarzmik@...e.fr>,
        Rob Herring <robh+dt@...nel.org>,
        Steve Longerbeam <slongerbeam@...il.com>
Subject: Re: [PATCH RESEND v7 2/2] Add support for OV5647 sensor.

Hi Sakari,

Thank you for your feedback.

On 2/3/2017 8:17 PM, Sakari Ailus wrote:
> Hi Ramiro,
> 
> Thanks for the update!
> 
> Please see some comments below... some streaming and hardware control
> related matters I missed earlier.
> 
> On Fri, Feb 03, 2017 at 06:18:33PM +0000, Ramiro Oliveira wrote:
>> Modes supported:
>>  - 640x480 RAW 8
>>
>> Signed-off-by: Ramiro Oliveira <roliveir@...opsys.com>
>> Acked-by: Pavel Machek <pavel@....cz>
>> ---
>>  MAINTAINERS                |   7 +
>>  drivers/media/i2c/Kconfig  |  12 +
>>  drivers/media/i2c/Makefile |   1 +
>>  drivers/media/i2c/ov5647.c | 718 +++++++++++++++++++++++++++++++++++++++++++++
>>  4 files changed, 738 insertions(+)
>>  create mode 100644 drivers/media/i2c/ov5647.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 421adffbe376..56f392fd2c39 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -9101,6 +9101,13 @@ M:	Harald Welte <laforge@...monks.org>
>>  S:	Maintained
>>  F:	drivers/char/pcmcia/cm4040_cs.*
>>  
>> +OMNIVISION OV5647 SENSOR DRIVER
>> +M:	Ramiro Oliveira <roliveir@...opsys.com>
>> +L:	linux-media@...r.kernel.org
>> +T:	git git://linuxtv.org/media_tree.git
>> +S:	Maintained
>> +F:	drivers/media/i2c/ov5647.c
>> +
>>  OMNIVISION OV7670 SENSOR DRIVER
>>  M:	Jonathan Corbet <corbet@....net>
>>  L:	linux-media@...r.kernel.org
>> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
>> index cee1dae6e014..ac388be5f9a8 100644
>> --- a/drivers/media/i2c/Kconfig
>> +++ b/drivers/media/i2c/Kconfig
>> @@ -531,6 +531,18 @@ config VIDEO_OV2659
>>  	  To compile this driver as a module, choose M here: the
>>  	  module will be called ov2659.
>>  
>> +config VIDEO_OV5647
>> +	tristate "OmniVision OV5647 sensor support"
>> +	depends on OF
>> +	depends on I2C && VIDEO_V4L2 && VIDEO_V4L2_SUBDEV_API
>> +	depends on MEDIA_CAMERA_SUPPORT
>> +	---help---
>> +	  This is a Video4Linux2 sensor-level driver for the OmniVision
>> +	  OV5647 camera.
>> +
>> +	  To compile this driver as a module, choose M here: the
>> +	  module will be called ov5647.
>> +
>>  config VIDEO_OV7640
>>  	tristate "OmniVision OV7640 sensor support"
>>  	depends on I2C && VIDEO_V4L2
>> diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
>> index 5bc7bbeb5499..ef2ccf65f94c 100644
>> --- a/drivers/media/i2c/Makefile
>> +++ b/drivers/media/i2c/Makefile
>> @@ -83,3 +83,4 @@ obj-$(CONFIG_VIDEO_IR_I2C)  += ir-kbd-i2c.o
>>  obj-$(CONFIG_VIDEO_ML86V7667)	+= ml86v7667.o
>>  obj-$(CONFIG_VIDEO_OV2659)	+= ov2659.o
>>  obj-$(CONFIG_VIDEO_TC358743)	+= tc358743.o
>> +obj-$(CONFIG_VIDEO_OV5647)	+= ov5647.o
>> diff --git a/drivers/media/i2c/ov5647.c b/drivers/media/i2c/ov5647.c
>> new file mode 100644
>> index 000000000000..c2828650d3a3
>> --- /dev/null
>> +++ b/drivers/media/i2c/ov5647.c
>> @@ -0,0 +1,718 @@
>> +/*
>> + * A V4L2 driver for OmniVision OV5647 cameras.
>> + *
>> + * Based on Samsung S5K6AAFX SXGA 1/6" 1.3M CMOS Image Sensor driver
>> + * Copyright (C) 2011 Sylwester Nawrocki <s.nawrocki@...sung.com>
>> + *
>> + * Based on Omnivision OV7670 Camera Driver
>> + * Copyright (C) 2006-7 Jonathan Corbet <corbet@....net>
>> + *
>> + * Copyright (C) 2016, Synopsys, Inc.
>> + *
>> + * This program is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU General Public License as
>> + * published by the Free Software Foundation version 2.
>> + *
>> + * This program is distributed .as is. WITHOUT ANY WARRANTY of any
>> + * kind, whether express or implied; without even the implied warranty
>> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/delay.h>
>> +#include <linux/i2c.h>
>> +#include <linux/init.h>
>> +#include <linux/io.h>
>> +#include <linux/module.h>
>> +#include <linux/slab.h>
>> +#include <linux/videodev2.h>
>> +#include <media/v4l2-ctrls.h>
>> +#include <media/v4l2-device.h>
>> +#include <media/v4l2-image-sizes.h>
>> +#include <media/v4l2-mediabus.h>
>> +#include <media/v4l2-of.h>
>> +
>> +#define SENSOR_NAME "ov5647"
>> +
>> +#define OV5647_SW_RESET		0x1003
>> +#define OV5647_REG_CHIPID_H	0x300A
>> +#define OV5647_REG_CHIPID_L	0x300B
>> +
>> +#define REG_TERM 0xfffe
>> +#define VAL_TERM 0xfe
>> +#define REG_DLY  0xffff
>> +
>> +#define OV5647_ROW_START		0x01
>> +#define OV5647_ROW_START_MIN		0
>> +#define OV5647_ROW_START_MAX		2004
>> +#define OV5647_ROW_START_DEF		54
>> +
>> +#define OV5647_COLUMN_START		0x02
>> +#define OV5647_COLUMN_START_MIN		0
>> +#define OV5647_COLUMN_START_MAX		2750
>> +#define OV5647_COLUMN_START_DEF		16
>> +
>> +#define OV5647_WINDOW_HEIGHT		0x03
>> +#define OV5647_WINDOW_HEIGHT_MIN	2
>> +#define OV5647_WINDOW_HEIGHT_MAX	2006
>> +#define OV5647_WINDOW_HEIGHT_DEF	1944
>> +
>> +#define OV5647_WINDOW_WIDTH		0x04
>> +#define OV5647_WINDOW_WIDTH_MIN		2
>> +#define OV5647_WINDOW_WIDTH_MAX		2752
>> +#define OV5647_WINDOW_WIDTH_DEF		2592
>> +
>> +struct regval_list {
>> +	u16 addr;
>> +	u8 data;
>> +};
>> +
>> +struct cfg_array {
>> +	struct regval_list *regs;
>> +	int size;
>> +};
>> +
>> +struct ov5647 {
>> +	struct device			*dev;
>> +	struct v4l2_subdev		sd;
>> +	struct media_pad		pad;
>> +	struct mutex			lock;
>> +	struct v4l2_mbus_framefmt	format;
>> +	unsigned int			width;
>> +	unsigned int			height;
>> +	int				power_count;
>> +	struct clk			*xclk;
>> +	/* External clock frequency currently supported is 30MHz */
>> +	u32				xclk_freq;
>> +};
>> +
>> +static inline struct ov5647 *to_state(struct v4l2_subdev *sd)
>> +{
>> +	return container_of(sd, struct ov5647, sd);
>> +}
>> +
>> +static struct regval_list sensor_oe_disable_regs[] = {
>> +	{0x3000, 0x00},
>> +	{0x3001, 0x00},
>> +	{0x3002, 0x00},
>> +};
>> +
>> +static struct regval_list sensor_oe_enable_regs[] = {
>> +	{0x3000, 0x0f},
>> +	{0x3001, 0xff},
>> +	{0x3002, 0xe4},
>> +};
>> +
>> +static struct regval_list ov5647_640x480[] = {
>> +	{0x0100, 0x00},
>> +	{0x0103, 0x01},
>> +	{0x3034, 0x08},
>> +	{0x3035, 0x21},
>> +	{0x3036, 0x46},
>> +	{0x303c, 0x11},
>> +	{0x3106, 0xf5},
>> +	{0x3821, 0x07},
>> +	{0x3820, 0x41},
>> +	{0x3827, 0xec},
>> +	{0x370c, 0x0f},
>> +	{0x3612, 0x59},
>> +	{0x3618, 0x00},
>> +	{0x5000, 0x06},
>> +	{0x5001, 0x01},
>> +	{0x5002, 0x41},
>> +	{0x5003, 0x08},
>> +	{0x5a00, 0x08},
>> +	{0x3000, 0x00},
>> +	{0x3001, 0x00},
>> +	{0x3002, 0x00},
>> +	{0x3016, 0x08},
>> +	{0x3017, 0xe0},
>> +	{0x3018, 0x44},
>> +	{0x301c, 0xf8},
>> +	{0x301d, 0xf0},
>> +	{0x3a18, 0x00},
>> +	{0x3a19, 0xf8},
>> +	{0x3c01, 0x80},
>> +	{0x3b07, 0x0c},
>> +	{0x380c, 0x07},
>> +	{0x380d, 0x68},
>> +	{0x380e, 0x03},
>> +	{0x380f, 0xd8},
>> +	{0x3814, 0x31},
>> +	{0x3815, 0x31},
>> +	{0x3708, 0x64},
>> +	{0x3709, 0x52},
>> +	{0x3808, 0x02},
>> +	{0x3809, 0x80},
>> +	{0x380a, 0x01},
>> +	{0x380b, 0xE0},
>> +	{0x3801, 0x00},
>> +	{0x3802, 0x00},
>> +	{0x3803, 0x00},
>> +	{0x3804, 0x0a},
>> +	{0x3805, 0x3f},
>> +	{0x3806, 0x07},
>> +	{0x3807, 0xa1},
>> +	{0x3811, 0x08},
>> +	{0x3813, 0x02},
>> +	{0x3630, 0x2e},
>> +	{0x3632, 0xe2},
>> +	{0x3633, 0x23},
>> +	{0x3634, 0x44},
>> +	{0x3636, 0x06},
>> +	{0x3620, 0x64},
>> +	{0x3621, 0xe0},
>> +	{0x3600, 0x37},
>> +	{0x3704, 0xa0},
>> +	{0x3703, 0x5a},
>> +	{0x3715, 0x78},
>> +	{0x3717, 0x01},
>> +	{0x3731, 0x02},
>> +	{0x370b, 0x60},
>> +	{0x3705, 0x1a},
>> +	{0x3f05, 0x02},
>> +	{0x3f06, 0x10},
>> +	{0x3f01, 0x0a},
>> +	{0x3a08, 0x01},
>> +	{0x3a09, 0x27},
>> +	{0x3a0a, 0x00},
>> +	{0x3a0b, 0xf6},
>> +	{0x3a0d, 0x04},
>> +	{0x3a0e, 0x03},
>> +	{0x3a0f, 0x58},
>> +	{0x3a10, 0x50},
>> +	{0x3a1b, 0x58},
>> +	{0x3a1e, 0x50},
>> +	{0x3a11, 0x60},
>> +	{0x3a1f, 0x28},
>> +	{0x4001, 0x02},
>> +	{0x4004, 0x02},
>> +	{0x4000, 0x09},
>> +	{0x4837, 0x24},
>> +	{0x4050, 0x6e},
>> +	{0x4051, 0x8f},
>> +	{0x0100, 0x01},
>> +};
>> +
>> +/**
>> + * @short I2C Write operation
>> + * @param[in] i2c_client I2C client
>> + * @param[in] reg register address
>> + * @param[in] val value to write
>> + * @return Error code
>> + */
>> +static int ov5647_write(struct v4l2_subdev *sd, u16 reg, u8 val)
>> +{
>> +	int ret;
>> +	unsigned char data[3] = { reg >> 8, reg & 0xff, val};
>> +	struct i2c_client *client = v4l2_get_subdevdata(sd);
>> +
>> +	ret = i2c_master_send(client, data, 3);
>> +	if (ret != 3) {
>> +		dev_dbg(&client->dev, "%s: i2c write error, reg: %x\n",
>> +				__func__, reg);
>> +		return ret < 0 ? ret : -EIO;
>> +	}
>> +	return 0;
>> +}
>> +
>> +/**
>> + * @short I2C Read operation
>> + * @param[in] i2c_client I2C client
>> + * @param[in] reg register address
>> + * @param[out] val value read
>> + * @return Error code
>> + */
>> +static int ov5647_read(struct v4l2_subdev *sd, u16 reg, u8 *val)
>> +{
>> +	int ret;
>> +	unsigned char data_w[2] = { reg >> 8, reg & 0xff };
>> +	struct i2c_client *client = v4l2_get_subdevdata(sd);
>> +
>> +
>> +	ret = i2c_master_send(client, data_w, 2);
>> +
>> +	if (ret < 2) {
>> +		dev_dbg(&client->dev, "%s: i2c read error, reg: %x\n",
>> +			__func__, reg);
>> +		return ret < 0 ? ret : -EIO;
>> +	}
>> +
>> +
>> +	ret = i2c_master_recv(client, val, 1);
>> +
>> +	if (ret < 1) {
>> +		dev_dbg(&client->dev, "%s: i2c read error, reg: %x\n",
>> +				__func__, reg);
>> +		return ret < 0 ? ret : -EIO;
>> +	}
>> +	return 0;
>> +}
>> +
>> +static int ov5647_write_array(struct v4l2_subdev *sd,
>> +				struct regval_list *regs, int array_size)
>> +{
>> +	int i = 0;
>> +	int ret = 0;
>> +
>> +	if (!regs)
>> +		return -EINVAL;
>> +
>> +	while (i < array_size) {
>> +		ret = ov5647_write(sd, regs->addr, regs->data);
>> +		if (ret < 0)
>> +			return ret;
>> +		i++;
>> +		regs++;
>> +	}
>> +	return 0;
>> +}
>> +
>> +static void ov5647_set_virtual_channel(struct v4l2_subdev *sd, int channel)
>> +{
>> +	u8 channel_id;
>> +
>> +	ov5647_read(sd, 0x4814, &channel_id);
>> +	channel_id &= ~(3 << 6);
>> +	ov5647_write(sd, 0x4814, channel_id | (channel << 6));
>> +}
>> +
>> +void ov5647_stream_on(struct v4l2_subdev *sd)
>> +{
>> +	struct i2c_client *client = v4l2_get_subdevdata(sd);
>> +
>> +	ov5647_write(sd, 0x4202, 0x00);
>> +	dev_dbg(&client->dev, "Stream on");
>> +	ov5647_write(sd, 0x300D, 0x00);
>> +}
>> +
>> +void ov5647_stream_off(struct v4l2_subdev *sd)
>> +{
>> +	struct i2c_client *client = v4l2_get_subdevdata(sd);
>> +
>> +	ov5647_write(sd, 0x4202, 0x0f);
>> +	dev_dbg(&client->dev, "Stream off");
>> +	ov5647_write(sd, 0x300D, 0x01);
>> +}
>> +
>> +/**
>> + * @short Set SW standby
>> + * @param[in] sd v4l2 sd
>> + * @param[in] stanby standby mode status (on or off)
>> + * @return Error code
>> + */
>> +static int set_sw_standby(struct v4l2_subdev *sd, bool standby)
>> +{
>> +	int ret;
>> +	unsigned char rdval;
>> +
>> +	ret = ov5647_read(sd, 0x0100, &rdval);
>> +	if (ret != 0)
>> +		return ret;
>> +
>> +	if (standby)
>> +		rdval &= 0xfe;
>> +	else
>> +		rdval |= 0x01;
>> +
>> +	ret = ov5647_write(sd, 0x0100, rdval);
>> +
>> +	return ret;
>> +}
>> +
>> +/**
>> + * @short Initialize sensor
>> + * @param[in] sd v4l2 subdev
>> + * @param[in] val not used
>> + * @return Error code
>> + */
>> +static int __sensor_init(struct v4l2_subdev *sd)
>> +{
>> +	int ret;
>> +	u8 resetval;
>> +	u8 rdval;
>> +	struct i2c_client *client = v4l2_get_subdevdata(sd);
>> +
>> +	dev_dbg(&client->dev, "sensor init\n");
>> +
>> +	ret = ov5647_read(sd, 0x0100, &rdval);
>> +	if (ret != 0)
>> +		return ret;
>> +
>> +	ov5647_write(sd, 0x4800, 0x25);
>> +	ov5647_stream_off(sd);
>> +
> 
> Your sensor configuration appears to begin with software reset, so I
> suppose whatever you do between powering the sensor on and that will be
> lost.
> 

Yes. You're right. This left-over from older code. I'll remove it and start with
the sensor configuration.

>> +	ret = ov5647_write_array(sd, ov5647_640x480,
>> +					ARRAY_SIZE(ov5647_640x480));
>> +	if (ret < 0) {
>> +		dev_err(&client->dev, "write sensor_default_regs error\n");
>> +		return ret;
>> +	}
>> +
>> +	ov5647_set_virtual_channel(sd, 0);
>> +
>> +	ov5647_read(sd, 0x0100, &resetval);
>> +	if (!(resetval & 0x01)) {
> 
> Can this ever happen? Streaming start is at the end of the register list.
> 

I'm not sure it can happen. It was just a safeguard, but I can remove it if you
think it's not necessary

>> +		dev_err(&client->dev, "Device was in SW standby");
>> +		ov5647_write(sd, 0x0100, 0x01);
>> +	}
>> +
>> +	ov5647_write(sd, 0x4800, 0x04);
>> +	ov5647_stream_on(sd);
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * @short Control sensor power state
>> + * @param[in] sd v4l2 subdev
>> + * @param[in] on Sensor power
>> + * @return Error code
>> + */
>> +static int sensor_power(struct v4l2_subdev *sd, int on)
>> +{
>> +	int ret;
>> +	struct ov5647 *ov5647 = to_state(sd);
>> +	struct i2c_client *client = v4l2_get_subdevdata(sd);
>> +
>> +	ret = 0;
>> +	mutex_lock(&ov5647->lock);
>> +
>> +	if (on && !ov5647->power_count)	{
>> +		dev_dbg(&client->dev, "OV5647 power on\n");
>> +
>> +		clk_set_rate(ov5647->xclk, ov5647->xclk_freq);
>> +
>> +		ret = clk_prepare_enable(ov5647->xclk);
>> +		if (ret < 0) {
>> +			dev_err(ov5647->dev, "clk prepare enable failed\n");
>> +			goto out;
>> +		}
>> +
>> +		ret = ov5647_write_array(sd, sensor_oe_enable_regs,
>> +				ARRAY_SIZE(sensor_oe_enable_regs));
>> +		if (ret < 0) {
>> +			clk_disable_unprepare(ov5647->xclk);
>> +			dev_err(&client->dev,
>> +				"write sensor_oe_enable_regs error\n");
>> +			goto out;
>> +		}
>> +
>> +		ret = __sensor_init(sd);
>> +		if (ret < 0) {
>> +			clk_disable_unprepare(ov5647->xclk);
>> +			dev_err(&client->dev,
>> +				"Camera not available, check Power\n");
>> +			goto out;
>> +		}
>> +	} else if (!on && ov5647->power_count == 1) {
>> +		dev_dbg(&client->dev, "OV5647 power off\n");
>> +
>> +		dev_dbg(&client->dev, "disable oe\n");
>> +		ret = ov5647_write_array(sd, sensor_oe_disable_regs,
>> +				ARRAY_SIZE(sensor_oe_disable_regs));
>> +
>> +		if (ret < 0)
>> +			dev_dbg(&client->dev, "disable oe failed\n");
>> +
>> +		ret = set_sw_standby(sd, true);
>> +
>> +		if (ret < 0)
>> +			dev_dbg(&client->dev, "soft stby failed\n");
>> +
>> +		clk_disable_unprepare(ov5647->xclk);
>> +	}
>> +
>> +	/* Update the power count. */
>> +	ov5647->power_count += on ? 1 : -1;
>> +	WARN_ON(ov5647->power_count < 0);
>> +
>> +out:
>> +	mutex_unlock(&ov5647->lock);
>> +
>> +	return ret;
>> +}
>> +
>> +#ifdef CONFIG_VIDEO_ADV_DEBUG
>> +/**
>> + * @short Get register value
>> + * @param[in] sd v4l2 subdev
>> + * @param[in] reg register struct
>> + * @return Error code
>> + */
>> +static int sensor_get_register(struct v4l2_subdev *sd,
>> +				struct v4l2_dbg_register *reg)
>> +{
>> +	unsigned char val = 0;
>> +	int ret;
>> +
>> +	ret = ov5647_read(sd, reg->reg & 0xff, &val);
>> +	if (ret != 0)
>> +		return ret;
>> +
>> +	reg->val = val;
>> +	reg->size = 1;
>> +
>> +	return ret;
>> +}
>> +
>> +/**
>> + * @short Set register value
>> + * @param[in] sd v4l2 subdev
>> + * @param[in] reg register struct
>> + * @return Error code
>> + */
>> +static int sensor_set_register(struct v4l2_subdev *sd,
>> +				const struct v4l2_dbg_register *reg)
>> +{
>> +	return ov5647_write(sd, reg->reg & 0xff, reg->val & 0xff);
>> +}
>> +#endif
>> +
>> +/**
>> + * @short Subdev core operations registration
>> + */
>> +static const struct v4l2_subdev_core_ops sensor_core_ops = {
>> +	.s_power		= sensor_power,
>> +#ifdef CONFIG_VIDEO_ADV_DEBUG
>> +	.g_register		= sensor_get_register,
>> +	.s_register		= sensor_set_register,
>> +#endif
>> +};
>> +
>> +static int enum_mbus_code(struct v4l2_subdev *sd,
>> +				struct v4l2_subdev_pad_config *cfg,
>> +				struct v4l2_subdev_mbus_code_enum *code)
>> +{
>> +	if (code->index > 0)
>> +		return -EINVAL;
>> +
>> +	code->code = MEDIA_BUS_FMT_SBGGR8_1X8;
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct v4l2_subdev_pad_ops subdev_pad_ops = {
>> +	.enum_mbus_code = enum_mbus_code,
>> +};
>> +
>> +
>> +/**
>> + * @short Subdev operations registration
>> + *
>> + */
>> +static const struct v4l2_subdev_ops subdev_ops = {
>> +	.core		= &sensor_core_ops,
>> +	.pad		= &subdev_pad_ops,
> 
> You should implement s_stream() in video ops to control the streaming state.
> 
> I don't know about this particular sensor, but on SMIA compliant sensors
> the SW standby means streaming is disabled. There seem to be additional
> registers as well; my educated guess is that writing all those to control
> streaming would be the right thing to do.
> 
> The CSI-2 bus initialisation could fail if you start streaming right away
> when the sensor is powered on.
> 

I haven't had any error yet, but I'll add set_stream() and start streaming video
there, just to be sure.

>> +};
>> +
>> +/**
>> + * @short Detect camera version and model
>> + * @param[in] sd v4l2 subdev
>> + * @return Error code
>> + */
>> +static int ov5647_detect(struct v4l2_subdev *sd)
>> +{
>> +	unsigned char v;
>> +	int ret;
>> +	struct i2c_client *client = v4l2_get_subdevdata(sd);
>> +
>> +	ret = ov5647_write(sd, OV5647_SW_RESET, 0x01);
>> +	if (ret < 0)
>> +		return ret;
>> +	ret = ov5647_read(sd, OV5647_REG_CHIPID_H, &v);
>> +	if (ret < 0)
>> +		return ret;
>> +	if (v != 0x56) {
>> +		dev_err(&client->dev, "Wrong model version detected");
>> +		return -ENODEV;
>> +	}
>> +	ret = ov5647_read(sd, OV5647_REG_CHIPID_L, &v);
>> +	if (ret < 0)
>> +		return ret;
>> +	if (v != 0x47) {
>> +		dev_err(&client->dev, "Wrong model version detected");
>> +		return -ENODEV;
>> +	}
>> +
>> +	ret = ov5647_write(sd, OV5647_SW_RESET, 0x00);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * @short Detect if camera is registered
>> + * @param[in] sd v4l2 subdev
>> + * @return Error code
>> + */
>> +static int ov5647_registered(struct v4l2_subdev *sd)
>> +{
>> +	return 0;
>> +}
>> +
>> +/**
>> + * @short Open device
>> + * @param[in] sd v4l2 subdev
>> + * @param[in] fh v4l2 file handler
>> + * @return Error code
>> + */
>> +static int ov5647_open(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
>> +{
>> +	struct v4l2_mbus_framefmt *format =
>> +				v4l2_subdev_get_try_format(sd, fh->pad, 0);
>> +	struct v4l2_rect *crop =
>> +				v4l2_subdev_get_try_crop(sd, fh->pad, 0);
>> +
>> +	crop->left = OV5647_COLUMN_START_DEF;
>> +	crop->top = OV5647_ROW_START_DEF;
>> +	crop->width = OV5647_WINDOW_WIDTH_DEF;
>> +	crop->height = OV5647_WINDOW_HEIGHT_DEF;
>> +
>> +	format->code = MEDIA_BUS_FMT_SBGGR8_1X8;
>> +
>> +	format->width = OV5647_WINDOW_WIDTH_DEF;
>> +	format->height = OV5647_WINDOW_HEIGHT_DEF;
>> +	format->field = V4L2_FIELD_NONE;
>> +	format->colorspace = V4L2_COLORSPACE_SRGB;
>> +
>> +	return sensor_power(sd, true);
>> +}
>> +
>> +/**
>> + * @short Open device
>> + * @param[in] sd v4l2 subdev
>> + * @param[in] fh v4l2 file handler
>> + * @return Error code
>> + */
>> +static int ov5647_close(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
>> +{
>> +	return sensor_power(sd, false);
>> +}
>> +
>> +/**
>> + * @short Subdev internal operations registration
>> + *
>> + */
>> +static const struct v4l2_subdev_internal_ops ov5647_subdev_internal_ops = {
>> +	.registered = ov5647_registered,
>> +	.open = ov5647_open,
>> +	.close = ov5647_close,
>> +};
>> +
>> +/**
>> + * @short Initialization routine - Entry point of the driver
>> + * @param[in] client pointer to the i2c client structure
>> + * @param[in] id pointer to the i2c device id structure
>> + * @return 0 on success and a negative number on failure
>> + */
>> +static int ov5647_probe(struct i2c_client *client,
>> +			const struct i2c_device_id *id)
>> +{
>> +	struct device *dev = &client->dev;
>> +	struct ov5647 *sensor;
>> +	int ret;
>> +	struct v4l2_subdev *sd;
>> +
>> +	dev_info(&client->dev, "Installing OmniVision OV5647 camera driver\n");
>> +
>> +	sensor = devm_kzalloc(dev, sizeof(*sensor), GFP_KERNEL);
>> +	if (sensor == NULL)
>> +		return -ENOMEM;
>> +
>> +	/* get system clock (xclk) */
>> +	sensor->xclk = devm_clk_get(dev, "xclk");
>> +	if (IS_ERR(sensor->xclk)) {
>> +		dev_err(dev, "could not get xclk");
>> +		return PTR_ERR(sensor->xclk);
>> +	}
>> +
>> +	ret = of_property_read_u32(dev->of_node, "clock-frequency",
>> +				    &sensor->xclk_freq);
>> +	if (ret) {
>> +		dev_err(dev, "could not get xclk frequency\n");
>> +		return ret;
>> +	}
>> +
>> +	mutex_init(&sensor->lock);
>> +	sensor->dev = dev;
>> +
>> +	sd = &sensor->sd;
>> +	v4l2_i2c_subdev_init(sd, client, &subdev_ops);
>> +	sensor->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
>> +
>> +	sensor->pad.flags = MEDIA_PAD_FL_SOURCE;
>> +	sd->entity.function = MEDIA_ENT_F_CAM_SENSOR;
>> +	ret = media_entity_pads_init(&sd->entity, 1, &sensor->pad);
>> +	if (ret < 0)
>> +		goto mutex_remove;
>> +
>> +	ret = ov5647_detect(sd);
>> +	if (ret < 0)
>> +		goto error;
>> +
>> +	ret = v4l2_async_register_subdev(sd);
>> +	if (ret < 0)
>> +		goto error;
>> +
>> +	return 0;
>> +error:
>> +	media_entity_cleanup(&sd->entity);
>> +mutex_remove:
>> +	mutex_destroy(&sensor->lock);
>> +	return ret;
>> +}
>> +
>> +/**
>> + * @short Exit routine - Exit point of the driver
>> + * @param[in] client pointer to the i2c client structure
>> + * @return 0 on success and a negative number on failure
>> + */
>> +static int ov5647_remove(struct i2c_client *client)
>> +{
>> +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
>> +	struct ov5647 *ov5647 = to_state(sd);
>> +
>> +	v4l2_async_unregister_subdev(&ov5647->sd);
>> +	media_entity_cleanup(&ov5647->sd.entity);
>> +	v4l2_device_unregister_subdev(sd);
>> +	mutex_destroy(&ov5647->lock);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct i2c_device_id ov5647_id[] = {
>> +	{ "ov5647", 0 },
>> +	{ }
>> +};
>> +MODULE_DEVICE_TABLE(i2c, ov5647_id);
>> +
>> +#if IS_ENABLED(CONFIG_OF)
>> +static const struct of_device_id ov5647_of_match[] = {
>> +	{ .compatible = "ovti,ov5647" },
>> +	{ /* sentinel */ },
>> +};
>> +MODULE_DEVICE_TABLE(of, ov5647_of_match);
>> +#endif
>> +
>> +/**
>> + * @short i2c driver structure
>> + */
>> +static struct i2c_driver ov5647_driver = {
>> +	.driver = {
>> +		.of_match_table = of_match_ptr(ov5647_of_match),
>> +		.owner	= THIS_MODULE,
>> +		.name	= "ov5647",
>> +	},
>> +	.probe		= ov5647_probe,
>> +	.remove		= ov5647_remove,
>> +	.id_table	= ov5647_id,
>> +};
>> +
>> +module_i2c_driver(ov5647_driver);
>> +
>> +MODULE_AUTHOR("Ramiro Oliveira <roliveir@...opsys.com>");
>> +MODULE_DESCRIPTION("A low-level driver for OmniVision ov5647 sensors");
>> +MODULE_LICENSE("GPL v2");
> 

-- 
Best Regards

Ramiro Oliveira
Ramiro.Oliveira@...opsys.com

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