[v6,1/2] Add driver for Aptina (Micron) mt9p031 sensor.

Commit Message

Javier Martin June 1, 2011, 3:36 p.m. UTC

Clock frequency of 57MHz used in previous version was wrong since
when VDD_IO is 1.8V it can only support 48MHz.

Two new platform flags have been added:

- vdd_io: indicates whether the chip is powered with 1.8 or 2.8 VDD_IO.
So that it can use the maximum allowed frequency.
- version: monochrome and color versions of the chip have exactly
the same ID, so the only way to select one of them is through
platform data.

Internal PLL is now used to generate PIXCLK depending on VDD_IO.

Signed-off-by: Javier Martin <[e-mail]>
---
 drivers/media/video/Kconfig   |    7 +
 drivers/media/video/Makefile  |    1 +
 drivers/media/video/mt9p031.c |  763 +++++++++++++++++++++++++++++++++++++++++
 include/media/mt9p031.h       |   23 ++
 4 files changed, 794 insertions(+), 0 deletions(-)
 create mode 100644 drivers/media/video/mt9p031.c
 create mode 100644 include/media/mt9p031.h

Comments

Guennadi Liakhovetski June 2, 2011, 7:57 a.m. UTC | #1

No technical review this time. Relying fully on Laurent and others to take 
care of that, just a couple of cosmetic points, which even checkpatch.pl 
failed to warn about:(

On Wed, 1 Jun 2011, Javier Martin wrote:

> Clock frequency of 57MHz used in previous version was wrong since
> when VDD_IO is 1.8V it can only support 48MHz.
> 
> Two new platform flags have been added:
> 
> - vdd_io: indicates whether the chip is powered with 1.8 or 2.8 VDD_IO.
> So that it can use the maximum allowed frequency.
> - version: monochrome and color versions of the chip have exactly
> the same ID, so the only way to select one of them is through
> platform data.
> 
> Internal PLL is now used to generate PIXCLK depending on VDD_IO.
> 
> Signed-off-by: Javier Martin <[e-mail]>
> ---
>  drivers/media/video/Kconfig   |    7 +
>  drivers/media/video/Makefile  |    1 +
>  drivers/media/video/mt9p031.c |  763 +++++++++++++++++++++++++++++++++++++++++
>  include/media/mt9p031.h       |   23 ++
>  4 files changed, 794 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/media/video/mt9p031.c
>  create mode 100644 include/media/mt9p031.h
> 
> diff --git a/drivers/media/video/Kconfig b/drivers/media/video/Kconfig
> index 00f51dd..cb87e35 100644
> --- a/drivers/media/video/Kconfig
> +++ b/drivers/media/video/Kconfig
> @@ -329,6 +329,13 @@ config VIDEO_OV7670
>  	  OV7670 VGA camera.  It currently only works with the M88ALP01
>  	  controller.
>  
> +config VIDEO_MT9P031
> +       tristate "Aptina MT9P031 support"
> +       depends on I2C && VIDEO_V4L2
> +       ---help---
> +        This is a Video4Linux2 sensor-level driver for the Aptina
> +        (Micron) mt9p031 5 Mpixel camera.
> +

Please, use TABs, not spaces

>  config VIDEO_MT9V011
>  	tristate "Micron mt9v011 sensor support"
>  	depends on I2C && VIDEO_V4L2
> diff --git a/drivers/media/video/Makefile b/drivers/media/video/Makefile
> index ace5d8b..912b29b 100644
> --- a/drivers/media/video/Makefile
> +++ b/drivers/media/video/Makefile
> @@ -65,6 +65,7 @@ obj-$(CONFIG_VIDEO_UPD64083) += upd64083.o
>  obj-$(CONFIG_VIDEO_OV7670) 	+= ov7670.o
>  obj-$(CONFIG_VIDEO_TCM825X) += tcm825x.o
>  obj-$(CONFIG_VIDEO_TVEEPROM) += tveeprom.o
> +obj-$(CONFIG_VIDEO_MT9P031) += mt9p031.o
>  obj-$(CONFIG_VIDEO_MT9V011) += mt9v011.o
>  obj-$(CONFIG_VIDEO_SR030PC30)	+= sr030pc30.o
>  obj-$(CONFIG_VIDEO_NOON010PC30)	+= noon010pc30.o
> diff --git a/drivers/media/video/mt9p031.c b/drivers/media/video/mt9p031.c
> new file mode 100644
> index 0000000..cd830b1
> --- /dev/null
> +++ b/drivers/media/video/mt9p031.c
> @@ -0,0 +1,763 @@
> +/*
> + * Driver for MT9P031 CMOS Image Sensor from Aptina
> + *
> + * Copyright (C) 2011, Javier Martin <[e-mail]>
> + *
> + * Copyright (C) 2011, Guennadi Liakhovetski <[e-mail]>
> + *
> + * Based on the MT9V032 driver and Bastian Hecht's code.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/i2c.h>
> +#include <linux/log2.h>
> +#include <linux/pm.h>
> +#include <linux/slab.h>
> +#include <media/v4l2-subdev.h>
> +#include <linux/videodev2.h>
> +
> +#include <media/mt9p031.h>
> +#include <media/v4l2-chip-ident.h>
> +#include <media/v4l2-subdev.h>
> +#include <media/v4l2-device.h>
> +
> +#define MT9P031_EXTCLK_FREQ			20000000
> +
> +#define MT9P031_CHIP_VERSION			0x00
> +#define		MT9P031_CHIP_VERSION_VALUE	0x1801
> +#define MT9P031_ROW_START			0x01
> +#define		MT9P031_ROW_START_MIN		1
> +#define		MT9P031_ROW_START_MAX		2004
> +#define		MT9P031_ROW_START_DEF		54
> +#define MT9P031_COLUMN_START			0x02
> +#define		MT9P031_COLUMN_START_MIN	1
> +#define		MT9P031_COLUMN_START_MAX	2750
> +#define		MT9P031_COLUMN_START_DEF	16
> +#define MT9P031_WINDOW_HEIGHT			0x03
> +#define		MT9P031_WINDOW_HEIGHT_MIN	2
> +#define		MT9P031_WINDOW_HEIGHT_MAX	2003
> +#define		MT9P031_WINDOW_HEIGHT_DEF	2003
> +#define MT9P031_WINDOW_WIDTH			0x04
> +#define		MT9P031_WINDOW_WIDTH_MIN	18
> +#define		MT9P031_WINDOW_WIDTH_MAX	2751
> +#define		MT9P031_WINDOW_WIDTH_DEF	2751
> +#define MT9P031_H_BLANKING			0x05
> +#define		MT9P031_H_BLANKING_VALUE	0
> +#define MT9P031_V_BLANKING			0x06
> +#define		MT9P031_V_BLANKING_VALUE	25
> +#define MT9P031_OUTPUT_CONTROL			0x07
> +#define		MT9P031_OUTPUT_CONTROL_CEN	2
> +#define		MT9P031_OUTPUT_CONTROL_SYN	1
> +#define MT9P031_SHUTTER_WIDTH_UPPER		0x08
> +#define MT9P031_SHUTTER_WIDTH			0x09
> +#define	MT9P031_PLL_CONTROL			0x10
> +#define		MT9P031_PLL_CONTROL_PWROFF	0x0050
> +#define		MT9P031_PLL_CONTROL_PWRON	0x0051
> +#define		MT9P031_PLL_CONTROL_USEPLL	0x0052
> +#define	MT9P031_PLL_CONFIG_1			0x11
> +#define		MT9P031_PLL_CONFIG_1_M_48MHZ	0x5000
> +#define		MT9P031_PLL_CONFIG_1_N_48MHZ	0x05
> +#define		MT9P031_PLL_CONFIG_1_M_96MHZ	0x3600
> +#define		MT9P031_PLL_CONFIG_1_N_96MHZ	0x05
> +#define	MT9P031_PLL_CONFIG_2			0x12
> +#define		MT9P031_PLL_CONFIG_2_P1_48MHZ	5
> +#define		MT9P031_PLL_CONFIG_2_P1_96MHZ	2
> +#define MT9P031_PIXEL_CLOCK_CONTROL		0x0a
> +#define MT9P031_FRAME_RESTART			0x0b
> +#define MT9P031_SHUTTER_DELAY			0x0c
> +#define MT9P031_RST				0x0d
> +#define		MT9P031_RST_ENABLE		1
> +#define		MT9P031_RST_DISABLE		0
> +#define MT9P031_READ_MODE_1			0x1e
> +#define MT9P031_READ_MODE_2			0x20
> +#define		MT9P031_READ_MODE_2_ROW_MIR	0x8000
> +#define		MT9P031_READ_MODE_2_COL_MIR	0x4000
> +#define MT9P031_ROW_ADDRESS_MODE		0x22
> +#define MT9P031_COLUMN_ADDRESS_MODE		0x23
> +#define MT9P031_GLOBAL_GAIN			0x35
> +
> +struct mt9p031 {
> +	struct v4l2_subdev subdev;
> +	struct media_pad pad;
> +	struct v4l2_rect rect;  /* Sensor window */
> +	struct v4l2_mbus_framefmt format;
> +	struct mt9p031_platform_data *pdata;
> +	struct mutex power_lock; /* lock to protect power_count */
> +	int power_count;
> +	u16 xskip;
> +	u16 yskip;
> +	/* cache register values */
> +	u16 output_control;
> +};
> +
> +static struct mt9p031 *to_mt9p031(const struct i2c_client *client)
> +{
> +	return container_of(i2c_get_clientdata(client), struct mt9p031, subdev);
> +}
> +
> +static int reg_read(struct i2c_client *client, const u8 reg)
> +{
> +	s32 data = i2c_smbus_read_word_data(client, reg);
> +	return data < 0 ? data : swab16(data);
> +}
> +
> +static int reg_write(struct i2c_client *client, const u8 reg,
> +			const u16 data)
> +{
> +	return i2c_smbus_write_word_data(client, reg, swab16(data));
> +}
> +
> +static int mt9p031_set_output_control(struct mt9p031 *mt9p031, u16 clear,
> +					u16 set)
> +{
> +	struct i2c_client *client = v4l2_get_subdevdata(&mt9p031->subdev);
> +	u16 value = (mt9p031->output_control & ~clear) | set;
> +	int ret;
> +
> +	ret = reg_write(client, MT9P031_OUTPUT_CONTROL, value);
> +	if (ret < 0)
> +		return ret;
> +	mt9p031->output_control = value;
> +	return 0;
> +}
> +
> +static int mt9p031_reset(struct i2c_client *client)
> +{
> +	struct mt9p031 *mt9p031 = to_mt9p031(client);
> +	int ret;
> +
> +	/* Disable chip output, synchronous option update */
> +	ret = reg_write(client, MT9P031_RST, MT9P031_RST_ENABLE);
> +	if (ret < 0)
> +		return ret;
> +	ret = reg_write(client, MT9P031_RST, MT9P031_RST_DISABLE);
> +	if (ret < 0)
> +		return ret;
> +	return mt9p031_set_output_control(mt9p031,
> +					MT9P031_OUTPUT_CONTROL_CEN, 0);
> +}
> +
> +static int mt9p031_power_on(struct mt9p031 *mt9p031)
> +{
> +	struct i2c_client *client = v4l2_get_subdevdata(&mt9p031->subdev);
> +	int ret;
> +
> +	/* Ensure RESET_BAR is low */
> +	if (mt9p031->pdata->reset) {
> +		mt9p031->pdata->reset(&mt9p031->subdev, 1);
> +		msleep(1);
> +	}
> +	/* Emable clock */
> +	if (mt9p031->pdata->set_xclk)
> +		mt9p031->pdata->set_xclk(&mt9p031->subdev, MT9P031_EXTCLK_FREQ);
> +	/* Now RESET_BAR must be high */
> +	if (mt9p031->pdata->reset) {
> +		mt9p031->pdata->reset(&mt9p031->subdev, 0);
> +		msleep(1);
> +	}
> +	/* soft reset */
> +	ret = mt9p031_reset(client);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "Failed to reset the camera\n");
> +		return ret;
> +	}
> +	return 0;
> +}
> +
> +static void mt9p031_power_off(struct mt9p031 *mt9p031)
> +{
> +	if (mt9p031->pdata->reset) {
> +		mt9p031->pdata->reset(&mt9p031->subdev, 1);
> +		msleep(1);
> +	}
> +	if (mt9p031->pdata->set_xclk)
> +		mt9p031->pdata->set_xclk(&mt9p031->subdev, 0);
> +}
> +
> +static int mt9p031_enum_mbus_code(struct v4l2_subdev *sd,
> +				struct v4l2_subdev_fh *fh,
> +				struct v4l2_subdev_mbus_code_enum *code)
> +{
> +	struct mt9p031 *mt9p031 = container_of(sd, struct mt9p031, subdev);
> +
> +	if (code->pad || code->index)
> +		return -EINVAL;
> +
> +	code->code = mt9p031->format.code;
> +	return 0;
> +}
> +
> +static struct v4l2_mbus_framefmt *mt9p031_get_pad_format(
> +	struct mt9p031 *mt9p031,
> +	struct v4l2_subdev_fh *fh,
> +	unsigned int pad, u32 which)
> +{
> +	switch (which) {
> +	case V4L2_SUBDEV_FORMAT_TRY:
> +		return v4l2_subdev_get_try_format(fh, pad);
> +	case V4L2_SUBDEV_FORMAT_ACTIVE:
> +		return &mt9p031->format;
> +	default:
> +		return NULL;
> +	}
> +}
> +
> +static struct v4l2_rect *mt9p031_get_pad_crop(struct mt9p031 *mt9p031,
> +			struct v4l2_subdev_fh *fh, unsigned int pad, u32 which)
> +{
> +	switch (which) {
> +	case V4L2_SUBDEV_FORMAT_TRY:
> +		return v4l2_subdev_get_try_crop(fh, pad);
> +	case V4L2_SUBDEV_FORMAT_ACTIVE:
> +		return &mt9p031->rect;
> +	default:
> +		return NULL;
> +	}
> +}
> +
> +static int mt9p031_get_crop(struct v4l2_subdev *sd,
> +				struct v4l2_subdev_fh *fh,
> +				struct v4l2_subdev_crop *crop)
> +{
> +	struct mt9p031 *mt9p031 = container_of(sd, struct mt9p031, subdev);
> +	struct v4l2_rect *rect = mt9p031_get_pad_crop(mt9p031, fh, crop->pad,
> +							crop->which);
> +	if (!rect)
> +		return -EINVAL;
> +
> +	crop->rect = *rect;
> +
> +	return 0;
> +}
> +
> +static u16 mt9p031_skip_for_crop(s32 source, s32 *target, s32 max_skip)
> +{
> +	unsigned int skip;
> +
> +	if (source - source / 4 < *target) {
> +		*target = source;
> +		return 1;
> +	}
> +
> +	skip = DIV_ROUND_CLOSEST(source, *target);
> +	if (skip > max_skip)
> +		skip = max_skip;
> +	*target = 2 * DIV_ROUND_UP(source, 2 * skip);
> +
> +	return skip;
> +}
> +
> +static int mt9p031_set_params(struct i2c_client *client,
> +				struct v4l2_rect *rect, u16 xskip, u16 yskip)
> +{
> +	struct mt9p031 *mt9p031 = to_mt9p031(client);
> +	int ret;
> +	u16 xbin, ybin;
> +	const u16 hblank = MT9P031_H_BLANKING_VALUE,
> +		vblank = MT9P031_V_BLANKING_VALUE;
> +	__s32 left;
> +
> +	/*
> +	* TODO: Attention! When implementing horizontal flipping, adjust
> +	* alignment according to R2 "Column Start" description in the datasheet
> +	*/

This is not the correct multi-line comment style. Please, double-check 
with Documentation/CodingStyle. Please, fix all accurrances.

> +	if (xskip & 1) {
> +		xbin = 1;
> +		left = rect->left & (~3);
> +	} else if (xskip & 2) {
> +		xbin = 2;
> +		left = rect->left & (~7);
> +	} else {
> +		xbin = 4;
> +		left = rect->left & (~15);
> +	}

Superfluous parenthesis in all three cases above.

> +	ybin = min(yskip, (u16)4);
> +
> +	/* Disable register update, reconfigure atomically */
> +	ret = mt9p031_set_output_control(mt9p031, 0,
> +					MT9P031_OUTPUT_CONTROL_SYN);
> +	if (ret < 0)
> +		return ret;
> +
> +	dev_dbg(&client->dev, "skip %u:%u, rect %ux%u@%u:%u\n",
> +		xskip, yskip, rect->width, rect->height, rect->left, rect->top);
> +
> +	/* Blanking and start values - default... */
> +	ret = reg_write(client, MT9P031_H_BLANKING, hblank);
> +	if (ret < 0)
> +		return ret;
> +	ret = reg_write(client, MT9P031_V_BLANKING, vblank);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = reg_write(client, MT9P031_COLUMN_ADDRESS_MODE,
> +				((xbin - 1) << 4) | (xskip - 1));
> +	if (ret < 0)
> +		return ret;
> +	ret = reg_write(client, MT9P031_ROW_ADDRESS_MODE,
> +				((ybin - 1) << 4) | (yskip - 1));
> +	if (ret < 0)
> +		return ret;
> +
> +	dev_dbg(&client->dev, "new physical left %u, top %u\n",
> +		rect->left, rect->top);
> +
> +	ret = reg_write(client, MT9P031_COLUMN_START,
> +				rect->left);
> +	if (ret < 0)
> +		return ret;
> +	ret = reg_write(client, MT9P031_ROW_START,
> +				rect->top);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = reg_write(client, MT9P031_WINDOW_WIDTH,
> +				rect->width - 1);
> +	if (ret < 0)
> +		return ret;
> +	ret = reg_write(client, MT9P031_WINDOW_HEIGHT,
> +				rect->height - 1);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Re-enable register update, commit all changes */
> +	ret = mt9p031_set_output_control(mt9p031,
> +					MT9P031_OUTPUT_CONTROL_SYN, 0);
> +	if (ret < 0)
> +		return ret;
> +
> +	mt9p031->xskip = xskip;
> +	mt9p031->yskip = yskip;
> +	return ret;
> +}
> +
> +static int mt9p031_set_crop(struct v4l2_subdev *sd,
> +				struct v4l2_subdev_fh *fh,
> +				struct v4l2_subdev_crop *crop)
> +{
> +	struct mt9p031 *mt9p031 = container_of(sd, struct mt9p031, subdev);
> +	struct v4l2_mbus_framefmt *f;
> +	struct v4l2_rect *c;
> +	struct v4l2_rect rect;
> +	u16 xskip, yskip;
> +	s32 width, height;
> +
> +	dev_dbg(mt9p031->subdev.v4l2_dev->dev, "%s(%ux%u@%u:%u : %u)\n",
> +			__func__, crop->rect.width, crop->rect.height,
> +			crop->rect.left, crop->rect.top, crop->which);
> +
> +	/*
> +	* Clamp the crop rectangle boundaries and align them to a multiple of 2
> +	* pixels.
> +	*/
> +	rect.width = ALIGN(clamp(crop->rect.width,
> +				MT9P031_WINDOW_WIDTH_MIN,
> +				MT9P031_WINDOW_WIDTH_MAX), 2);
> +	rect.height = ALIGN(clamp(crop->rect.height,
> +				MT9P031_WINDOW_HEIGHT_MIN,
> +				MT9P031_WINDOW_HEIGHT_MAX), 2);
> +	rect.left = ALIGN(clamp(crop->rect.left,
> +				MT9P031_COLUMN_START_MIN,
> +				MT9P031_COLUMN_START_MAX), 2);
> +	rect.top = ALIGN(clamp(crop->rect.top,
> +				MT9P031_ROW_START_MIN,
> +				MT9P031_ROW_START_MAX), 2);
> +
> +	c = mt9p031_get_pad_crop(mt9p031, fh, crop->pad, crop->which);
> +
> +	if (rect.width != c->width || rect.height != c->height) {
> +		/*
> +		* Reset the output image size if the crop rectangle size has
> +		* been modified.
> +		*/
> +		f = mt9p031_get_pad_format(mt9p031, fh, crop->pad,
> +						crop->which);
> +		width = f->width;
> +		height = f->height;
> +
> +		xskip = mt9p031_skip_for_crop(rect.width, &width, 7);
> +		yskip = mt9p031_skip_for_crop(rect.height, &height, 8);
> +	} else {
> +		xskip = mt9p031->xskip;
> +		yskip = mt9p031->yskip;
> +		f = NULL;
> +	}
> +	if (f) {
> +		f->width = width;
> +		f->height = height;
> +	}
> +
> +	*c = rect;
> +	crop->rect = rect;
> +
> +	mt9p031->xskip = xskip;
> +	mt9p031->yskip = yskip;
> +	mt9p031->rect = *c;
> +	return 0;
> +}
> +
> +static int mt9p031_get_format(struct v4l2_subdev *sd,
> +				struct v4l2_subdev_fh *fh,
> +				struct v4l2_subdev_format *fmt)
> +{
> +	struct mt9p031 *mt9p031 = container_of(sd, struct mt9p031, subdev);
> +
> +	fmt->format =
> +		*mt9p031_get_pad_format(mt9p031, fh, fmt->pad, fmt->which);
> +	return 0;
> +}
> +
> +static u16 mt9p031_skip_for_scale(s32 *source, s32 target,
> +					s32 max_skip, s32 max)
> +{
> +	unsigned int skip;
> +
> +	if (*source - *source / 4 < target) {
> +		*source = target;
> +		return 1;
> +	}
> +
> +	skip = min(max, *source + target / 2) / target;
> +	if (skip > max_skip)
> +		skip = max_skip;
> +	*source = target * skip;
> +
> +	return skip;
> +}
> +
> +static int mt9p031_set_format(struct v4l2_subdev *sd,
> +				struct v4l2_subdev_fh *fh,
> +				struct v4l2_subdev_format *format)
> +{
> +	struct v4l2_mbus_framefmt *__format;
> +	struct v4l2_rect *__crop, rect;
> +	struct mt9p031 *mt9p031 = container_of(sd, struct mt9p031, subdev);
> +	unsigned int width;
> +	unsigned int height;
> +	u16 xskip, yskip;
> +
> +	__crop = mt9p031_get_pad_crop(mt9p031, fh, format->pad, format->which);
> +
> +	width = clamp_t(int, ALIGN(format->format.width, 2), 2,
> +						MT9P031_WINDOW_WIDTH_MAX);
> +	height = clamp_t(int, ALIGN(format->format.height, 2), 2,
> +						MT9P031_WINDOW_HEIGHT_MAX);
> +
> +	rect.width = __crop->width;
> +	rect.height = __crop->height;
> +
> +	xskip = mt9p031_skip_for_scale(&rect.width, width, 7,
> +				MT9P031_WINDOW_WIDTH_MAX);
> +	if (rect.width + __crop->left > MT9P031_WINDOW_WIDTH_MAX)
> +		rect.left = (MT9P031_WINDOW_WIDTH_MAX - rect.width) / 2;
> +	else
> +		rect.left = __crop->left;
> +	yskip = mt9p031_skip_for_scale(&rect.height, height, 8,
> +				MT9P031_WINDOW_HEIGHT_MAX);
> +	if (rect.height + __crop->top > MT9P031_WINDOW_HEIGHT_MAX)
> +		rect.top = (MT9P031_WINDOW_HEIGHT_MAX - rect.height) / 2;
> +	else
> +		rect.top = __crop->top;
> +
> +	dev_dbg(mt9p031->subdev.v4l2_dev->dev, "%s(%ux%u : %u)\n", __func__,
> +		width, height, format->which);
> +	if (__crop)
> +		*__crop = rect;
> +
> +	__format = mt9p031_get_pad_format(mt9p031, fh, format->pad,
> +						format->which);
> +	__format->width = width;
> +	__format->height = height;
> +	format->format = *__format;
> +
> +	mt9p031->xskip = xskip;
> +	mt9p031->yskip = yskip;
> +	mt9p031->rect = *__crop;
> +	return 0;
> +}
> +
> +static int mt9p031_pll_enable(struct i2c_client *client)
> +{
> +	struct mt9p031 *mt9p031 = to_mt9p031(client);
> +	int ret;
> +
> +	ret = reg_write(client, MT9P031_PLL_CONTROL, MT9P031_PLL_CONTROL_PWRON);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Always set the maximum frequency allowed by VDD_IO */
> +	if (mt9p031->pdata->vdd_io == MT9P031_VDD_IO_2V8) {
> +		ret = reg_write(client, MT9P031_PLL_CONFIG_1,
> +			MT9P031_PLL_CONFIG_1_M_96MHZ |
> +			MT9P031_PLL_CONFIG_1_N_96MHZ);
> +		if (ret < 0)
> +			return ret;
> +		ret = reg_write(client, MT9P031_PLL_CONFIG_2,
> +				MT9P031_PLL_CONFIG_2_P1_96MHZ);
> +		if (ret < 0)
> +			return ret;
> +	} else {
> +		ret = reg_write(client, MT9P031_PLL_CONFIG_1,
> +			MT9P031_PLL_CONFIG_1_M_48MHZ |
> +			MT9P031_PLL_CONFIG_1_N_48MHZ);
> +		if (ret < 0)
> +			return ret;
> +		ret = reg_write(client, MT9P031_PLL_CONFIG_2,
> +				MT9P031_PLL_CONFIG_2_P1_48MHZ);
> +		if (ret < 0)
> +			return ret;
> +	}
> +	mdelay(1);
> +	ret = reg_write(client, MT9P031_PLL_CONTROL,
> +			MT9P031_PLL_CONTROL_PWRON |
> +			MT9P031_PLL_CONTROL_USEPLL);
> +	mdelay(1);
> +	return ret;
> +}
> +
> +static inline int mt9p031_pll_disable(struct i2c_client *client)
> +{
> +	return reg_write(client, MT9P031_PLL_CONTROL,
> +			 MT9P031_PLL_CONTROL_PWROFF);
> +}
> +
> +static int mt9p031_s_stream(struct v4l2_subdev *sd, int enable)
> +{
> +	struct mt9p031 *mt9p031 = container_of(sd, struct mt9p031, subdev);
> +	struct i2c_client *client = v4l2_get_subdevdata(&mt9p031->subdev);
> +	struct v4l2_rect rect = mt9p031->rect;
> +	u16 xskip = mt9p031->xskip;
> +	u16 yskip = mt9p031->yskip;
> +	int ret;
> +
> +	if (enable) {
> +		ret = mt9p031_set_params(client, &rect, xskip, yskip);
> +		if (ret < 0)
> +			return ret;
> +		/* Switch to master "normal" mode */
> +		ret = mt9p031_set_output_control(mt9p031, 0,
> +						MT9P031_OUTPUT_CONTROL_CEN);
> +		if (ret < 0)
> +			return ret;
> +		ret = mt9p031_pll_enable(client);
> +	} else {
> +		/* Stop sensor readout */
> +		ret = mt9p031_set_output_control(mt9p031,
> +						MT9P031_OUTPUT_CONTROL_CEN, 0);
> +		if (ret < 0)
> +			return ret;
> +		ret = mt9p031_pll_disable(client);
> +	}
> +	return ret;
> +}
> +
> +static int mt9p031_video_probe(struct i2c_client *client)
> +{
> +	s32 data;
> +
> +	/* Read out the chip version register */
> +	data = reg_read(client, MT9P031_CHIP_VERSION);
> +	if (data != MT9P031_CHIP_VERSION_VALUE) {
> +		dev_err(&client->dev,
> +			"No MT9P031 chip detected, register read %x\n", data);
> +		return -ENODEV;
> +	}
> +
> +	dev_info(&client->dev, "Detected a MT9P031 chip ID %x\n", data);
> +
> +	return 0;
> +}
> +
> +static int mt9p031_set_power(struct v4l2_subdev *sd, int on)
> +{
> +	struct mt9p031 *mt9p031 = container_of(sd, struct mt9p031, subdev);
> +	int ret = 0;
> +
> +	mutex_lock(&mt9p031->power_lock);
> +
> +	/*
> +	* If the power count is modified from 0 to != 0 or from != 0 to 0,
> +	* update the power state.
> +	*/
> +	if (mt9p031->power_count == !on) {
> +		if (on) {
> +			ret = mt9p031_power_on(mt9p031);
> +			if (ret) {
> +				dev_err(mt9p031->subdev.v4l2_dev->dev,
> +				"Failed to power on: %d\n", ret);

Please, indent the line continuation deeper, don't worry about 80 
characters.

> +				goto out;
> +			}
> +		} else {
> +			mt9p031_power_off(mt9p031);
> +		}
> +	}
> +
> +	/* Update the power count. */
> +	mt9p031->power_count += on ? 1 : -1;
> +	WARN_ON(mt9p031->power_count < 0);
> +
> +out:
> +	mutex_unlock(&mt9p031->power_lock);
> +	return ret;
> +}
> +
> +static int mt9p031_registered(struct v4l2_subdev *sd)
> +{
> +	struct mt9p031 *mt9p031 = container_of(sd, struct mt9p031, subdev);
> +	struct i2c_client *client = v4l2_get_subdevdata(&mt9p031->subdev);
> +	int ret;
> +
> +	ret = mt9p031_set_power(&mt9p031->subdev, 1);
> +	if (ret) {
> +		dev_err(&client->dev,
> +			"Failed to power on device: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = mt9p031_video_probe(client);
> +
> +	mt9p031_set_power(&mt9p031->subdev, 0);
> +
> +	return ret;
> +}
> +
> +static int mt9p031_open(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
> +{
> +	struct mt9p031 *mt9p031;
> +	mt9p031 = container_of(sd, struct mt9p031, subdev);
> +
> +	mt9p031->rect.width     = MT9P031_WINDOW_WIDTH_DEF;
> +	mt9p031->rect.height    = MT9P031_WINDOW_HEIGHT_DEF;
> +	mt9p031->rect.left      = MT9P031_COLUMN_START_DEF;
> +	mt9p031->rect.top       = MT9P031_ROW_START_DEF;
> +
> +	if (mt9p031->pdata->version == MT9P031_MONOCHROME_VERSION)
> +		mt9p031->format.code = V4L2_MBUS_FMT_Y12_1X12;
> +	else
> +		mt9p031->format.code = V4L2_MBUS_FMT_SGRBG12_1X12;
> +
> +	mt9p031->format.width = MT9P031_WINDOW_WIDTH_DEF;
> +	mt9p031->format.height = MT9P031_WINDOW_HEIGHT_DEF;
> +	mt9p031->format.field = V4L2_FIELD_NONE;
> +	mt9p031->format.colorspace = V4L2_COLORSPACE_SRGB;
> +
> +	mt9p031->xskip = 1;
> +	mt9p031->yskip = 1;
> +	return mt9p031_set_power(sd, 1);
> +}
> +
> +static int mt9p031_close(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
> +{
> +	return mt9p031_set_power(sd, 0);
> +}
> +
> +static struct v4l2_subdev_core_ops mt9p031_subdev_core_ops = {
> +	.s_power        = mt9p031_set_power,
> +};
> +
> +static struct v4l2_subdev_video_ops mt9p031_subdev_video_ops = {
> +	.s_stream       = mt9p031_s_stream,
> +};
> +
> +static struct v4l2_subdev_pad_ops mt9p031_subdev_pad_ops = {
> +	.enum_mbus_code = mt9p031_enum_mbus_code,
> +	.get_fmt = mt9p031_get_format,
> +	.set_fmt = mt9p031_set_format,
> +	.get_crop = mt9p031_get_crop,
> +	.set_crop = mt9p031_set_crop,
> +};
> +
> +static struct v4l2_subdev_ops mt9p031_subdev_ops = {
> +	.core   = &mt9p031_subdev_core_ops,
> +	.video  = &mt9p031_subdev_video_ops,
> +	.pad    = &mt9p031_subdev_pad_ops,
> +};
> +
> +static const struct v4l2_subdev_internal_ops mt9p031_subdev_internal_ops = {
> +	.registered = mt9p031_registered,
> +	.open = mt9p031_open,
> +	.close = mt9p031_close,
> +};
> +
> +static int mt9p031_probe(struct i2c_client *client,
> +				const struct i2c_device_id *did)
> +{
> +	int ret;
> +	struct mt9p031 *mt9p031;
> +	struct mt9p031_platform_data *pdata = client->dev.platform_data;
> +	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
> +
> +	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA)) {
> +		dev_warn(&adapter->dev,
> +			"I2C-Adapter doesn't support I2C_FUNC_SMBUS_WORD\n");
> +		return -EIO;
> +	}
> +
> +	mt9p031 = kzalloc(sizeof(struct mt9p031), GFP_KERNEL);
> +	if (!mt9p031)
> +		return -ENOMEM;
> +
> +	mutex_init(&mt9p031->power_lock);
> +	v4l2_i2c_subdev_init(&mt9p031->subdev, client, &mt9p031_subdev_ops);
> +	mt9p031->subdev.internal_ops = &mt9p031_subdev_internal_ops;
> +
> +	mt9p031->pdata          = pdata;
> +
> +	mt9p031->pad.flags = MEDIA_PAD_FL_SOURCE;
> +	ret = media_entity_init(&mt9p031->subdev.entity, 1, &mt9p031->pad, 0);
> +	if (ret)
> +		return ret;
> +
> +	mt9p031->subdev.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> +
> +	return 0;
> +}
> +
> +static int mt9p031_remove(struct i2c_client *client)
> +{
> +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> +	struct mt9p031 *mt9p031 = container_of(sd, struct mt9p031, subdev);
> +
> +	v4l2_device_unregister_subdev(sd);
> +	media_entity_cleanup(&sd->entity);
> +	kfree(mt9p031);
> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id mt9p031_id[] = {
> +	{ "mt9p031", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, mt9p031_id);
> +
> +static struct i2c_driver mt9p031_i2c_driver = {
> +	.driver = {
> +		.name = "mt9p031",
> +	},
> +	.probe          = mt9p031_probe,
> +	.remove         = mt9p031_remove,
> +	.id_table       = mt9p031_id,
> +};
> +
> +static int __init mt9p031_mod_init(void)
> +{
> +	return i2c_add_driver(&mt9p031_i2c_driver);
> +}
> +
> +static void __exit mt9p031_mod_exit(void)
> +{
> +	i2c_del_driver(&mt9p031_i2c_driver);
> +}
> +
> +module_init(mt9p031_mod_init);
> +module_exit(mt9p031_mod_exit);
> +
> +MODULE_DESCRIPTION("Aptina MT9P031 Camera driver");
> +MODULE_AUTHOR("Bastian Hecht <[e-mail]>");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/media/mt9p031.h b/include/media/mt9p031.h
> new file mode 100644
> index 0000000..27b4c75
> --- /dev/null
> +++ b/include/media/mt9p031.h
> @@ -0,0 +1,23 @@
> +#ifndef MT9P031_H
> +#define MT9P031_H
> +
> +struct v4l2_subdev;
> +
> +enum {
> +	MT9P031_COLOR_VERSION = 0,
> +	MT9P031_MONOCHROME_VERSION = 1,

Do you really need explicit number assignments?

> +};
> +
> +enum {
> +	MT9P031_VDD_IO_1V8 = 0,
> +	MT9P031_VDD_IO_2V8 = 1,

ditto

> +};
> +
> +struct mt9p031_platform_data {
> +	int (*set_xclk)(struct v4l2_subdev *subdev, int hz);
> +	int (*reset)(struct v4l2_subdev *subdev, int active);
> +	int vdd_io; /* MT9P031_VDD_IO_1V8 or MT9P031_VDD_IO_2V8 */
> +	int version; /* MT9P031_COLOR_VERSION or MT9P031_MONOCHROME_VERSION */
> +};
> +
> +#endif
> -- 
> 1.7.0.4
> 

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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Javier Martin June 2, 2011, 10:11 a.m. UTC | #2

OK Guennadi,
I'll fix those cosmetics issues in my next version where I will add
VFLIP and HFLIP control support (which I removed previously to make
the code less complex).

Now we talk about controls I have a question regarding controls
defined in video subdevices like mt9p031 or mt9v032:

What device node should I use to set these controls through an ioctl() ?
For instance, with mt9p031 + Beagleboard xM we have:

./media-ctl -r -l '"mt9p031 2-0048":0->"OMAP3 ISP CCDC":0[1], "OMAP3
ISP CCDC":1->"OMAP3 ISP CCDC output":0[1]'
./media-ctl -f '"mt9p031 2-0048":0[SGRBG12 320x240], "OMAP3 ISP
CCDC":0[SGRBG8 320x240], "OMAP3 ISP CCDC":1[SGRBG8 320x240]'
./yavta --stdout -f SGRBG8 -s 320x240 -n 4 --capture=100 --skip 3 -F
`./media-ctl -e "OMAP3 ISP CCDC output"` | nc 192.168.0.42 3000

Where

root@beagleboard:~# ./media-ctl -e "OMAP3 ISP CCDC output"
/dev/video2

However, if I try to set sensor controls using /dev/video2 I get an
error (invalid argument).

Guennadi Liakhovetski June 2, 2011, 10:36 a.m. UTC | #3

On Thu, 2 Jun 2011, javier Martin wrote:

> OK Guennadi,
> I'll fix those cosmetics issues in my next version where I will add
> VFLIP and HFLIP control support (which I removed previously to make
> the code less complex).

Please, don't. Let's first get the simple version of your driver in the 
mainline, then it can be extended. Just, please, make sure to address all 
remaining issues without changing anything else:)

Thanks
Guennadi

> 
> Now we talk about controls I have a question regarding controls
> defined in video subdevices like mt9p031 or mt9v032:
> 
> What device node should I use to set these controls through an ioctl() ?
> For instance, with mt9p031 + Beagleboard xM we have:
> 
> ./media-ctl -r -l '"mt9p031 2-0048":0->"OMAP3 ISP CCDC":0[1], "OMAP3
> ISP CCDC":1->"OMAP3 ISP CCDC output":0[1]'
> ./media-ctl -f '"mt9p031 2-0048":0[SGRBG12 320x240], "OMAP3 ISP
> CCDC":0[SGRBG8 320x240], "OMAP3 ISP CCDC":1[SGRBG8 320x240]'
> ./yavta --stdout -f SGRBG8 -s 320x240 -n 4 --capture=100 --skip 3 -F
> `./media-ctl -e "OMAP3 ISP CCDC output"` | nc 192.168.0.42 3000
> 
> Where
> 
> root@beagleboard:~# ./media-ctl -e "OMAP3 ISP CCDC output"
> /dev/video2
> 
> However, if I try to set sensor controls using /dev/video2 I get an
> error (invalid argument).
> 
> -- 
> Javier Martin
> Vista Silicon S.L.
> CDTUC - FASE C - Oficina S-345
> Avda de los Castros s/n
> 39005- Santander. Cantabria. Spain
> [phone]
> www.vista-silicon.com
> 

---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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Javier Martin June 2, 2011, 10:46 a.m. UTC | #4

On 2 June 2011 12:36, Guennadi Liakhovetski <[e-mail]> wrote:
> On Thu, 2 Jun 2011, javier Martin wrote:
>
>> OK Guennadi,
>> I'll fix those cosmetics issues in my next version where I will add
>> VFLIP and HFLIP control support (which I removed previously to make
>> the code less complex).
>
> Please, don't. Let's first get the simple version of your driver in the
> mainline, then it can be extended. Just, please, make sure to address all
> remaining issues without changing anything else:)

Ok, thanks.

Patch

diff --git a/drivers/media/video/Kconfig b/drivers/media/video/Kconfig
index 00f51dd..cb87e35 100644
--- a/drivers/media/video/Kconfig
+++ b/drivers/media/video/Kconfig
@@ -329,6 +329,13 @@  config VIDEO_OV7670
 	  OV7670 VGA camera.  It currently only works with the M88ALP01
 	  controller.
 
+config VIDEO_MT9P031
+       tristate "Aptina MT9P031 support"
+       depends on I2C && VIDEO_V4L2
+       ---help---
+        This is a Video4Linux2 sensor-level driver for the Aptina
+        (Micron) mt9p031 5 Mpixel camera.
+
 config VIDEO_MT9V011
 	tristate "Micron mt9v011 sensor support"
 	depends on I2C && VIDEO_V4L2
diff --git a/drivers/media/video/Makefile b/drivers/media/video/Makefile
index ace5d8b..912b29b 100644
--- a/drivers/media/video/Makefile
+++ b/drivers/media/video/Makefile
@@ -65,6 +65,7 @@  obj-$(CONFIG_VIDEO_UPD64083) += upd64083.o
 obj-$(CONFIG_VIDEO_OV7670) 	+= ov7670.o
 obj-$(CONFIG_VIDEO_TCM825X) += tcm825x.o
 obj-$(CONFIG_VIDEO_TVEEPROM) += tveeprom.o
+obj-$(CONFIG_VIDEO_MT9P031) += mt9p031.o
 obj-$(CONFIG_VIDEO_MT9V011) += mt9v011.o
 obj-$(CONFIG_VIDEO_SR030PC30)	+= sr030pc30.o
 obj-$(CONFIG_VIDEO_NOON010PC30)	+= noon010pc30.o
diff --git a/drivers/media/video/mt9p031.c b/drivers/media/video/mt9p031.c
new file mode 100644
index 0000000..cd830b1
--- /dev/null
+++ b/drivers/media/video/mt9p031.c
@@ -0,0 +1,763 @@ 
+/*
+ * Driver for MT9P031 CMOS Image Sensor from Aptina
+ *
+ * Copyright (C) 2011, Javier Martin <[e-mail]>
+ *
+ * Copyright (C) 2011, Guennadi Liakhovetski <[e-mail]>
+ *
+ * Based on the MT9V032 driver and Bastian Hecht's code.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/log2.h>
+#include <linux/pm.h>
+#include <linux/slab.h>
+#include <media/v4l2-subdev.h>
+#include <linux/videodev2.h>
+
+#include <media/mt9p031.h>
+#include <media/v4l2-chip-ident.h>
+#include <media/v4l2-subdev.h>
+#include <media/v4l2-device.h>
+
+#define MT9P031_EXTCLK_FREQ			20000000
+
+#define MT9P031_CHIP_VERSION			0x00
+#define		MT9P031_CHIP_VERSION_VALUE	0x1801
+#define MT9P031_ROW_START			0x01
+#define		MT9P031_ROW_START_MIN		1
+#define		MT9P031_ROW_START_MAX		2004
+#define		MT9P031_ROW_START_DEF		54
+#define MT9P031_COLUMN_START			0x02
+#define		MT9P031_COLUMN_START_MIN	1
+#define		MT9P031_COLUMN_START_MAX	2750
+#define		MT9P031_COLUMN_START_DEF	16
+#define MT9P031_WINDOW_HEIGHT			0x03
+#define		MT9P031_WINDOW_HEIGHT_MIN	2
+#define		MT9P031_WINDOW_HEIGHT_MAX	2003
+#define		MT9P031_WINDOW_HEIGHT_DEF	2003
+#define MT9P031_WINDOW_WIDTH			0x04
+#define		MT9P031_WINDOW_WIDTH_MIN	18
+#define		MT9P031_WINDOW_WIDTH_MAX	2751
+#define		MT9P031_WINDOW_WIDTH_DEF	2751
+#define MT9P031_H_BLANKING			0x05
+#define		MT9P031_H_BLANKING_VALUE	0
+#define MT9P031_V_BLANKING			0x06
+#define		MT9P031_V_BLANKING_VALUE	25
+#define MT9P031_OUTPUT_CONTROL			0x07
+#define		MT9P031_OUTPUT_CONTROL_CEN	2
+#define		MT9P031_OUTPUT_CONTROL_SYN	1
+#define MT9P031_SHUTTER_WIDTH_UPPER		0x08
+#define MT9P031_SHUTTER_WIDTH			0x09
+#define	MT9P031_PLL_CONTROL			0x10
+#define		MT9P031_PLL_CONTROL_PWROFF	0x0050
+#define		MT9P031_PLL_CONTROL_PWRON	0x0051
+#define		MT9P031_PLL_CONTROL_USEPLL	0x0052
+#define	MT9P031_PLL_CONFIG_1			0x11
+#define		MT9P031_PLL_CONFIG_1_M_48MHZ	0x5000
+#define		MT9P031_PLL_CONFIG_1_N_48MHZ	0x05
+#define		MT9P031_PLL_CONFIG_1_M_96MHZ	0x3600
+#define		MT9P031_PLL_CONFIG_1_N_96MHZ	0x05
+#define	MT9P031_PLL_CONFIG_2			0x12
+#define		MT9P031_PLL_CONFIG_2_P1_48MHZ	5
+#define		MT9P031_PLL_CONFIG_2_P1_96MHZ	2
+#define MT9P031_PIXEL_CLOCK_CONTROL		0x0a
+#define MT9P031_FRAME_RESTART			0x0b
+#define MT9P031_SHUTTER_DELAY			0x0c
+#define MT9P031_RST				0x0d
+#define		MT9P031_RST_ENABLE		1
+#define		MT9P031_RST_DISABLE		0
+#define MT9P031_READ_MODE_1			0x1e
+#define MT9P031_READ_MODE_2			0x20
+#define		MT9P031_READ_MODE_2_ROW_MIR	0x8000
+#define		MT9P031_READ_MODE_2_COL_MIR	0x4000
+#define MT9P031_ROW_ADDRESS_MODE		0x22
+#define MT9P031_COLUMN_ADDRESS_MODE		0x23
+#define MT9P031_GLOBAL_GAIN			0x35
+
+struct mt9p031 {
+	struct v4l2_subdev subdev;
+	struct media_pad pad;
+	struct v4l2_rect rect;  /* Sensor window */
+	struct v4l2_mbus_framefmt format;
+	struct mt9p031_platform_data *pdata;
+	struct mutex power_lock; /* lock to protect power_count */
+	int power_count;
+	u16 xskip;
+	u16 yskip;
+	/* cache register values */
+	u16 output_control;
+};
+
+static struct mt9p031 *to_mt9p031(const struct i2c_client *client)
+{
+	return container_of(i2c_get_clientdata(client), struct mt9p031, subdev);
+}
+
+static int reg_read(struct i2c_client *client, const u8 reg)
+{
+	s32 data = i2c_smbus_read_word_data(client, reg);
+	return data < 0 ? data : swab16(data);
+}
+
+static int reg_write(struct i2c_client *client, const u8 reg,
+			const u16 data)
+{
+	return i2c_smbus_write_word_data(client, reg, swab16(data));
+}
+
+static int mt9p031_set_output_control(struct mt9p031 *mt9p031, u16 clear,
+					u16 set)
+{
+	struct i2c_client *client = v4l2_get_subdevdata(&mt9p031->subdev);
+	u16 value = (mt9p031->output_control & ~clear) | set;
+	int ret;
+
+	ret = reg_write(client, MT9P031_OUTPUT_CONTROL, value);
+	if (ret < 0)
+		return ret;
+	mt9p031->output_control = value;
+	return 0;
+}
+
+static int mt9p031_reset(struct i2c_client *client)
+{
+	struct mt9p031 *mt9p031 = to_mt9p031(client);
+	int ret;
+
+	/* Disable chip output, synchronous option update */
+	ret = reg_write(client, MT9P031_RST, MT9P031_RST_ENABLE);
+	if (ret < 0)
+		return ret;
+	ret = reg_write(client, MT9P031_RST, MT9P031_RST_DISABLE);
+	if (ret < 0)
+		return ret;
+	return mt9p031_set_output_control(mt9p031,
+					MT9P031_OUTPUT_CONTROL_CEN, 0);
+}
+
+static int mt9p031_power_on(struct mt9p031 *mt9p031)
+{
+	struct i2c_client *client = v4l2_get_subdevdata(&mt9p031->subdev);
+	int ret;
+
+	/* Ensure RESET_BAR is low */
+	if (mt9p031->pdata->reset) {
+		mt9p031->pdata->reset(&mt9p031->subdev, 1);
+		msleep(1);
+	}
+	/* Emable clock */
+	if (mt9p031->pdata->set_xclk)
+		mt9p031->pdata->set_xclk(&mt9p031->subdev, MT9P031_EXTCLK_FREQ);
+	/* Now RESET_BAR must be high */
+	if (mt9p031->pdata->reset) {
+		mt9p031->pdata->reset(&mt9p031->subdev, 0);
+		msleep(1);
+	}
+	/* soft reset */
+	ret = mt9p031_reset(client);
+	if (ret < 0) {
+		dev_err(&client->dev, "Failed to reset the camera\n");
+		return ret;
+	}
+	return 0;
+}
+
+static void mt9p031_power_off(struct mt9p031 *mt9p031)
+{
+	if (mt9p031->pdata->reset) {
+		mt9p031->pdata->reset(&mt9p031->subdev, 1);
+		msleep(1);
+	}
+	if (mt9p031->pdata->set_xclk)
+		mt9p031->pdata->set_xclk(&mt9p031->subdev, 0);
+}
+
+static int mt9p031_enum_mbus_code(struct v4l2_subdev *sd,
+				struct v4l2_subdev_fh *fh,
+				struct v4l2_subdev_mbus_code_enum *code)
+{
+	struct mt9p031 *mt9p031 = container_of(sd, struct mt9p031, subdev);
+
+	if (code->pad || code->index)
+		return -EINVAL;
+
+	code->code = mt9p031->format.code;
+	return 0;
+}
+
+static struct v4l2_mbus_framefmt *mt9p031_get_pad_format(
+	struct mt9p031 *mt9p031,
+	struct v4l2_subdev_fh *fh,
+	unsigned int pad, u32 which)
+{
+	switch (which) {
+	case V4L2_SUBDEV_FORMAT_TRY:
+		return v4l2_subdev_get_try_format(fh, pad);
+	case V4L2_SUBDEV_FORMAT_ACTIVE:
+		return &mt9p031->format;
+	default:
+		return NULL;
+	}
+}
+
+static struct v4l2_rect *mt9p031_get_pad_crop(struct mt9p031 *mt9p031,
+			struct v4l2_subdev_fh *fh, unsigned int pad, u32 which)
+{
+	switch (which) {
+	case V4L2_SUBDEV_FORMAT_TRY:
+		return v4l2_subdev_get_try_crop(fh, pad);
+	case V4L2_SUBDEV_FORMAT_ACTIVE:
+		return &mt9p031->rect;
+	default:
+		return NULL;
+	}
+}
+
+static int mt9p031_get_crop(struct v4l2_subdev *sd,
+				struct v4l2_subdev_fh *fh,
+				struct v4l2_subdev_crop *crop)
+{
+	struct mt9p031 *mt9p031 = container_of(sd, struct mt9p031, subdev);
+	struct v4l2_rect *rect = mt9p031_get_pad_crop(mt9p031, fh, crop->pad,
+							crop->which);
+	if (!rect)
+		return -EINVAL;
+
+	crop->rect = *rect;
+
+	return 0;
+}
+
+static u16 mt9p031_skip_for_crop(s32 source, s32 *target, s32 max_skip)
+{
+	unsigned int skip;
+
+	if (source - source / 4 < *target) {
+		*target = source;
+		return 1;
+	}
+
+	skip = DIV_ROUND_CLOSEST(source, *target);
+	if (skip > max_skip)
+		skip = max_skip;
+	*target = 2 * DIV_ROUND_UP(source, 2 * skip);
+
+	return skip;
+}
+
+static int mt9p031_set_params(struct i2c_client *client,
+				struct v4l2_rect *rect, u16 xskip, u16 yskip)
+{
+	struct mt9p031 *mt9p031 = to_mt9p031(client);
+	int ret;
+	u16 xbin, ybin;
+	const u16 hblank = MT9P031_H_BLANKING_VALUE,
+		vblank = MT9P031_V_BLANKING_VALUE;
+	__s32 left;
+
+	/*
+	* TODO: Attention! When implementing horizontal flipping, adjust
+	* alignment according to R2 "Column Start" description in the datasheet
+	*/
+	if (xskip & 1) {
+		xbin = 1;
+		left = rect->left & (~3);
+	} else if (xskip & 2) {
+		xbin = 2;
+		left = rect->left & (~7);
+	} else {
+		xbin = 4;
+		left = rect->left & (~15);
+	}
+	ybin = min(yskip, (u16)4);
+
+	/* Disable register update, reconfigure atomically */
+	ret = mt9p031_set_output_control(mt9p031, 0,
+					MT9P031_OUTPUT_CONTROL_SYN);
+	if (ret < 0)
+		return ret;
+
+	dev_dbg(&client->dev, "skip %u:%u, rect %ux%u@%u:%u\n",
+		xskip, yskip, rect->width, rect->height, rect->left, rect->top);
+
+	/* Blanking and start values - default... */
+	ret = reg_write(client, MT9P031_H_BLANKING, hblank);
+	if (ret < 0)
+		return ret;
+	ret = reg_write(client, MT9P031_V_BLANKING, vblank);
+	if (ret < 0)
+		return ret;
+
+	ret = reg_write(client, MT9P031_COLUMN_ADDRESS_MODE,
+				((xbin - 1) << 4) | (xskip - 1));
+	if (ret < 0)
+		return ret;
+	ret = reg_write(client, MT9P031_ROW_ADDRESS_MODE,
+				((ybin - 1) << 4) | (yskip - 1));
+	if (ret < 0)
+		return ret;
+
+	dev_dbg(&client->dev, "new physical left %u, top %u\n",
+		rect->left, rect->top);
+
+	ret = reg_write(client, MT9P031_COLUMN_START,
+				rect->left);
+	if (ret < 0)
+		return ret;
+	ret = reg_write(client, MT9P031_ROW_START,
+				rect->top);
+	if (ret < 0)
+		return ret;
+
+	ret = reg_write(client, MT9P031_WINDOW_WIDTH,
+				rect->width - 1);
+	if (ret < 0)
+		return ret;
+	ret = reg_write(client, MT9P031_WINDOW_HEIGHT,
+				rect->height - 1);
+	if (ret < 0)
+		return ret;
+
+	/* Re-enable register update, commit all changes */
+	ret = mt9p031_set_output_control(mt9p031,
+					MT9P031_OUTPUT_CONTROL_SYN, 0);
+	if (ret < 0)
+		return ret;
+
+	mt9p031->xskip = xskip;
+	mt9p031->yskip = yskip;
+	return ret;
+}
+
+static int mt9p031_set_crop(struct v4l2_subdev *sd,
+				struct v4l2_subdev_fh *fh,
+				struct v4l2_subdev_crop *crop)
+{
+	struct mt9p031 *mt9p031 = container_of(sd, struct mt9p031, subdev);
+	struct v4l2_mbus_framefmt *f;
+	struct v4l2_rect *c;
+	struct v4l2_rect rect;
+	u16 xskip, yskip;
+	s32 width, height;
+
+	dev_dbg(mt9p031->subdev.v4l2_dev->dev, "%s(%ux%u@%u:%u : %u)\n",
+			__func__, crop->rect.width, crop->rect.height,
+			crop->rect.left, crop->rect.top, crop->which);
+
+	/*
+	* Clamp the crop rectangle boundaries and align them to a multiple of 2
+	* pixels.
+	*/
+	rect.width = ALIGN(clamp(crop->rect.width,
+				MT9P031_WINDOW_WIDTH_MIN,
+				MT9P031_WINDOW_WIDTH_MAX), 2);
+	rect.height = ALIGN(clamp(crop->rect.height,
+				MT9P031_WINDOW_HEIGHT_MIN,
+				MT9P031_WINDOW_HEIGHT_MAX), 2);
+	rect.left = ALIGN(clamp(crop->rect.left,
+				MT9P031_COLUMN_START_MIN,
+				MT9P031_COLUMN_START_MAX), 2);
+	rect.top = ALIGN(clamp(crop->rect.top,
+				MT9P031_ROW_START_MIN,
+				MT9P031_ROW_START_MAX), 2);
+
+	c = mt9p031_get_pad_crop(mt9p031, fh, crop->pad, crop->which);
+
+	if (rect.width != c->width || rect.height != c->height) {
+		/*
+		* Reset the output image size if the crop rectangle size has
+		* been modified.
+		*/
+		f = mt9p031_get_pad_format(mt9p031, fh, crop->pad,
+						crop->which);
+		width = f->width;
+		height = f->height;
+
+		xskip = mt9p031_skip_for_crop(rect.width, &width, 7);
+		yskip = mt9p031_skip_for_crop(rect.height, &height, 8);
+	} else {
+		xskip = mt9p031->xskip;
+		yskip = mt9p031->yskip;
+		f = NULL;
+	}
+	if (f) {
+		f->width = width;
+		f->height = height;
+	}
+
+	*c = rect;
+	crop->rect = rect;
+
+	mt9p031->xskip = xskip;
+	mt9p031->yskip = yskip;
+	mt9p031->rect = *c;
+	return 0;
+}
+
+static int mt9p031_get_format(struct v4l2_subdev *sd,
+				struct v4l2_subdev_fh *fh,
+				struct v4l2_subdev_format *fmt)
+{
+	struct mt9p031 *mt9p031 = container_of(sd, struct mt9p031, subdev);
+
+	fmt->format =
+		*mt9p031_get_pad_format(mt9p031, fh, fmt->pad, fmt->which);
+	return 0;
+}
+
+static u16 mt9p031_skip_for_scale(s32 *source, s32 target,
+					s32 max_skip, s32 max)
+{
+	unsigned int skip;
+
+	if (*source - *source / 4 < target) {
+		*source = target;
+		return 1;
+	}
+
+	skip = min(max, *source + target / 2) / target;
+	if (skip > max_skip)
+		skip = max_skip;
+	*source = target * skip;
+
+	return skip;
+}
+
+static int mt9p031_set_format(struct v4l2_subdev *sd,
+				struct v4l2_subdev_fh *fh,
+				struct v4l2_subdev_format *format)
+{
+	struct v4l2_mbus_framefmt *__format;
+	struct v4l2_rect *__crop, rect;
+	struct mt9p031 *mt9p031 = container_of(sd, struct mt9p031, subdev);
+	unsigned int width;
+	unsigned int height;
+	u16 xskip, yskip;
+
+	__crop = mt9p031_get_pad_crop(mt9p031, fh, format->pad, format->which);
+
+	width = clamp_t(int, ALIGN(format->format.width, 2), 2,
+						MT9P031_WINDOW_WIDTH_MAX);
+	height = clamp_t(int, ALIGN(format->format.height, 2), 2,
+						MT9P031_WINDOW_HEIGHT_MAX);
+
+	rect.width = __crop->width;
+	rect.height = __crop->height;
+
+	xskip = mt9p031_skip_for_scale(&rect.width, width, 7,
+				MT9P031_WINDOW_WIDTH_MAX);
+	if (rect.width + __crop->left > MT9P031_WINDOW_WIDTH_MAX)
+		rect.left = (MT9P031_WINDOW_WIDTH_MAX - rect.width) / 2;
+	else
+		rect.left = __crop->left;
+	yskip = mt9p031_skip_for_scale(&rect.height, height, 8,
+				MT9P031_WINDOW_HEIGHT_MAX);
+	if (rect.height + __crop->top > MT9P031_WINDOW_HEIGHT_MAX)
+		rect.top = (MT9P031_WINDOW_HEIGHT_MAX - rect.height) / 2;
+	else
+		rect.top = __crop->top;
+
+	dev_dbg(mt9p031->subdev.v4l2_dev->dev, "%s(%ux%u : %u)\n", __func__,
+		width, height, format->which);
+	if (__crop)
+		*__crop = rect;
+
+	__format = mt9p031_get_pad_format(mt9p031, fh, format->pad,
+						format->which);
+	__format->width = width;
+	__format->height = height;
+	format->format = *__format;
+
+	mt9p031->xskip = xskip;
+	mt9p031->yskip = yskip;
+	mt9p031->rect = *__crop;
+	return 0;
+}
+
+static int mt9p031_pll_enable(struct i2c_client *client)
+{
+	struct mt9p031 *mt9p031 = to_mt9p031(client);
+	int ret;
+
+	ret = reg_write(client, MT9P031_PLL_CONTROL, MT9P031_PLL_CONTROL_PWRON);
+	if (ret < 0)
+		return ret;
+
+	/* Always set the maximum frequency allowed by VDD_IO */
+	if (mt9p031->pdata->vdd_io == MT9P031_VDD_IO_2V8) {
+		ret = reg_write(client, MT9P031_PLL_CONFIG_1,
+			MT9P031_PLL_CONFIG_1_M_96MHZ |
+			MT9P031_PLL_CONFIG_1_N_96MHZ);
+		if (ret < 0)
+			return ret;
+		ret = reg_write(client, MT9P031_PLL_CONFIG_2,
+				MT9P031_PLL_CONFIG_2_P1_96MHZ);
+		if (ret < 0)
+			return ret;
+	} else {
+		ret = reg_write(client, MT9P031_PLL_CONFIG_1,
+			MT9P031_PLL_CONFIG_1_M_48MHZ |
+			MT9P031_PLL_CONFIG_1_N_48MHZ);
+		if (ret < 0)
+			return ret;
+		ret = reg_write(client, MT9P031_PLL_CONFIG_2,
+				MT9P031_PLL_CONFIG_2_P1_48MHZ);
+		if (ret < 0)
+			return ret;
+	}
+	mdelay(1);
+	ret = reg_write(client, MT9P031_PLL_CONTROL,
+			MT9P031_PLL_CONTROL_PWRON |
+			MT9P031_PLL_CONTROL_USEPLL);
+	mdelay(1);
+	return ret;
+}
+
+static inline int mt9p031_pll_disable(struct i2c_client *client)
+{
+	return reg_write(client, MT9P031_PLL_CONTROL,
+			 MT9P031_PLL_CONTROL_PWROFF);
+}
+
+static int mt9p031_s_stream(struct v4l2_subdev *sd, int enable)
+{
+	struct mt9p031 *mt9p031 = container_of(sd, struct mt9p031, subdev);
+	struct i2c_client *client = v4l2_get_subdevdata(&mt9p031->subdev);
+	struct v4l2_rect rect = mt9p031->rect;
+	u16 xskip = mt9p031->xskip;
+	u16 yskip = mt9p031->yskip;
+	int ret;
+
+	if (enable) {
+		ret = mt9p031_set_params(client, &rect, xskip, yskip);
+		if (ret < 0)
+			return ret;
+		/* Switch to master "normal" mode */
+		ret = mt9p031_set_output_control(mt9p031, 0,
+						MT9P031_OUTPUT_CONTROL_CEN);
+		if (ret < 0)
+			return ret;
+		ret = mt9p031_pll_enable(client);
+	} else {
+		/* Stop sensor readout */
+		ret = mt9p031_set_output_control(mt9p031,
+						MT9P031_OUTPUT_CONTROL_CEN, 0);
+		if (ret < 0)
+			return ret;
+		ret = mt9p031_pll_disable(client);
+	}
+	return ret;
+}
+
+static int mt9p031_video_probe(struct i2c_client *client)
+{
+	s32 data;
+
+	/* Read out the chip version register */
+	data = reg_read(client, MT9P031_CHIP_VERSION);
+	if (data != MT9P031_CHIP_VERSION_VALUE) {
+		dev_err(&client->dev,
+			"No MT9P031 chip detected, register read %x\n", data);
+		return -ENODEV;
+	}
+
+	dev_info(&client->dev, "Detected a MT9P031 chip ID %x\n", data);
+
+	return 0;
+}
+
+static int mt9p031_set_power(struct v4l2_subdev *sd, int on)
+{
+	struct mt9p031 *mt9p031 = container_of(sd, struct mt9p031, subdev);
+	int ret = 0;
+
+	mutex_lock(&mt9p031->power_lock);
+
+	/*
+	* If the power count is modified from 0 to != 0 or from != 0 to 0,
+	* update the power state.
+	*/
+	if (mt9p031->power_count == !on) {
+		if (on) {
+			ret = mt9p031_power_on(mt9p031);
+			if (ret) {
+				dev_err(mt9p031->subdev.v4l2_dev->dev,
+				"Failed to power on: %d\n", ret);
+				goto out;
+			}
+		} else {
+			mt9p031_power_off(mt9p031);
+		}
+	}
+
+	/* Update the power count. */
+	mt9p031->power_count += on ? 1 : -1;
+	WARN_ON(mt9p031->power_count < 0);
+
+out:
+	mutex_unlock(&mt9p031->power_lock);
+	return ret;
+}
+
+static int mt9p031_registered(struct v4l2_subdev *sd)
+{
+	struct mt9p031 *mt9p031 = container_of(sd, struct mt9p031, subdev);
+	struct i2c_client *client = v4l2_get_subdevdata(&mt9p031->subdev);
+	int ret;
+
+	ret = mt9p031_set_power(&mt9p031->subdev, 1);
+	if (ret) {
+		dev_err(&client->dev,
+			"Failed to power on device: %d\n", ret);
+		return ret;
+	}
+
+	ret = mt9p031_video_probe(client);
+
+	mt9p031_set_power(&mt9p031->subdev, 0);
+
+	return ret;
+}
+
+static int mt9p031_open(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
+{
+	struct mt9p031 *mt9p031;
+	mt9p031 = container_of(sd, struct mt9p031, subdev);
+
+	mt9p031->rect.width     = MT9P031_WINDOW_WIDTH_DEF;
+	mt9p031->rect.height    = MT9P031_WINDOW_HEIGHT_DEF;
+	mt9p031->rect.left      = MT9P031_COLUMN_START_DEF;
+	mt9p031->rect.top       = MT9P031_ROW_START_DEF;
+
+	if (mt9p031->pdata->version == MT9P031_MONOCHROME_VERSION)
+		mt9p031->format.code = V4L2_MBUS_FMT_Y12_1X12;
+	else
+		mt9p031->format.code = V4L2_MBUS_FMT_SGRBG12_1X12;
+
+	mt9p031->format.width = MT9P031_WINDOW_WIDTH_DEF;
+	mt9p031->format.height = MT9P031_WINDOW_HEIGHT_DEF;
+	mt9p031->format.field = V4L2_FIELD_NONE;
+	mt9p031->format.colorspace = V4L2_COLORSPACE_SRGB;
+
+	mt9p031->xskip = 1;
+	mt9p031->yskip = 1;
+	return mt9p031_set_power(sd, 1);
+}
+
+static int mt9p031_close(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
+{
+	return mt9p031_set_power(sd, 0);
+}
+
+static struct v4l2_subdev_core_ops mt9p031_subdev_core_ops = {
+	.s_power        = mt9p031_set_power,
+};
+
+static struct v4l2_subdev_video_ops mt9p031_subdev_video_ops = {
+	.s_stream       = mt9p031_s_stream,
+};
+
+static struct v4l2_subdev_pad_ops mt9p031_subdev_pad_ops = {
+	.enum_mbus_code = mt9p031_enum_mbus_code,
+	.get_fmt = mt9p031_get_format,
+	.set_fmt = mt9p031_set_format,
+	.get_crop = mt9p031_get_crop,
+	.set_crop = mt9p031_set_crop,
+};
+
+static struct v4l2_subdev_ops mt9p031_subdev_ops = {
+	.core   = &mt9p031_subdev_core_ops,
+	.video  = &mt9p031_subdev_video_ops,
+	.pad    = &mt9p031_subdev_pad_ops,
+};
+
+static const struct v4l2_subdev_internal_ops mt9p031_subdev_internal_ops = {
+	.registered = mt9p031_registered,
+	.open = mt9p031_open,
+	.close = mt9p031_close,
+};
+
+static int mt9p031_probe(struct i2c_client *client,
+				const struct i2c_device_id *did)
+{
+	int ret;
+	struct mt9p031 *mt9p031;
+	struct mt9p031_platform_data *pdata = client->dev.platform_data;
+	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA)) {
+		dev_warn(&adapter->dev,
+			"I2C-Adapter doesn't support I2C_FUNC_SMBUS_WORD\n");
+		return -EIO;
+	}
+
+	mt9p031 = kzalloc(sizeof(struct mt9p031), GFP_KERNEL);
+	if (!mt9p031)
+		return -ENOMEM;
+
+	mutex_init(&mt9p031->power_lock);
+	v4l2_i2c_subdev_init(&mt9p031->subdev, client, &mt9p031_subdev_ops);
+	mt9p031->subdev.internal_ops = &mt9p031_subdev_internal_ops;
+
+	mt9p031->pdata          = pdata;
+
+	mt9p031->pad.flags = MEDIA_PAD_FL_SOURCE;
+	ret = media_entity_init(&mt9p031->subdev.entity, 1, &mt9p031->pad, 0);
+	if (ret)
+		return ret;
+
+	mt9p031->subdev.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
+
+	return 0;
+}
+
+static int mt9p031_remove(struct i2c_client *client)
+{
+	struct v4l2_subdev *sd = i2c_get_clientdata(client);
+	struct mt9p031 *mt9p031 = container_of(sd, struct mt9p031, subdev);
+
+	v4l2_device_unregister_subdev(sd);
+	media_entity_cleanup(&sd->entity);
+	kfree(mt9p031);
+
+	return 0;
+}
+
+static const struct i2c_device_id mt9p031_id[] = {
+	{ "mt9p031", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, mt9p031_id);
+
+static struct i2c_driver mt9p031_i2c_driver = {
+	.driver = {
+		.name = "mt9p031",
+	},
+	.probe          = mt9p031_probe,
+	.remove         = mt9p031_remove,
+	.id_table       = mt9p031_id,
+};
+
+static int __init mt9p031_mod_init(void)
+{
+	return i2c_add_driver(&mt9p031_i2c_driver);
+}
+
+static void __exit mt9p031_mod_exit(void)
+{
+	i2c_del_driver(&mt9p031_i2c_driver);
+}
+
+module_init(mt9p031_mod_init);
+module_exit(mt9p031_mod_exit);
+
+MODULE_DESCRIPTION("Aptina MT9P031 Camera driver");
+MODULE_AUTHOR("Bastian Hecht <[e-mail]>");
+MODULE_LICENSE("GPL v2");
diff --git a/include/media/mt9p031.h b/include/media/mt9p031.h
new file mode 100644
index 0000000..27b4c75
--- /dev/null
+++ b/include/media/mt9p031.h
@@ -0,0 +1,23 @@ 
+#ifndef MT9P031_H
+#define MT9P031_H
+
+struct v4l2_subdev;
+
+enum {
+	MT9P031_COLOR_VERSION = 0,
+	MT9P031_MONOCHROME_VERSION = 1,
+};
+
+enum {
+	MT9P031_VDD_IO_1V8 = 0,
+	MT9P031_VDD_IO_2V8 = 1,
+};
+
+struct mt9p031_platform_data {
+	int (*set_xclk)(struct v4l2_subdev *subdev, int hz);
+	int (*reset)(struct v4l2_subdev *subdev, int active);
+	int vdd_io; /* MT9P031_VDD_IO_1V8 or MT9P031_VDD_IO_2V8 */
+	int version; /* MT9P031_COLOR_VERSION or MT9P031_MONOCHROME_VERSION */
+};
+
+#endif