drivers/media/usb/em28xx/em28xx-camera.c - nest-cam/v366/kernel_backports - Git at Google

 /*
    em28xx-camera.c - driver for Empia EM25xx/27xx/28xx USB video capture devices

    Copyright (C) 2009 Mauro Carvalho Chehab <mchehab@infradead.org>
    Copyright (C) 2013 Frank Schäfer <fschaefer.oss@googlemail.com>

    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; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

 #include <linux/i2c.h>
 #include <media/soc_camera.h>
 #include <media/mt9v011.h>
 #include <media/v4l2-clk.h>
 #include <media/v4l2-common.h>

 #include "em28xx.h"


 /* Possible i2c addresses of Micron sensors */
 static unsigned short micron_sensor_addrs[] = {
 	0xb8 >> 1,   /* MT9V111, MT9V403 */
 	0xba >> 1,   /* MT9M001/011/111/112, MT9V011/012/112, MT9D011 */
 	0x90 >> 1,   /* MT9V012/112, MT9D011 (alternative address) */
 	I2C_CLIENT_END
 };

 /* Possible i2c addresses of Omnivision sensors */
 static unsigned short omnivision_sensor_addrs[] = {
 	0x42 >> 1,   /* OV7725, OV7670/60/48 */
 	0x60 >> 1,   /* OV2640, OV9650/53/55 */
 	I2C_CLIENT_END
 };


 static struct soc_camera_link camlink = {
 	.bus_id = 0,
 	.flags = 0,
 	.module_name = "em28xx",
 	.unbalanced_power = true,
 };


 /* FIXME: Should be replaced by a proper mt9m111 driver */
 static int em28xx_initialize_mt9m111(struct em28xx *dev)
 {
 	int i;
 	unsigned char regs[][3] = {
 		{ 0x0d, 0x00, 0x01, },  /* reset and use defaults */
 		{ 0x0d, 0x00, 0x00, },
 		{ 0x0a, 0x00, 0x21, },
 		{ 0x21, 0x04, 0x00, },  /* full readout speed, no row/col skipping */
 	};

 	for (i = 0; i < ARRAY_SIZE(regs); i++)
 		i2c_master_send(&dev->i2c_client[dev->def_i2c_bus],
 				&regs[i][0], 3);

 	return 0;
 }


 /* FIXME: Should be replaced by a proper mt9m001 driver */
 static int em28xx_initialize_mt9m001(struct em28xx *dev)
 {
 	int i;
 	unsigned char regs[][3] = {
 		{ 0x0d, 0x00, 0x01, },
 		{ 0x0d, 0x00, 0x00, },
 		{ 0x04, 0x05, 0x00, },	/* hres = 1280 */
 		{ 0x03, 0x04, 0x00, },  /* vres = 1024 */
 		{ 0x20, 0x11, 0x00, },
 		{ 0x06, 0x00, 0x10, },
 		{ 0x2b, 0x00, 0x24, },
 		{ 0x2e, 0x00, 0x24, },
 		{ 0x35, 0x00, 0x24, },
 		{ 0x2d, 0x00, 0x20, },
 		{ 0x2c, 0x00, 0x20, },
 		{ 0x09, 0x0a, 0xd4, },
 		{ 0x35, 0x00, 0x57, },
 	};

 	for (i = 0; i < ARRAY_SIZE(regs); i++)
 		i2c_master_send(&dev->i2c_client[dev->def_i2c_bus],
 				&regs[i][0], 3);

 	return 0;
 }


 /*
  * Probes Micron sensors with 8 bit address and 16 bit register width
  */
 static int em28xx_probe_sensor_micron(struct em28xx *dev)
 {
 	int ret, i;
 	char *name;
 	u8 reg;
 	__be16 id_be;
 	u16 id;

 	struct i2c_client client = dev->i2c_client[dev->def_i2c_bus];

 	dev->em28xx_sensor = EM28XX_NOSENSOR;
 	for (i = 0; micron_sensor_addrs[i] != I2C_CLIENT_END; i++) {
 		client.addr = micron_sensor_addrs[i];
 		/* NOTE: i2c_smbus_read_word_data() doesn't work with BE data */
 		/* Read chip ID from register 0x00 */
 		reg = 0x00;
 		ret = i2c_master_send(&client, &reg, 1);
 		if (ret < 0) {
 			if (ret != -ENODEV)
 				em28xx_errdev("couldn't read from i2c device 0x%02x: error %i\n",
 					      client.addr << 1, ret);
 			continue;
 		}
 		ret = i2c_master_recv(&client, (u8 *)&id_be, 2);
 		if (ret < 0) {
 			em28xx_errdev("couldn't read from i2c device 0x%02x: error %i\n",
 				      client.addr << 1, ret);
 			continue;
 		}
 		id = be16_to_cpu(id_be);
 		/* Read chip ID from register 0xff */
 		reg = 0xff;
 		ret = i2c_master_send(&client, &reg, 1);
 		if (ret < 0) {
 			em28xx_errdev("couldn't read from i2c device 0x%02x: error %i\n",
 				      client.addr << 1, ret);
 			continue;
 		}
 		ret = i2c_master_recv(&client, (u8 *)&id_be, 2);
 		if (ret < 0) {
 			em28xx_errdev("couldn't read from i2c device 0x%02x: error %i\n",
 				      client.addr << 1, ret);
 			continue;
 		}
 		/* Validate chip ID to be sure we have a Micron device */
 		if (id != be16_to_cpu(id_be))
 			continue;
 		/* Check chip ID */
 		id = be16_to_cpu(id_be);
 		switch (id) {
 		case 0x1222:
 			name = "MT9V012"; /* MI370 */ /* 640x480 */
 			break;
 		case 0x1229:
 			name = "MT9V112"; /* 640x480 */
 			break;
 		case 0x1433:
 			name = "MT9M011"; /* 1280x1024 */
 			break;
 		case 0x143a:    /* found in the ECS G200 */
 			name = "MT9M111"; /* MI1310 */ /* 1280x1024 */
 			dev->em28xx_sensor = EM28XX_MT9M111;
 			break;
 		case 0x148c:
 			name = "MT9M112"; /* MI1320 */ /* 1280x1024 */
 			break;
 		case 0x1511:
 			name = "MT9D011"; /* MI2010 */ /* 1600x1200 */
 			break;
 		case 0x8232:
 		case 0x8243:	/* rev B */
 			name = "MT9V011"; /* MI360 */ /* 640x480 */
 			dev->em28xx_sensor = EM28XX_MT9V011;
 			break;
 		case 0x8431:
 			name = "MT9M001"; /* 1280x1024 */
 			dev->em28xx_sensor = EM28XX_MT9M001;
 			break;
 		default:
 			em28xx_info("unknown Micron sensor detected: 0x%04x\n",
 				    id);
 			return 0;
 		}

 		if (dev->em28xx_sensor == EM28XX_NOSENSOR)
 			em28xx_info("unsupported sensor detected: %s\n", name);
 		else
 			em28xx_info("sensor %s detected\n", name);

 		dev->i2c_client[dev->def_i2c_bus].addr = client.addr;
 		return 0;
 	}

 	return -ENODEV;
 }

 /*
  * Probes Omnivision sensors with 8 bit address and register width
  */
 static int em28xx_probe_sensor_omnivision(struct em28xx *dev)
 {
 	int ret, i;
 	char *name;
 	u8 reg;
 	u16 id;
 	struct i2c_client client = dev->i2c_client[dev->def_i2c_bus];

 	dev->em28xx_sensor = EM28XX_NOSENSOR;
 	/* NOTE: these devices have the register auto incrementation disabled
 	 * by default, so we have to use single byte reads !              */
 	for (i = 0; omnivision_sensor_addrs[i] != I2C_CLIENT_END; i++) {
 		client.addr = omnivision_sensor_addrs[i];
 		/* Read manufacturer ID from registers 0x1c-0x1d (BE) */
 		reg = 0x1c;
 		ret = i2c_smbus_read_byte_data(&client, reg);
 		if (ret < 0) {
 			if (ret != -ENODEV)
 				em28xx_errdev("couldn't read from i2c device 0x%02x: error %i\n",
 					      client.addr << 1, ret);
 			continue;
 		}
 		id = ret << 8;
 		reg = 0x1d;
 		ret = i2c_smbus_read_byte_data(&client, reg);
 		if (ret < 0) {
 			em28xx_errdev("couldn't read from i2c device 0x%02x: error %i\n",
 				      client.addr << 1, ret);
 			continue;
 		}
 		id += ret;
 		/* Check manufacturer ID */
 		if (id != 0x7fa2)
 			continue;
 		/* Read product ID from registers 0x0a-0x0b (BE) */
 		reg = 0x0a;
 		ret = i2c_smbus_read_byte_data(&client, reg);
 		if (ret < 0) {
 			em28xx_errdev("couldn't read from i2c device 0x%02x: error %i\n",
 				      client.addr << 1, ret);
 			continue;
 		}
 		id = ret << 8;
 		reg = 0x0b;
 		ret = i2c_smbus_read_byte_data(&client, reg);
 		if (ret < 0) {
 			em28xx_errdev("couldn't read from i2c device 0x%02x: error %i\n",
 				      client.addr << 1, ret);
 			continue;
 		}
 		id += ret;
 		/* Check product ID */
 		switch (id) {
 		case 0x2642:
 			name = "OV2640";
 			dev->em28xx_sensor = EM28XX_OV2640;
 			break;
 		case 0x7648:
 			name = "OV7648";
 			break;
 		case 0x7660:
 			name = "OV7660";
 			break;
 		case 0x7673:
 			name = "OV7670";
 			break;
 		case 0x7720:
 			name = "OV7720";
 			break;
 		case 0x7721:
 			name = "OV7725";
 			break;
 		case 0x9648: /* Rev 2 */
 		case 0x9649: /* Rev 3 */
 			name = "OV9640";
 			break;
 		case 0x9650:
 		case 0x9652: /* OV9653 */
 			name = "OV9650";
 			break;
 		case 0x9656: /* Rev 4 */
 		case 0x9657: /* Rev 5 */
 			name = "OV9655";
 			break;
 		default:
 			em28xx_info("unknown OmniVision sensor detected: 0x%04x\n",
 				    id);
 			return 0;
 		}

 		if (dev->em28xx_sensor == EM28XX_NOSENSOR)
 			em28xx_info("unsupported sensor detected: %s\n", name);
 		else
 			em28xx_info("sensor %s detected\n", name);

 		dev->i2c_client[dev->def_i2c_bus].addr = client.addr;
 		return 0;
 	}

 	return -ENODEV;
 }

 int em28xx_detect_sensor(struct em28xx *dev)
 {
 	int ret;

 	ret = em28xx_probe_sensor_micron(dev);

 	if (dev->em28xx_sensor == EM28XX_NOSENSOR && ret < 0)
 		ret = em28xx_probe_sensor_omnivision(dev);

 	/*
 	 * NOTE: the Windows driver also probes i2c addresses
 	 *       0x22 (Samsung ?) and 0x66 (Kodak ?)
 	 */

 	if (dev->em28xx_sensor == EM28XX_NOSENSOR && ret < 0) {
 		em28xx_info("No sensor detected\n");
 		return -ENODEV;
 	}

 	return 0;
 }

 int em28xx_init_camera(struct em28xx *dev)
 {
 	char clk_name[V4L2_SUBDEV_NAME_SIZE];
 	struct i2c_client *client = &dev->i2c_client[dev->def_i2c_bus];
 	struct i2c_adapter *adap = &dev->i2c_adap[dev->def_i2c_bus];
 	int ret = 0;

 	v4l2_clk_name_i2c(clk_name, sizeof(clk_name),
 			  i2c_adapter_id(adap), client->addr);
 	dev->clk = v4l2_clk_register_fixed(clk_name, "mclk", -EINVAL);
 	if (IS_ERR(dev->clk))
 		return PTR_ERR(dev->clk);

 	switch (dev->em28xx_sensor) {
 	case EM28XX_MT9V011:
 	{
 		struct mt9v011_platform_data pdata;
 		struct i2c_board_info mt9v011_info = {
 			.type = "mt9v011",
 			.addr = client->addr,
 			.platform_data = &pdata,
 		};

 		dev->sensor_xres = 640;
 		dev->sensor_yres = 480;

 		/*
 		 * FIXME: mt9v011 uses I2S speed as xtal clk - at least with
 		 * the Silvercrest cam I have here for testing - for higher
 		 * resolutions, a high clock cause horizontal artifacts, so we
 		 * need to use a lower xclk frequency.
 		 * Yet, it would be possible to adjust xclk depending on the
 		 * desired resolution, since this affects directly the
 		 * frame rate.
 		 */
 		dev->board.xclk = EM28XX_XCLK_FREQUENCY_4_3MHZ;
 		em28xx_write_reg(dev, EM28XX_R0F_XCLK, dev->board.xclk);
 		dev->sensor_xtal = 4300000;
 		pdata.xtal = dev->sensor_xtal;
 		if (NULL ==
 		    v4l2_i2c_new_subdev_board(&dev->v4l2_dev, adap,
 					      &mt9v011_info, NULL)) {
 			ret = -ENODEV;
 			break;
 		}
 		/* probably means GRGB 16 bit bayer */
 		dev->vinmode = 0x0d;
 		dev->vinctl = 0x00;

 		break;
 	}
 	case EM28XX_MT9M001:
 		dev->sensor_xres = 1280;
 		dev->sensor_yres = 1024;

 		em28xx_initialize_mt9m001(dev);

 		/* probably means BGGR 16 bit bayer */
 		dev->vinmode = 0x0c;
 		dev->vinctl = 0x00;

 		break;
 	case EM28XX_MT9M111:
 		dev->sensor_xres = 640;
 		dev->sensor_yres = 512;

 		dev->board.xclk = EM28XX_XCLK_FREQUENCY_48MHZ;
 		em28xx_write_reg(dev, EM28XX_R0F_XCLK, dev->board.xclk);
 		em28xx_initialize_mt9m111(dev);

 		dev->vinmode = 0x0a;
 		dev->vinctl = 0x00;

 		break;
 	case EM28XX_OV2640:
 	{
 		struct v4l2_subdev *subdev;
 		struct i2c_board_info ov2640_info = {
 			.type = "ov2640",
 			.flags = I2C_CLIENT_SCCB,
 			.addr = client->addr,
 			.platform_data = &camlink,
 		};
 		struct v4l2_mbus_framefmt fmt;

 		/*
 		 * FIXME: sensor supports resolutions up to 1600x1200, but
 		 * resolution setting/switching needs to be modified to
 		 * - switch sensor output resolution (including further
 		 *   configuration changes)
 		 * - adjust bridge xclk
 		 * - disable 16 bit (12 bit) output formats on high resolutions
 		 */
 		dev->sensor_xres = 640;
 		dev->sensor_yres = 480;

 		subdev =
 		     v4l2_i2c_new_subdev_board(&dev->v4l2_dev, adap,
 					       &ov2640_info, NULL);
 		if (NULL == subdev) {
 			ret = -ENODEV;
 			break;
 		}

 		fmt.code = V4L2_MBUS_FMT_YUYV8_2X8;
 		fmt.width = 640;
 		fmt.height = 480;
 		v4l2_subdev_call(subdev, video, s_mbus_fmt, &fmt);

 		/* NOTE: for UXGA=1600x1200 switch to 12MHz */
 		dev->board.xclk = EM28XX_XCLK_FREQUENCY_24MHZ;
 		em28xx_write_reg(dev, EM28XX_R0F_XCLK, dev->board.xclk);
 		dev->vinmode = 0x08;
 		dev->vinctl = 0x00;

 		break;
 	}
 	case EM28XX_NOSENSOR:
 	default:
 		ret = -EINVAL;
 	}

 	if (ret < 0) {
 		v4l2_clk_unregister_fixed(dev->clk);
 		dev->clk = NULL;
 	}

 	return ret;
 }
 EXPORT_SYMBOL_GPL(em28xx_init_camera);
	/*
	em28xx-camera.c - driver for Empia EM25xx/27xx/28xx USB video capture devices

	Copyright (C) 2009 Mauro Carvalho Chehab <mchehab@infradead.org>
	Copyright (C) 2013 Frank Schäfer <fschaefer.oss@googlemail.com>

	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; either version 2 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program; if not, write to the Free Software
	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	*/

	#include <linux/i2c.h>
	#include <media/soc_camera.h>
	#include <media/mt9v011.h>
	#include <media/v4l2-clk.h>
	#include <media/v4l2-common.h>

	#include "em28xx.h"


	/* Possible i2c addresses of Micron sensors */
	static unsigned short micron_sensor_addrs[] = {
	0xb8 >> 1, /* MT9V111, MT9V403 */
	0xba >> 1, /* MT9M001/011/111/112, MT9V011/012/112, MT9D011 */
	0x90 >> 1, /* MT9V012/112, MT9D011 (alternative address) */
	I2C_CLIENT_END
	};

	/* Possible i2c addresses of Omnivision sensors */
	static unsigned short omnivision_sensor_addrs[] = {
	0x42 >> 1, /* OV7725, OV7670/60/48 */
	0x60 >> 1, /* OV2640, OV9650/53/55 */
	I2C_CLIENT_END
	};


	static struct soc_camera_link camlink = {
	.bus_id = 0,
	.flags = 0,
	.module_name = "em28xx",
	.unbalanced_power = true,
	};


	/* FIXME: Should be replaced by a proper mt9m111 driver */
	static int em28xx_initialize_mt9m111(struct em28xx *dev)
	{
	int i;
	unsigned char regs[][3] = {
	{ 0x0d, 0x00, 0x01, }, /* reset and use defaults */
	{ 0x0d, 0x00, 0x00, },
	{ 0x0a, 0x00, 0x21, },
	{ 0x21, 0x04, 0x00, }, /* full readout speed, no row/col skipping */
	};

	for (i = 0; i < ARRAY_SIZE(regs); i++)
	i2c_master_send(&dev->i2c_client[dev->def_i2c_bus],
	&regs[i][0], 3);

	return 0;
	}


	/* FIXME: Should be replaced by a proper mt9m001 driver */
	static int em28xx_initialize_mt9m001(struct em28xx *dev)
	{
	int i;
	unsigned char regs[][3] = {
	{ 0x0d, 0x00, 0x01, },
	{ 0x0d, 0x00, 0x00, },
	{ 0x04, 0x05, 0x00, }, /* hres = 1280 */
	{ 0x03, 0x04, 0x00, }, /* vres = 1024 */
	{ 0x20, 0x11, 0x00, },
	{ 0x06, 0x00, 0x10, },
	{ 0x2b, 0x00, 0x24, },
	{ 0x2e, 0x00, 0x24, },
	{ 0x35, 0x00, 0x24, },
	{ 0x2d, 0x00, 0x20, },
	{ 0x2c, 0x00, 0x20, },
	{ 0x09, 0x0a, 0xd4, },
	{ 0x35, 0x00, 0x57, },
	};

	for (i = 0; i < ARRAY_SIZE(regs); i++)
	i2c_master_send(&dev->i2c_client[dev->def_i2c_bus],
	&regs[i][0], 3);

	return 0;
	}


	/*
	* Probes Micron sensors with 8 bit address and 16 bit register width
	*/
	static int em28xx_probe_sensor_micron(struct em28xx *dev)
	{
	int ret, i;
	char *name;
	u8 reg;
	__be16 id_be;
	u16 id;

	struct i2c_client client = dev->i2c_client[dev->def_i2c_bus];

	dev->em28xx_sensor = EM28XX_NOSENSOR;
	for (i = 0; micron_sensor_addrs[i] != I2C_CLIENT_END; i++) {
	client.addr = micron_sensor_addrs[i];
	/* NOTE: i2c_smbus_read_word_data() doesn't work with BE data */
	/* Read chip ID from register 0x00 */
	reg = 0x00;
	ret = i2c_master_send(&client, &reg, 1);
	if (ret < 0) {
	if (ret != -ENODEV)
	em28xx_errdev("couldn't read from i2c device 0x%02x: error %i\n",
	client.addr << 1, ret);
	continue;
	}
	ret = i2c_master_recv(&client, (u8 *)&id_be, 2);
	if (ret < 0) {
	em28xx_errdev("couldn't read from i2c device 0x%02x: error %i\n",
	client.addr << 1, ret);
	continue;
	}
	id = be16_to_cpu(id_be);
	/* Read chip ID from register 0xff */
	reg = 0xff;
	ret = i2c_master_send(&client, &reg, 1);
	if (ret < 0) {
	em28xx_errdev("couldn't read from i2c device 0x%02x: error %i\n",
	client.addr << 1, ret);
	continue;
	}
	ret = i2c_master_recv(&client, (u8 *)&id_be, 2);
	if (ret < 0) {
	em28xx_errdev("couldn't read from i2c device 0x%02x: error %i\n",
	client.addr << 1, ret);
	continue;
	}
	/* Validate chip ID to be sure we have a Micron device */
	if (id != be16_to_cpu(id_be))
	continue;
	/* Check chip ID */
	id = be16_to_cpu(id_be);
	switch (id) {
	case 0x1222:
	name = "MT9V012"; /* MI370 / / 640x480 */
	break;
	case 0x1229:
	name = "MT9V112"; /* 640x480 */
	break;
	case 0x1433:
	name = "MT9M011"; /* 1280x1024 */
	break;
	case 0x143a: /* found in the ECS G200 */
	name = "MT9M111"; /* MI1310 / / 1280x1024 */
	dev->em28xx_sensor = EM28XX_MT9M111;
	break;
	case 0x148c:
	name = "MT9M112"; /* MI1320 / / 1280x1024 */
	break;
	case 0x1511:
	name = "MT9D011"; /* MI2010 / / 1600x1200 */
	break;
	case 0x8232:
	case 0x8243: /* rev B */
	name = "MT9V011"; /* MI360 / / 640x480 */
	dev->em28xx_sensor = EM28XX_MT9V011;
	break;
	case 0x8431:
	name = "MT9M001"; /* 1280x1024 */
	dev->em28xx_sensor = EM28XX_MT9M001;
	break;
	default:
	em28xx_info("unknown Micron sensor detected: 0x%04x\n",
	id);
	return 0;
	}

	if (dev->em28xx_sensor == EM28XX_NOSENSOR)
	em28xx_info("unsupported sensor detected: %s\n", name);
	else
	em28xx_info("sensor %s detected\n", name);

	dev->i2c_client[dev->def_i2c_bus].addr = client.addr;
	return 0;
	}

	return -ENODEV;
	}

	/*
	* Probes Omnivision sensors with 8 bit address and register width
	*/
	static int em28xx_probe_sensor_omnivision(struct em28xx *dev)
	{
	int ret, i;
	char *name;
	u8 reg;
	u16 id;
	struct i2c_client client = dev->i2c_client[dev->def_i2c_bus];

	dev->em28xx_sensor = EM28XX_NOSENSOR;
	/* NOTE: these devices have the register auto incrementation disabled
	* by default, so we have to use single byte reads ! */
	for (i = 0; omnivision_sensor_addrs[i] != I2C_CLIENT_END; i++) {
	client.addr = omnivision_sensor_addrs[i];
	/* Read manufacturer ID from registers 0x1c-0x1d (BE) */
	reg = 0x1c;
	ret = i2c_smbus_read_byte_data(&client, reg);
	if (ret < 0) {
	if (ret != -ENODEV)
	em28xx_errdev("couldn't read from i2c device 0x%02x: error %i\n",
	client.addr << 1, ret);
	continue;
	}
	id = ret << 8;
	reg = 0x1d;
	ret = i2c_smbus_read_byte_data(&client, reg);
	if (ret < 0) {
	em28xx_errdev("couldn't read from i2c device 0x%02x: error %i\n",
	client.addr << 1, ret);
	continue;
	}
	id += ret;
	/* Check manufacturer ID */
	if (id != 0x7fa2)
	continue;
	/* Read product ID from registers 0x0a-0x0b (BE) */
	reg = 0x0a;
	ret = i2c_smbus_read_byte_data(&client, reg);
	if (ret < 0) {
	em28xx_errdev("couldn't read from i2c device 0x%02x: error %i\n",
	client.addr << 1, ret);
	continue;
	}
	id = ret << 8;
	reg = 0x0b;
	ret = i2c_smbus_read_byte_data(&client, reg);
	if (ret < 0) {
	em28xx_errdev("couldn't read from i2c device 0x%02x: error %i\n",
	client.addr << 1, ret);
	continue;
	}
	id += ret;
	/* Check product ID */
	switch (id) {
	case 0x2642:
	name = "OV2640";
	dev->em28xx_sensor = EM28XX_OV2640;
	break;
	case 0x7648:
	name = "OV7648";
	break;
	case 0x7660:
	name = "OV7660";
	break;
	case 0x7673:
	name = "OV7670";
	break;
	case 0x7720:
	name = "OV7720";
	break;
	case 0x7721:
	name = "OV7725";
	break;
	case 0x9648: /* Rev 2 */
	case 0x9649: /* Rev 3 */
	name = "OV9640";
	break;
	case 0x9650:
	case 0x9652: /* OV9653 */
	name = "OV9650";
	break;
	case 0x9656: /* Rev 4 */
	case 0x9657: /* Rev 5 */
	name = "OV9655";
	break;
	default:
	em28xx_info("unknown OmniVision sensor detected: 0x%04x\n",
	id);
	return 0;
	}

	if (dev->em28xx_sensor == EM28XX_NOSENSOR)
	em28xx_info("unsupported sensor detected: %s\n", name);
	else
	em28xx_info("sensor %s detected\n", name);

	dev->i2c_client[dev->def_i2c_bus].addr = client.addr;
	return 0;
	}

	return -ENODEV;
	}

	int em28xx_detect_sensor(struct em28xx *dev)
	{
	int ret;

	ret = em28xx_probe_sensor_micron(dev);

	if (dev->em28xx_sensor == EM28XX_NOSENSOR && ret < 0)
	ret = em28xx_probe_sensor_omnivision(dev);

	/*
	* NOTE: the Windows driver also probes i2c addresses
	* 0x22 (Samsung ?) and 0x66 (Kodak ?)
	*/

	if (dev->em28xx_sensor == EM28XX_NOSENSOR && ret < 0) {
	em28xx_info("No sensor detected\n");
	return -ENODEV;
	}

	return 0;
	}

	int em28xx_init_camera(struct em28xx *dev)
	{
	char clk_name[V4L2_SUBDEV_NAME_SIZE];
	struct i2c_client *client = &dev->i2c_client[dev->def_i2c_bus];
	struct i2c_adapter *adap = &dev->i2c_adap[dev->def_i2c_bus];
	int ret = 0;

	v4l2_clk_name_i2c(clk_name, sizeof(clk_name),
	i2c_adapter_id(adap), client->addr);
	dev->clk = v4l2_clk_register_fixed(clk_name, "mclk", -EINVAL);
	if (IS_ERR(dev->clk))
	return PTR_ERR(dev->clk);

	switch (dev->em28xx_sensor) {
	case EM28XX_MT9V011:
	{
	struct mt9v011_platform_data pdata;
	struct i2c_board_info mt9v011_info = {
	.type = "mt9v011",
	.addr = client->addr,
	.platform_data = &pdata,
	};

	dev->sensor_xres = 640;
	dev->sensor_yres = 480;

	/*
	* FIXME: mt9v011 uses I2S speed as xtal clk - at least with
	* the Silvercrest cam I have here for testing - for higher
	* resolutions, a high clock cause horizontal artifacts, so we
	* need to use a lower xclk frequency.
	* Yet, it would be possible to adjust xclk depending on the
	* desired resolution, since this affects directly the
	* frame rate.
	*/
	dev->board.xclk = EM28XX_XCLK_FREQUENCY_4_3MHZ;
	em28xx_write_reg(dev, EM28XX_R0F_XCLK, dev->board.xclk);
	dev->sensor_xtal = 4300000;
	pdata.xtal = dev->sensor_xtal;
	if (NULL ==
	v4l2_i2c_new_subdev_board(&dev->v4l2_dev, adap,
	&mt9v011_info, NULL)) {
	ret = -ENODEV;
	break;
	}
	/* probably means GRGB 16 bit bayer */
	dev->vinmode = 0x0d;
	dev->vinctl = 0x00;

	break;
	}
	case EM28XX_MT9M001:
	dev->sensor_xres = 1280;
	dev->sensor_yres = 1024;

	em28xx_initialize_mt9m001(dev);

	/* probably means BGGR 16 bit bayer */
	dev->vinmode = 0x0c;
	dev->vinctl = 0x00;

	break;
	case EM28XX_MT9M111:
	dev->sensor_xres = 640;
	dev->sensor_yres = 512;

	dev->board.xclk = EM28XX_XCLK_FREQUENCY_48MHZ;
	em28xx_write_reg(dev, EM28XX_R0F_XCLK, dev->board.xclk);
	em28xx_initialize_mt9m111(dev);

	dev->vinmode = 0x0a;
	dev->vinctl = 0x00;

	break;
	case EM28XX_OV2640:
	{
	struct v4l2_subdev *subdev;
	struct i2c_board_info ov2640_info = {
	.type = "ov2640",
	.flags = I2C_CLIENT_SCCB,
	.addr = client->addr,
	.platform_data = &camlink,
	};
	struct v4l2_mbus_framefmt fmt;

	/*
	* FIXME: sensor supports resolutions up to 1600x1200, but
	* resolution setting/switching needs to be modified to
	* - switch sensor output resolution (including further
	* configuration changes)
	* - adjust bridge xclk
	* - disable 16 bit (12 bit) output formats on high resolutions
	*/
	dev->sensor_xres = 640;
	dev->sensor_yres = 480;

	subdev =
	v4l2_i2c_new_subdev_board(&dev->v4l2_dev, adap,
	&ov2640_info, NULL);
	if (NULL == subdev) {
	ret = -ENODEV;
	break;
	}

	fmt.code = V4L2_MBUS_FMT_YUYV8_2X8;
	fmt.width = 640;
	fmt.height = 480;
	v4l2_subdev_call(subdev, video, s_mbus_fmt, &fmt);

	/* NOTE: for UXGA=1600x1200 switch to 12MHz */
	dev->board.xclk = EM28XX_XCLK_FREQUENCY_24MHZ;
	em28xx_write_reg(dev, EM28XX_R0F_XCLK, dev->board.xclk);
	dev->vinmode = 0x08;
	dev->vinctl = 0x00;

	break;
	}
	case EM28XX_NOSENSOR:
	default:
	ret = -EINVAL;
	}

	if (ret < 0) {
	v4l2_clk_unregister_fixed(dev->clk);
	dev->clk = NULL;
	}

	return ret;
	}
	EXPORT_SYMBOL_GPL(em28xx_init_camera);