/*
 * drivers/media/i2c/ad5820.c
 *
 * AD5820 DAC driver for camera voice coil focus.
 *
 * Copyright (C) 2008 Nokia Corporation
 * Copyright (C) 2007 Texas Instruments
 * Copyright (C) 2016 Pavel Machek <pavel@ucw.cz>
 *
 * Contact: Tuukka Toivonen <tuukkat76@gmail.com>
 *	    Sakari Ailus <sakari.ailus@iki.fi>
 *
 * Based on af_d88.c by Texas Instruments.
 *
 * 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.
 *
 * 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.
 */

#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/regulator/consumer.h>

#include <media/v4l2-ctrls.h>
#include <media/v4l2-device.h>
#include <media/v4l2-subdev.h>

#define AD5820_NAME		"ad5820"

/* Register definitions */
#define AD5820_POWER_DOWN		(1 << 15)
#define AD5820_DAC_SHIFT		4
#define AD5820_RAMP_MODE_LINEAR		(0 << 3)
#define AD5820_RAMP_MODE_64_16		(1 << 3)

#define CODE_TO_RAMP_US(s)	((s) == 0 ? 0 : (1 << ((s) - 1)) * 50)
#define RAMP_US_TO_CODE(c)	fls(((c) + ((c)>>1)) / 50)

#define to_ad5820_device(sd)	container_of(sd, struct ad5820_device, subdev)

struct ad5820_device {
	struct v4l2_subdev subdev;
	struct ad5820_platform_data *platform_data;
	struct regulator *vana;

	struct v4l2_ctrl_handler ctrls;
	u32 focus_absolute;
	u32 focus_ramp_time;
	u32 focus_ramp_mode;

	struct mutex power_lock;
	int power_count;

	bool standby;
};

static int ad5820_write(struct ad5820_device *coil, u16 data)
{
	struct i2c_client *client = v4l2_get_subdevdata(&coil->subdev);
	struct i2c_msg msg;
	__be16 be_data;
	int r;

	if (!client->adapter)
		return -ENODEV;

	be_data = cpu_to_be16(data);
	msg.addr  = client->addr;
	msg.flags = 0;
	msg.len   = 2;
	msg.buf   = (u8 *)&be_data;

	r = i2c_transfer(client->adapter, &msg, 1);
	if (r < 0) {
		dev_err(&client->dev, "write failed, error %d\n", r);
		return r;
	}

	return 0;
}

/*
 * Calculate status word and write it to the device based on current
 * values of V4L2 controls. It is assumed that the stored V4L2 control
 * values are properly limited and rounded.
 */
static int ad5820_update_hw(struct ad5820_device *coil)
{
	u16 status;

	status = RAMP_US_TO_CODE(coil->focus_ramp_time);
	status |= coil->focus_ramp_mode
		? AD5820_RAMP_MODE_64_16 : AD5820_RAMP_MODE_LINEAR;
	status |= coil->focus_absolute << AD5820_DAC_SHIFT;

	if (coil->standby)
		status |= AD5820_POWER_DOWN;

	return ad5820_write(coil, status);
}

/*
 * Power handling
 */
static int ad5820_power_off(struct ad5820_device *coil, bool standby)
{
	int ret = 0, ret2;

	/*
	 * Go to standby first as real power off my be denied by the hardware
	 * (single power line control for both coil and sensor).
	 */
	if (standby) {
		coil->standby = true;
		ret = ad5820_update_hw(coil);
	}

	ret2 = regulator_disable(coil->vana);
	if (ret)
		return ret;
	return ret2;
}

static int ad5820_power_on(struct ad5820_device *coil, bool restore)
{
	int ret;

	ret = regulator_enable(coil->vana);
	if (ret < 0)
		return ret;

	if (restore) {
		/* Restore the hardware settings. */
		coil->standby = false;
		ret = ad5820_update_hw(coil);
		if (ret)
			goto fail;
	}
	return 0;

fail:
	coil->standby = true;
	regulator_disable(coil->vana);

	return ret;
}

/*
 * V4L2 controls
 */
static int ad5820_set_ctrl(struct v4l2_ctrl *ctrl)
{
	struct ad5820_device *coil =
		container_of(ctrl->handler, struct ad5820_device, ctrls);

	switch (ctrl->id) {
	case V4L2_CID_FOCUS_ABSOLUTE:
		coil->focus_absolute = ctrl->val;
		return ad5820_update_hw(coil);
	}

	return 0;
}

static const struct v4l2_ctrl_ops ad5820_ctrl_ops = {
	.s_ctrl = ad5820_set_ctrl,
};


static int ad5820_init_controls(struct ad5820_device *coil)
{
	v4l2_ctrl_handler_init(&coil->ctrls, 1);

	/*
	 * V4L2_CID_FOCUS_ABSOLUTE
	 *
	 * Minimum current is 0 mA, maximum is 100 mA. Thus, 1 code is
	 * equivalent to 100/1023 = 0.0978 mA. Nevertheless, we do not use [mA]
	 * for focus position, because it is meaningless for user. Meaningful
	 * would be to use focus distance or even its inverse, but since the
	 * driver doesn't have sufficiently knowledge to do the conversion, we
	 * will just use abstract codes here. In any case, smaller value = focus
	 * position farther from camera. The default zero value means focus at
	 * infinity, and also least current consumption.
	 */
	v4l2_ctrl_new_std(&coil->ctrls, &ad5820_ctrl_ops,
			  V4L2_CID_FOCUS_ABSOLUTE, 0, 1023, 1, 0);

	if (coil->ctrls.error)
		return coil->ctrls.error;

	coil->focus_absolute = 0;
	coil->focus_ramp_time = 0;
	coil->focus_ramp_mode = 0;

	coil->subdev.ctrl_handler = &coil->ctrls;

	return 0;
}

/*
 * V4L2 subdev operations
 */
static int ad5820_registered(struct v4l2_subdev *subdev)
{
	struct ad5820_device *coil = to_ad5820_device(subdev);

	return ad5820_init_controls(coil);
}

static int
ad5820_set_power(struct v4l2_subdev *subdev, int on)
{
	struct ad5820_device *coil = to_ad5820_device(subdev);
	int ret = 0;

	mutex_lock(&coil->power_lock);

	/*
	 * If the power count is modified from 0 to != 0 or from != 0 to 0,
	 * update the power state.
	 */
	if (coil->power_count == !on) {
		ret = on ? ad5820_power_on(coil, true) :
			ad5820_power_off(coil, true);
		if (ret < 0)
			goto done;
	}

	/* Update the power count. */
	coil->power_count += on ? 1 : -1;
	WARN_ON(coil->power_count < 0);

done:
	mutex_unlock(&coil->power_lock);
	return ret;
}

static int ad5820_open(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
{
	return ad5820_set_power(sd, 1);
}

static int ad5820_close(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
{
	return ad5820_set_power(sd, 0);
}

static const struct v4l2_subdev_core_ops ad5820_core_ops = {
	.s_power = ad5820_set_power,
};

static const struct v4l2_subdev_ops ad5820_ops = {
	.core = &ad5820_core_ops,
};

static const struct v4l2_subdev_internal_ops ad5820_internal_ops = {
	.registered = ad5820_registered,
	.open = ad5820_open,
	.close = ad5820_close,
};

/*
 * I2C driver
 */
static int __maybe_unused ad5820_suspend(struct device *dev)
{
	struct i2c_client *client = container_of(dev, struct i2c_client, dev);
	struct v4l2_subdev *subdev = i2c_get_clientdata(client);
	struct ad5820_device *coil = to_ad5820_device(subdev);

	if (!coil->power_count)
		return 0;

	return ad5820_power_off(coil, false);
}

static int __maybe_unused ad5820_resume(struct device *dev)
{
	struct i2c_client *client = container_of(dev, struct i2c_client, dev);
	struct v4l2_subdev *subdev = i2c_get_clientdata(client);
	struct ad5820_device *coil = to_ad5820_device(subdev);

	if (!coil->power_count)
		return 0;

	return ad5820_power_on(coil, true);
}

static int ad5820_probe(struct i2c_client *client,
			const struct i2c_device_id *devid)
{
	struct ad5820_device *coil;
	int ret;

	coil = devm_kzalloc(&client->dev, sizeof(*coil), GFP_KERNEL);
	if (!coil)
		return -ENOMEM;

	coil->vana = devm_regulator_get(&client->dev, "VANA");
	if (IS_ERR(coil->vana)) {
		ret = PTR_ERR(coil->vana);
		if (ret != -EPROBE_DEFER)
			dev_err(&client->dev, "could not get regulator for vana\n");
		return ret;
	}

	mutex_init(&coil->power_lock);

	v4l2_i2c_subdev_init(&coil->subdev, client, &ad5820_ops);
	coil->subdev.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
	coil->subdev.internal_ops = &ad5820_internal_ops;
	strcpy(coil->subdev.name, "ad5820 focus");

	ret = media_entity_pads_init(&coil->subdev.entity, 0, NULL);
	if (ret < 0)
		goto cleanup2;

	ret = v4l2_async_register_subdev(&coil->subdev);
	if (ret < 0)
		goto cleanup;

	return ret;

cleanup2:
	mutex_destroy(&coil->power_lock);
cleanup:
	media_entity_cleanup(&coil->subdev.entity);
	return ret;
}

static int __exit ad5820_remove(struct i2c_client *client)
{
	struct v4l2_subdev *subdev = i2c_get_clientdata(client);
	struct ad5820_device *coil = to_ad5820_device(subdev);

	v4l2_device_unregister_subdev(&coil->subdev);
	v4l2_ctrl_handler_free(&coil->ctrls);
	media_entity_cleanup(&coil->subdev.entity);
	mutex_destroy(&coil->power_lock);
	return 0;
}

static const struct i2c_device_id ad5820_id_table[] = {
	{ AD5820_NAME, 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, ad5820_id_table);

static SIMPLE_DEV_PM_OPS(ad5820_pm, ad5820_suspend, ad5820_resume);

static struct i2c_driver ad5820_i2c_driver = {
	.driver		= {
		.name	= AD5820_NAME,
		.pm	= &ad5820_pm,
	},
	.probe		= ad5820_probe,
	.remove		= __exit_p(ad5820_remove),
	.id_table	= ad5820_id_table,
};

module_i2c_driver(ad5820_i2c_driver);

MODULE_AUTHOR("Tuukka Toivonen");
MODULE_DESCRIPTION("AD5820 camera lens driver");
MODULE_LICENSE("GPL");