Brooklyn/drivers/media/i2c/ad5398_vcm.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * AD5398 DAC driver for camera voice coil focus.
 * Copyright (C) 2021 Raspberry Pi (Trading) Ltd.
 *
 * Based on AD5820 DAC driver by Nokia and TI.
 *
 * This driver uses the regulator framework notification hooks on the
 * assumption that the VCM and sensor share a regulator. This means the VCM
 * position will be restored when either the sensor or VCM subdevices are opened
 * or powered up. The client can therefore choose to ignore the VCM subdevice,
 * and the lens position will be as previously requested. Without that, there
 * is a hard requirement to have the VCM subdevice open in order for the VCM
 * to be powered and at the requested position.
 */

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

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

/* Register definitions */
#define AD5398_POWER_DOWN		BIT(15)
#define AD5398_DAC_SHIFT		4

#define to_ad5398_device(sd)	container_of(sd, struct ad5398_device, subdev)

struct ad5398_device {
	struct v4l2_subdev subdev;
	struct ad5398_platform_data *platform_data;
	struct regulator *vana;
	struct notifier_block nb;

	struct v4l2_ctrl_handler ctrls;
	u32 focus_absolute;

	bool standby;
};

static int ad5398_write(struct ad5398_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 ad5398_update_hw(struct ad5398_device *coil)
{
	u16 status;

	status = coil->focus_absolute << AD5398_DAC_SHIFT;

	if (coil->standby)
		status |= AD5398_POWER_DOWN;

	return ad5398_write(coil, status);
}

/*
 * Power handling
 */
static int ad5398_power_off(struct ad5398_device *coil)
{
	int ret = 0;

	coil->standby = true;
	ret = ad5398_update_hw(coil);

	return ret;
}

static int ad5398_power_on(struct ad5398_device *coil)
{
	int ret;

	/* Restore the hardware settings. */
	coil->standby = false;
	ret = ad5398_update_hw(coil);
	if (ret)
		goto fail;

	return 0;

fail:
	coil->standby = true;

	return ret;
}

/*
 * V4L2 controls
 */
static int ad5398_set_ctrl(struct v4l2_ctrl *ctrl)
{
	struct ad5398_device *coil =
		container_of(ctrl->handler, struct ad5398_device, ctrls);

	switch (ctrl->id) {
	case V4L2_CID_FOCUS_ABSOLUTE:
		coil->focus_absolute = ctrl->val;
		return ad5398_update_hw(coil);
	}

	return 0;
}

static const struct v4l2_ctrl_ops ad5398_ctrl_ops = {
	.s_ctrl = ad5398_set_ctrl,
};

static int ad5398_init_controls(struct ad5398_device *coil)
{
	v4l2_ctrl_handler_init(&coil->ctrls, 1);

	/*
	 * V4L2_CID_FOCUS_ABSOLUTE
	 *
	 * Minimum current is 0 mA, maximum is 120 mA. Thus, 1 code is
	 * equivalent to 120/1023 = 0.1173 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 sufficient 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, &ad5398_ctrl_ops,
			  V4L2_CID_FOCUS_ABSOLUTE, 0, 1023, 1, 0);

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

	coil->focus_absolute = 0;

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

	return 0;
}

/*
 * V4L2 subdev operations
 */
static int ad5398_registered(struct v4l2_subdev *subdev)
{
	struct ad5398_device *coil = to_ad5398_device(subdev);

	return ad5398_init_controls(coil);
}

static int
ad5398_set_power(struct v4l2_subdev *subdev, int on)
{
	struct ad5398_device *coil = to_ad5398_device(subdev);
	int ret;

	if (on)
		ret = regulator_enable(coil->vana);
	else
		ret = regulator_disable(coil->vana);

	return ret;
}

static int ad5398_open(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
{
	struct ad5398_device *coil = to_ad5398_device(sd);

	return regulator_enable(coil->vana);
}

static int ad5398_close(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
{
	struct ad5398_device *coil = to_ad5398_device(sd);

	return regulator_disable(coil->vana);
}

static const struct v4l2_subdev_core_ops ad5398_core_ops = {
	.s_power = ad5398_set_power,
};

static const struct v4l2_subdev_ops ad5398_ops = {
	.core = &ad5398_core_ops,
};

static const struct v4l2_subdev_internal_ops ad5398_internal_ops = {
	.registered = ad5398_registered,
	.open = ad5398_open,
	.close = ad5398_close,
};

/*
 * I2C driver
 */
static int __maybe_unused ad5398_suspend(struct device *dev)
{
	struct i2c_client *client = container_of(dev, struct i2c_client, dev);
	struct v4l2_subdev *subdev = i2c_get_clientdata(client);
	struct ad5398_device *coil = to_ad5398_device(subdev);

	return regulator_enable(coil->vana);
}

static int __maybe_unused ad5398_resume(struct device *dev)
{
	struct i2c_client *client = container_of(dev, struct i2c_client, dev);
	struct v4l2_subdev *subdev = i2c_get_clientdata(client);
	struct ad5398_device *coil = to_ad5398_device(subdev);

	return regulator_disable(coil->vana);
}

static int ad5398_regulator_notifier(struct notifier_block *nb,
				     unsigned long event,
				     void *ignored)
{
	struct ad5398_device *coil = container_of(nb, struct ad5398_device, nb);

	if (event == REGULATOR_EVENT_ENABLE)
		ad5398_power_on(coil);
	else if (event == REGULATOR_EVENT_PRE_DISABLE)
		ad5398_power_off(coil);

	return NOTIFY_OK;
}

static int ad5398_probe(struct i2c_client *client,
			const struct i2c_device_id *devid)
{
	struct ad5398_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;
	}

	v4l2_i2c_subdev_init(&coil->subdev, client, &ad5398_ops);
	coil->subdev.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
	coil->subdev.internal_ops = &ad5398_internal_ops;
	coil->subdev.entity.function = MEDIA_ENT_F_LENS;
	strscpy(coil->subdev.name, "ad5398 focus", sizeof(coil->subdev.name));

	coil->nb.notifier_call = &ad5398_regulator_notifier;
	ret = regulator_register_notifier(coil->vana, &coil->nb);
	if (ret < 0)
		return ret;

	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;

cleanup:
	media_entity_cleanup(&coil->subdev.entity);
cleanup2:
	regulator_unregister_notifier(coil->vana, &coil->nb);
	return ret;
}

static int ad5398_remove(struct i2c_client *client)
{
	struct v4l2_subdev *subdev = i2c_get_clientdata(client);
	struct ad5398_device *coil = to_ad5398_device(subdev);

	v4l2_async_unregister_subdev(&coil->subdev);
	v4l2_ctrl_handler_free(&coil->ctrls);
	media_entity_cleanup(&coil->subdev.entity);
	return 0;
}

static const struct i2c_device_id ad5398_id_table[] = {
	{ "ad5398", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, ad5398_id_table);

static const struct of_device_id ad5398_of_table[] = {
	{ .compatible = "adi,ad5398" },
	{ }
};
MODULE_DEVICE_TABLE(of, ad5398_of_table);

static SIMPLE_DEV_PM_OPS(ad5398_pm, ad5398_suspend, ad5398_resume);

static struct i2c_driver ad5398_i2c_driver = {
	.driver		= {
		.name	= "ad5398",
		.pm	= &ad5398_pm,
		.of_match_table = ad5398_of_table,
	},
	.probe		= ad5398_probe,
	.remove		= ad5398_remove,
	.id_table	= ad5398_id_table,
};

module_i2c_driver(ad5398_i2c_driver);

MODULE_AUTHOR("Dave Stevenson <dave.stevenson@raspberrypi.com>");
MODULE_DESCRIPTION("AD5398 camera lens driver");
MODULE_LICENSE("GPL");