media: i2c: Add driver for AD5398 VCM lens driver

Adds a driver for the Analog Devices AD5398 10 bit
I2C DAC which is commonly used for driving VCM lens
mechanisms.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>

drivers/media/i2c/Kconfig

@@ -1284,6 +1284,13 @@ endmenu
 menu "Lens drivers"
 	visible if MEDIA_CAMERA_SUPPORT
 
+config VIDEO_AD5398
+	tristate "AD5398 lens voice coil support"
+	depends on GPIOLIB && I2C && VIDEO_V4L2
+	select MEDIA_CONTROLLER
+	help
+	  This is a driver for the AD5398 camera lens voice coil.
+
 config VIDEO_AD5820
 	tristate "AD5820 lens voice coil support"
 	depends on GPIOLIB && I2C && VIDEO_V4L2

drivers/media/i2c/Makefile

@@ -21,6 +21,7 @@ obj-$(CONFIG_VIDEO_SAA717X) += saa717x.o
 obj-$(CONFIG_VIDEO_SAA7127) += saa7127.o
 obj-$(CONFIG_VIDEO_SAA7185) += saa7185.o
 obj-$(CONFIG_VIDEO_SAA6752HS) += saa6752hs.o
+obj-$(CONFIG_VIDEO_AD5398)  += ad5398.o
 obj-$(CONFIG_VIDEO_AD5820)  += ad5820.o
 obj-$(CONFIG_VIDEO_AK7375)  += ak7375.o
 obj-$(CONFIG_VIDEO_DW9714)  += dw9714.o

drivers/media/i2c/ad5398.c

@@ -0,0 +1,334 @@
+// 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.
+ */
+
+#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");