linux/drivers/video/backlight/wm831x_bl.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Backlight driver for Wolfson Microelectronics WM831x PMICs
 *
 * Copyright 2009 Wolfson Microelectonics plc
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/fb.h>
#include <linux/backlight.h>
#include <linux/slab.h>

#include <linux/mfd/wm831x/core.h>
#include <linux/mfd/wm831x/pdata.h>
#include <linux/mfd/wm831x/regulator.h>

struct wm831x_backlight_data {
	struct wm831x *wm831x;
	int isink_reg;
	int current_brightness;
};

static int wm831x_backlight_set(struct backlight_device *bl, int brightness)
{
	struct wm831x_backlight_data *data = bl_get_data(bl);
	struct wm831x *wm831x = data->wm831x;
	int power_up = !data->current_brightness && brightness;
	int power_down = data->current_brightness && !brightness;
	int ret;

	if (power_up) {
		/* Enable the ISINK */
		ret = wm831x_set_bits(wm831x, data->isink_reg,
				      WM831X_CS1_ENA, WM831X_CS1_ENA);
		if (ret < 0)
			goto err;

		/* Enable the DC-DC */
		ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE,
				      WM831X_DC4_ENA, WM831X_DC4_ENA);
		if (ret < 0)
			goto err;
	}

	if (power_down) {
		/* DCDC first */
		ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE,
				      WM831X_DC4_ENA, 0);
		if (ret < 0)
			goto err;

		/* ISINK */
		ret = wm831x_set_bits(wm831x, data->isink_reg,
				      WM831X_CS1_DRIVE | WM831X_CS1_ENA, 0);
		if (ret < 0)
			goto err;
	}

	/* Set the new brightness */
	ret = wm831x_set_bits(wm831x, data->isink_reg,
			      WM831X_CS1_ISEL_MASK, brightness);
	if (ret < 0)
		goto err;

	if (power_up) {
		/* Drive current through the ISINK */
		ret = wm831x_set_bits(wm831x, data->isink_reg,
				      WM831X_CS1_DRIVE, WM831X_CS1_DRIVE);
		if (ret < 0)
			return ret;
	}

	data->current_brightness = brightness;

	return 0;

err:
	/* If we were in the middle of a power transition always shut down
	 * for safety.
	 */
	if (power_up || power_down) {
		wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);
		wm831x_set_bits(wm831x, data->isink_reg, WM831X_CS1_ENA, 0);
	}

	return ret;
}

static int wm831x_backlight_update_status(struct backlight_device *bl)
{
	return wm831x_backlight_set(bl, backlight_get_brightness(bl));
}

static int wm831x_backlight_get_brightness(struct backlight_device *bl)
{
	struct wm831x_backlight_data *data = bl_get_data(bl);

	return data->current_brightness;
}

static const struct backlight_ops wm831x_backlight_ops = {
	.options = BL_CORE_SUSPENDRESUME,
	.update_status	= wm831x_backlight_update_status,
	.get_brightness	= wm831x_backlight_get_brightness,
};

static int wm831x_backlight_probe(struct platform_device *pdev)
{
	struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
	struct wm831x_pdata *wm831x_pdata = dev_get_platdata(pdev->dev.parent);
	struct wm831x_backlight_pdata *pdata;
	struct wm831x_backlight_data *data;
	struct backlight_device *bl;
	struct backlight_properties props;
	int ret, i, max_isel, isink_reg, dcdc_cfg;

	/* We need platform data */
	if (wm831x_pdata)
		pdata = wm831x_pdata->backlight;
	else
		pdata = NULL;

	if (!pdata) {
		dev_err(&pdev->dev, "No platform data supplied\n");
		return -EINVAL;
	}

	/* Figure out the maximum current we can use */
	for (i = 0; i < WM831X_ISINK_MAX_ISEL; i++) {
		if (wm831x_isinkv_values[i] > pdata->max_uA)
			break;
	}

	if (i == 0) {
		dev_err(&pdev->dev, "Invalid max_uA: %duA\n", pdata->max_uA);
		return -EINVAL;
	}
	max_isel = i - 1;

	if (pdata->max_uA != wm831x_isinkv_values[max_isel])
		dev_warn(&pdev->dev,
			 "Maximum current is %duA not %duA as requested\n",
			 wm831x_isinkv_values[max_isel], pdata->max_uA);

	switch (pdata->isink) {
	case 1:
		isink_reg = WM831X_CURRENT_SINK_1;
		dcdc_cfg = 0;
		break;
	case 2:
		isink_reg = WM831X_CURRENT_SINK_2;
		dcdc_cfg = WM831X_DC4_FBSRC;
		break;
	default:
		dev_err(&pdev->dev, "Invalid ISINK %d\n", pdata->isink);
		return -EINVAL;
	}

	/* Configure the ISINK to use for feedback */
	ret = wm831x_reg_unlock(wm831x);
	if (ret < 0)
		return ret;

	ret = wm831x_set_bits(wm831x, WM831X_DC4_CONTROL, WM831X_DC4_FBSRC,
			      dcdc_cfg);

	wm831x_reg_lock(wm831x);
	if (ret < 0)
		return ret;

	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
	if (data == NULL)
		return -ENOMEM;

	data->wm831x = wm831x;
	data->current_brightness = 0;
	data->isink_reg = isink_reg;

	memset(&props, 0, sizeof(props));
	props.type = BACKLIGHT_RAW;
	props.max_brightness = max_isel;
	bl = devm_backlight_device_register(&pdev->dev, "wm831x", &pdev->dev,
					data, &wm831x_backlight_ops, &props);
	if (IS_ERR(bl)) {
		dev_err(&pdev->dev, "failed to register backlight\n");
		return PTR_ERR(bl);
	}

	bl->props.brightness = max_isel;

	platform_set_drvdata(pdev, bl);

	/* Disable the DCDC if it was started so we can bootstrap */
	wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);

	backlight_update_status(bl);

	return 0;
}

static struct platform_driver wm831x_backlight_driver = {
	.driver		= {
		.name	= "wm831x-backlight",
	},
	.probe		= wm831x_backlight_probe,
};

module_platform_driver(wm831x_backlight_driver);

MODULE_DESCRIPTION("Backlight Driver for WM831x PMICs");
MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:wm831x-backlight");