wm831x_bl.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Backlight driver for Wolfson Microelectronics WM831x PMICs
  4 *
  5 * Copyright 2009 Wolfson Microelectonics plc
  6 */
  7
  8#include <linux/kernel.h>
  9#include <linux/init.h>
 10#include <linux/platform_device.h>
 11#include <linux/module.h>
 12#include <linux/backlight.h>
 13#include <linux/slab.h>
 14
 15#include <linux/mfd/wm831x/core.h>
 16#include <linux/mfd/wm831x/pdata.h>
 17#include <linux/mfd/wm831x/regulator.h>
 18
 19struct wm831x_backlight_data {
 20	struct wm831x *wm831x;
 21	int isink_reg;
 22	int current_brightness;
 23};
 24
 25static int wm831x_backlight_set(struct backlight_device *bl, int brightness)
 26{
 27	struct wm831x_backlight_data *data = bl_get_data(bl);
 28	struct wm831x *wm831x = data->wm831x;
 29	int power_up = !data->current_brightness && brightness;
 30	int power_down = data->current_brightness && !brightness;
 31	int ret;
 32
 33	if (power_up) {
 34		/* Enable the ISINK */
 35		ret = wm831x_set_bits(wm831x, data->isink_reg,
 36				      WM831X_CS1_ENA, WM831X_CS1_ENA);
 37		if (ret < 0)
 38			goto err;
 39
 40		/* Enable the DC-DC */
 41		ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE,
 42				      WM831X_DC4_ENA, WM831X_DC4_ENA);
 43		if (ret < 0)
 44			goto err;
 45	}
 46
 47	if (power_down) {
 48		/* DCDC first */
 49		ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE,
 50				      WM831X_DC4_ENA, 0);
 51		if (ret < 0)
 52			goto err;
 53
 54		/* ISINK */
 55		ret = wm831x_set_bits(wm831x, data->isink_reg,
 56				      WM831X_CS1_DRIVE | WM831X_CS1_ENA, 0);
 57		if (ret < 0)
 58			goto err;
 59	}
 60
 61	/* Set the new brightness */
 62	ret = wm831x_set_bits(wm831x, data->isink_reg,
 63			      WM831X_CS1_ISEL_MASK, brightness);
 64	if (ret < 0)
 65		goto err;
 66
 67	if (power_up) {
 68		/* Drive current through the ISINK */
 69		ret = wm831x_set_bits(wm831x, data->isink_reg,
 70				      WM831X_CS1_DRIVE, WM831X_CS1_DRIVE);
 71		if (ret < 0)
 72			return ret;
 73	}
 74
 75	data->current_brightness = brightness;
 76
 77	return 0;
 78
 79err:
 80	/* If we were in the middle of a power transition always shut down
 81	 * for safety.
 82	 */
 83	if (power_up || power_down) {
 84		wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);
 85		wm831x_set_bits(wm831x, data->isink_reg, WM831X_CS1_ENA, 0);
 86	}
 87
 88	return ret;
 89}
 90
 91static int wm831x_backlight_update_status(struct backlight_device *bl)
 92{
 93	return wm831x_backlight_set(bl, backlight_get_brightness(bl));
 94}
 95
 96static int wm831x_backlight_get_brightness(struct backlight_device *bl)
 97{
 98	struct wm831x_backlight_data *data = bl_get_data(bl);
 99
100	return data->current_brightness;
101}
102
103static const struct backlight_ops wm831x_backlight_ops = {
104	.options = BL_CORE_SUSPENDRESUME,
105	.update_status	= wm831x_backlight_update_status,
106	.get_brightness	= wm831x_backlight_get_brightness,
107};
108
109static int wm831x_backlight_probe(struct platform_device *pdev)
110{
111	struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
112	struct wm831x_pdata *wm831x_pdata = dev_get_platdata(pdev->dev.parent);
113	struct wm831x_backlight_pdata *pdata;
114	struct wm831x_backlight_data *data;
115	struct backlight_device *bl;
116	struct backlight_properties props;
117	int ret, i, max_isel, isink_reg, dcdc_cfg;
118
119	/* We need platform data */
120	if (wm831x_pdata)
121		pdata = wm831x_pdata->backlight;
122	else
123		pdata = NULL;
124
125	if (!pdata) {
126		dev_err(&pdev->dev, "No platform data supplied\n");
127		return -EINVAL;
128	}
129
130	/* Figure out the maximum current we can use */
131	for (i = 0; i < WM831X_ISINK_MAX_ISEL; i++) {
132		if (wm831x_isinkv_values[i] > pdata->max_uA)
133			break;
134	}
135
136	if (i == 0) {
137		dev_err(&pdev->dev, "Invalid max_uA: %duA\n", pdata->max_uA);
138		return -EINVAL;
139	}
140	max_isel = i - 1;
141
142	if (pdata->max_uA != wm831x_isinkv_values[max_isel])
143		dev_warn(&pdev->dev,
144			 "Maximum current is %duA not %duA as requested\n",
145			 wm831x_isinkv_values[max_isel], pdata->max_uA);
146
147	switch (pdata->isink) {
148	case 1:
149		isink_reg = WM831X_CURRENT_SINK_1;
150		dcdc_cfg = 0;
151		break;
152	case 2:
153		isink_reg = WM831X_CURRENT_SINK_2;
154		dcdc_cfg = WM831X_DC4_FBSRC;
155		break;
156	default:
157		dev_err(&pdev->dev, "Invalid ISINK %d\n", pdata->isink);
158		return -EINVAL;
159	}
160
161	/* Configure the ISINK to use for feedback */
162	ret = wm831x_reg_unlock(wm831x);
163	if (ret < 0)
164		return ret;
165
166	ret = wm831x_set_bits(wm831x, WM831X_DC4_CONTROL, WM831X_DC4_FBSRC,
167			      dcdc_cfg);
168
169	wm831x_reg_lock(wm831x);
170	if (ret < 0)
171		return ret;
172
173	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
174	if (data == NULL)
175		return -ENOMEM;
176
177	data->wm831x = wm831x;
178	data->current_brightness = 0;
179	data->isink_reg = isink_reg;
180
181	memset(&props, 0, sizeof(props));
182	props.type = BACKLIGHT_RAW;
183	props.max_brightness = max_isel;
184	bl = devm_backlight_device_register(&pdev->dev, "wm831x", &pdev->dev,
185					data, &wm831x_backlight_ops, &props);
186	if (IS_ERR(bl)) {
187		dev_err(&pdev->dev, "failed to register backlight\n");
188		return PTR_ERR(bl);
189	}
190
191	bl->props.brightness = max_isel;
192
193	platform_set_drvdata(pdev, bl);
194
195	/* Disable the DCDC if it was started so we can bootstrap */
196	wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);
197
198	backlight_update_status(bl);
199
200	return 0;
201}
202
203static struct platform_driver wm831x_backlight_driver = {
204	.driver		= {
205		.name	= "wm831x-backlight",
206	},
207	.probe		= wm831x_backlight_probe,
208};
209
210module_platform_driver(wm831x_backlight_driver);
211
212MODULE_DESCRIPTION("Backlight Driver for WM831x PMICs");
213MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com");
214MODULE_LICENSE("GPL");
215MODULE_ALIAS("platform:wm831x-backlight");