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/fb.h>
13#include <linux/backlight.h>
14#include <linux/slab.h>
15
16#include <linux/mfd/wm831x/core.h>
17#include <linux/mfd/wm831x/pdata.h>
18#include <linux/mfd/wm831x/regulator.h>
19
20struct wm831x_backlight_data {
21	struct wm831x *wm831x;
22	int isink_reg;
23	int current_brightness;
24};
25
26static int wm831x_backlight_set(struct backlight_device *bl, int brightness)
27{
28	struct wm831x_backlight_data *data = bl_get_data(bl);
29	struct wm831x *wm831x = data->wm831x;
30	int power_up = !data->current_brightness && brightness;
31	int power_down = data->current_brightness && !brightness;
32	int ret;
33
34	if (power_up) {
35		/* Enable the ISINK */
36		ret = wm831x_set_bits(wm831x, data->isink_reg,
37				      WM831X_CS1_ENA, WM831X_CS1_ENA);
38		if (ret < 0)
39			goto err;
40
41		/* Enable the DC-DC */
42		ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE,
43				      WM831X_DC4_ENA, WM831X_DC4_ENA);
44		if (ret < 0)
45			goto err;
46	}
47
48	if (power_down) {
49		/* DCDC first */
50		ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE,
51				      WM831X_DC4_ENA, 0);
52		if (ret < 0)
53			goto err;
54
55		/* ISINK */
56		ret = wm831x_set_bits(wm831x, data->isink_reg,
57				      WM831X_CS1_DRIVE | WM831X_CS1_ENA, 0);
58		if (ret < 0)
59			goto err;
60	}
61
62	/* Set the new brightness */
63	ret = wm831x_set_bits(wm831x, data->isink_reg,
64			      WM831X_CS1_ISEL_MASK, brightness);
65	if (ret < 0)
66		goto err;
67
68	if (power_up) {
69		/* Drive current through the ISINK */
70		ret = wm831x_set_bits(wm831x, data->isink_reg,
71				      WM831X_CS1_DRIVE, WM831X_CS1_DRIVE);
72		if (ret < 0)
73			return ret;
74	}
75
76	data->current_brightness = brightness;
77
78	return 0;
79
80err:
81	/* If we were in the middle of a power transition always shut down
82	 * for safety.
83	 */
84	if (power_up || power_down) {
85		wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);
86		wm831x_set_bits(wm831x, data->isink_reg, WM831X_CS1_ENA, 0);
87	}
88
89	return ret;
90}
91
92static int wm831x_backlight_update_status(struct backlight_device *bl)
93{
94	return wm831x_backlight_set(bl, backlight_get_brightness(bl));
95}
96
97static int wm831x_backlight_get_brightness(struct backlight_device *bl)
98{
99	struct wm831x_backlight_data *data = bl_get_data(bl);
100
101	return data->current_brightness;
102}
103
104static const struct backlight_ops wm831x_backlight_ops = {
105	.options = BL_CORE_SUSPENDRESUME,
106	.update_status	= wm831x_backlight_update_status,
107	.get_brightness	= wm831x_backlight_get_brightness,
108};
109
110static int wm831x_backlight_probe(struct platform_device *pdev)
111{
112	struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
113	struct wm831x_pdata *wm831x_pdata = dev_get_platdata(pdev->dev.parent);
114	struct wm831x_backlight_pdata *pdata;
115	struct wm831x_backlight_data *data;
116	struct backlight_device *bl;
117	struct backlight_properties props;
118	int ret, i, max_isel, isink_reg, dcdc_cfg;
119
120	/* We need platform data */
121	if (wm831x_pdata)
122		pdata = wm831x_pdata->backlight;
123	else
124		pdata = NULL;
125
126	if (!pdata) {
127		dev_err(&pdev->dev, "No platform data supplied\n");
128		return -EINVAL;
129	}
130
131	/* Figure out the maximum current we can use */
132	for (i = 0; i < WM831X_ISINK_MAX_ISEL; i++) {
133		if (wm831x_isinkv_values[i] > pdata->max_uA)
134			break;
135	}
136
137	if (i == 0) {
138		dev_err(&pdev->dev, "Invalid max_uA: %duA\n", pdata->max_uA);
139		return -EINVAL;
140	}
141	max_isel = i - 1;
142
143	if (pdata->max_uA != wm831x_isinkv_values[max_isel])
144		dev_warn(&pdev->dev,
145			 "Maximum current is %duA not %duA as requested\n",
146			 wm831x_isinkv_values[max_isel], pdata->max_uA);
147
148	switch (pdata->isink) {
149	case 1:
150		isink_reg = WM831X_CURRENT_SINK_1;
151		dcdc_cfg = 0;
152		break;
153	case 2:
154		isink_reg = WM831X_CURRENT_SINK_2;
155		dcdc_cfg = WM831X_DC4_FBSRC;
156		break;
157	default:
158		dev_err(&pdev->dev, "Invalid ISINK %d\n", pdata->isink);
159		return -EINVAL;
160	}
161
162	/* Configure the ISINK to use for feedback */
163	ret = wm831x_reg_unlock(wm831x);
164	if (ret < 0)
165		return ret;
166
167	ret = wm831x_set_bits(wm831x, WM831X_DC4_CONTROL, WM831X_DC4_FBSRC,
168			      dcdc_cfg);
169
170	wm831x_reg_lock(wm831x);
171	if (ret < 0)
172		return ret;
173
174	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
175	if (data == NULL)
176		return -ENOMEM;
177
178	data->wm831x = wm831x;
179	data->current_brightness = 0;
180	data->isink_reg = isink_reg;
181
182	memset(&props, 0, sizeof(props));
183	props.type = BACKLIGHT_RAW;
184	props.max_brightness = max_isel;
185	bl = devm_backlight_device_register(&pdev->dev, "wm831x", &pdev->dev,
186					data, &wm831x_backlight_ops, &props);
187	if (IS_ERR(bl)) {
188		dev_err(&pdev->dev, "failed to register backlight\n");
189		return PTR_ERR(bl);
190	}
191
192	bl->props.brightness = max_isel;
193
194	platform_set_drvdata(pdev, bl);
195
196	/* Disable the DCDC if it was started so we can bootstrap */
197	wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);
198
199	backlight_update_status(bl);
200
201	return 0;
202}
203
204static struct platform_driver wm831x_backlight_driver = {
205	.driver		= {
206		.name	= "wm831x-backlight",
207	},
208	.probe		= wm831x_backlight_probe,
209};
210
211module_platform_driver(wm831x_backlight_driver);
212
213MODULE_DESCRIPTION("Backlight Driver for WM831x PMICs");
214MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com");
215MODULE_LICENSE("GPL");
216MODULE_ALIAS("platform:wm831x-backlight");
217