1/*
2 * Backlight driver for Wolfson Microelectronics WM831x PMICs
3 *
4 * Copyright 2009 Wolfson Microelectonics plc
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10
11#include <linux/kernel.h>
12#include <linux/init.h>
13#include <linux/platform_device.h>
14#include <linux/module.h>
15#include <linux/fb.h>
16#include <linux/backlight.h>
17#include <linux/slab.h>
18
19#include <linux/mfd/wm831x/core.h>
20#include <linux/mfd/wm831x/pdata.h>
21#include <linux/mfd/wm831x/regulator.h>
22
23struct wm831x_backlight_data {
24	struct wm831x *wm831x;
25	int isink_reg;
26	int current_brightness;
27};
28
29static int wm831x_backlight_set(struct backlight_device *bl, int brightness)
30{
31	struct wm831x_backlight_data *data = bl_get_data(bl);
32	struct wm831x *wm831x = data->wm831x;
33	int power_up = !data->current_brightness && brightness;
34	int power_down = data->current_brightness && !brightness;
35	int ret;
36
37	if (power_up) {
38		/* Enable the ISINK */
39		ret = wm831x_set_bits(wm831x, data->isink_reg,
40				      WM831X_CS1_ENA, WM831X_CS1_ENA);
41		if (ret < 0)
42			goto err;
43
44		/* Enable the DC-DC */
45		ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE,
46				      WM831X_DC4_ENA, WM831X_DC4_ENA);
47		if (ret < 0)
48			goto err;
49	}
50
51	if (power_down) {
52		/* DCDC first */
53		ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE,
54				      WM831X_DC4_ENA, 0);
55		if (ret < 0)
56			goto err;
57
58		/* ISINK */
59		ret = wm831x_set_bits(wm831x, data->isink_reg,
60				      WM831X_CS1_DRIVE | WM831X_CS1_ENA, 0);
61		if (ret < 0)
62			goto err;
63	}
64
65	/* Set the new brightness */
66	ret = wm831x_set_bits(wm831x, data->isink_reg,
67			      WM831X_CS1_ISEL_MASK, brightness);
68	if (ret < 0)
69		goto err;
70
71	if (power_up) {
72		/* Drive current through the ISINK */
73		ret = wm831x_set_bits(wm831x, data->isink_reg,
74				      WM831X_CS1_DRIVE, WM831X_CS1_DRIVE);
75		if (ret < 0)
76			return ret;
77	}
78
79	data->current_brightness = brightness;
80
81	return 0;
82
83err:
84	/* If we were in the middle of a power transition always shut down
85	 * for safety.
86	 */
87	if (power_up || power_down) {
88		wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);
89		wm831x_set_bits(wm831x, data->isink_reg, WM831X_CS1_ENA, 0);
90	}
91
92	return ret;
93}
94
95static int wm831x_backlight_update_status(struct backlight_device *bl)
96{
97	int brightness = bl->props.brightness;
98
99	if (bl->props.power != FB_BLANK_UNBLANK)
100		brightness = 0;
101
102	if (bl->props.fb_blank != FB_BLANK_UNBLANK)
103		brightness = 0;
104
105	if (bl->props.state & BL_CORE_SUSPENDED)
106		brightness = 0;
107
108	return wm831x_backlight_set(bl, brightness);
109}
110
111static int wm831x_backlight_get_brightness(struct backlight_device *bl)
112{
113	struct wm831x_backlight_data *data = bl_get_data(bl);
114
115	return data->current_brightness;
116}
117
118static const struct backlight_ops wm831x_backlight_ops = {
119	.options = BL_CORE_SUSPENDRESUME,
120	.update_status	= wm831x_backlight_update_status,
121	.get_brightness	= wm831x_backlight_get_brightness,
122};
123
124static int wm831x_backlight_probe(struct platform_device *pdev)
125{
126	struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
127	struct wm831x_pdata *wm831x_pdata = dev_get_platdata(pdev->dev.parent);
128	struct wm831x_backlight_pdata *pdata;
129	struct wm831x_backlight_data *data;
130	struct backlight_device *bl;
131	struct backlight_properties props;
132	int ret, i, max_isel, isink_reg, dcdc_cfg;
133
134	/* We need platform data */
135	if (wm831x_pdata)
136		pdata = wm831x_pdata->backlight;
137	else
138		pdata = NULL;
139
140	if (!pdata) {
141		dev_err(&pdev->dev, "No platform data supplied\n");
142		return -EINVAL;
143	}
144
145	/* Figure out the maximum current we can use */
146	for (i = 0; i < WM831X_ISINK_MAX_ISEL; i++) {
147		if (wm831x_isinkv_values[i] > pdata->max_uA)
148			break;
149	}
150
151	if (i == 0) {
152		dev_err(&pdev->dev, "Invalid max_uA: %duA\n", pdata->max_uA);
153		return -EINVAL;
154	}
155	max_isel = i - 1;
156
157	if (pdata->max_uA != wm831x_isinkv_values[max_isel])
158		dev_warn(&pdev->dev,
159			 "Maximum current is %duA not %duA as requested\n",
160			 wm831x_isinkv_values[max_isel], pdata->max_uA);
161
162	switch (pdata->isink) {
163	case 1:
164		isink_reg = WM831X_CURRENT_SINK_1;
165		dcdc_cfg = 0;
166		break;
167	case 2:
168		isink_reg = WM831X_CURRENT_SINK_2;
169		dcdc_cfg = WM831X_DC4_FBSRC;
170		break;
171	default:
172		dev_err(&pdev->dev, "Invalid ISINK %d\n", pdata->isink);
173		return -EINVAL;
174	}
175
176	/* Configure the ISINK to use for feedback */
177	ret = wm831x_reg_unlock(wm831x);
178	if (ret < 0)
179		return ret;
180
181	ret = wm831x_set_bits(wm831x, WM831X_DC4_CONTROL, WM831X_DC4_FBSRC,
182			      dcdc_cfg);
183
184	wm831x_reg_lock(wm831x);
185	if (ret < 0)
186		return ret;
187
188	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
189	if (data == NULL)
190		return -ENOMEM;
191
192	data->wm831x = wm831x;
193	data->current_brightness = 0;
194	data->isink_reg = isink_reg;
195
196	memset(&props, 0, sizeof(props));
197	props.type = BACKLIGHT_RAW;
198	props.max_brightness = max_isel;
199	bl = devm_backlight_device_register(&pdev->dev, "wm831x", &pdev->dev,
200					data, &wm831x_backlight_ops, &props);
201	if (IS_ERR(bl)) {
202		dev_err(&pdev->dev, "failed to register backlight\n");
203		return PTR_ERR(bl);
204	}
205
206	bl->props.brightness = max_isel;
207
208	platform_set_drvdata(pdev, bl);
209
210	/* Disable the DCDC if it was started so we can bootstrap */
211	wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);
212
213	backlight_update_status(bl);
214
215	return 0;
216}
217
218static struct platform_driver wm831x_backlight_driver = {
219	.driver		= {
220		.name	= "wm831x-backlight",
221	},
222	.probe		= wm831x_backlight_probe,
223};
224
225module_platform_driver(wm831x_backlight_driver);
226
227MODULE_DESCRIPTION("Backlight Driver for WM831x PMICs");
228MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com");
229MODULE_LICENSE("GPL");
230MODULE_ALIAS("platform:wm831x-backlight");
231