1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Backlight driver for Pandora handheld.
4 * Pandora uses TWL4030 PWM0 -> TPS61161 combo for control backlight.
5 * Based on pwm_bl.c
6 *
7 * Copyright 2009,2012 Gra��vydas Ignotas <notasas@gmail.com>
8 */
9
10#include <linux/module.h>
11#include <linux/kernel.h>
12#include <linux/platform_device.h>
13#include <linux/delay.h>
14#include <linux/fb.h>
15#include <linux/backlight.h>
16#include <linux/mfd/twl.h>
17#include <linux/err.h>
18
19#define TWL_PWM0_ON		0x00
20#define TWL_PWM0_OFF		0x01
21
22#define TWL_INTBR_GPBR1		0x0c
23#define TWL_INTBR_PMBR1		0x0d
24
25#define TWL_PMBR1_PWM0_MUXMASK	0x0c
26#define TWL_PMBR1_PWM0		0x04
27#define PWM0_CLK_ENABLE		BIT(0)
28#define PWM0_ENABLE		BIT(2)
29
30/* range accepted by hardware */
31#define MIN_VALUE 9
32#define MAX_VALUE 63
33#define MAX_USER_VALUE (MAX_VALUE - MIN_VALUE)
34
35struct pandora_private {
36	unsigned old_state;
37#define PANDORABL_WAS_OFF 1
38};
39
40static int pandora_backlight_update_status(struct backlight_device *bl)
41{
42	int brightness = bl->props.brightness;
43	struct pandora_private *priv = bl_get_data(bl);
44	u8 r;
45
46	if (bl->props.power != FB_BLANK_UNBLANK)
47		brightness = 0;
48	if (bl->props.state & BL_CORE_FBBLANK)
49		brightness = 0;
50	if (bl->props.state & BL_CORE_SUSPENDED)
51		brightness = 0;
52
53	if ((unsigned int)brightness > MAX_USER_VALUE)
54		brightness = MAX_USER_VALUE;
55
56	if (brightness == 0) {
57		if (priv->old_state == PANDORABL_WAS_OFF)
58			goto done;
59
60		/* first disable PWM0 output, then clock */
61		twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
62		r &= ~PWM0_ENABLE;
63		twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
64		r &= ~PWM0_CLK_ENABLE;
65		twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
66
67		goto done;
68	}
69
70	if (priv->old_state == PANDORABL_WAS_OFF) {
71		/*
72		 * set PWM duty cycle to max. TPS61161 seems to use this
73		 * to calibrate it's PWM sensitivity when it starts.
74		 */
75		twl_i2c_write_u8(TWL_MODULE_PWM, MAX_VALUE, TWL_PWM0_OFF);
76
77		/* first enable clock, then PWM0 out */
78		twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
79		r &= ~PWM0_ENABLE;
80		r |= PWM0_CLK_ENABLE;
81		twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
82		r |= PWM0_ENABLE;
83		twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
84
85		/*
86		 * TI made it very easy to enable digital control, so easy that
87		 * it often triggers unintentionally and disabes PWM control,
88		 * so wait until 1 wire mode detection window ends.
89		 */
90		usleep_range(2000, 10000);
91	}
92
93	twl_i2c_write_u8(TWL_MODULE_PWM, MIN_VALUE + brightness, TWL_PWM0_OFF);
94
95done:
96	if (brightness != 0)
97		priv->old_state = 0;
98	else
99		priv->old_state = PANDORABL_WAS_OFF;
100
101	return 0;
102}
103
104static const struct backlight_ops pandora_backlight_ops = {
105	.options	= BL_CORE_SUSPENDRESUME,
106	.update_status	= pandora_backlight_update_status,
107};
108
109static int pandora_backlight_probe(struct platform_device *pdev)
110{
111	struct backlight_properties props;
112	struct backlight_device *bl;
113	struct pandora_private *priv;
114	u8 r;
115
116	priv = devm_kmalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
117	if (!priv)
118		return -ENOMEM;
119
120	memset(&props, 0, sizeof(props));
121	props.max_brightness = MAX_USER_VALUE;
122	props.type = BACKLIGHT_RAW;
123	bl = devm_backlight_device_register(&pdev->dev, pdev->name, &pdev->dev,
124					priv, &pandora_backlight_ops, &props);
125	if (IS_ERR(bl)) {
126		dev_err(&pdev->dev, "failed to register backlight\n");
127		return PTR_ERR(bl);
128	}
129
130	platform_set_drvdata(pdev, bl);
131
132	/* 64 cycle period, ON position 0 */
133	twl_i2c_write_u8(TWL_MODULE_PWM, 0x80, TWL_PWM0_ON);
134
135	priv->old_state = PANDORABL_WAS_OFF;
136	bl->props.brightness = MAX_USER_VALUE;
137	backlight_update_status(bl);
138
139	/* enable PWM function in pin mux */
140	twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_PMBR1);
141	r &= ~TWL_PMBR1_PWM0_MUXMASK;
142	r |= TWL_PMBR1_PWM0;
143	twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_PMBR1);
144
145	return 0;
146}
147
148static struct platform_driver pandora_backlight_driver = {
149	.driver		= {
150		.name	= "pandora-backlight",
151	},
152	.probe		= pandora_backlight_probe,
153};
154
155module_platform_driver(pandora_backlight_driver);
156
157MODULE_AUTHOR("Gra��vydas Ignotas <notasas@gmail.com>");
158MODULE_DESCRIPTION("Pandora Backlight Driver");
159MODULE_LICENSE("GPL");
160MODULE_ALIAS("platform:pandora-backlight");
161