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 Gražvydas 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_dev: 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(mod_no: TWL4030_MODULE_INTBR, val: &r, TWL_INTBR_GPBR1);
62 r &= ~PWM0_ENABLE;
63 twl_i2c_write_u8(mod_no: TWL4030_MODULE_INTBR, val: r, TWL_INTBR_GPBR1);
64 r &= ~PWM0_CLK_ENABLE;
65 twl_i2c_write_u8(mod_no: TWL4030_MODULE_INTBR, val: 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(mod_no: TWL_MODULE_PWM, MAX_VALUE, TWL_PWM0_OFF);
76
77 /* first enable clock, then PWM0 out */
78 twl_i2c_read_u8(mod_no: TWL4030_MODULE_INTBR, val: &r, TWL_INTBR_GPBR1);
79 r &= ~PWM0_ENABLE;
80 r |= PWM0_CLK_ENABLE;
81 twl_i2c_write_u8(mod_no: TWL4030_MODULE_INTBR, val: r, TWL_INTBR_GPBR1);
82 r |= PWM0_ENABLE;
83 twl_i2c_write_u8(mod_no: TWL4030_MODULE_INTBR, val: 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(min: 2000, max: 10000);
91 }
92
93 twl_i2c_write_u8(mod_no: 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(dev: &pdev->dev, size: 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(dev: &pdev->dev, name: pdev->name, parent: &pdev->dev,
124 devdata: priv, ops: &pandora_backlight_ops, props: &props);
125 if (IS_ERR(ptr: bl)) {
126 dev_err(&pdev->dev, "failed to register backlight\n");
127 return PTR_ERR(ptr: bl);
128 }
129
130 platform_set_drvdata(pdev, data: bl);
131
132 /* 64 cycle period, ON position 0 */
133 twl_i2c_write_u8(mod_no: TWL_MODULE_PWM, val: 0x80, TWL_PWM0_ON);
134
135 priv->old_state = PANDORABL_WAS_OFF;
136 bl->props.brightness = MAX_USER_VALUE;
137 backlight_update_status(bd: bl);
138
139 /* enable PWM function in pin mux */
140 twl_i2c_read_u8(mod_no: TWL4030_MODULE_INTBR, val: &r, TWL_INTBR_PMBR1);
141 r &= ~TWL_PMBR1_PWM0_MUXMASK;
142 r |= TWL_PMBR1_PWM0;
143 twl_i2c_write_u8(mod_no: TWL4030_MODULE_INTBR, val: 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("Gražvydas Ignotas <notasas@gmail.com>");
158MODULE_DESCRIPTION("Pandora Backlight Driver");
159MODULE_LICENSE("GPL");
160MODULE_ALIAS("platform:pandora-backlight");
161

source code of linux/drivers/video/backlight/pandora_bl.c