tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Backlight driver for Pandora handheld.
3 * Pandora uses TWL4030 PWM0 -> TPS61161 combo for control backlight.
4 * Based on pwm_bl.c
5 *
6 * Copyright 2009,2012 Gražvydas Ignotas <notasas@gmail.com>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13#include <linux/module.h>
14#include <linux/kernel.h>
15#include <linux/platform_device.h>
16#include <linux/delay.h>
17#include <linux/fb.h>
18#include <linux/backlight.h>
19#include <linux/i2c/twl.h>
20#include <linux/err.h>
21
22#define TWL_PWM0_ON 0x00
23#define TWL_PWM0_OFF 0x01
24
25#define TWL_INTBR_GPBR1 0x0c
26#define TWL_INTBR_PMBR1 0x0d
27
28#define TWL_PMBR1_PWM0_MUXMASK 0x0c
29#define TWL_PMBR1_PWM0 0x04
30#define PWM0_CLK_ENABLE BIT(0)
31#define PWM0_ENABLE BIT(2)
32
33/* range accepted by hardware */
34#define MIN_VALUE 9
35#define MAX_VALUE 63
36#define MAX_USER_VALUE (MAX_VALUE - MIN_VALUE)
37
38#define PANDORABL_WAS_OFF BL_CORE_DRIVER1
39
40static int pandora_backlight_update_status(struct backlight_device *bl)
41{
42 int brightness = bl->props.brightness;
43 u8 r;
44
45 if (bl->props.power != FB_BLANK_UNBLANK)
46 brightness = 0;
47 if (bl->props.state & BL_CORE_FBBLANK)
48 brightness = 0;
49 if (bl->props.state & BL_CORE_SUSPENDED)
50 brightness = 0;
51
52 if ((unsigned int)brightness > MAX_USER_VALUE)
53 brightness = MAX_USER_VALUE;
54
55 if (brightness == 0) {
56 if (bl->props.state & PANDORABL_WAS_OFF)
57 goto done;
58
59 /* first disable PWM0 output, then clock */
60 twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
61 r &= ~PWM0_ENABLE;
62 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
63 r &= ~PWM0_CLK_ENABLE;
64 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
65
66 goto done;
67 }
68
69 if (bl->props.state & PANDORABL_WAS_OFF) {
70 /*
71 * set PWM duty cycle to max. TPS61161 seems to use this
72 * to calibrate it's PWM sensitivity when it starts.
73 */
74 twl_i2c_write_u8(TWL4030_MODULE_PWM0, MAX_VALUE,
75 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(TWL4030_MODULE_PWM0, MIN_VALUE + brightness,
94 TWL_PWM0_OFF);
95
96done:
97 if (brightness != 0)
98 bl->props.state &= ~PANDORABL_WAS_OFF;
99 else
100 bl->props.state |= PANDORABL_WAS_OFF;
101
102 return 0;
103}
104
105static int pandora_backlight_get_brightness(struct backlight_device *bl)
106{
107 return bl->props.brightness;
108}
109
110static const struct backlight_ops pandora_backlight_ops = {
111 .options = BL_CORE_SUSPENDRESUME,
112 .update_status = pandora_backlight_update_status,
113 .get_brightness = pandora_backlight_get_brightness,
114};
115
116static int pandora_backlight_probe(struct platform_device *pdev)
117{
118 struct backlight_properties props;
119 struct backlight_device *bl;
120 u8 r;
121
122 memset(&props, 0, sizeof(props));
123 props.max_brightness = MAX_USER_VALUE;
124 props.type = BACKLIGHT_RAW;
125 bl = backlight_device_register(pdev->name, &pdev->dev,
126 NULL, &pandora_backlight_ops, &props);
127 if (IS_ERR(bl)) {
128 dev_err(&pdev->dev, "failed to register backlight\n");
129 return PTR_ERR(bl);
130 }
131
132 platform_set_drvdata(pdev, bl);
133
134 /* 64 cycle period, ON position 0 */
135 twl_i2c_write_u8(TWL4030_MODULE_PWM0, 0x80, TWL_PWM0_ON);
136
137 bl->props.state |= PANDORABL_WAS_OFF;
138 bl->props.brightness = MAX_USER_VALUE;
139 backlight_update_status(bl);
140
141 /* enable PWM function in pin mux */
142 twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_PMBR1);
143 r &= ~TWL_PMBR1_PWM0_MUXMASK;
144 r |= TWL_PMBR1_PWM0;
145 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_PMBR1);
146
147 return 0;
148}
149
150static int pandora_backlight_remove(struct platform_device *pdev)
151{
152 struct backlight_device *bl = platform_get_drvdata(pdev);
153 backlight_device_unregister(bl);
154 return 0;
155}
156
157static struct platform_driver pandora_backlight_driver = {
158 .driver = {
159 .name = "pandora-backlight",
160 .owner = THIS_MODULE,
161 },
162 .probe = pandora_backlight_probe,
163 .remove = pandora_backlight_remove,
164};
165
166module_platform_driver(pandora_backlight_driver);
167
168MODULE_AUTHOR("Gražvydas Ignotas <notasas@gmail.com>");
169MODULE_DESCRIPTION("Pandora Backlight Driver");
170MODULE_LICENSE("GPL");
171MODULE_ALIAS("platform:pandora-backlight");