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 | |
35 | struct pandora_private { |
36 | unsigned old_state; |
37 | #define PANDORABL_WAS_OFF 1 |
38 | }; |
39 | |
40 | static 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 | |
95 | done: |
96 | if (brightness != 0) |
97 | priv->old_state = 0; |
98 | else |
99 | priv->old_state = PANDORABL_WAS_OFF; |
100 | |
101 | return 0; |
102 | } |
103 | |
104 | static const struct backlight_ops pandora_backlight_ops = { |
105 | .options = BL_CORE_SUSPENDRESUME, |
106 | .update_status = pandora_backlight_update_status, |
107 | }; |
108 | |
109 | static 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 | |
148 | static struct platform_driver pandora_backlight_driver = { |
149 | .driver = { |
150 | .name = "pandora-backlight" , |
151 | }, |
152 | .probe = pandora_backlight_probe, |
153 | }; |
154 | |
155 | module_platform_driver(pandora_backlight_driver); |
156 | |
157 | MODULE_AUTHOR("Gražvydas Ignotas <notasas@gmail.com>" ); |
158 | MODULE_DESCRIPTION("Pandora Backlight Driver" ); |
159 | MODULE_LICENSE("GPL" ); |
160 | MODULE_ALIAS("platform:pandora-backlight" ); |
161 | |