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/backlight.h>
15 #include <linux/mfd/twl.h>
16 #include <linux/err.h>
17
18 #define TWL_PWM0_ON 0x00
19 #define TWL_PWM0_OFF 0x01
20
21 #define TWL_INTBR_GPBR1 0x0c
22 #define TWL_INTBR_PMBR1 0x0d
23
24 #define TWL_PMBR1_PWM0_MUXMASK 0x0c
25 #define TWL_PMBR1_PWM0 0x04
26 #define PWM0_CLK_ENABLE BIT(0)
27 #define PWM0_ENABLE BIT(2)
28
29 /* range accepted by hardware */
30 #define MIN_VALUE 9
31 #define MAX_VALUE 63
32 #define MAX_USER_VALUE (MAX_VALUE - MIN_VALUE)
33
34 struct pandora_private {
35 unsigned old_state;
36 #define PANDORABL_WAS_OFF 1
37 };
38
pandora_backlight_update_status(struct backlight_device * bl)39 static int pandora_backlight_update_status(struct backlight_device *bl)
40 {
41 int brightness = bl->props.brightness;
42 struct pandora_private *priv = bl_get_data(bl);
43 u8 r;
44
45 if (bl->props.power != BACKLIGHT_POWER_ON)
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 (priv->old_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 (priv->old_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(TWL_MODULE_PWM, MAX_VALUE, TWL_PWM0_OFF);
75
76 /* first enable clock, then PWM0 out */
77 twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
78 r &= ~PWM0_ENABLE;
79 r |= PWM0_CLK_ENABLE;
80 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
81 r |= PWM0_ENABLE;
82 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
83
84 /*
85 * TI made it very easy to enable digital control, so easy that
86 * it often triggers unintentionally and disabes PWM control,
87 * so wait until 1 wire mode detection window ends.
88 */
89 usleep_range(2000, 10000);
90 }
91
92 twl_i2c_write_u8(TWL_MODULE_PWM, MIN_VALUE + brightness, TWL_PWM0_OFF);
93
94 done:
95 if (brightness != 0)
96 priv->old_state = 0;
97 else
98 priv->old_state = PANDORABL_WAS_OFF;
99
100 return 0;
101 }
102
103 static const struct backlight_ops pandora_backlight_ops = {
104 .options = BL_CORE_SUSPENDRESUME,
105 .update_status = pandora_backlight_update_status,
106 };
107
pandora_backlight_probe(struct platform_device * pdev)108 static int pandora_backlight_probe(struct platform_device *pdev)
109 {
110 struct backlight_properties props;
111 struct backlight_device *bl;
112 struct pandora_private *priv;
113 u8 r;
114
115 priv = devm_kmalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
116 if (!priv)
117 return -ENOMEM;
118
119 memset(&props, 0, sizeof(props));
120 props.max_brightness = MAX_USER_VALUE;
121 props.type = BACKLIGHT_RAW;
122 bl = devm_backlight_device_register(&pdev->dev, pdev->name, &pdev->dev,
123 priv, &pandora_backlight_ops, &props);
124 if (IS_ERR(bl)) {
125 dev_err(&pdev->dev, "failed to register backlight\n");
126 return PTR_ERR(bl);
127 }
128
129 platform_set_drvdata(pdev, bl);
130
131 /* 64 cycle period, ON position 0 */
132 twl_i2c_write_u8(TWL_MODULE_PWM, 0x80, TWL_PWM0_ON);
133
134 priv->old_state = PANDORABL_WAS_OFF;
135 bl->props.brightness = MAX_USER_VALUE;
136 backlight_update_status(bl);
137
138 /* enable PWM function in pin mux */
139 twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_PMBR1);
140 r &= ~TWL_PMBR1_PWM0_MUXMASK;
141 r |= TWL_PMBR1_PWM0;
142 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_PMBR1);
143
144 return 0;
145 }
146
147 static struct platform_driver pandora_backlight_driver = {
148 .driver = {
149 .name = "pandora-backlight",
150 },
151 .probe = pandora_backlight_probe,
152 };
153
154 module_platform_driver(pandora_backlight_driver);
155
156 MODULE_AUTHOR("Gražvydas Ignotas <notasas@gmail.com>");
157 MODULE_DESCRIPTION("Pandora Backlight Driver");
158 MODULE_LICENSE("GPL");
159 MODULE_ALIAS("platform:pandora-backlight");
160