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c8df7428 CG |
1 | /* |
2 | * Copyright (C) 2012 Bachmann electronic GmbH | |
3 | * Christian Gmeiner <christian.gmeiner@gmail.com> | |
4 | * | |
5 | * Backlight driver for ot200 visualisation device from | |
6 | * Bachmann electronic GmbH. | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify it | |
9 | * under the terms of the GNU General Public License version 2 as published by | |
10 | * the Free Software Foundation. | |
11 | */ | |
12 | ||
13 | #include <linux/module.h> | |
14 | #include <linux/fb.h> | |
15 | #include <linux/backlight.h> | |
16 | #include <linux/gpio.h> | |
17 | #include <linux/cs5535.h> | |
18 | ||
19 | static struct cs5535_mfgpt_timer *pwm_timer; | |
20 | ||
21 | /* this array defines the mapping of brightness in % to pwm frequency */ | |
22 | static const u8 dim_table[101] = {0, 0, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, | |
23 | 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, | |
24 | 4, 5, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 9, 9, | |
25 | 10, 10, 11, 11, 12, 12, 13, 14, 15, 15, 16, | |
26 | 17, 18, 19, 20, 21, 22, 23, 24, 26, 27, 28, | |
27 | 30, 31, 33, 35, 37, 39, 41, 43, 45, 47, 50, | |
28 | 53, 55, 58, 61, 65, 68, 72, 75, 79, 84, 88, | |
29 | 93, 97, 103, 108, 114, 120, 126, 133, 140, | |
30 | 147, 155, 163}; | |
31 | ||
32 | struct ot200_backlight_data { | |
33 | int current_brightness; | |
34 | }; | |
35 | ||
36 | #define GPIO_DIMM 27 | |
37 | #define SCALE 1 | |
38 | #define CMP1MODE 0x2 /* compare on GE; output high on compare | |
39 | * greater than or equal */ | |
40 | #define PWM_SETUP (SCALE | CMP1MODE << 6 | MFGPT_SETUP_CNTEN) | |
41 | #define MAX_COMP2 163 | |
42 | ||
43 | static int ot200_backlight_update_status(struct backlight_device *bl) | |
44 | { | |
45 | struct ot200_backlight_data *data = bl_get_data(bl); | |
46 | int brightness = bl->props.brightness; | |
47 | ||
48 | if (bl->props.state & BL_CORE_FBBLANK) | |
49 | brightness = 0; | |
50 | ||
51 | /* enable or disable PWM timer */ | |
52 | if (brightness == 0) | |
53 | cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP, 0); | |
54 | else if (data->current_brightness == 0) { | |
55 | cs5535_mfgpt_write(pwm_timer, MFGPT_REG_COUNTER, 0); | |
56 | cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP, | |
57 | MFGPT_SETUP_CNTEN); | |
58 | } | |
59 | ||
60 | /* apply new brightness value */ | |
61 | cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP1, | |
62 | MAX_COMP2 - dim_table[brightness]); | |
63 | data->current_brightness = brightness; | |
64 | ||
65 | return 0; | |
66 | } | |
67 | ||
68 | static int ot200_backlight_get_brightness(struct backlight_device *bl) | |
69 | { | |
70 | struct ot200_backlight_data *data = bl_get_data(bl); | |
71 | return data->current_brightness; | |
72 | } | |
73 | ||
74 | static const struct backlight_ops ot200_backlight_ops = { | |
75 | .update_status = ot200_backlight_update_status, | |
76 | .get_brightness = ot200_backlight_get_brightness, | |
77 | }; | |
78 | ||
79 | static int ot200_backlight_probe(struct platform_device *pdev) | |
80 | { | |
81 | struct backlight_device *bl; | |
82 | struct ot200_backlight_data *data; | |
83 | struct backlight_properties props; | |
84 | int retval = 0; | |
85 | ||
86 | /* request gpio */ | |
87 | if (gpio_request(GPIO_DIMM, "ot200 backlight dimmer") < 0) { | |
88 | dev_err(&pdev->dev, "failed to request GPIO %d\n", GPIO_DIMM); | |
89 | return -ENODEV; | |
90 | } | |
91 | ||
92 | /* request timer */ | |
93 | pwm_timer = cs5535_mfgpt_alloc_timer(7, MFGPT_DOMAIN_ANY); | |
94 | if (!pwm_timer) { | |
95 | dev_err(&pdev->dev, "MFGPT 7 not available\n"); | |
96 | retval = -ENODEV; | |
97 | goto error_mfgpt_alloc; | |
98 | } | |
99 | ||
f1b60d46 | 100 | data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); |
c8df7428 CG |
101 | if (!data) { |
102 | retval = -ENOMEM; | |
f1b60d46 | 103 | goto error_devm_kzalloc; |
c8df7428 CG |
104 | } |
105 | ||
106 | /* setup gpio */ | |
107 | cs5535_gpio_set(GPIO_DIMM, GPIO_OUTPUT_ENABLE); | |
108 | cs5535_gpio_set(GPIO_DIMM, GPIO_OUTPUT_AUX1); | |
109 | ||
110 | /* setup timer */ | |
111 | cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP1, 0); | |
112 | cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP2, MAX_COMP2); | |
113 | cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP, PWM_SETUP); | |
114 | ||
115 | data->current_brightness = 100; | |
116 | props.max_brightness = 100; | |
117 | props.brightness = 100; | |
118 | props.type = BACKLIGHT_RAW; | |
119 | ||
120 | bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, data, | |
121 | &ot200_backlight_ops, &props); | |
122 | if (IS_ERR(bl)) { | |
123 | dev_err(&pdev->dev, "failed to register backlight\n"); | |
124 | retval = PTR_ERR(bl); | |
f1b60d46 | 125 | goto error_devm_kzalloc; |
c8df7428 CG |
126 | } |
127 | ||
128 | platform_set_drvdata(pdev, bl); | |
129 | ||
130 | return 0; | |
131 | ||
f1b60d46 | 132 | error_devm_kzalloc: |
c8df7428 CG |
133 | cs5535_mfgpt_free_timer(pwm_timer); |
134 | error_mfgpt_alloc: | |
135 | gpio_free(GPIO_DIMM); | |
136 | return retval; | |
137 | } | |
138 | ||
139 | static int ot200_backlight_remove(struct platform_device *pdev) | |
140 | { | |
141 | struct backlight_device *bl = platform_get_drvdata(pdev); | |
c8df7428 CG |
142 | |
143 | backlight_device_unregister(bl); | |
144 | ||
145 | /* on module unload set brightness to 100% */ | |
146 | cs5535_mfgpt_write(pwm_timer, MFGPT_REG_COUNTER, 0); | |
147 | cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN); | |
148 | cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP1, | |
149 | MAX_COMP2 - dim_table[100]); | |
150 | ||
151 | cs5535_mfgpt_free_timer(pwm_timer); | |
152 | gpio_free(GPIO_DIMM); | |
153 | ||
c8df7428 CG |
154 | return 0; |
155 | } | |
156 | ||
157 | static struct platform_driver ot200_backlight_driver = { | |
158 | .driver = { | |
159 | .name = "ot200-backlight", | |
160 | .owner = THIS_MODULE, | |
161 | }, | |
162 | .probe = ot200_backlight_probe, | |
163 | .remove = ot200_backlight_remove, | |
164 | }; | |
165 | ||
166 | module_platform_driver(ot200_backlight_driver); | |
167 | ||
168 | MODULE_DESCRIPTION("backlight driver for ot200 visualisation device"); | |
169 | MODULE_AUTHOR("Christian Gmeiner <christian.gmeiner@gmail.com>"); | |
170 | MODULE_LICENSE("GPL"); | |
171 | MODULE_ALIAS("platform:ot200-backlight"); |