Commit | Line | Data |
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3e074058 HCE |
1 | /* |
2 | * Copyright (C) 2008 Atmel Corporation | |
3 | * | |
4 | * Backlight driver using Atmel PWM peripheral. | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify it | |
7 | * under the terms of the GNU General Public License version 2 as published by | |
8 | * the Free Software Foundation. | |
9 | */ | |
10 | #include <linux/init.h> | |
11 | #include <linux/kernel.h> | |
12 | #include <linux/module.h> | |
13 | #include <linux/platform_device.h> | |
14 | #include <linux/fb.h> | |
15 | #include <linux/clk.h> | |
16 | #include <linux/gpio.h> | |
17 | #include <linux/backlight.h> | |
18 | #include <linux/atmel_pwm.h> | |
19 | #include <linux/atmel-pwm-bl.h> | |
5a0e3ad6 | 20 | #include <linux/slab.h> |
3e074058 HCE |
21 | |
22 | struct atmel_pwm_bl { | |
23 | const struct atmel_pwm_bl_platform_data *pdata; | |
24 | struct backlight_device *bldev; | |
25 | struct platform_device *pdev; | |
26 | struct pwm_channel pwmc; | |
27 | int gpio_on; | |
28 | }; | |
29 | ||
30 | static int atmel_pwm_bl_set_intensity(struct backlight_device *bd) | |
31 | { | |
32 | struct atmel_pwm_bl *pwmbl = bl_get_data(bd); | |
33 | int intensity = bd->props.brightness; | |
34 | int pwm_duty; | |
35 | ||
36 | if (bd->props.power != FB_BLANK_UNBLANK) | |
37 | intensity = 0; | |
38 | if (bd->props.fb_blank != FB_BLANK_UNBLANK) | |
39 | intensity = 0; | |
40 | ||
41 | if (pwmbl->pdata->pwm_active_low) | |
42 | pwm_duty = pwmbl->pdata->pwm_duty_min + intensity; | |
43 | else | |
44 | pwm_duty = pwmbl->pdata->pwm_duty_max - intensity; | |
45 | ||
46 | if (pwm_duty > pwmbl->pdata->pwm_duty_max) | |
47 | pwm_duty = pwmbl->pdata->pwm_duty_max; | |
48 | if (pwm_duty < pwmbl->pdata->pwm_duty_min) | |
49 | pwm_duty = pwmbl->pdata->pwm_duty_min; | |
50 | ||
51 | if (!intensity) { | |
52 | if (pwmbl->gpio_on != -1) { | |
53 | gpio_set_value(pwmbl->gpio_on, | |
54 | 0 ^ pwmbl->pdata->on_active_low); | |
55 | } | |
56 | pwm_channel_writel(&pwmbl->pwmc, PWM_CUPD, pwm_duty); | |
57 | pwm_channel_disable(&pwmbl->pwmc); | |
58 | } else { | |
59 | pwm_channel_enable(&pwmbl->pwmc); | |
60 | pwm_channel_writel(&pwmbl->pwmc, PWM_CUPD, pwm_duty); | |
61 | if (pwmbl->gpio_on != -1) { | |
62 | gpio_set_value(pwmbl->gpio_on, | |
63 | 1 ^ pwmbl->pdata->on_active_low); | |
64 | } | |
65 | } | |
66 | ||
67 | return 0; | |
68 | } | |
69 | ||
70 | static int atmel_pwm_bl_get_intensity(struct backlight_device *bd) | |
71 | { | |
72 | struct atmel_pwm_bl *pwmbl = bl_get_data(bd); | |
73 | u8 intensity; | |
74 | ||
75 | if (pwmbl->pdata->pwm_active_low) { | |
76 | intensity = pwm_channel_readl(&pwmbl->pwmc, PWM_CDTY) - | |
77 | pwmbl->pdata->pwm_duty_min; | |
78 | } else { | |
79 | intensity = pwmbl->pdata->pwm_duty_max - | |
80 | pwm_channel_readl(&pwmbl->pwmc, PWM_CDTY); | |
81 | } | |
82 | ||
83 | return intensity; | |
84 | } | |
85 | ||
86 | static int atmel_pwm_bl_init_pwm(struct atmel_pwm_bl *pwmbl) | |
87 | { | |
88 | unsigned long pwm_rate = pwmbl->pwmc.mck; | |
89 | unsigned long prescale = DIV_ROUND_UP(pwm_rate, | |
90 | (pwmbl->pdata->pwm_frequency * | |
91 | pwmbl->pdata->pwm_compare_max)) - 1; | |
92 | ||
93 | /* | |
94 | * Prescale must be power of two and maximum 0xf in size because of | |
95 | * hardware limit. PWM speed will be: | |
96 | * PWM module clock speed / (2 ^ prescale). | |
97 | */ | |
98 | prescale = fls(prescale); | |
99 | if (prescale > 0xf) | |
100 | prescale = 0xf; | |
101 | ||
102 | pwm_channel_writel(&pwmbl->pwmc, PWM_CMR, prescale); | |
103 | pwm_channel_writel(&pwmbl->pwmc, PWM_CDTY, | |
104 | pwmbl->pdata->pwm_duty_min + | |
105 | pwmbl->bldev->props.brightness); | |
106 | pwm_channel_writel(&pwmbl->pwmc, PWM_CPRD, | |
107 | pwmbl->pdata->pwm_compare_max); | |
108 | ||
109 | dev_info(&pwmbl->pdev->dev, "Atmel PWM backlight driver " | |
110 | "(%lu Hz)\n", pwmbl->pwmc.mck / | |
111 | pwmbl->pdata->pwm_compare_max / | |
112 | (1 << prescale)); | |
113 | ||
114 | return pwm_channel_enable(&pwmbl->pwmc); | |
115 | } | |
116 | ||
9905a43b | 117 | static const struct backlight_ops atmel_pwm_bl_ops = { |
3e074058 HCE |
118 | .get_brightness = atmel_pwm_bl_get_intensity, |
119 | .update_status = atmel_pwm_bl_set_intensity, | |
120 | }; | |
121 | ||
122 | static int atmel_pwm_bl_probe(struct platform_device *pdev) | |
123 | { | |
a19a6ee6 | 124 | struct backlight_properties props; |
3e074058 HCE |
125 | const struct atmel_pwm_bl_platform_data *pdata; |
126 | struct backlight_device *bldev; | |
127 | struct atmel_pwm_bl *pwmbl; | |
128 | int retval; | |
129 | ||
130 | pwmbl = kzalloc(sizeof(struct atmel_pwm_bl), GFP_KERNEL); | |
131 | if (!pwmbl) | |
132 | return -ENOMEM; | |
133 | ||
134 | pwmbl->pdev = pdev; | |
135 | ||
136 | pdata = pdev->dev.platform_data; | |
137 | if (!pdata) { | |
138 | retval = -ENODEV; | |
139 | goto err_free_mem; | |
140 | } | |
141 | ||
142 | if (pdata->pwm_compare_max < pdata->pwm_duty_max || | |
143 | pdata->pwm_duty_min > pdata->pwm_duty_max || | |
144 | pdata->pwm_frequency == 0) { | |
145 | retval = -EINVAL; | |
146 | goto err_free_mem; | |
147 | } | |
148 | ||
149 | pwmbl->pdata = pdata; | |
150 | pwmbl->gpio_on = pdata->gpio_on; | |
151 | ||
152 | retval = pwm_channel_alloc(pdata->pwm_channel, &pwmbl->pwmc); | |
153 | if (retval) | |
154 | goto err_free_mem; | |
155 | ||
156 | if (pwmbl->gpio_on != -1) { | |
157 | retval = gpio_request(pwmbl->gpio_on, "gpio_atmel_pwm_bl"); | |
158 | if (retval) { | |
159 | pwmbl->gpio_on = -1; | |
160 | goto err_free_pwm; | |
161 | } | |
162 | ||
af901ca1 | 163 | /* Turn display off by default. */ |
3e074058 HCE |
164 | retval = gpio_direction_output(pwmbl->gpio_on, |
165 | 0 ^ pdata->on_active_low); | |
166 | if (retval) | |
167 | goto err_free_gpio; | |
168 | } | |
169 | ||
a19a6ee6 MG |
170 | memset(&props, 0, sizeof(struct backlight_properties)); |
171 | props.max_brightness = pdata->pwm_duty_max - pdata->pwm_duty_min; | |
172 | bldev = backlight_device_register("atmel-pwm-bl", &pdev->dev, pwmbl, | |
173 | &atmel_pwm_bl_ops, &props); | |
3e074058 HCE |
174 | if (IS_ERR(bldev)) { |
175 | retval = PTR_ERR(bldev); | |
176 | goto err_free_gpio; | |
177 | } | |
178 | ||
179 | pwmbl->bldev = bldev; | |
180 | ||
181 | platform_set_drvdata(pdev, pwmbl); | |
182 | ||
183 | /* Power up the backlight by default at middle intesity. */ | |
184 | bldev->props.power = FB_BLANK_UNBLANK; | |
3e074058 HCE |
185 | bldev->props.brightness = bldev->props.max_brightness / 2; |
186 | ||
187 | retval = atmel_pwm_bl_init_pwm(pwmbl); | |
188 | if (retval) | |
189 | goto err_free_bl_dev; | |
190 | ||
191 | atmel_pwm_bl_set_intensity(bldev); | |
192 | ||
193 | return 0; | |
194 | ||
195 | err_free_bl_dev: | |
196 | platform_set_drvdata(pdev, NULL); | |
197 | backlight_device_unregister(bldev); | |
198 | err_free_gpio: | |
199 | if (pwmbl->gpio_on != -1) | |
200 | gpio_free(pwmbl->gpio_on); | |
201 | err_free_pwm: | |
202 | pwm_channel_free(&pwmbl->pwmc); | |
203 | err_free_mem: | |
204 | kfree(pwmbl); | |
205 | return retval; | |
206 | } | |
207 | ||
208 | static int __exit atmel_pwm_bl_remove(struct platform_device *pdev) | |
209 | { | |
210 | struct atmel_pwm_bl *pwmbl = platform_get_drvdata(pdev); | |
211 | ||
212 | if (pwmbl->gpio_on != -1) { | |
213 | gpio_set_value(pwmbl->gpio_on, 0); | |
214 | gpio_free(pwmbl->gpio_on); | |
215 | } | |
216 | pwm_channel_disable(&pwmbl->pwmc); | |
217 | pwm_channel_free(&pwmbl->pwmc); | |
218 | backlight_device_unregister(pwmbl->bldev); | |
219 | platform_set_drvdata(pdev, NULL); | |
220 | kfree(pwmbl); | |
221 | ||
222 | return 0; | |
223 | } | |
224 | ||
225 | static struct platform_driver atmel_pwm_bl_driver = { | |
226 | .driver = { | |
227 | .name = "atmel-pwm-bl", | |
228 | }, | |
229 | /* REVISIT add suspend() and resume() */ | |
230 | .remove = __exit_p(atmel_pwm_bl_remove), | |
231 | }; | |
232 | ||
233 | static int __init atmel_pwm_bl_init(void) | |
234 | { | |
235 | return platform_driver_probe(&atmel_pwm_bl_driver, atmel_pwm_bl_probe); | |
236 | } | |
237 | module_init(atmel_pwm_bl_init); | |
238 | ||
239 | static void __exit atmel_pwm_bl_exit(void) | |
240 | { | |
241 | platform_driver_unregister(&atmel_pwm_bl_driver); | |
242 | } | |
243 | module_exit(atmel_pwm_bl_exit); | |
244 | ||
245 | MODULE_AUTHOR("Hans-Christian egtvedt <hans-christian.egtvedt@atmel.com>"); | |
246 | MODULE_DESCRIPTION("Atmel PWM backlight driver"); | |
247 | MODULE_LICENSE("GPL"); |