f625ffc69ad3139cef6ba88688ac1e76878ff1e4
[linux-2.6.git] / drivers / video / backlight / atmel-pwm-bl.c
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>
20
21 struct atmel_pwm_bl {
22         const struct atmel_pwm_bl_platform_data *pdata;
23         struct backlight_device                 *bldev;
24         struct platform_device                  *pdev;
25         struct pwm_channel                      pwmc;
26         int                                     gpio_on;
27 };
28
29 static int atmel_pwm_bl_set_intensity(struct backlight_device *bd)
30 {
31         struct atmel_pwm_bl *pwmbl = bl_get_data(bd);
32         int intensity = bd->props.brightness;
33         int pwm_duty;
34
35         if (bd->props.power != FB_BLANK_UNBLANK)
36                 intensity = 0;
37         if (bd->props.fb_blank != FB_BLANK_UNBLANK)
38                 intensity = 0;
39
40         if (pwmbl->pdata->pwm_active_low)
41                 pwm_duty = pwmbl->pdata->pwm_duty_min + intensity;
42         else
43                 pwm_duty = pwmbl->pdata->pwm_duty_max - intensity;
44
45         if (pwm_duty > pwmbl->pdata->pwm_duty_max)
46                 pwm_duty = pwmbl->pdata->pwm_duty_max;
47         if (pwm_duty < pwmbl->pdata->pwm_duty_min)
48                 pwm_duty = pwmbl->pdata->pwm_duty_min;
49
50         if (!intensity) {
51                 if (pwmbl->gpio_on != -1) {
52                         gpio_set_value(pwmbl->gpio_on,
53                                         0 ^ pwmbl->pdata->on_active_low);
54                 }
55                 pwm_channel_writel(&pwmbl->pwmc, PWM_CUPD, pwm_duty);
56                 pwm_channel_disable(&pwmbl->pwmc);
57         } else {
58                 pwm_channel_enable(&pwmbl->pwmc);
59                 pwm_channel_writel(&pwmbl->pwmc, PWM_CUPD, pwm_duty);
60                 if (pwmbl->gpio_on != -1) {
61                         gpio_set_value(pwmbl->gpio_on,
62                                         1 ^ pwmbl->pdata->on_active_low);
63                 }
64         }
65
66         return 0;
67 }
68
69 static int atmel_pwm_bl_get_intensity(struct backlight_device *bd)
70 {
71         struct atmel_pwm_bl *pwmbl = bl_get_data(bd);
72         u8 intensity;
73
74         if (pwmbl->pdata->pwm_active_low) {
75                 intensity = pwm_channel_readl(&pwmbl->pwmc, PWM_CDTY) -
76                         pwmbl->pdata->pwm_duty_min;
77         } else {
78                 intensity = pwmbl->pdata->pwm_duty_max -
79                         pwm_channel_readl(&pwmbl->pwmc, PWM_CDTY);
80         }
81
82         return intensity;
83 }
84
85 static int atmel_pwm_bl_init_pwm(struct atmel_pwm_bl *pwmbl)
86 {
87         unsigned long pwm_rate = pwmbl->pwmc.mck;
88         unsigned long prescale = DIV_ROUND_UP(pwm_rate,
89                         (pwmbl->pdata->pwm_frequency *
90                          pwmbl->pdata->pwm_compare_max)) - 1;
91
92         /*
93          * Prescale must be power of two and maximum 0xf in size because of
94          * hardware limit. PWM speed will be:
95          *      PWM module clock speed / (2 ^ prescale).
96          */
97         prescale = fls(prescale);
98         if (prescale > 0xf)
99                 prescale = 0xf;
100
101         pwm_channel_writel(&pwmbl->pwmc, PWM_CMR, prescale);
102         pwm_channel_writel(&pwmbl->pwmc, PWM_CDTY,
103                         pwmbl->pdata->pwm_duty_min +
104                         pwmbl->bldev->props.brightness);
105         pwm_channel_writel(&pwmbl->pwmc, PWM_CPRD,
106                         pwmbl->pdata->pwm_compare_max);
107
108         dev_info(&pwmbl->pdev->dev, "Atmel PWM backlight driver "
109                         "(%lu Hz)\n", pwmbl->pwmc.mck /
110                         pwmbl->pdata->pwm_compare_max /
111                         (1 << prescale));
112
113         return pwm_channel_enable(&pwmbl->pwmc);
114 }
115
116 static const struct backlight_ops atmel_pwm_bl_ops = {
117         .get_brightness = atmel_pwm_bl_get_intensity,
118         .update_status  = atmel_pwm_bl_set_intensity,
119 };
120
121 static int atmel_pwm_bl_probe(struct platform_device *pdev)
122 {
123         const struct atmel_pwm_bl_platform_data *pdata;
124         struct backlight_device *bldev;
125         struct atmel_pwm_bl *pwmbl;
126         int retval;
127
128         pwmbl = kzalloc(sizeof(struct atmel_pwm_bl), GFP_KERNEL);
129         if (!pwmbl)
130                 return -ENOMEM;
131
132         pwmbl->pdev = pdev;
133
134         pdata = pdev->dev.platform_data;
135         if (!pdata) {
136                 retval = -ENODEV;
137                 goto err_free_mem;
138         }
139
140         if (pdata->pwm_compare_max < pdata->pwm_duty_max ||
141                         pdata->pwm_duty_min > pdata->pwm_duty_max ||
142                         pdata->pwm_frequency == 0) {
143                 retval = -EINVAL;
144                 goto err_free_mem;
145         }
146
147         pwmbl->pdata = pdata;
148         pwmbl->gpio_on = pdata->gpio_on;
149
150         retval = pwm_channel_alloc(pdata->pwm_channel, &pwmbl->pwmc);
151         if (retval)
152                 goto err_free_mem;
153
154         if (pwmbl->gpio_on != -1) {
155                 retval = gpio_request(pwmbl->gpio_on, "gpio_atmel_pwm_bl");
156                 if (retval) {
157                         pwmbl->gpio_on = -1;
158                         goto err_free_pwm;
159                 }
160
161                 /* Turn display off by default. */
162                 retval = gpio_direction_output(pwmbl->gpio_on,
163                                 0 ^ pdata->on_active_low);
164                 if (retval)
165                         goto err_free_gpio;
166         }
167
168         bldev = backlight_device_register("atmel-pwm-bl",
169                         &pdev->dev, pwmbl, &atmel_pwm_bl_ops);
170         if (IS_ERR(bldev)) {
171                 retval = PTR_ERR(bldev);
172                 goto err_free_gpio;
173         }
174
175         pwmbl->bldev = bldev;
176
177         platform_set_drvdata(pdev, pwmbl);
178
179         /* Power up the backlight by default at middle intesity. */
180         bldev->props.power = FB_BLANK_UNBLANK;
181         bldev->props.max_brightness = pdata->pwm_duty_max - pdata->pwm_duty_min;
182         bldev->props.brightness = bldev->props.max_brightness / 2;
183
184         retval = atmel_pwm_bl_init_pwm(pwmbl);
185         if (retval)
186                 goto err_free_bl_dev;
187
188         atmel_pwm_bl_set_intensity(bldev);
189
190         return 0;
191
192 err_free_bl_dev:
193         platform_set_drvdata(pdev, NULL);
194         backlight_device_unregister(bldev);
195 err_free_gpio:
196         if (pwmbl->gpio_on != -1)
197                 gpio_free(pwmbl->gpio_on);
198 err_free_pwm:
199         pwm_channel_free(&pwmbl->pwmc);
200 err_free_mem:
201         kfree(pwmbl);
202         return retval;
203 }
204
205 static int __exit atmel_pwm_bl_remove(struct platform_device *pdev)
206 {
207         struct atmel_pwm_bl *pwmbl = platform_get_drvdata(pdev);
208
209         if (pwmbl->gpio_on != -1) {
210                 gpio_set_value(pwmbl->gpio_on, 0);
211                 gpio_free(pwmbl->gpio_on);
212         }
213         pwm_channel_disable(&pwmbl->pwmc);
214         pwm_channel_free(&pwmbl->pwmc);
215         backlight_device_unregister(pwmbl->bldev);
216         platform_set_drvdata(pdev, NULL);
217         kfree(pwmbl);
218
219         return 0;
220 }
221
222 static struct platform_driver atmel_pwm_bl_driver = {
223         .driver = {
224                 .name = "atmel-pwm-bl",
225         },
226         /* REVISIT add suspend() and resume() */
227         .remove = __exit_p(atmel_pwm_bl_remove),
228 };
229
230 static int __init atmel_pwm_bl_init(void)
231 {
232         return platform_driver_probe(&atmel_pwm_bl_driver, atmel_pwm_bl_probe);
233 }
234 module_init(atmel_pwm_bl_init);
235
236 static void __exit atmel_pwm_bl_exit(void)
237 {
238         platform_driver_unregister(&atmel_pwm_bl_driver);
239 }
240 module_exit(atmel_pwm_bl_exit);
241
242 MODULE_AUTHOR("Hans-Christian egtvedt <hans-christian.egtvedt@atmel.com>");
243 MODULE_DESCRIPTION("Atmel PWM backlight driver");
244 MODULE_LICENSE("GPL");