df1cbb7ef6ca0370551904b190ba968315ee92c7
[~shefty/rdma-dev.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 #include <linux/slab.h>
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
117 static const struct backlight_ops atmel_pwm_bl_ops = {
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 {
124         struct backlight_properties props;
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 = devm_kzalloc(&pdev->dev, sizeof(struct atmel_pwm_bl),
131                                 GFP_KERNEL);
132         if (!pwmbl)
133                 return -ENOMEM;
134
135         pwmbl->pdev = pdev;
136
137         pdata = pdev->dev.platform_data;
138         if (!pdata) {
139                 retval = -ENODEV;
140                 goto err_free_mem;
141         }
142
143         if (pdata->pwm_compare_max < pdata->pwm_duty_max ||
144                         pdata->pwm_duty_min > pdata->pwm_duty_max ||
145                         pdata->pwm_frequency == 0) {
146                 retval = -EINVAL;
147                 goto err_free_mem;
148         }
149
150         pwmbl->pdata = pdata;
151         pwmbl->gpio_on = pdata->gpio_on;
152
153         retval = pwm_channel_alloc(pdata->pwm_channel, &pwmbl->pwmc);
154         if (retval)
155                 goto err_free_mem;
156
157         if (pwmbl->gpio_on != -1) {
158                 retval = devm_gpio_request(&pdev->dev, pwmbl->gpio_on,
159                                         "gpio_atmel_pwm_bl");
160                 if (retval) {
161                         pwmbl->gpio_on = -1;
162                         goto err_free_pwm;
163                 }
164
165                 /* Turn display off by default. */
166                 retval = gpio_direction_output(pwmbl->gpio_on,
167                                 0 ^ pdata->on_active_low);
168                 if (retval)
169                         goto err_free_pwm;
170         }
171
172         memset(&props, 0, sizeof(struct backlight_properties));
173         props.type = BACKLIGHT_RAW;
174         props.max_brightness = pdata->pwm_duty_max - pdata->pwm_duty_min;
175         bldev = backlight_device_register("atmel-pwm-bl", &pdev->dev, pwmbl,
176                                           &atmel_pwm_bl_ops, &props);
177         if (IS_ERR(bldev)) {
178                 retval = PTR_ERR(bldev);
179                 goto err_free_pwm;
180         }
181
182         pwmbl->bldev = bldev;
183
184         platform_set_drvdata(pdev, pwmbl);
185
186         /* Power up the backlight by default at middle intesity. */
187         bldev->props.power = FB_BLANK_UNBLANK;
188         bldev->props.brightness = bldev->props.max_brightness / 2;
189
190         retval = atmel_pwm_bl_init_pwm(pwmbl);
191         if (retval)
192                 goto err_free_bl_dev;
193
194         atmel_pwm_bl_set_intensity(bldev);
195
196         return 0;
197
198 err_free_bl_dev:
199         platform_set_drvdata(pdev, NULL);
200         backlight_device_unregister(bldev);
201 err_free_pwm:
202         pwm_channel_free(&pwmbl->pwmc);
203 err_free_mem:
204         return retval;
205 }
206
207 static int __exit atmel_pwm_bl_remove(struct platform_device *pdev)
208 {
209         struct atmel_pwm_bl *pwmbl = platform_get_drvdata(pdev);
210
211         if (pwmbl->gpio_on != -1)
212                 gpio_set_value(pwmbl->gpio_on, 0);
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
218         return 0;
219 }
220
221 static struct platform_driver atmel_pwm_bl_driver = {
222         .driver = {
223                 .name = "atmel-pwm-bl",
224         },
225         /* REVISIT add suspend() and resume() */
226         .remove = __exit_p(atmel_pwm_bl_remove),
227 };
228
229 static int __init atmel_pwm_bl_init(void)
230 {
231         return platform_driver_probe(&atmel_pwm_bl_driver, atmel_pwm_bl_probe);
232 }
233 module_init(atmel_pwm_bl_init);
234
235 static void __exit atmel_pwm_bl_exit(void)
236 {
237         platform_driver_unregister(&atmel_pwm_bl_driver);
238 }
239 module_exit(atmel_pwm_bl_exit);
240
241 MODULE_AUTHOR("Hans-Christian egtvedt <hans-christian.egtvedt@atmel.com>");
242 MODULE_DESCRIPTION("Atmel PWM backlight driver");
243 MODULE_LICENSE("GPL");