backlight: atmel-pwm-bl: fix checkpatch warning
[~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 (%lu Hz)\n",
110                 pwmbl->pwmc.mck / 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         struct backlight_properties props;
124         const struct atmel_pwm_bl_platform_data *pdata;
125         struct backlight_device *bldev;
126         struct atmel_pwm_bl *pwmbl;
127         int retval;
128
129         pwmbl = devm_kzalloc(&pdev->dev, sizeof(struct atmel_pwm_bl),
130                                 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 = devm_gpio_request(&pdev->dev, pwmbl->gpio_on,
158                                         "gpio_atmel_pwm_bl");
159                 if (retval) {
160                         pwmbl->gpio_on = -1;
161                         goto err_free_pwm;
162                 }
163
164                 /* Turn display off by default. */
165                 retval = gpio_direction_output(pwmbl->gpio_on,
166                                 0 ^ pdata->on_active_low);
167                 if (retval)
168                         goto err_free_pwm;
169         }
170
171         memset(&props, 0, sizeof(struct backlight_properties));
172         props.type = BACKLIGHT_RAW;
173         props.max_brightness = pdata->pwm_duty_max - pdata->pwm_duty_min;
174         bldev = backlight_device_register("atmel-pwm-bl", &pdev->dev, pwmbl,
175                                           &atmel_pwm_bl_ops, &props);
176         if (IS_ERR(bldev)) {
177                 retval = PTR_ERR(bldev);
178                 goto err_free_pwm;
179         }
180
181         pwmbl->bldev = bldev;
182
183         platform_set_drvdata(pdev, pwmbl);
184
185         /* Power up the backlight by default at middle intesity. */
186         bldev->props.power = FB_BLANK_UNBLANK;
187         bldev->props.brightness = bldev->props.max_brightness / 2;
188
189         retval = atmel_pwm_bl_init_pwm(pwmbl);
190         if (retval)
191                 goto err_free_bl_dev;
192
193         atmel_pwm_bl_set_intensity(bldev);
194
195         return 0;
196
197 err_free_bl_dev:
198         platform_set_drvdata(pdev, NULL);
199         backlight_device_unregister(bldev);
200 err_free_pwm:
201         pwm_channel_free(&pwmbl->pwmc);
202 err_free_mem:
203         return retval;
204 }
205
206 static int __exit atmel_pwm_bl_remove(struct platform_device *pdev)
207 {
208         struct atmel_pwm_bl *pwmbl = platform_get_drvdata(pdev);
209
210         if (pwmbl->gpio_on != -1)
211                 gpio_set_value(pwmbl->gpio_on, 0);
212         pwm_channel_disable(&pwmbl->pwmc);
213         pwm_channel_free(&pwmbl->pwmc);
214         backlight_device_unregister(pwmbl->bldev);
215         platform_set_drvdata(pdev, NULL);
216
217         return 0;
218 }
219
220 static struct platform_driver atmel_pwm_bl_driver = {
221         .driver = {
222                 .name = "atmel-pwm-bl",
223         },
224         /* REVISIT add suspend() and resume() */
225         .remove = __exit_p(atmel_pwm_bl_remove),
226 };
227
228 static int __init atmel_pwm_bl_init(void)
229 {
230         return platform_driver_probe(&atmel_pwm_bl_driver, atmel_pwm_bl_probe);
231 }
232 module_init(atmel_pwm_bl_init);
233
234 static void __exit atmel_pwm_bl_exit(void)
235 {
236         platform_driver_unregister(&atmel_pwm_bl_driver);
237 }
238 module_exit(atmel_pwm_bl_exit);
239
240 MODULE_AUTHOR("Hans-Christian egtvedt <hans-christian.egtvedt@atmel.com>");
241 MODULE_DESCRIPTION("Atmel PWM backlight driver");
242 MODULE_LICENSE("GPL");