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[~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 = 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
163                 /* Turn display off by default. */
164                 retval = gpio_direction_output(pwmbl->gpio_on,
165                                 0 ^ pdata->on_active_low);
166                 if (retval)
167                         goto err_free_gpio;
168         }
169
170         memset(&props, 0, sizeof(struct backlight_properties));
171         props.type = BACKLIGHT_RAW;
172         props.max_brightness = pdata->pwm_duty_max - pdata->pwm_duty_min;
173         bldev = backlight_device_register("atmel-pwm-bl", &pdev->dev, pwmbl,
174                                           &atmel_pwm_bl_ops, &props);
175         if (IS_ERR(bldev)) {
176                 retval = PTR_ERR(bldev);
177                 goto err_free_gpio;
178         }
179
180         pwmbl->bldev = bldev;
181
182         platform_set_drvdata(pdev, pwmbl);
183
184         /* Power up the backlight by default at middle intesity. */
185         bldev->props.power = FB_BLANK_UNBLANK;
186         bldev->props.brightness = bldev->props.max_brightness / 2;
187
188         retval = atmel_pwm_bl_init_pwm(pwmbl);
189         if (retval)
190                 goto err_free_bl_dev;
191
192         atmel_pwm_bl_set_intensity(bldev);
193
194         return 0;
195
196 err_free_bl_dev:
197         platform_set_drvdata(pdev, NULL);
198         backlight_device_unregister(bldev);
199 err_free_gpio:
200         if (pwmbl->gpio_on != -1)
201                 gpio_free(pwmbl->gpio_on);
202 err_free_pwm:
203         pwm_channel_free(&pwmbl->pwmc);
204 err_free_mem:
205         kfree(pwmbl);
206         return retval;
207 }
208
209 static int __exit atmel_pwm_bl_remove(struct platform_device *pdev)
210 {
211         struct atmel_pwm_bl *pwmbl = platform_get_drvdata(pdev);
212
213         if (pwmbl->gpio_on != -1) {
214                 gpio_set_value(pwmbl->gpio_on, 0);
215                 gpio_free(pwmbl->gpio_on);
216         }
217         pwm_channel_disable(&pwmbl->pwmc);
218         pwm_channel_free(&pwmbl->pwmc);
219         backlight_device_unregister(pwmbl->bldev);
220         platform_set_drvdata(pdev, NULL);
221         kfree(pwmbl);
222
223         return 0;
224 }
225
226 static struct platform_driver atmel_pwm_bl_driver = {
227         .driver = {
228                 .name = "atmel-pwm-bl",
229         },
230         /* REVISIT add suspend() and resume() */
231         .remove = __exit_p(atmel_pwm_bl_remove),
232 };
233
234 static int __init atmel_pwm_bl_init(void)
235 {
236         return platform_driver_probe(&atmel_pwm_bl_driver, atmel_pwm_bl_probe);
237 }
238 module_init(atmel_pwm_bl_init);
239
240 static void __exit atmel_pwm_bl_exit(void)
241 {
242         platform_driver_unregister(&atmel_pwm_bl_driver);
243 }
244 module_exit(atmel_pwm_bl_exit);
245
246 MODULE_AUTHOR("Hans-Christian egtvedt <hans-christian.egtvedt@atmel.com>");
247 MODULE_DESCRIPTION("Atmel PWM backlight driver");
248 MODULE_LICENSE("GPL");