LXR linux/drivers/video/backlight/pcf50633-backlight.c

   1/*
   2 *  Copyright (C) 2009-2010, Lars-Peter Clausen <lars@metafoo.de>
   3 *      PCF50633 backlight device driver
   4 *
   5 *  This program is free software; you can redistribute  it and/or modify it
   6 *  under  the terms of  the GNU General  Public License as published by the
   7 *  Free Software Foundation;  either version 2 of the  License, or (at your
   8 *  option) any later version.
   9 *
  10 *  You should have received a copy of the  GNU General Public License along
  11 *  with this program; if not, write  to the Free Software Foundation, Inc.,
  12 *  675 Mass Ave, Cambridge, MA 02139, USA.
  13 *
  14 */
  15
  16#include <linux/kernel.h>
  17#include <linux/module.h>
  18#include <linux/slab.h>
  19#include <linux/platform_device.h>
  20
  21#include <linux/backlight.h>
  22#include <linux/fb.h>
  23
  24#include <linux/mfd/pcf50633/core.h>
  25#include <linux/mfd/pcf50633/backlight.h>
  26
  27struct pcf50633_bl {
  28        struct pcf50633 *pcf;
  29        struct backlight_device *bl;
  30
  31        unsigned int brightness;
  32        unsigned int brightness_limit;
  33};
  34
  35/*
  36 * pcf50633_bl_set_brightness_limit
  37 *
  38 * Update the brightness limit for the pc50633 backlight. The actual brightness
  39 * will not go above the limit. This is useful to limit power drain for example
  40 * on low battery.
  41 *
  42 * @dev: Pointer to a pcf50633 device
  43 * @limit: The brightness limit. Valid values are 0-63
  44 */
  45int pcf50633_bl_set_brightness_limit(struct pcf50633 *pcf, unsigned int limit)
  46{
  47        struct pcf50633_bl *pcf_bl = platform_get_drvdata(pcf->bl_pdev);
  48
  49        if (!pcf_bl)
  50                return -ENODEV;
  51
  52        pcf_bl->brightness_limit = limit & 0x3f;
  53        backlight_update_status(pcf_bl->bl);
  54
  55        return 0;
  56}
  57
  58static int pcf50633_bl_update_status(struct backlight_device *bl)
  59{
  60        struct pcf50633_bl *pcf_bl = bl_get_data(bl);
  61        unsigned int new_brightness;
  62
  63
  64        if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK) ||
  65                bl->props.power != FB_BLANK_UNBLANK)
  66                new_brightness = 0;
  67        else if (bl->props.brightness < pcf_bl->brightness_limit)
  68                new_brightness = bl->props.brightness;
  69        else
  70                new_brightness = pcf_bl->brightness_limit;
  71
  72
  73        if (pcf_bl->brightness == new_brightness)
  74                return 0;
  75
  76        if (new_brightness) {
  77                pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDOUT,
  78                                        new_brightness);
  79                if (!pcf_bl->brightness)
  80                        pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDENA, 1);
  81        } else {
  82                pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDENA, 0);
  83        }
  84
  85        pcf_bl->brightness = new_brightness;
  86
  87        return 0;
  88}
  89
  90static int pcf50633_bl_get_brightness(struct backlight_device *bl)
  91{
  92        struct pcf50633_bl *pcf_bl = bl_get_data(bl);
  93
  94        return pcf_bl->brightness;
  95}
  96
  97static const struct backlight_ops pcf50633_bl_ops = {
  98        .get_brightness = pcf50633_bl_get_brightness,
  99        .update_status  = pcf50633_bl_update_status,
 100        .options        = BL_CORE_SUSPENDRESUME,
 101};
 102
 103static int pcf50633_bl_probe(struct platform_device *pdev)
 104{
 105        struct pcf50633_bl *pcf_bl;
 106        struct device *parent = pdev->dev.parent;
 107        struct pcf50633_platform_data *pcf50633_data = dev_get_platdata(parent);
 108        struct pcf50633_bl_platform_data *pdata = pcf50633_data->backlight_data;
 109        struct backlight_properties bl_props;
 110
 111        pcf_bl = devm_kzalloc(&pdev->dev, sizeof(*pcf_bl), GFP_KERNEL);
 112        if (!pcf_bl)
 113                return -ENOMEM;
 114
 115        memset(&bl_props, 0, sizeof(bl_props));
 116        bl_props.type = BACKLIGHT_RAW;
 117        bl_props.max_brightness = 0x3f;
 118        bl_props.power = FB_BLANK_UNBLANK;
 119
 120        if (pdata) {
 121                bl_props.brightness = pdata->default_brightness;
 122                pcf_bl->brightness_limit = pdata->default_brightness_limit;
 123        } else {
 124                bl_props.brightness = 0x3f;
 125                pcf_bl->brightness_limit = 0x3f;
 126        }
 127
 128        pcf_bl->pcf = dev_to_pcf50633(pdev->dev.parent);
 129
 130        pcf_bl->bl = devm_backlight_device_register(&pdev->dev, pdev->name,
 131                                                &pdev->dev, pcf_bl,
 132                                                &pcf50633_bl_ops, &bl_props);
 133
 134        if (IS_ERR(pcf_bl->bl))
 135                return PTR_ERR(pcf_bl->bl);
 136
 137        platform_set_drvdata(pdev, pcf_bl);
 138
 139        pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDDIM, pdata->ramp_time);
 140
 141        /*
 142         * Should be different from bl_props.brightness, so we do not exit
 143         * update_status early the first time it's called
 144         */
 145        pcf_bl->brightness = pcf_bl->bl->props.brightness + 1;
 146
 147        backlight_update_status(pcf_bl->bl);
 148
 149        return 0;
 150}
 151
 152static struct platform_driver pcf50633_bl_driver = {
 153        .probe =        pcf50633_bl_probe,
 154        .driver = {
 155                .name = "pcf50633-backlight",
 156        },
 157};
 158
 159module_platform_driver(pcf50633_bl_driver);
 160
 161MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 162MODULE_DESCRIPTION("PCF50633 backlight driver");
 163MODULE_LICENSE("GPL");
 164MODULE_ALIAS("platform:pcf50633-backlight");
 165