drivers/video/backlight/jornada720_bl.c

   1 /*
   2  *
   3  * Backlight driver for HP Jornada 700 series (710/720/728)
   4  * Copyright (C) 2006-2009 Kristoffer Ericson <kristoffer.ericson@gmail.com>
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License version
   8  * 2 or any later version as published by the Free Software Foundation.
   9  *
  10  */
  11
  12 #include <linux/backlight.h>
  13 #include <linux/device.h>
  14 #include <linux/fb.h>
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <linux/platform_device.h>
  18
  19 #include <mach/jornada720.h>
  20 #include <mach/hardware.h>
  21
  22 #include <video/s1d13xxxfb.h>
  23
  24 #define BL_MAX_BRIGHT   255
  25 #define BL_DEF_BRIGHT   25
  26
  27 static int jornada_bl_get_brightness(struct backlight_device *bd)
  28 {
  29         int ret;
  30
  31         /* check if backlight is on */
  32         if (!(PPSR & PPC_LDD1))
  33                 return 0;
  34
  35         jornada_ssp_start();
  36
  37         /* cmd should return txdummy */
  38         ret = jornada_ssp_byte(GETBRIGHTNESS);
  39
  40         if (jornada_ssp_byte(GETBRIGHTNESS) != TXDUMMY) {
  41                 printk(KERN_ERR "bl : get brightness timeout\n");
  42                 jornada_ssp_end();
  43                 return -ETIMEDOUT;
  44         } else /* exchange txdummy for value */
  45                 ret = jornada_ssp_byte(TXDUMMY);
  46
  47         jornada_ssp_end();
  48
  49         return (BL_MAX_BRIGHT - ret);
  50 }
  51
  52 static int jornada_bl_update_status(struct backlight_device *bd)
  53 {
  54         int ret = 0;
  55
  56         jornada_ssp_start();
  57
  58         /* If backlight is off then really turn it off */
  59         if ((bd->props.power != FB_BLANK_UNBLANK) || (bd->props.fb_blank != FB_BLANK_UNBLANK)) {
  60                 ret = jornada_ssp_byte(BRIGHTNESSOFF);
  61                 if (ret != TXDUMMY) {
  62                         printk(KERN_INFO "bl : brightness off timeout\n");
  63                         /* turn off backlight */
  64                         PPSR &= ~PPC_LDD1;
  65                         PPDR |= PPC_LDD1;
  66                         ret = -ETIMEDOUT;
  67                 }
  68         } else  /* turn on backlight */
  69                 PPSR |= PPC_LDD1;
  70
  71                 /* send command to our mcu */
  72                 if (jornada_ssp_byte(SETBRIGHTNESS) != TXDUMMY) {
  73                         printk(KERN_INFO "bl : failed to set brightness\n");
  74                         ret = -ETIMEDOUT;
  75                         goto out;
  76                 }
  77
  78                 /* at this point we expect that the mcu has accepted
  79                    our command and is waiting for our new value
  80                    please note that maximum brightness is 255,
  81                    but due to physical layout it is equal to 0, so we simply
  82                    invert the value (MAX VALUE - NEW VALUE). */
  83                 if (jornada_ssp_byte(BL_MAX_BRIGHT - bd->props.brightness) != TXDUMMY) {
  84                         printk(KERN_ERR "bl : set brightness failed\n");
  85                         ret = -ETIMEDOUT;
  86                 }
  87
  88                 /* If infact we get an TXDUMMY as output we are happy and dont
  89                    make any further comments about it */
  90 out:
  91         jornada_ssp_end();
  92
  93         return ret;
  94 }
  95
  96 static struct backlight_ops jornada_bl_ops = {
  97         .get_brightness = jornada_bl_get_brightness,
  98         .update_status = jornada_bl_update_status,
  99         .options = BL_CORE_SUSPENDRESUME,
 100 };
 101
 102 static int jornada_bl_probe(struct platform_device *pdev)
 103 {
 104         int ret;
 105         struct backlight_device *bd;
 106
 107         bd = backlight_device_register(S1D_DEVICENAME, &pdev->dev, NULL, &jornada_bl_ops);
 108
 109         if (IS_ERR(bd)) {
 110                 ret = PTR_ERR(bd);
 111                 printk(KERN_ERR "bl : failed to register device, err=%x\n", ret);
 112                 return ret;
 113         }
 114
 115         bd->props.power = FB_BLANK_UNBLANK;
 116         bd->props.brightness = BL_DEF_BRIGHT;
 117         /* note. make sure max brightness is set otherwise
 118            you will get seemingly non-related errors when
 119            trying to change brightness */
 120         bd->props.max_brightness = BL_MAX_BRIGHT;
 121         jornada_bl_update_status(bd);
 122
 123         platform_set_drvdata(pdev, bd);
 124         printk(KERN_INFO "HP Jornada 700 series backlight driver\n");
 125
 126         return 0;
 127 }
 128
 129 static int jornada_bl_remove(struct platform_device *pdev)
 130 {
 131         struct backlight_device *bd = platform_get_drvdata(pdev);
 132
 133         backlight_device_unregister(bd);
 134
 135         return 0;
 136 }
 137
 138 static struct platform_driver jornada_bl_driver = {
 139         .probe          = jornada_bl_probe,
 140         .remove         = jornada_bl_remove,
 141         .driver = {
 142                 .name   = "jornada_bl",
 143         },
 144 };
 145
 146 int __init jornada_bl_init(void)
 147 {
 148         return platform_driver_register(&jornada_bl_driver);
 149 }
 150
 151 void __exit jornada_bl_exit(void)
 152 {
 153         platform_driver_unregister(&jornada_bl_driver);
 154 }
 155
 156 MODULE_AUTHOR("Kristoffer Ericson <kristoffer.ericson>");
 157 MODULE_DESCRIPTION("HP Jornada 710/720/728 Backlight driver");
 158 MODULE_LICENSE("GPL");
 159
 160 module_init(jornada_bl_init);
 161 module_exit(jornada_bl_exit);