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                 dev_err(&bd->dev, "get brightness timeout\n");
  42                 jornada_ssp_end();
  43                 return -ETIMEDOUT;
  44         }
  45
  46         /* exchange txdummy for value */
  47         ret = jornada_ssp_byte(TXDUMMY);
  48
  49         jornada_ssp_end();
  50
  51         return BL_MAX_BRIGHT - ret;
  52 }
  53
  54 static int jornada_bl_update_status(struct backlight_device *bd)
  55 {
  56         int ret = 0;
  57
  58         jornada_ssp_start();
  59
  60         /* If backlight is off then really turn it off */
  61         if ((bd->props.power != FB_BLANK_UNBLANK) || (bd->props.fb_blank != FB_BLANK_UNBLANK)) {
  62                 ret = jornada_ssp_byte(BRIGHTNESSOFF);
  63                 if (ret != TXDUMMY) {
  64                         dev_info(&bd->dev, "brightness off timeout\n");
  65                         /* turn off backlight */
  66                         PPSR &= ~PPC_LDD1;
  67                         PPDR |= PPC_LDD1;
  68                         ret = -ETIMEDOUT;
  69                 }
  70         } else  /* turn on backlight */
  71                 PPSR |= PPC_LDD1;
  72
  73                 /* send command to our mcu */
  74                 if (jornada_ssp_byte(SETBRIGHTNESS) != TXDUMMY) {
  75                         dev_info(&bd->dev, "failed to set brightness\n");
  76                         ret = -ETIMEDOUT;
  77                         goto out;
  78                 }
  79
  80                 /*
  81                  * at this point we expect that the mcu has accepted
  82                  * our command and is waiting for our new value
  83                  * please note that maximum brightness is 255,
  84                  * but due to physical layout it is equal to 0, so we simply
  85                  * invert the value (MAX VALUE - NEW VALUE).
  86                  */
  87                 if (jornada_ssp_byte(BL_MAX_BRIGHT - bd->props.brightness)
  88                         != TXDUMMY) {
  89                         dev_err(&bd->dev, "set brightness failed\n");
  90                         ret = -ETIMEDOUT;
  91                 }
  92
  93                 /*
  94                  * If infact we get an TXDUMMY as output we are happy and dont
  95                  * make any further comments about it
  96                  */
  97 out:
  98         jornada_ssp_end();
  99
 100         return ret;
 101 }
 102
 103 static const struct backlight_ops jornada_bl_ops = {
 104         .get_brightness = jornada_bl_get_brightness,
 105         .update_status = jornada_bl_update_status,
 106         .options = BL_CORE_SUSPENDRESUME,
 107 };
 108
 109 static int jornada_bl_probe(struct platform_device *pdev)
 110 {
 111         struct backlight_properties props;
 112         int ret;
 113         struct backlight_device *bd;
 114
 115         memset(&props, 0, sizeof(struct backlight_properties));
 116         props.type = BACKLIGHT_RAW;
 117         props.max_brightness = BL_MAX_BRIGHT;
 118
 119         bd = devm_backlight_device_register(&pdev->dev, S1D_DEVICENAME,
 120                                         &pdev->dev, NULL, &jornada_bl_ops,
 121                                         &props);
 122         if (IS_ERR(bd)) {
 123                 ret = PTR_ERR(bd);
 124                 dev_err(&pdev->dev, "failed to register device, err=%x\n", ret);
 125                 return ret;
 126         }
 127
 128         bd->props.power = FB_BLANK_UNBLANK;
 129         bd->props.brightness = BL_DEF_BRIGHT;
 130         /*
 131          * note. make sure max brightness is set otherwise
 132          * you will get seemingly non-related errors when
 133          * trying to change brightness
 134          */
 135         jornada_bl_update_status(bd);
 136
 137         platform_set_drvdata(pdev, bd);
 138         dev_info(&pdev->dev, "HP Jornada 700 series backlight driver\n");
 139
 140         return 0;
 141 }
 142
 143 static struct platform_driver jornada_bl_driver = {
 144         .probe          = jornada_bl_probe,
 145         .driver = {
 146                 .name   = "jornada_bl",
 147         },
 148 };
 149
 150 module_platform_driver(jornada_bl_driver);
 151
 152 MODULE_AUTHOR("Kristoffer Ericson <kristoffer.ericson>");
 153 MODULE_DESCRIPTION("HP Jornada 710/720/728 Backlight driver");
 154 MODULE_LICENSE("GPL");