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 const 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         struct backlight_properties props;
 105         int ret;
 106         struct backlight_device *bd;
 107
 108         memset(&props, 0, sizeof(struct backlight_properties));
 109         props.type = BACKLIGHT_RAW;
 110         props.max_brightness = BL_MAX_BRIGHT;
 111         bd = backlight_device_register(S1D_DEVICENAME, &pdev->dev, NULL,
 112                                        &jornada_bl_ops, &props);
 113
 114         if (IS_ERR(bd)) {
 115                 ret = PTR_ERR(bd);
 116                 printk(KERN_ERR "bl : failed to register device, err=%x\n", ret);
 117                 return ret;
 118         }
 119
 120         bd->props.power = FB_BLANK_UNBLANK;
 121         bd->props.brightness = BL_DEF_BRIGHT;
 122         /* note. make sure max brightness is set otherwise
 123            you will get seemingly non-related errors when
 124            trying to change brightness */
 125         jornada_bl_update_status(bd);
 126
 127         platform_set_drvdata(pdev, bd);
 128         printk(KERN_INFO "HP Jornada 700 series backlight driver\n");
 129
 130         return 0;
 131 }
 132
 133 static int jornada_bl_remove(struct platform_device *pdev)
 134 {
 135         struct backlight_device *bd = platform_get_drvdata(pdev);
 136
 137         backlight_device_unregister(bd);
 138
 139         return 0;
 140 }
 141
 142 static struct platform_driver jornada_bl_driver = {
 143         .probe          = jornada_bl_probe,
 144         .remove         = jornada_bl_remove,
 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");