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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/backlight.h>
  15 #include <linux/device.h>
  16 #include <linux/fb.h>
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/platform_device.h>
  20
  21 #include <mach/jornada720.h>
  22 #include <mach/hardware.h>
  23
  24 #include <video/s1d13xxxfb.h>
  25
  26 #define BL_MAX_BRIGHT   255
  27 #define BL_DEF_BRIGHT   25
  28
  29 static int jornada_bl_get_brightness(struct backlight_device *bd)
  30 {
  31         int ret;
  32
  33         /* check if backlight is on */
  34         if (!(PPSR & PPC_LDD1))
  35                 return 0;
  36
  37         jornada_ssp_start();
  38
  39         /* cmd should return txdummy */
  40         ret = jornada_ssp_byte(GETBRIGHTNESS);
  41
  42         if (jornada_ssp_byte(GETBRIGHTNESS) != TXDUMMY) {
  43                 pr_err("get brightness timeout\n");
  44                 jornada_ssp_end();
  45                 return -ETIMEDOUT;
  46         } else /* 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                         pr_info("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                         pr_info("failed to set brightness\n");
  76                         ret = -ETIMEDOUT;
  77                         goto out;
  78                 }
  79
  80                 /* at this point we expect that the mcu has accepted
  81                    our command and is waiting for our new value
  82                    please note that maximum brightness is 255,
  83                    but due to physical layout it is equal to 0, so we simply
  84                    invert the value (MAX VALUE - NEW VALUE). */
  85                 if (jornada_ssp_byte(BL_MAX_BRIGHT - bd->props.brightness) != TXDUMMY) {
  86                         pr_err("set brightness failed\n");
  87                         ret = -ETIMEDOUT;
  88                 }
  89
  90                 /* If infact we get an TXDUMMY as output we are happy and dont
  91                    make any further comments about it */
  92 out:
  93         jornada_ssp_end();
  94
  95         return ret;
  96 }
  97
  98 static const struct backlight_ops jornada_bl_ops = {
  99         .get_brightness = jornada_bl_get_brightness,
 100         .update_status = jornada_bl_update_status,
 101         .options = BL_CORE_SUSPENDRESUME,
 102 };
 103
 104 static int jornada_bl_probe(struct platform_device *pdev)
 105 {
 106         struct backlight_properties props;
 107         int ret;
 108         struct backlight_device *bd;
 109
 110         memset(&props, 0, sizeof(struct backlight_properties));
 111         props.type = BACKLIGHT_RAW;
 112         props.max_brightness = BL_MAX_BRIGHT;
 113         bd = backlight_device_register(S1D_DEVICENAME, &pdev->dev, NULL,
 114                                        &jornada_bl_ops, &props);
 115
 116         if (IS_ERR(bd)) {
 117                 ret = PTR_ERR(bd);
 118                 pr_err("failed to register device, err=%x\n", ret);
 119                 return ret;
 120         }
 121
 122         bd->props.power = FB_BLANK_UNBLANK;
 123         bd->props.brightness = BL_DEF_BRIGHT;
 124         /* note. make sure max brightness is set otherwise
 125            you will get seemingly non-related errors when
 126            trying to change brightness */
 127         jornada_bl_update_status(bd);
 128
 129         platform_set_drvdata(pdev, bd);
 130         pr_info("HP Jornada 700 series backlight driver\n");
 131
 132         return 0;
 133 }
 134
 135 static int jornada_bl_remove(struct platform_device *pdev)
 136 {
 137         struct backlight_device *bd = platform_get_drvdata(pdev);
 138
 139         backlight_device_unregister(bd);
 140
 141         return 0;
 142 }
 143
 144 static struct platform_driver jornada_bl_driver = {
 145         .probe          = jornada_bl_probe,
 146         .remove         = jornada_bl_remove,
 147         .driver = {
 148                 .name   = "jornada_bl",
 149         },
 150 };
 151
 152 module_platform_driver(jornada_bl_driver);
 153
 154 MODULE_AUTHOR("Kristoffer Ericson <kristoffer.ericson>");
 155 MODULE_DESCRIPTION("HP Jornada 710/720/728 Backlight driver");
 156 MODULE_LICENSE("GPL");