drivers/video/backlight/jornada720_bl.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *
   4  * Backlight driver for HP Jornada 700 series (710/720/728)
   5  * Copyright (C) 2006-2009 Kristoffer Ericson <kristoffer.ericson@gmail.com>
   6  */
   7
   8 #include <linux/backlight.h>
   9 #include <linux/device.h>
  10 #include <linux/fb.h>
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/platform_device.h>
  14
  15 #include <mach/jornada720.h>
  16 #include <mach/hardware.h>
  17
  18 #include <video/s1d13xxxfb.h>
  19
  20 #define BL_MAX_BRIGHT   255
  21 #define BL_DEF_BRIGHT   25
  22
  23 static int jornada_bl_get_brightness(struct backlight_device *bd)
  24 {
  25         int ret;
  26
  27         /* check if backlight is on */
  28         if (!(PPSR & PPC_LDD1))
  29                 return 0;
  30
  31         jornada_ssp_start();
  32
  33         /* cmd should return txdummy */
  34         ret = jornada_ssp_byte(GETBRIGHTNESS);
  35
  36         if (jornada_ssp_byte(GETBRIGHTNESS) != TXDUMMY) {
  37                 dev_err(&bd->dev, "get brightness timeout\n");
  38                 jornada_ssp_end();
  39                 return -ETIMEDOUT;
  40         }
  41
  42         /* exchange txdummy for value */
  43         ret = jornada_ssp_byte(TXDUMMY);
  44
  45         jornada_ssp_end();
  46
  47         return BL_MAX_BRIGHT - ret;
  48 }
  49
  50 static int jornada_bl_update_status(struct backlight_device *bd)
  51 {
  52         int ret = 0;
  53
  54         jornada_ssp_start();
  55
  56         /* If backlight is off then really turn it off */
  57         if (backlight_is_blank(bd)) {
  58                 ret = jornada_ssp_byte(BRIGHTNESSOFF);
  59                 if (ret != TXDUMMY) {
  60                         dev_info(&bd->dev, "brightness off timeout\n");
  61                         /* turn off backlight */
  62                         PPSR &= ~PPC_LDD1;
  63                         PPDR |= PPC_LDD1;
  64                         ret = -ETIMEDOUT;
  65                 }
  66         } else  /* turn on backlight */
  67                 PPSR |= PPC_LDD1;
  68
  69                 /* send command to our mcu */
  70                 if (jornada_ssp_byte(SETBRIGHTNESS) != TXDUMMY) {
  71                         dev_info(&bd->dev, "failed to set brightness\n");
  72                         ret = -ETIMEDOUT;
  73                         goto out;
  74                 }
  75
  76                 /*
  77                  * at this point we expect that the mcu has accepted
  78                  * our command and is waiting for our new value
  79                  * please note that maximum brightness is 255,
  80                  * but due to physical layout it is equal to 0, so we simply
  81                  * invert the value (MAX VALUE - NEW VALUE).
  82                  */
  83                 if (jornada_ssp_byte(BL_MAX_BRIGHT - bd->props.brightness)
  84                         != TXDUMMY) {
  85                         dev_err(&bd->dev, "set brightness failed\n");
  86                         ret = -ETIMEDOUT;
  87                 }
  88
  89                 /*
  90                  * If infact we get an TXDUMMY as output we are happy and dont
  91                  * make any further comments about it
  92                  */
  93 out:
  94         jornada_ssp_end();
  95
  96         return ret;
  97 }
  98
  99 static const struct backlight_ops jornada_bl_ops = {
 100         .get_brightness = jornada_bl_get_brightness,
 101         .update_status = jornada_bl_update_status,
 102         .options = BL_CORE_SUSPENDRESUME,
 103 };
 104
 105 static int jornada_bl_probe(struct platform_device *pdev)
 106 {
 107         struct backlight_properties props;
 108         int ret;
 109         struct backlight_device *bd;
 110
 111         memset(&props, 0, sizeof(struct backlight_properties));
 112         props.type = BACKLIGHT_RAW;
 113         props.max_brightness = BL_MAX_BRIGHT;
 114
 115         bd = devm_backlight_device_register(&pdev->dev, S1D_DEVICENAME,
 116                                         &pdev->dev, NULL, &jornada_bl_ops,
 117                                         &props);
 118         if (IS_ERR(bd)) {
 119                 ret = PTR_ERR(bd);
 120                 dev_err(&pdev->dev, "failed to register device, err=%x\n", ret);
 121                 return ret;
 122         }
 123
 124         bd->props.power = FB_BLANK_UNBLANK;
 125         bd->props.brightness = BL_DEF_BRIGHT;
 126         /*
 127          * note. make sure max brightness is set otherwise
 128          * you will get seemingly non-related errors when
 129          * trying to change brightness
 130          */
 131         jornada_bl_update_status(bd);
 132
 133         platform_set_drvdata(pdev, bd);
 134         dev_info(&pdev->dev, "HP Jornada 700 series backlight driver\n");
 135
 136         return 0;
 137 }
 138
 139 static struct platform_driver jornada_bl_driver = {
 140         .probe          = jornada_bl_probe,
 141         .driver = {
 142                 .name   = "jornada_bl",
 143         },
 144 };
 145
 146 module_platform_driver(jornada_bl_driver);
 147
 148 MODULE_AUTHOR("Kristoffer Ericson <kristoffer.ericson>");
 149 MODULE_DESCRIPTION("HP Jornada 710/720/728 Backlight driver");
 150 MODULE_LICENSE("GPL");