drivers/video/backlight/pandora_bl.c

   1 /*
   2  * Backlight driver for Pandora handheld.
   3  * Pandora uses TWL4030 PWM0 -> TPS61161 combo for control backlight.
   4  * Based on pwm_bl.c
   5  *
   6  * Copyright 2009,2012 Gražvydas Ignotas <notasas@gmail.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/kernel.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/delay.h>
  17 #include <linux/fb.h>
  18 #include <linux/backlight.h>
  19 #include <linux/mfd/twl.h>
  20 #include <linux/err.h>
  21
  22 #define TWL_PWM0_ON             0x00
  23 #define TWL_PWM0_OFF            0x01
  24
  25 #define TWL_INTBR_GPBR1         0x0c
  26 #define TWL_INTBR_PMBR1         0x0d
  27
  28 #define TWL_PMBR1_PWM0_MUXMASK  0x0c
  29 #define TWL_PMBR1_PWM0          0x04
  30 #define PWM0_CLK_ENABLE         BIT(0)
  31 #define PWM0_ENABLE             BIT(2)
  32
  33 /* range accepted by hardware */
  34 #define MIN_VALUE 9
  35 #define MAX_VALUE 63
  36 #define MAX_USER_VALUE (MAX_VALUE - MIN_VALUE)
  37
  38 struct pandora_private {
  39         unsigned old_state;
  40 #define PANDORABL_WAS_OFF 1
  41 };
  42
  43 static int pandora_backlight_update_status(struct backlight_device *bl)
  44 {
  45         int brightness = bl->props.brightness;
  46         struct pandora_private *priv = bl_get_data(bl);
  47         u8 r;
  48
  49         if (bl->props.power != FB_BLANK_UNBLANK)
  50                 brightness = 0;
  51         if (bl->props.state & BL_CORE_FBBLANK)
  52                 brightness = 0;
  53         if (bl->props.state & BL_CORE_SUSPENDED)
  54                 brightness = 0;
  55
  56         if ((unsigned int)brightness > MAX_USER_VALUE)
  57                 brightness = MAX_USER_VALUE;
  58
  59         if (brightness == 0) {
  60                 if (priv->old_state == PANDORABL_WAS_OFF)
  61                         goto done;
  62
  63                 /* first disable PWM0 output, then clock */
  64                 twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
  65                 r &= ~PWM0_ENABLE;
  66                 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  67                 r &= ~PWM0_CLK_ENABLE;
  68                 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  69
  70                 goto done;
  71         }
  72
  73         if (priv->old_state == PANDORABL_WAS_OFF) {
  74                 /*
  75                  * set PWM duty cycle to max. TPS61161 seems to use this
  76                  * to calibrate it's PWM sensitivity when it starts.
  77                  */
  78                 twl_i2c_write_u8(TWL_MODULE_PWM, MAX_VALUE, TWL_PWM0_OFF);
  79
  80                 /* first enable clock, then PWM0 out */
  81                 twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
  82                 r &= ~PWM0_ENABLE;
  83                 r |= PWM0_CLK_ENABLE;
  84                 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  85                 r |= PWM0_ENABLE;
  86                 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  87
  88                 /*
  89                  * TI made it very easy to enable digital control, so easy that
  90                  * it often triggers unintentionally and disabes PWM control,
  91                  * so wait until 1 wire mode detection window ends.
  92                  */
  93                 usleep_range(2000, 10000);
  94         }
  95
  96         twl_i2c_write_u8(TWL_MODULE_PWM, MIN_VALUE + brightness, TWL_PWM0_OFF);
  97
  98 done:
  99         if (brightness != 0)
 100                 priv->old_state = 0;
 101         else
 102                 priv->old_state = PANDORABL_WAS_OFF;
 103
 104         return 0;
 105 }
 106
 107 static const struct backlight_ops pandora_backlight_ops = {
 108         .options        = BL_CORE_SUSPENDRESUME,
 109         .update_status  = pandora_backlight_update_status,
 110 };
 111
 112 static int pandora_backlight_probe(struct platform_device *pdev)
 113 {
 114         struct backlight_properties props;
 115         struct backlight_device *bl;
 116         struct pandora_private *priv;
 117         u8 r;
 118
 119         priv = devm_kmalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 120         if (!priv) {
 121                 dev_err(&pdev->dev, "failed to allocate driver private data\n");
 122                 return -ENOMEM;
 123         }
 124
 125         memset(&props, 0, sizeof(props));
 126         props.max_brightness = MAX_USER_VALUE;
 127         props.type = BACKLIGHT_RAW;
 128         bl = devm_backlight_device_register(&pdev->dev, pdev->name, &pdev->dev,
 129                                         priv, &pandora_backlight_ops, &props);
 130         if (IS_ERR(bl)) {
 131                 dev_err(&pdev->dev, "failed to register backlight\n");
 132                 return PTR_ERR(bl);
 133         }
 134
 135         platform_set_drvdata(pdev, bl);
 136
 137         /* 64 cycle period, ON position 0 */
 138         twl_i2c_write_u8(TWL_MODULE_PWM, 0x80, TWL_PWM0_ON);
 139
 140         priv->old_state = PANDORABL_WAS_OFF;
 141         bl->props.brightness = MAX_USER_VALUE;
 142         backlight_update_status(bl);
 143
 144         /* enable PWM function in pin mux */
 145         twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_PMBR1);
 146         r &= ~TWL_PMBR1_PWM0_MUXMASK;
 147         r |= TWL_PMBR1_PWM0;
 148         twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_PMBR1);
 149
 150         return 0;
 151 }
 152
 153 static struct platform_driver pandora_backlight_driver = {
 154         .driver         = {
 155                 .name   = "pandora-backlight",
 156         },
 157         .probe          = pandora_backlight_probe,
 158 };
 159
 160 module_platform_driver(pandora_backlight_driver);
 161
 162 MODULE_AUTHOR("Gražvydas Ignotas <notasas@gmail.com>");
 163 MODULE_DESCRIPTION("Pandora Backlight Driver");
 164 MODULE_LICENSE("GPL");
 165 MODULE_ALIAS("platform:pandora-backlight");