LXR linux/drivers/video/backlight/pandora

   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
  38struct pandora_private {
  39        unsigned old_state;
  40#define PANDORABL_WAS_OFF 1
  41};
  42
  43static 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
  98done:
  99        if (brightness != 0)
 100                priv->old_state = 0;
 101        else
 102                priv->old_state = PANDORABL_WAS_OFF;
 103
 104        return 0;
 105}
 106
 107static const struct backlight_ops pandora_backlight_ops = {
 108        .options        = BL_CORE_SUSPENDRESUME,
 109        .update_status  = pandora_backlight_update_status,
 110};
 111
 112static 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
 153static struct platform_driver pandora_backlight_driver = {
 154        .driver         = {
 155                .name   = "pandora-backlight",
 156        },
 157        .probe          = pandora_backlight_probe,
 158};
 159
 160module_platform_driver(pandora_backlight_driver);
 161
 162MODULE_AUTHOR("Gražvydas Ignotas <notasas@gmail.com>");
 163MODULE_DESCRIPTION("Pandora Backlight Driver");
 164MODULE_LICENSE("GPL");
 165MODULE_ALIAS("platform:pandora-backlight");
 166