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/i2c/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#define PANDORABL_WAS_OFF BL_CORE_DRIVER1
  39
  40static int pandora_backlight_update_status(struct backlight_device *bl)
  41{
  42        int brightness = bl->props.brightness;
  43        u8 r;
  44
  45        if (bl->props.power != FB_BLANK_UNBLANK)
  46                brightness = 0;
  47        if (bl->props.state & BL_CORE_FBBLANK)
  48                brightness = 0;
  49        if (bl->props.state & BL_CORE_SUSPENDED)
  50                brightness = 0;
  51
  52        if ((unsigned int)brightness > MAX_USER_VALUE)
  53                brightness = MAX_USER_VALUE;
  54
  55        if (brightness == 0) {
  56                if (bl->props.state & PANDORABL_WAS_OFF)
  57                        goto done;
  58
  59                /* first disable PWM0 output, then clock */
  60                twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
  61                r &= ~PWM0_ENABLE;
  62                twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  63                r &= ~PWM0_CLK_ENABLE;
  64                twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  65
  66                goto done;
  67        }
  68
  69        if (bl->props.state & PANDORABL_WAS_OFF) {
  70                /*
  71                 * set PWM duty cycle to max. TPS61161 seems to use this
  72                 * to calibrate it's PWM sensitivity when it starts.
  73                 */
  74                twl_i2c_write_u8(TWL_MODULE_PWM, MAX_VALUE, TWL_PWM0_OFF);
  75
  76                /* first enable clock, then PWM0 out */
  77                twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
  78                r &= ~PWM0_ENABLE;
  79                r |= PWM0_CLK_ENABLE;
  80                twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  81                r |= PWM0_ENABLE;
  82                twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  83
  84                /*
  85                 * TI made it very easy to enable digital control, so easy that
  86                 * it often triggers unintentionally and disabes PWM control,
  87                 * so wait until 1 wire mode detection window ends.
  88                 */
  89                usleep_range(2000, 10000);
  90        }
  91
  92        twl_i2c_write_u8(TWL_MODULE_PWM, MIN_VALUE + brightness, TWL_PWM0_OFF);
  93
  94done:
  95        if (brightness != 0)
  96                bl->props.state &= ~PANDORABL_WAS_OFF;
  97        else
  98                bl->props.state |= PANDORABL_WAS_OFF;
  99
 100        return 0;
 101}
 102
 103static const struct backlight_ops pandora_backlight_ops = {
 104        .options        = BL_CORE_SUSPENDRESUME,
 105        .update_status  = pandora_backlight_update_status,
 106};
 107
 108static int pandora_backlight_probe(struct platform_device *pdev)
 109{
 110        struct backlight_properties props;
 111        struct backlight_device *bl;
 112        u8 r;
 113
 114        memset(&props, 0, sizeof(props));
 115        props.max_brightness = MAX_USER_VALUE;
 116        props.type = BACKLIGHT_RAW;
 117        bl = devm_backlight_device_register(&pdev->dev, pdev->name, &pdev->dev,
 118                                        NULL, &pandora_backlight_ops, &props);
 119        if (IS_ERR(bl)) {
 120                dev_err(&pdev->dev, "failed to register backlight\n");
 121                return PTR_ERR(bl);
 122        }
 123
 124        platform_set_drvdata(pdev, bl);
 125
 126        /* 64 cycle period, ON position 0 */
 127        twl_i2c_write_u8(TWL_MODULE_PWM, 0x80, TWL_PWM0_ON);
 128
 129        bl->props.state |= PANDORABL_WAS_OFF;
 130        bl->props.brightness = MAX_USER_VALUE;
 131        backlight_update_status(bl);
 132
 133        /* enable PWM function in pin mux */
 134        twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_PMBR1);
 135        r &= ~TWL_PMBR1_PWM0_MUXMASK;
 136        r |= TWL_PMBR1_PWM0;
 137        twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_PMBR1);
 138
 139        return 0;
 140}
 141
 142static struct platform_driver pandora_backlight_driver = {
 143        .driver         = {
 144                .name   = "pandora-backlight",
 145        },
 146        .probe          = pandora_backlight_probe,
 147};
 148
 149module_platform_driver(pandora_backlight_driver);
 150
 151MODULE_AUTHOR("Gražvydas Ignotas <notasas@gmail.com>");
 152MODULE_DESCRIPTION("Pandora Backlight Driver");
 153MODULE_LICENSE("GPL");
 154MODULE_ALIAS("platform:pandora-backlight");
 155