LXR linux/drivers/video/backlight/pandora

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Backlight driver for Pandora handheld.
   4 * Pandora uses TWL4030 PWM0 -> TPS61161 combo for control backlight.
   5 * Based on pwm_bl.c
   6 *
   7 * Copyright 2009,2012 Gražvydas Ignotas <notasas@gmail.com>
   8 */
   9
  10#include <linux/module.h>
  11#include <linux/kernel.h>
  12#include <linux/platform_device.h>
  13#include <linux/delay.h>
  14#include <linux/fb.h>
  15#include <linux/backlight.h>
  16#include <linux/mfd/twl.h>
  17#include <linux/err.h>
  18
  19#define TWL_PWM0_ON             0x00
  20#define TWL_PWM0_OFF            0x01
  21
  22#define TWL_INTBR_GPBR1         0x0c
  23#define TWL_INTBR_PMBR1         0x0d
  24
  25#define TWL_PMBR1_PWM0_MUXMASK  0x0c
  26#define TWL_PMBR1_PWM0          0x04
  27#define PWM0_CLK_ENABLE         BIT(0)
  28#define PWM0_ENABLE             BIT(2)
  29
  30/* range accepted by hardware */
  31#define MIN_VALUE 9
  32#define MAX_VALUE 63
  33#define MAX_USER_VALUE (MAX_VALUE - MIN_VALUE)
  34
  35struct pandora_private {
  36        unsigned old_state;
  37#define PANDORABL_WAS_OFF 1
  38};
  39
  40static int pandora_backlight_update_status(struct backlight_device *bl)
  41{
  42        int brightness = bl->props.brightness;
  43        struct pandora_private *priv = bl_get_data(bl);
  44        u8 r;
  45
  46        if (bl->props.power != FB_BLANK_UNBLANK)
  47                brightness = 0;
  48        if (bl->props.state & BL_CORE_FBBLANK)
  49                brightness = 0;
  50        if (bl->props.state & BL_CORE_SUSPENDED)
  51                brightness = 0;
  52
  53        if ((unsigned int)brightness > MAX_USER_VALUE)
  54                brightness = MAX_USER_VALUE;
  55
  56        if (brightness == 0) {
  57                if (priv->old_state == PANDORABL_WAS_OFF)
  58                        goto done;
  59
  60                /* first disable PWM0 output, then clock */
  61                twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
  62                r &= ~PWM0_ENABLE;
  63                twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  64                r &= ~PWM0_CLK_ENABLE;
  65                twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  66
  67                goto done;
  68        }
  69
  70        if (priv->old_state == PANDORABL_WAS_OFF) {
  71                /*
  72                 * set PWM duty cycle to max. TPS61161 seems to use this
  73                 * to calibrate it's PWM sensitivity when it starts.
  74                 */
  75                twl_i2c_write_u8(TWL_MODULE_PWM, MAX_VALUE, TWL_PWM0_OFF);
  76
  77                /* first enable clock, then PWM0 out */
  78                twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
  79                r &= ~PWM0_ENABLE;
  80                r |= PWM0_CLK_ENABLE;
  81                twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  82                r |= PWM0_ENABLE;
  83                twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  84
  85                /*
  86                 * TI made it very easy to enable digital control, so easy that
  87                 * it often triggers unintentionally and disabes PWM control,
  88                 * so wait until 1 wire mode detection window ends.
  89                 */
  90                usleep_range(2000, 10000);
  91        }
  92
  93        twl_i2c_write_u8(TWL_MODULE_PWM, MIN_VALUE + brightness, TWL_PWM0_OFF);
  94
  95done:
  96        if (brightness != 0)
  97                priv->old_state = 0;
  98        else
  99                priv->old_state = PANDORABL_WAS_OFF;
 100
 101        return 0;
 102}
 103
 104static const struct backlight_ops pandora_backlight_ops = {
 105        .options        = BL_CORE_SUSPENDRESUME,
 106        .update_status  = pandora_backlight_update_status,
 107};
 108
 109static int pandora_backlight_probe(struct platform_device *pdev)
 110{
 111        struct backlight_properties props;
 112        struct backlight_device *bl;
 113        struct pandora_private *priv;
 114        u8 r;
 115
 116        priv = devm_kmalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 117        if (!priv) {
 118                dev_err(&pdev->dev, "failed to allocate driver private data\n");
 119                return -ENOMEM;
 120        }
 121
 122        memset(&props, 0, sizeof(props));
 123        props.max_brightness = MAX_USER_VALUE;
 124        props.type = BACKLIGHT_RAW;
 125        bl = devm_backlight_device_register(&pdev->dev, pdev->name, &pdev->dev,
 126                                        priv, &pandora_backlight_ops, &props);
 127        if (IS_ERR(bl)) {
 128                dev_err(&pdev->dev, "failed to register backlight\n");
 129                return PTR_ERR(bl);
 130        }
 131
 132        platform_set_drvdata(pdev, bl);
 133
 134        /* 64 cycle period, ON position 0 */
 135        twl_i2c_write_u8(TWL_MODULE_PWM, 0x80, TWL_PWM0_ON);
 136
 137        priv->old_state = PANDORABL_WAS_OFF;
 138        bl->props.brightness = MAX_USER_VALUE;
 139        backlight_update_status(bl);
 140
 141        /* enable PWM function in pin mux */
 142        twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_PMBR1);
 143        r &= ~TWL_PMBR1_PWM0_MUXMASK;
 144        r |= TWL_PMBR1_PWM0;
 145        twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_PMBR1);
 146
 147        return 0;
 148}
 149
 150static struct platform_driver pandora_backlight_driver = {
 151        .driver         = {
 152                .name   = "pandora-backlight",
 153        },
 154        .probe          = pandora_backlight_probe,
 155};
 156
 157module_platform_driver(pandora_backlight_driver);
 158
 159MODULE_AUTHOR("Gražvydas Ignotas <notasas@gmail.com>");
 160MODULE_DESCRIPTION("Pandora Backlight Driver");
 161MODULE_LICENSE("GPL");
 162MODULE_ALIAS("platform:pandora-backlight");
 163