root/drivers/video/backlight/pandora_bl.c

DEFINITIONS

1. pandora_backlight_update_status
2. pandora_backlight_probe

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