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/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
  40 static 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
  94 done:
  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
 103 static const struct backlight_ops pandora_backlight_ops = {
 104         .options        = BL_CORE_SUSPENDRESUME,
 105         .update_status  = pandora_backlight_update_status,
 106 };
 107
 108 static 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
 142 static struct platform_driver pandora_backlight_driver = {
 143         .driver         = {
 144                 .name   = "pandora-backlight",
 145         },
 146         .probe          = pandora_backlight_probe,
 147 };
 148
 149 module_platform_driver(pandora_backlight_driver);
 150
 151 MODULE_AUTHOR("Gražvydas Ignotas <notasas@gmail.com>");
 152 MODULE_DESCRIPTION("Pandora Backlight Driver");
 153 MODULE_LICENSE("GPL");
 154 MODULE_ALIAS("platform:pandora-backlight");