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(TWL4030_MODULE_PWM0, MAX_VALUE,
  75                                         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(TWL4030_MODULE_PWM0, MIN_VALUE + brightness,
  94                                 TWL_PWM0_OFF);
  95
  96 done:
  97         if (brightness != 0)
  98                 bl->props.state &= ~PANDORABL_WAS_OFF;
  99         else
 100                 bl->props.state |= PANDORABL_WAS_OFF;
 101
 102         return 0;
 103 }
 104
 105 static int pandora_backlight_get_brightness(struct backlight_device *bl)
 106 {
 107         return bl->props.brightness;
 108 }
 109
 110 static const struct backlight_ops pandora_backlight_ops = {
 111         .options        = BL_CORE_SUSPENDRESUME,
 112         .update_status  = pandora_backlight_update_status,
 113         .get_brightness = pandora_backlight_get_brightness,
 114 };
 115
 116 static int pandora_backlight_probe(struct platform_device *pdev)
 117 {
 118         struct backlight_properties props;
 119         struct backlight_device *bl;
 120         u8 r;
 121
 122         memset(&props, 0, sizeof(props));
 123         props.max_brightness = MAX_USER_VALUE;
 124         props.type = BACKLIGHT_RAW;
 125         bl = backlight_device_register(pdev->name, &pdev->dev,
 126                         NULL, &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(TWL4030_MODULE_PWM0, 0x80, TWL_PWM0_ON);
 136
 137         bl->props.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 int pandora_backlight_remove(struct platform_device *pdev)
 151 {
 152         struct backlight_device *bl = platform_get_drvdata(pdev);
 153         backlight_device_unregister(bl);
 154         return 0;
 155 }
 156
 157 static struct platform_driver pandora_backlight_driver = {
 158         .driver         = {
 159                 .name   = "pandora-backlight",
 160                 .owner  = THIS_MODULE,
 161         },
 162         .probe          = pandora_backlight_probe,
 163         .remove         = pandora_backlight_remove,
 164 };
 165
 166 module_platform_driver(pandora_backlight_driver);
 167
 168 MODULE_AUTHOR("Gražvydas Ignotas <notasas@gmail.com>");
 169 MODULE_DESCRIPTION("Pandora Backlight Driver");
 170 MODULE_LICENSE("GPL");
 171 MODULE_ALIAS("platform:pandora-backlight");