drivers/video/backlight/pandora_bl.c

   1 /*
   2  * Backlight driver for TWL4030 PWM0 -> TPS61161 combo.
   3  * Based on pwm_bl.c
   4  *
   5  * Author: Gražvydas Ignotas <notasas@gmail.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/kernel.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/delay.h>
  16 #include <linux/fb.h>
  17 #include <linux/backlight.h>
  18 #include <linux/i2c/twl.h>
  19 #include <linux/err.h>
  20
  21 #define TWL_PWM0_ON     0x00
  22 #define TWL_PWM0_OFF    0x01
  23
  24 #define TWL_INTBR_GPBR1 0x0c
  25 #define TWL_INTBR_PMBR1 0x0d
  26
  27 #define PWM0_CLK_ENABLE 1
  28 #define PWM0_ENABLE     4
  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 static int old_brightness;
  36
  37 static void pwm0_disable(void)
  38 {
  39         u8 r;
  40
  41         /* first disable PWM0 output, then clock */
  42         twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
  43         r &= ~PWM0_ENABLE;
  44         twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  45         r &= ~PWM0_CLK_ENABLE;
  46         twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  47 }
  48
  49 static int pwm0_backlight_update_status(struct backlight_device *bl)
  50 {
  51         int brightness = bl->props.brightness;
  52         u8 r;
  53
  54         if (bl->props.power != FB_BLANK_UNBLANK)
  55                 brightness = 0;
  56         if (bl->props.state & BL_CORE_SUSPENDED)
  57                 brightness = 0;
  58
  59         /* ignore fb blank for now
  60         if (bl->props.fb_blank != FB_BLANK_UNBLANK)
  61                 brightness = 0;
  62         */
  63
  64         if ((unsigned int)brightness > MAX_USER_VALUE)
  65                 brightness = MAX_USER_VALUE;
  66
  67         if (brightness == 0) {
  68                 if (old_brightness != 0)
  69                         pwm0_disable();
  70
  71                 goto done;
  72         }
  73
  74         if (old_brightness == 0) {
  75                 /* set PWM duty cycle to max. TPS61161 seems to use this
  76                  * to calibrate it's PWM sensitivity when it starts. */
  77                 twl_i2c_write_u8(TWL4030_MODULE_PWM0, MAX_VALUE,
  78                                         TWL_PWM0_OFF);
  79
  80                 /* first enable clock, then PWM0 out */
  81                 twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
  82                 r &= ~PWM0_ENABLE;
  83                 r |= PWM0_CLK_ENABLE;
  84                 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  85                 r |= PWM0_ENABLE;
  86                 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  87
  88                 /* TI made it very easy to enable digital control, so easy that
  89                  * it often triggers unintentionally and disabes PWM control,
  90                  * so wait until 1 wire mode detection window ends. */
  91                 udelay(2000);
  92         }
  93
  94         twl_i2c_write_u8(TWL4030_MODULE_PWM0, MIN_VALUE + brightness,
  95                                 TWL_PWM0_OFF);
  96
  97 done:
  98         old_brightness = brightness;
  99         return 0;
 100 }
 101
 102 static int pwm0_backlight_get_brightness(struct backlight_device *bl)
 103 {
 104         return bl->props.brightness;
 105 }
 106
 107 static const struct backlight_ops pwm0_backlight_ops = {
 108         .options        = BL_CORE_SUSPENDRESUME,
 109         .update_status  = pwm0_backlight_update_status,
 110         .get_brightness = pwm0_backlight_get_brightness,
 111 };
 112
 113 static int pwm0_backlight_probe(struct platform_device *pdev)
 114 {
 115         struct backlight_properties props;
 116         struct backlight_device *bl;
 117         u8 r;
 118
 119         memset(&props, 0, sizeof(props));
 120         props.max_brightness = MAX_USER_VALUE;
 121         props.type = BACKLIGHT_RAW;
 122         bl = backlight_device_register(pdev->name, &pdev->dev,
 123                         NULL, &pwm0_backlight_ops, &props);
 124         if (IS_ERR(bl)) {
 125                 dev_err(&pdev->dev, "failed to register backlight\n");
 126                 return PTR_ERR(bl);
 127         }
 128
 129         platform_set_drvdata(pdev, bl);
 130
 131         /* 64 cycle period, ON position 0 */
 132         twl_i2c_write_u8(TWL4030_MODULE_PWM0, 0x80, TWL_PWM0_ON);
 133
 134         bl->props.brightness = MAX_USER_VALUE;
 135         backlight_update_status(bl);
 136
 137         /* enable PWM function in pin mux (i2c addr 0x49 0x92) */
 138         twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_PMBR1);
 139         r &= ~0x0c;
 140         r |= 0x04;
 141         twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_PMBR1);
 142
 143         return 0;
 144 }
 145
 146 static int pwm0_backlight_remove(struct platform_device *pdev)
 147 {
 148         struct backlight_device *bl = platform_get_drvdata(pdev);
 149         backlight_device_unregister(bl);
 150         return 0;
 151 }
 152
 153 static struct platform_driver pwm0_backlight_driver = {
 154         .driver         = {
 155                 .name   = "twl4030-pwm0-bl",
 156                 .owner  = THIS_MODULE,
 157         },
 158         .probe          = pwm0_backlight_probe,
 159         .remove         = pwm0_backlight_remove,
 160 };
 161
 162 static int __init pwm0_backlight_init(void)
 163 {
 164         return platform_driver_register(&pwm0_backlight_driver);
 165 }
 166 module_init(pwm0_backlight_init);
 167
 168 static void __exit pwm0_backlight_exit(void)
 169 {
 170         platform_driver_unregister(&pwm0_backlight_driver);
 171 }
 172 module_exit(pwm0_backlight_exit);
 173
 174 MODULE_DESCRIPTION("TWL4030 PWM0 Backlight Driver");
 175 MODULE_LICENSE("GPL");
 176 MODULE_ALIAS("platform:twl4030-pwm0-bl");