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
  57         /* ignore fb blank for now
  58         if (bl->props.fb_blank != FB_BLANK_UNBLANK)
  59                 brightness = 0;
  60         */
  61
  62         if ((unsigned int)brightness > MAX_USER_VALUE)
  63                 brightness = MAX_USER_VALUE;
  64
  65         if (brightness == 0) {
  66                 if (old_brightness != 0)
  67                         pwm0_disable();
  68
  69                 goto done;
  70         }
  71
  72         if (old_brightness == 0) {
  73                 /* set PWM duty cycle to max. TPS61161 seems to use this
  74                  * to calibrate it's PWM sensitivity when it starts. */
  75                 twl_i2c_write_u8(TWL4030_MODULE_PWM0, MAX_VALUE,
  76                                         TWL_PWM0_OFF);
  77
  78                 /* first enable clock, then PWM0 out */
  79                 twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
  80                 r &= ~PWM0_ENABLE;
  81                 r |= PWM0_CLK_ENABLE;
  82                 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  83                 r |= PWM0_ENABLE;
  84                 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  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                 udelay(2000);
  90         }
  91
  92         twl_i2c_write_u8(TWL4030_MODULE_PWM0, MIN_VALUE + brightness,
  93                                 TWL_PWM0_OFF);
  94
  95 done:
  96         old_brightness = brightness;
  97         return 0;
  98 }
  99
 100 static int pwm0_backlight_get_brightness(struct backlight_device *bl)
 101 {
 102         return bl->props.brightness;
 103 }
 104
 105 static const struct backlight_ops pwm0_backlight_ops = {
 106         .update_status  = pwm0_backlight_update_status,
 107         .get_brightness = pwm0_backlight_get_brightness,
 108 };
 109
 110 static int pwm0_backlight_probe(struct platform_device *pdev)
 111 {
 112         struct backlight_properties props;
 113         struct backlight_device *bl;
 114         u8 r;
 115
 116         memset(&props, 0, sizeof(props));
 117         props.max_brightness = MAX_USER_VALUE;
 118         props.type = BACKLIGHT_RAW;
 119         bl = backlight_device_register(pdev->name, &pdev->dev,
 120                         NULL, &pwm0_backlight_ops, &props);
 121         if (IS_ERR(bl)) {
 122                 dev_err(&pdev->dev, "failed to register backlight\n");
 123                 return PTR_ERR(bl);
 124         }
 125
 126         /* 64 cycle period, ON position 0 */
 127         twl_i2c_write_u8(TWL4030_MODULE_PWM0, 0x80, TWL_PWM0_ON);
 128
 129         bl->props.brightness = MAX_USER_VALUE;
 130         backlight_update_status(bl);
 131
 132         /* enable PWM function in pin mux (i2c addr 0x49 0x92) */
 133         twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_PMBR1);
 134         r &= ~0x0c;
 135         r |= 0x04;
 136         twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_PMBR1);
 137
 138         return 0;
 139 }
 140
 141 static int pwm0_backlight_remove(struct platform_device *pdev)
 142 {
 143         struct backlight_device *bl = platform_get_drvdata(pdev);
 144         backlight_device_unregister(bl);
 145         return 0;
 146 }
 147
 148 #ifdef CONFIG_PM
 149 static int pwm0_backlight_suspend(struct platform_device *pdev,
 150                                  pm_message_t state)
 151 {
 152         pwm0_disable();
 153         old_brightness = 0;
 154
 155         return 0;
 156 }
 157
 158 static int pwm0_backlight_resume(struct platform_device *pdev)
 159 {
 160         struct backlight_device *bl = platform_get_drvdata(pdev);
 161
 162         backlight_update_status(bl);
 163         return 0;
 164 }
 165 #else
 166 #define pwm0_backlight_suspend  NULL
 167 #define pwm0_backlight_resume   NULL
 168 #endif
 169
 170 static struct platform_driver pwm0_backlight_driver = {
 171         .driver         = {
 172                 .name   = "twl4030-pwm0-bl",
 173                 .owner  = THIS_MODULE,
 174         },
 175         .probe          = pwm0_backlight_probe,
 176         .remove         = pwm0_backlight_remove,
 177         .suspend        = pwm0_backlight_suspend,
 178         .resume         = pwm0_backlight_resume,
 179 };
 180
 181 static int __init pwm0_backlight_init(void)
 182 {
 183         return platform_driver_register(&pwm0_backlight_driver);
 184 }
 185 module_init(pwm0_backlight_init);
 186
 187 static void __exit pwm0_backlight_exit(void)
 188 {
 189         platform_driver_unregister(&pwm0_backlight_driver);
 190 }
 191 module_exit(pwm0_backlight_exit);
 192
 193 MODULE_DESCRIPTION("TWL4030 PWM0 Backlight Driver");
 194 MODULE_LICENSE("GPL");
 195 MODULE_ALIAS("platform:twl4030-pwm0-bl");