drivers/video/backlight/ot200_bl.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2012 Bachmann electronic GmbH
   4  *      Christian Gmeiner <christian.gmeiner@gmail.com>
   5  *
   6  * Backlight driver for ot200 visualisation device from
   7  * Bachmann electronic GmbH.
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/fb.h>
  12 #include <linux/backlight.h>
  13 #include <linux/gpio.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/cs5535.h>
  16
  17 static struct cs5535_mfgpt_timer *pwm_timer;
  18
  19 /* this array defines the mapping of brightness in % to pwm frequency */
  20 static const u8 dim_table[101] = {0, 0, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2,
  21                                   2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4,
  22                                   4, 5, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 9, 9,
  23                                   10, 10, 11, 11, 12, 12, 13, 14, 15, 15, 16,
  24                                   17, 18, 19, 20, 21, 22, 23, 24, 26, 27, 28,
  25                                   30, 31, 33, 35, 37, 39, 41, 43, 45, 47, 50,
  26                                   53, 55, 58, 61, 65, 68, 72, 75, 79, 84, 88,
  27                                   93, 97, 103, 108, 114, 120, 126, 133, 140,
  28                                   147, 155, 163};
  29
  30 struct ot200_backlight_data {
  31         int current_brightness;
  32 };
  33
  34 #define GPIO_DIMM       27
  35 #define SCALE           1
  36 #define CMP1MODE        0x2     /* compare on GE; output high on compare
  37                                  * greater than or equal */
  38 #define PWM_SETUP       (SCALE | CMP1MODE << 6 | MFGPT_SETUP_CNTEN)
  39 #define MAX_COMP2       163
  40
  41 static int ot200_backlight_update_status(struct backlight_device *bl)
  42 {
  43         struct ot200_backlight_data *data = bl_get_data(bl);
  44         int brightness = bl->props.brightness;
  45
  46         if (bl->props.state & BL_CORE_FBBLANK)
  47                 brightness = 0;
  48
  49         /* enable or disable PWM timer */
  50         if (brightness == 0)
  51                 cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP, 0);
  52         else if (data->current_brightness == 0) {
  53                 cs5535_mfgpt_write(pwm_timer, MFGPT_REG_COUNTER, 0);
  54                 cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP,
  55                         MFGPT_SETUP_CNTEN);
  56         }
  57
  58         /* apply new brightness value */
  59         cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP1,
  60                 MAX_COMP2 - dim_table[brightness]);
  61         data->current_brightness = brightness;
  62
  63         return 0;
  64 }
  65
  66 static int ot200_backlight_get_brightness(struct backlight_device *bl)
  67 {
  68         struct ot200_backlight_data *data = bl_get_data(bl);
  69         return data->current_brightness;
  70 }
  71
  72 static const struct backlight_ops ot200_backlight_ops = {
  73         .update_status  = ot200_backlight_update_status,
  74         .get_brightness = ot200_backlight_get_brightness,
  75 };
  76
  77 static int ot200_backlight_probe(struct platform_device *pdev)
  78 {
  79         struct backlight_device *bl;
  80         struct ot200_backlight_data *data;
  81         struct backlight_properties props;
  82         int retval = 0;
  83
  84         /* request gpio */
  85         if (devm_gpio_request(&pdev->dev, GPIO_DIMM,
  86                                 "ot200 backlight dimmer") < 0) {
  87                 dev_err(&pdev->dev, "failed to request GPIO %d\n", GPIO_DIMM);
  88                 return -ENODEV;
  89         }
  90
  91         /* request timer */
  92         pwm_timer = cs5535_mfgpt_alloc_timer(7, MFGPT_DOMAIN_ANY);
  93         if (!pwm_timer) {
  94                 dev_err(&pdev->dev, "MFGPT 7 not available\n");
  95                 return -ENODEV;
  96         }
  97
  98         data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
  99         if (!data) {
 100                 retval = -ENOMEM;
 101                 goto error_devm_kzalloc;
 102         }
 103
 104         /* setup gpio */
 105         cs5535_gpio_set(GPIO_DIMM, GPIO_OUTPUT_ENABLE);
 106         cs5535_gpio_set(GPIO_DIMM, GPIO_OUTPUT_AUX1);
 107
 108         /* setup timer */
 109         cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP1, 0);
 110         cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP2, MAX_COMP2);
 111         cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP, PWM_SETUP);
 112
 113         data->current_brightness = 100;
 114         props.max_brightness = 100;
 115         props.brightness = 100;
 116         props.type = BACKLIGHT_RAW;
 117
 118         bl = devm_backlight_device_register(&pdev->dev, dev_name(&pdev->dev),
 119                                         &pdev->dev, data, &ot200_backlight_ops,
 120                                         &props);
 121         if (IS_ERR(bl)) {
 122                 dev_err(&pdev->dev, "failed to register backlight\n");
 123                 retval = PTR_ERR(bl);
 124                 goto error_devm_kzalloc;
 125         }
 126
 127         platform_set_drvdata(pdev, bl);
 128
 129         return 0;
 130
 131 error_devm_kzalloc:
 132         cs5535_mfgpt_free_timer(pwm_timer);
 133         return retval;
 134 }
 135
 136 static int ot200_backlight_remove(struct platform_device *pdev)
 137 {
 138         /* on module unload set brightness to 100% */
 139         cs5535_mfgpt_write(pwm_timer, MFGPT_REG_COUNTER, 0);
 140         cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);
 141         cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP1,
 142                 MAX_COMP2 - dim_table[100]);
 143
 144         cs5535_mfgpt_free_timer(pwm_timer);
 145
 146         return 0;
 147 }
 148
 149 static struct platform_driver ot200_backlight_driver = {
 150         .driver         = {
 151                 .name   = "ot200-backlight",
 152         },
 153         .probe          = ot200_backlight_probe,
 154         .remove         = ot200_backlight_remove,
 155 };
 156
 157 module_platform_driver(ot200_backlight_driver);
 158
 159 MODULE_DESCRIPTION("backlight driver for ot200 visualisation device");
 160 MODULE_AUTHOR("Christian Gmeiner <christian.gmeiner@gmail.com>");
 161 MODULE_LICENSE("GPL");
 162 MODULE_ALIAS("platform:ot200-backlight");