LXR linux/drivers/video/backlight/ot200

   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
  17static struct cs5535_mfgpt_timer *pwm_timer;
  18
  19/* this array defines the mapping of brightness in % to pwm frequency */
  20static 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
  30struct 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
  41static 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
  66static 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
  72static const struct backlight_ops ot200_backlight_ops = {
  73        .update_status  = ot200_backlight_update_status,
  74        .get_brightness = ot200_backlight_get_brightness,
  75};
  76
  77static 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
 131error_devm_kzalloc:
 132        cs5535_mfgpt_free_timer(pwm_timer);
 133        return retval;
 134}
 135
 136static 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
 149static 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
 157module_platform_driver(ot200_backlight_driver);
 158
 159MODULE_DESCRIPTION("backlight driver for ot200 visualisation device");
 160MODULE_AUTHOR("Christian Gmeiner <christian.gmeiner@gmail.com>");
 161MODULE_LICENSE("GPL");
 162MODULE_ALIAS("platform:ot200-backlight");
 163