Quelle  hid-picolcd_backlight.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-only
/***************************************************************************
 *   Copyright (C) 2010-2012 by Bruno Prémont <bonbons@linux-vserver.org>  *
 *                                                                         *
 *   Based on Logitech G13 driver (v0.4)                                   *
 *     Copyright (C) 2009 by Rick L. Vinyard, Jr. <rvinyard@cs.nmsu.edu>   *
 *                                                                         *
 ***************************************************************************/

#include <linux/hid.h>

#include <linux/backlight.h>

#include "hid-picolcd.h"

static int picolcd_get_brightness(struct backlight_device *bdev)
{
 struct picolcd_data *data = bl_get_data(bdev);
 return data->lcd_brightness;
}

static int picolcd_set_brightness(struct backlight_device *bdev)
{
 struct picolcd_data *data = bl_get_data(bdev);
 struct hid_report *report = picolcd_out_report(REPORT_BRIGHTNESS, data->hdev);
 unsigned long flags;

 if (!report || report->maxfield != 1 || report->field[0]->report_count != 1)
  return -ENODEV;

 data->lcd_brightness = bdev->props.brightness & 0x0ff;
 data->lcd_power      = bdev->props.power;
 spin_lock_irqsave(&data->lock, flags);
 hid_set_field(report->field[0], 0,
        data->lcd_power == BACKLIGHT_POWER_ON ? data->lcd_brightness : 0);
 if (!(data->status & PICOLCD_FAILED))
  hid_hw_request(data->hdev, report, HID_REQ_SET_REPORT);
 spin_unlock_irqrestore(&data->lock, flags);
 return 0;
}

static const struct backlight_ops picolcd_blops = {
 .update_status  = picolcd_set_brightness,
 .get_brightness = picolcd_get_brightness,
};

int picolcd_init_backlight(struct picolcd_data *data, struct hid_report *report)
{
 struct device *dev = &data->hdev->dev;
 struct backlight_device *bdev;
 struct backlight_properties props;
 if (!report)
  return -ENODEV;
 if (report->maxfield != 1 || report->field[0]->report_count != 1 ||
   report->field[0]->report_size != 8) {
  dev_err(dev, "unsupported BRIGHTNESS report");
  return -EINVAL;
 }

 memset(&props, 0, sizeof(props));
 props.type = BACKLIGHT_RAW;
 props.max_brightness = 0xff;
 bdev = backlight_device_register(dev_name(dev), dev, data,
   &picolcd_blops, &props);
 if (IS_ERR(bdev)) {
  dev_err(dev, "failed to register backlight\n");
  return PTR_ERR(bdev);
 }
 bdev->props.brightness     = 0xff;
 data->lcd_brightness       = 0xff;
 data->backlight            = bdev;
 picolcd_set_brightness(bdev);
 return 0;
}

void picolcd_exit_backlight(struct picolcd_data *data)
{
 struct backlight_device *bdev = data->backlight;

 data->backlight = NULL;
 backlight_device_unregister(bdev);
}

int picolcd_resume_backlight(struct picolcd_data *data)
{
 if (!data->backlight)
  return 0;
 return picolcd_set_brightness(data->backlight);
}

#ifdef CONFIG_PM
void picolcd_suspend_backlight(struct picolcd_data *data)
{
 int bl_power = data->lcd_power;
 if (!data->backlight)
  return;

 data->backlight->props.power = BACKLIGHT_POWER_OFF;
 picolcd_set_brightness(data->backlight);
 data->lcd_power = data->backlight->props.power = bl_power;
}
#endif /* CONFIG_PM */