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* Backlight Driver for Intel-based Apples
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* Copyright (c) Red Hat <mjg@redhat.com>
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* Based on code from Pommed:
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* Copyright (C) 2006 Nicolas Boichat <nicolas @boichat.ch>
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* Copyright (C) 2006 Felipe Alfaro Solana <felipe_alfaro @linuxmail.org>
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* Copyright (C) 2007 Julien BLACHE <jb@jblache.org>
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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* This driver triggers SMIs which cause the firmware to change the
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* backlight brightness. This is icky in many ways, but it's impractical to
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* get at the firmware code in order to figure out what it's actually doing.
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/backlight.h>
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#include <linux/err.h>
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#include <linux/pci.h>
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#include <linux/acpi.h>
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static struct backlight_device *apple_backlight_device;
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/* I/O resource to allocate. */
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unsigned long iostart;
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/* Backlight operations structure. */
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const struct backlight_ops backlight_ops;
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void (*set_brightness)(int);
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static const struct hw_data *hw_data;
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#define DRIVER "apple_backlight: "
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/* Module parameters. */
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module_param_named(debug, debug, int, 0644);
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MODULE_PARM_DESC(debug, "Set to one to enable debugging messages.");
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* Implementation for machines with Intel chipset.
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static void intel_chipset_set_brightness(int intensity)
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outb(0x04 | (intensity << 4), 0xb3);
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static int intel_chipset_send_intensity(struct backlight_device *bd)
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int intensity = bd->props.brightness;
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printk(KERN_DEBUG DRIVER "setting brightness to %d\n",
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intel_chipset_set_brightness(intensity);
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static int intel_chipset_get_intensity(struct backlight_device *bd)
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intensity = inb(0xb3) >> 4;
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printk(KERN_DEBUG DRIVER "read brightness of %d\n",
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static const struct hw_data intel_chipset_data = {
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.options = BL_CORE_SUSPENDRESUME,
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.get_brightness = intel_chipset_get_intensity,
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.update_status = intel_chipset_send_intensity,
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.set_brightness = intel_chipset_set_brightness,
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* Implementation for machines with Nvidia chipset.
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static void nvidia_chipset_set_brightness(int intensity)
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outb(0x04 | (intensity << 4), 0x52f);
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static int nvidia_chipset_send_intensity(struct backlight_device *bd)
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int intensity = bd->props.brightness;
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printk(KERN_DEBUG DRIVER "setting brightness to %d\n",
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nvidia_chipset_set_brightness(intensity);
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static int nvidia_chipset_get_intensity(struct backlight_device *bd)
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intensity = inb(0x52f) >> 4;
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printk(KERN_DEBUG DRIVER "read brightness of %d\n",
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static const struct hw_data nvidia_chipset_data = {
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.options = BL_CORE_SUSPENDRESUME,
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.get_brightness = nvidia_chipset_get_intensity,
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.update_status = nvidia_chipset_send_intensity
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.set_brightness = nvidia_chipset_set_brightness,
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static int __devinit apple_bl_add(struct acpi_device *dev)
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struct backlight_properties props;
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struct pci_dev *host;
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host = pci_get_bus_and_slot(0, 0);
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printk(KERN_ERR DRIVER "unable to find PCI host\n");
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if (host->vendor == PCI_VENDOR_ID_INTEL)
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hw_data = &intel_chipset_data;
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else if (host->vendor == PCI_VENDOR_ID_NVIDIA)
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hw_data = &nvidia_chipset_data;
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printk(KERN_ERR DRIVER "unknown hardware\n");
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/* Check that the hardware responds - this may not work under EFI */
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intensity = hw_data->backlight_ops.get_brightness(NULL);
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hw_data->set_brightness(1);
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if (!hw_data->backlight_ops.get_brightness(NULL))
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hw_data->set_brightness(0);
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if (!request_region(hw_data->iostart, hw_data->iolen,
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memset(&props, 0, sizeof(struct backlight_properties));
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props.type = BACKLIGHT_PLATFORM;
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props.max_brightness = 15;
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apple_backlight_device = backlight_device_register("apple_backlight",
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NULL, NULL, &hw_data->backlight_ops, &props);
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if (IS_ERR(apple_backlight_device)) {
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release_region(hw_data->iostart, hw_data->iolen);
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return PTR_ERR(apple_backlight_device);
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apple_backlight_device->props.brightness =
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hw_data->backlight_ops.get_brightness(apple_backlight_device);
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backlight_update_status(apple_backlight_device);
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static int __devexit apple_bl_remove(struct acpi_device *dev, int type)
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backlight_device_unregister(apple_backlight_device);
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release_region(hw_data->iostart, hw_data->iolen);
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static const struct acpi_device_id apple_bl_ids[] = {
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static struct acpi_driver apple_bl_driver = {
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.name = "Apple backlight",
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.remove = apple_bl_remove,
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static int __init apple_bl_init(void)
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return acpi_bus_register_driver(&apple_bl_driver);
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static void __exit apple_bl_exit(void)
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acpi_bus_unregister_driver(&apple_bl_driver);
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module_init(apple_bl_init);
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module_exit(apple_bl_exit);
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MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
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MODULE_DESCRIPTION("Apple Backlight Driver");
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MODULE_LICENSE("GPL");
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MODULE_DEVICE_TABLE(acpi, apple_bl_ids);
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MODULE_ALIAS("mbp_nvidia_bl");