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// SPDX-License-Identifier: GPL-2.0-only
/*
* Backlight Driver for Intel-based Apples
*
* Copyright (c) Red Hat <mjg@redhat.com>
* Based on code from Pommed:
* Copyright (C) 2006 Nicolas Boichat <nicolas @boichat.ch>
* Copyright (C) 2006 Felipe Alfaro Solana <felipe_alfaro @linuxmail.org>
* Copyright (C) 2007 Julien BLACHE <jb@jblache.org>
*
* This driver triggers SMIs which cause the firmware to change the
* backlight brightness. This is icky in many ways, but it's impractical to
* get at the firmware code in order to figure out what it's actually doing.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/backlight.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/pci.h>
#include <linux/acpi.h>
#include <linux/atomic.h>
#include <linux/apple_bl.h>
static struct backlight_device *apple_backlight_device;
struct hw_data {
/* I/O resource to allocate. */
unsigned long iostart;
unsigned long iolen;
/* Backlight operations structure. */
const struct backlight_ops backlight_ops;
void (*set_brightness)(int);
};
static const struct hw_data *hw_data;
/* Module parameters. */
static int debug;
module_param_named(debug, debug, int, 0644);
MODULE_PARM_DESC(debug, "Set to one to enable debugging messages.");
/*
* Implementation for machines with Intel chipset.
*/
static void intel_chipset_set_brightness(int intensity)
{
outb(0x04 | (intensity << 4), 0xb3);
outb(0xbf, 0xb2);
}
static int intel_chipset_send_intensity(struct backlight_device *bd)
{
int intensity = bd->props.brightness;
if (debug)
pr_debug("setting brightness to %d\n", intensity);
intel_chipset_set_brightness(intensity);
return 0;
}
static int intel_chipset_get_intensity(struct backlight_device *bd)
{
int intensity;
outb(0x03, 0xb3);
outb(0xbf, 0xb2);
intensity = inb(0xb3) >> 4;
if (debug)
pr_debug("read brightness of %d\n", intensity);
return intensity;
}
static const struct hw_data intel_chipset_data = {
.iostart = 0xb2,
.iolen = 2,
.backlight_ops = {
.options = BL_CORE_SUSPENDRESUME,
.get_brightness = intel_chipset_get_intensity,
.update_status = intel_chipset_send_intensity,
},
.set_brightness = intel_chipset_set_brightness,
};
/*
* Implementation for machines with Nvidia chipset.
*/
static void nvidia_chipset_set_brightness(int intensity)
{
outb(0x04 | (intensity << 4), 0x52f);
outb(0xbf, 0x52e);
}
static int nvidia_chipset_send_intensity(struct backlight_device *bd)
{
int intensity = bd->props.brightness;
if (debug)
pr_debug("setting brightness to %d\n", intensity);
nvidia_chipset_set_brightness(intensity);
return 0;
}
static int nvidia_chipset_get_intensity(struct backlight_device *bd)
{
int intensity;
outb(0x03, 0x52f);
outb(0xbf, 0x52e);
intensity = inb(0x52f) >> 4;
if (debug)
pr_debug("read brightness of %d\n", intensity);
return intensity;
}
static const struct hw_data nvidia_chipset_data = {
.iostart = 0x52e,
.iolen = 2,
.backlight_ops = {
.options = BL_CORE_SUSPENDRESUME,
.get_brightness = nvidia_chipset_get_intensity,
.update_status = nvidia_chipset_send_intensity
},
.set_brightness = nvidia_chipset_set_brightness,
};
static int apple_bl_add(struct acpi_device *dev)
{
struct backlight_properties props;
struct pci_dev *host;
int intensity;
host = pci_get_domain_bus_and_slot(0, 0, 0);
if (!host) {
pr_err("unable to find PCI host\n");
return -ENODEV;
}
if (host->vendor == PCI_VENDOR_ID_INTEL)
hw_data = &intel_chipset_data;
else if (host->vendor == PCI_VENDOR_ID_NVIDIA)
hw_data = &nvidia_chipset_data;
pci_dev_put(host);
if (!hw_data) {
pr_err("unknown hardware\n");
return -ENODEV;
}
/* Check that the hardware responds - this may not work under EFI */
intensity = hw_data->backlight_ops.get_brightness(NULL);
if (!intensity) {
hw_data->set_brightness(1);
if (!hw_data->backlight_ops.get_brightness(NULL))
return -ENODEV;
hw_data->set_brightness(0);
}
if (!request_region(hw_data->iostart, hw_data->iolen,
"Apple backlight"))
return -ENXIO;
memset(&props, 0, sizeof(struct backlight_properties));
props.type = BACKLIGHT_PLATFORM;
props.max_brightness = 15;
apple_backlight_device = backlight_device_register("apple_backlight",
NULL, NULL, &hw_data->backlight_ops, &props);
if (IS_ERR(apple_backlight_device)) {
release_region(hw_data->iostart, hw_data->iolen);
return PTR_ERR(apple_backlight_device);
}
apple_backlight_device->props.brightness =
hw_data->backlight_ops.get_brightness(apple_backlight_device);
backlight_update_status(apple_backlight_device);
return 0;
}
static void apple_bl_remove(struct acpi_device *dev)
{
backlight_device_unregister(apple_backlight_device);
release_region(hw_data->iostart, hw_data->iolen);
hw_data = NULL;
}
static const struct acpi_device_id apple_bl_ids[] = {
{"APP0002", 0},
{"", 0},
};
static struct acpi_driver apple_bl_driver = {
.name = "Apple backlight",
.ids = apple_bl_ids,
.ops = {
.add = apple_bl_add,
.remove = apple_bl_remove,
},
};
static atomic_t apple_bl_registered = ATOMIC_INIT(0);
int apple_bl_register(void)
{
if (atomic_xchg(&apple_bl_registered, 1) == 0)
return acpi_bus_register_driver(&apple_bl_driver);
return 0;
}
EXPORT_SYMBOL_GPL(apple_bl_register);
void apple_bl_unregister(void)
{
if (atomic_xchg(&apple_bl_registered, 0) == 1)
acpi_bus_unregister_driver(&apple_bl_driver);
}
EXPORT_SYMBOL_GPL(apple_bl_unregister);
static int __init apple_bl_init(void)
{
return apple_bl_register();
}
static void __exit apple_bl_exit(void)
{
apple_bl_unregister();
}
module_init(apple_bl_init);
module_exit(apple_bl_exit);
MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
MODULE_DESCRIPTION("Apple Backlight Driver");
MODULE_LICENSE("GPL");
MODULE_DEVICE_TABLE(acpi, apple_bl_ids);
MODULE_ALIAS("mbp_nvidia_bl");
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