linux/drivers/video/backlight/apple_bl.c
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   1/*
   2 *  Backlight Driver for Intel-based Apples
   3 *
   4 *  Copyright (c) Red Hat <mjg@redhat.com>
   5 *  Based on code from Pommed:
   6 *  Copyright (C) 2006 Nicolas Boichat <nicolas @boichat.ch>
   7 *  Copyright (C) 2006 Felipe Alfaro Solana <felipe_alfaro @linuxmail.org>
   8 *  Copyright (C) 2007 Julien BLACHE <jb@jblache.org>
   9 *
  10 *  This program is free software; you can redistribute it and/or modify
  11 *  it under the terms of the GNU General Public License version 2 as
  12 *  published by the Free Software Foundation.
  13 *
  14 *  This driver triggers SMIs which cause the firmware to change the
  15 *  backlight brightness. This is icky in many ways, but it's impractical to
  16 *  get at the firmware code in order to figure out what it's actually doing.
  17 */
  18
  19#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  20
  21#include <linux/module.h>
  22#include <linux/kernel.h>
  23#include <linux/init.h>
  24#include <linux/backlight.h>
  25#include <linux/err.h>
  26#include <linux/io.h>
  27#include <linux/pci.h>
  28#include <linux/acpi.h>
  29#include <linux/atomic.h>
  30#include <linux/apple_bl.h>
  31
  32static struct backlight_device *apple_backlight_device;
  33
  34struct hw_data {
  35        /* I/O resource to allocate. */
  36        unsigned long iostart;
  37        unsigned long iolen;
  38        /* Backlight operations structure. */
  39        const struct backlight_ops backlight_ops;
  40        void (*set_brightness)(int);
  41};
  42
  43static const struct hw_data *hw_data;
  44
  45/* Module parameters. */
  46static int debug;
  47module_param_named(debug, debug, int, 0644);
  48MODULE_PARM_DESC(debug, "Set to one to enable debugging messages.");
  49
  50/*
  51 * Implementation for machines with Intel chipset.
  52 */
  53static void intel_chipset_set_brightness(int intensity)
  54{
  55        outb(0x04 | (intensity << 4), 0xb3);
  56        outb(0xbf, 0xb2);
  57}
  58
  59static int intel_chipset_send_intensity(struct backlight_device *bd)
  60{
  61        int intensity = bd->props.brightness;
  62
  63        if (debug)
  64                pr_debug("setting brightness to %d\n", intensity);
  65
  66        intel_chipset_set_brightness(intensity);
  67        return 0;
  68}
  69
  70static int intel_chipset_get_intensity(struct backlight_device *bd)
  71{
  72        int intensity;
  73
  74        outb(0x03, 0xb3);
  75        outb(0xbf, 0xb2);
  76        intensity = inb(0xb3) >> 4;
  77
  78        if (debug)
  79                pr_debug("read brightness of %d\n", intensity);
  80
  81        return intensity;
  82}
  83
  84static const struct hw_data intel_chipset_data = {
  85        .iostart = 0xb2,
  86        .iolen = 2,
  87        .backlight_ops  = {
  88                .options        = BL_CORE_SUSPENDRESUME,
  89                .get_brightness = intel_chipset_get_intensity,
  90                .update_status  = intel_chipset_send_intensity,
  91        },
  92        .set_brightness = intel_chipset_set_brightness,
  93};
  94
  95/*
  96 * Implementation for machines with Nvidia chipset.
  97 */
  98static void nvidia_chipset_set_brightness(int intensity)
  99{
 100        outb(0x04 | (intensity << 4), 0x52f);
 101        outb(0xbf, 0x52e);
 102}
 103
 104static int nvidia_chipset_send_intensity(struct backlight_device *bd)
 105{
 106        int intensity = bd->props.brightness;
 107
 108        if (debug)
 109                pr_debug("setting brightness to %d\n", intensity);
 110
 111        nvidia_chipset_set_brightness(intensity);
 112        return 0;
 113}
 114
 115static int nvidia_chipset_get_intensity(struct backlight_device *bd)
 116{
 117        int intensity;
 118
 119        outb(0x03, 0x52f);
 120        outb(0xbf, 0x52e);
 121        intensity = inb(0x52f) >> 4;
 122
 123        if (debug)
 124                pr_debug("read brightness of %d\n", intensity);
 125
 126        return intensity;
 127}
 128
 129static const struct hw_data nvidia_chipset_data = {
 130        .iostart = 0x52e,
 131        .iolen = 2,
 132        .backlight_ops          = {
 133                .options        = BL_CORE_SUSPENDRESUME,
 134                .get_brightness = nvidia_chipset_get_intensity,
 135                .update_status  = nvidia_chipset_send_intensity
 136        },
 137        .set_brightness = nvidia_chipset_set_brightness,
 138};
 139
 140static int apple_bl_add(struct acpi_device *dev)
 141{
 142        struct backlight_properties props;
 143        struct pci_dev *host;
 144        int intensity;
 145
 146        host = pci_get_bus_and_slot(0, 0);
 147
 148        if (!host) {
 149                pr_err("unable to find PCI host\n");
 150                return -ENODEV;
 151        }
 152
 153        if (host->vendor == PCI_VENDOR_ID_INTEL)
 154                hw_data = &intel_chipset_data;
 155        else if (host->vendor == PCI_VENDOR_ID_NVIDIA)
 156                hw_data = &nvidia_chipset_data;
 157
 158        pci_dev_put(host);
 159
 160        if (!hw_data) {
 161                pr_err("unknown hardware\n");
 162                return -ENODEV;
 163        }
 164
 165        /* Check that the hardware responds - this may not work under EFI */
 166
 167        intensity = hw_data->backlight_ops.get_brightness(NULL);
 168
 169        if (!intensity) {
 170                hw_data->set_brightness(1);
 171                if (!hw_data->backlight_ops.get_brightness(NULL))
 172                        return -ENODEV;
 173
 174                hw_data->set_brightness(0);
 175        }
 176
 177        if (!request_region(hw_data->iostart, hw_data->iolen,
 178                            "Apple backlight"))
 179                return -ENXIO;
 180
 181        memset(&props, 0, sizeof(struct backlight_properties));
 182        props.type = BACKLIGHT_PLATFORM;
 183        props.max_brightness = 15;
 184        apple_backlight_device = backlight_device_register("apple_backlight",
 185                                  NULL, NULL, &hw_data->backlight_ops, &props);
 186
 187        if (IS_ERR(apple_backlight_device)) {
 188                release_region(hw_data->iostart, hw_data->iolen);
 189                return PTR_ERR(apple_backlight_device);
 190        }
 191
 192        apple_backlight_device->props.brightness =
 193                hw_data->backlight_ops.get_brightness(apple_backlight_device);
 194        backlight_update_status(apple_backlight_device);
 195
 196        return 0;
 197}
 198
 199static int apple_bl_remove(struct acpi_device *dev)
 200{
 201        backlight_device_unregister(apple_backlight_device);
 202
 203        release_region(hw_data->iostart, hw_data->iolen);
 204        hw_data = NULL;
 205        return 0;
 206}
 207
 208static const struct acpi_device_id apple_bl_ids[] = {
 209        {"APP0002", 0},
 210        {"", 0},
 211};
 212
 213static struct acpi_driver apple_bl_driver = {
 214        .name = "Apple backlight",
 215        .ids = apple_bl_ids,
 216        .ops = {
 217                .add = apple_bl_add,
 218                .remove = apple_bl_remove,
 219        },
 220};
 221
 222static atomic_t apple_bl_registered = ATOMIC_INIT(0);
 223
 224int apple_bl_register(void)
 225{
 226        if (atomic_xchg(&apple_bl_registered, 1) == 0)
 227                return acpi_bus_register_driver(&apple_bl_driver);
 228
 229        return 0;
 230}
 231EXPORT_SYMBOL_GPL(apple_bl_register);
 232
 233void apple_bl_unregister(void)
 234{
 235        if (atomic_xchg(&apple_bl_registered, 0) == 1)
 236                acpi_bus_unregister_driver(&apple_bl_driver);
 237}
 238EXPORT_SYMBOL_GPL(apple_bl_unregister);
 239
 240static int __init apple_bl_init(void)
 241{
 242        return apple_bl_register();
 243}
 244
 245static void __exit apple_bl_exit(void)
 246{
 247        apple_bl_unregister();
 248}
 249
 250module_init(apple_bl_init);
 251module_exit(apple_bl_exit);
 252
 253MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
 254MODULE_DESCRIPTION("Apple Backlight Driver");
 255MODULE_LICENSE("GPL");
 256MODULE_DEVICE_TABLE(acpi, apple_bl_ids);
 257MODULE_ALIAS("mbp_nvidia_bl");
 258
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