drivers/video/backlight/apple_bl.c

   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
  32 static struct backlight_device *apple_backlight_device;
  33
  34 struct 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
  43 static const struct hw_data *hw_data;
  44
  45 /* Module parameters. */
  46 static int debug;
  47 module_param_named(debug, debug, int, 0644);
  48 MODULE_PARM_DESC(debug, "Set to one to enable debugging messages.");
  49
  50 /*
  51  * Implementation for machines with Intel chipset.
  52  */
  53 static void intel_chipset_set_brightness(int intensity)
  54 {
  55         outb(0x04 | (intensity << 4), 0xb3);
  56         outb(0xbf, 0xb2);
  57 }
  58
  59 static 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
  70 static 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
  84 static 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  */
  98 static void nvidia_chipset_set_brightness(int intensity)
  99 {
 100         outb(0x04 | (intensity << 4), 0x52f);
 101         outb(0xbf, 0x52e);
 102 }
 103
 104 static 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
 115 static 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
 129 static 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
 140 static 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_domain_bus_and_slot(0, 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
 199 static 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
 208 static const struct acpi_device_id apple_bl_ids[] = {
 209         {"APP0002", 0},
 210         {"", 0},
 211 };
 212
 213 static 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
 222 static atomic_t apple_bl_registered = ATOMIC_INIT(0);
 223
 224 int 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 }
 231 EXPORT_SYMBOL_GPL(apple_bl_register);
 232
 233 void apple_bl_unregister(void)
 234 {
 235         if (atomic_xchg(&apple_bl_registered, 0) == 1)
 236                 acpi_bus_unregister_driver(&apple_bl_driver);
 237 }
 238 EXPORT_SYMBOL_GPL(apple_bl_unregister);
 239
 240 static int __init apple_bl_init(void)
 241 {
 242         return apple_bl_register();
 243 }
 244
 245 static void __exit apple_bl_exit(void)
 246 {
 247         apple_bl_unregister();
 248 }
 249
 250 module_init(apple_bl_init);
 251 module_exit(apple_bl_exit);
 252
 253 MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
 254 MODULE_DESCRIPTION("Apple Backlight Driver");
 255 MODULE_LICENSE("GPL");
 256 MODULE_DEVICE_TABLE(acpi, apple_bl_ids);
 257 MODULE_ALIAS("mbp_nvidia_bl");