drivers/platform/x86/apple-gmux.c

   1 /*
   2  *  Gmux driver for Apple laptops
   3  *
   4  *  Copyright (C) Canonical Ltd. <seth.forshee@canonical.com>
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License version 2 as
   8  *  published by the Free Software Foundation.
   9  */
  10
  11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  12
  13 #include <linux/module.h>
  14 #include <linux/kernel.h>
  15 #include <linux/init.h>
  16 #include <linux/backlight.h>
  17 #include <linux/acpi.h>
  18 #include <linux/pnp.h>
  19 #include <linux/apple_bl.h>
  20 #include <linux/slab.h>
  21 #include <acpi/video.h>
  22 #include <asm/io.h>
  23
  24 struct apple_gmux_data {
  25         unsigned long iostart;
  26         unsigned long iolen;
  27
  28         struct backlight_device *bdev;
  29 };
  30
  31 /*
  32  * gmux port offsets. Many of these are not yet used, but may be in the
  33  * future, and it's useful to have them documented here anyhow.
  34  */
  35 #define GMUX_PORT_VERSION_MAJOR         0x04
  36 #define GMUX_PORT_VERSION_MINOR         0x05
  37 #define GMUX_PORT_VERSION_RELEASE       0x06
  38 #define GMUX_PORT_SWITCH_DISPLAY        0x10
  39 #define GMUX_PORT_SWITCH_GET_DISPLAY    0x11
  40 #define GMUX_PORT_INTERRUPT_ENABLE      0x14
  41 #define GMUX_PORT_INTERRUPT_STATUS      0x16
  42 #define GMUX_PORT_SWITCH_DDC            0x28
  43 #define GMUX_PORT_SWITCH_EXTERNAL       0x40
  44 #define GMUX_PORT_SWITCH_GET_EXTERNAL   0x41
  45 #define GMUX_PORT_DISCRETE_POWER        0x50
  46 #define GMUX_PORT_MAX_BRIGHTNESS        0x70
  47 #define GMUX_PORT_BRIGHTNESS            0x74
  48
  49 #define GMUX_MIN_IO_LEN                 (GMUX_PORT_BRIGHTNESS + 4)
  50
  51 #define GMUX_INTERRUPT_ENABLE           0xff
  52 #define GMUX_INTERRUPT_DISABLE          0x00
  53
  54 #define GMUX_INTERRUPT_STATUS_ACTIVE    0
  55 #define GMUX_INTERRUPT_STATUS_DISPLAY   (1 << 0)
  56 #define GMUX_INTERRUPT_STATUS_POWER     (1 << 2)
  57 #define GMUX_INTERRUPT_STATUS_HOTPLUG   (1 << 3)
  58
  59 #define GMUX_BRIGHTNESS_MASK            0x00ffffff
  60 #define GMUX_MAX_BRIGHTNESS             GMUX_BRIGHTNESS_MASK
  61
  62 static inline u8 gmux_read8(struct apple_gmux_data *gmux_data, int port)
  63 {
  64         return inb(gmux_data->iostart + port);
  65 }
  66
  67 static inline void gmux_write8(struct apple_gmux_data *gmux_data, int port,
  68                                u8 val)
  69 {
  70         outb(val, gmux_data->iostart + port);
  71 }
  72
  73 static inline u32 gmux_read32(struct apple_gmux_data *gmux_data, int port)
  74 {
  75         return inl(gmux_data->iostart + port);
  76 }
  77
  78 static int gmux_get_brightness(struct backlight_device *bd)
  79 {
  80         struct apple_gmux_data *gmux_data = bl_get_data(bd);
  81         return gmux_read32(gmux_data, GMUX_PORT_BRIGHTNESS) &
  82                GMUX_BRIGHTNESS_MASK;
  83 }
  84
  85 static int gmux_update_status(struct backlight_device *bd)
  86 {
  87         struct apple_gmux_data *gmux_data = bl_get_data(bd);
  88         u32 brightness = bd->props.brightness;
  89
  90         /*
  91          * Older gmux versions require writing out lower bytes first then
  92          * setting the upper byte to 0 to flush the values. Newer versions
  93          * accept a single u32 write, but the old method also works, so we
  94          * just use the old method for all gmux versions.
  95          */
  96         gmux_write8(gmux_data, GMUX_PORT_BRIGHTNESS, brightness);
  97         gmux_write8(gmux_data, GMUX_PORT_BRIGHTNESS + 1, brightness >> 8);
  98         gmux_write8(gmux_data, GMUX_PORT_BRIGHTNESS + 2, brightness >> 16);
  99         gmux_write8(gmux_data, GMUX_PORT_BRIGHTNESS + 3, 0);
 100
 101         return 0;
 102 }
 103
 104 static const struct backlight_ops gmux_bl_ops = {
 105         .get_brightness = gmux_get_brightness,
 106         .update_status = gmux_update_status,
 107 };
 108
 109 static int __devinit gmux_probe(struct pnp_dev *pnp,
 110                                 const struct pnp_device_id *id)
 111 {
 112         struct apple_gmux_data *gmux_data;
 113         struct resource *res;
 114         struct backlight_properties props;
 115         struct backlight_device *bdev;
 116         u8 ver_major, ver_minor, ver_release;
 117         int ret = -ENXIO;
 118
 119         gmux_data = kzalloc(sizeof(*gmux_data), GFP_KERNEL);
 120         if (!gmux_data)
 121                 return -ENOMEM;
 122         pnp_set_drvdata(pnp, gmux_data);
 123
 124         res = pnp_get_resource(pnp, IORESOURCE_IO, 0);
 125         if (!res) {
 126                 pr_err("Failed to find gmux I/O resource\n");
 127                 goto err_free;
 128         }
 129
 130         gmux_data->iostart = res->start;
 131         gmux_data->iolen = res->end - res->start;
 132
 133         if (gmux_data->iolen < GMUX_MIN_IO_LEN) {
 134                 pr_err("gmux I/O region too small (%lu < %u)\n",
 135                        gmux_data->iolen, GMUX_MIN_IO_LEN);
 136                 goto err_free;
 137         }
 138
 139         if (!request_region(gmux_data->iostart, gmux_data->iolen,
 140                             "Apple gmux")) {
 141                 pr_err("gmux I/O already in use\n");
 142                 goto err_free;
 143         }
 144
 145         /*
 146          * On some machines the gmux is in ACPI even thought the machine
 147          * doesn't really have a gmux. Check for invalid version information
 148          * to detect this.
 149          */
 150         ver_major = gmux_read8(gmux_data, GMUX_PORT_VERSION_MAJOR);
 151         ver_minor = gmux_read8(gmux_data, GMUX_PORT_VERSION_MINOR);
 152         ver_release = gmux_read8(gmux_data, GMUX_PORT_VERSION_RELEASE);
 153         if (ver_major == 0xff && ver_minor == 0xff && ver_release == 0xff) {
 154                 pr_info("gmux device not present\n");
 155                 ret = -ENODEV;
 156                 goto err_release;
 157         }
 158
 159         pr_info("Found gmux version %d.%d.%d\n", ver_major, ver_minor,
 160                 ver_release);
 161
 162         memset(&props, 0, sizeof(props));
 163         props.type = BACKLIGHT_PLATFORM;
 164         props.max_brightness = gmux_read32(gmux_data, GMUX_PORT_MAX_BRIGHTNESS);
 165
 166         /*
 167          * Currently it's assumed that the maximum brightness is less than
 168          * 2^24 for compatibility with old gmux versions. Cap the max
 169          * brightness at this value, but print a warning if the hardware
 170          * reports something higher so that it can be fixed.
 171          */
 172         if (WARN_ON(props.max_brightness > GMUX_MAX_BRIGHTNESS))
 173                 props.max_brightness = GMUX_MAX_BRIGHTNESS;
 174
 175         bdev = backlight_device_register("gmux_backlight", &pnp->dev,
 176                                          gmux_data, &gmux_bl_ops, &props);
 177         if (IS_ERR(bdev)) {
 178                 ret = PTR_ERR(bdev);
 179                 goto err_release;
 180         }
 181
 182         gmux_data->bdev = bdev;
 183         bdev->props.brightness = gmux_get_brightness(bdev);
 184         backlight_update_status(bdev);
 185
 186         /*
 187          * The backlight situation on Macs is complicated. If the gmux is
 188          * present it's the best choice, because it always works for
 189          * backlight control and supports more levels than other options.
 190          * Disable the other backlight choices.
 191          */
 192         acpi_video_unregister();
 193         apple_bl_unregister();
 194
 195         return 0;
 196
 197 err_release:
 198         release_region(gmux_data->iostart, gmux_data->iolen);
 199 err_free:
 200         kfree(gmux_data);
 201         return ret;
 202 }
 203
 204 static void __devexit gmux_remove(struct pnp_dev *pnp)
 205 {
 206         struct apple_gmux_data *gmux_data = pnp_get_drvdata(pnp);
 207
 208         backlight_device_unregister(gmux_data->bdev);
 209         release_region(gmux_data->iostart, gmux_data->iolen);
 210         kfree(gmux_data);
 211
 212         acpi_video_register();
 213         apple_bl_register();
 214 }
 215
 216 static const struct pnp_device_id gmux_device_ids[] = {
 217         {"APP000B", 0},
 218         {"", 0}
 219 };
 220
 221 static struct pnp_driver gmux_pnp_driver = {
 222         .name           = "apple-gmux",
 223         .probe          = gmux_probe,
 224         .remove         = __devexit_p(gmux_remove),
 225         .id_table       = gmux_device_ids,
 226 };
 227
 228 static int __init apple_gmux_init(void)
 229 {
 230         return pnp_register_driver(&gmux_pnp_driver);
 231 }
 232
 233 static void __exit apple_gmux_exit(void)
 234 {
 235         pnp_unregister_driver(&gmux_pnp_driver);
 236 }
 237
 238 module_init(apple_gmux_init);
 239 module_exit(apple_gmux_exit);
 240
 241 MODULE_AUTHOR("Seth Forshee <seth.forshee@canonical.com>");
 242 MODULE_DESCRIPTION("Apple Gmux Driver");
 243 MODULE_LICENSE("GPL");
 244 MODULE_DEVICE_TABLE(pnp, gmux_device_ids);