2 * Gmux driver for Apple laptops
4 * Copyright (C) Canonical Ltd. <seth.forshee@canonical.com>
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.
11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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>
24 struct apple_gmux_data {
25 unsigned long iostart;
28 struct backlight_device *bdev;
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.
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
49 #define GMUX_MIN_IO_LEN (GMUX_PORT_BRIGHTNESS + 4)
51 #define GMUX_INTERRUPT_ENABLE 0xff
52 #define GMUX_INTERRUPT_DISABLE 0x00
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)
59 #define GMUX_BRIGHTNESS_MASK 0x00ffffff
60 #define GMUX_MAX_BRIGHTNESS GMUX_BRIGHTNESS_MASK
62 static inline u8 gmux_read8(struct apple_gmux_data *gmux_data, int port)
64 return inb(gmux_data->iostart + port);
67 static inline void gmux_write8(struct apple_gmux_data *gmux_data, int port,
70 outb(val, gmux_data->iostart + port);
73 static inline u32 gmux_read32(struct apple_gmux_data *gmux_data, int port)
75 return inl(gmux_data->iostart + port);
78 static int gmux_get_brightness(struct backlight_device *bd)
80 struct apple_gmux_data *gmux_data = bl_get_data(bd);
81 return gmux_read32(gmux_data, GMUX_PORT_BRIGHTNESS) &
85 static int gmux_update_status(struct backlight_device *bd)
87 struct apple_gmux_data *gmux_data = bl_get_data(bd);
88 u32 brightness = bd->props.brightness;
90 if (bd->props.state & BL_CORE_SUSPENDED)
94 * Older gmux versions require writing out lower bytes first then
95 * setting the upper byte to 0 to flush the values. Newer versions
96 * accept a single u32 write, but the old method also works, so we
97 * just use the old method for all gmux versions.
99 gmux_write8(gmux_data, GMUX_PORT_BRIGHTNESS, brightness);
100 gmux_write8(gmux_data, GMUX_PORT_BRIGHTNESS + 1, brightness >> 8);
101 gmux_write8(gmux_data, GMUX_PORT_BRIGHTNESS + 2, brightness >> 16);
102 gmux_write8(gmux_data, GMUX_PORT_BRIGHTNESS + 3, 0);
107 static const struct backlight_ops gmux_bl_ops = {
108 .options = BL_CORE_SUSPENDRESUME,
109 .get_brightness = gmux_get_brightness,
110 .update_status = gmux_update_status,
113 static int __devinit gmux_probe(struct pnp_dev *pnp,
114 const struct pnp_device_id *id)
116 struct apple_gmux_data *gmux_data;
117 struct resource *res;
118 struct backlight_properties props;
119 struct backlight_device *bdev;
120 u8 ver_major, ver_minor, ver_release;
123 gmux_data = kzalloc(sizeof(*gmux_data), GFP_KERNEL);
126 pnp_set_drvdata(pnp, gmux_data);
128 res = pnp_get_resource(pnp, IORESOURCE_IO, 0);
130 pr_err("Failed to find gmux I/O resource\n");
134 gmux_data->iostart = res->start;
135 gmux_data->iolen = res->end - res->start;
137 if (gmux_data->iolen < GMUX_MIN_IO_LEN) {
138 pr_err("gmux I/O region too small (%lu < %u)\n",
139 gmux_data->iolen, GMUX_MIN_IO_LEN);
143 if (!request_region(gmux_data->iostart, gmux_data->iolen,
145 pr_err("gmux I/O already in use\n");
150 * On some machines the gmux is in ACPI even thought the machine
151 * doesn't really have a gmux. Check for invalid version information
154 ver_major = gmux_read8(gmux_data, GMUX_PORT_VERSION_MAJOR);
155 ver_minor = gmux_read8(gmux_data, GMUX_PORT_VERSION_MINOR);
156 ver_release = gmux_read8(gmux_data, GMUX_PORT_VERSION_RELEASE);
157 if (ver_major == 0xff && ver_minor == 0xff && ver_release == 0xff) {
158 pr_info("gmux device not present\n");
163 pr_info("Found gmux version %d.%d.%d\n", ver_major, ver_minor,
166 memset(&props, 0, sizeof(props));
167 props.type = BACKLIGHT_PLATFORM;
168 props.max_brightness = gmux_read32(gmux_data, GMUX_PORT_MAX_BRIGHTNESS);
171 * Currently it's assumed that the maximum brightness is less than
172 * 2^24 for compatibility with old gmux versions. Cap the max
173 * brightness at this value, but print a warning if the hardware
174 * reports something higher so that it can be fixed.
176 if (WARN_ON(props.max_brightness > GMUX_MAX_BRIGHTNESS))
177 props.max_brightness = GMUX_MAX_BRIGHTNESS;
179 bdev = backlight_device_register("gmux_backlight", &pnp->dev,
180 gmux_data, &gmux_bl_ops, &props);
186 gmux_data->bdev = bdev;
187 bdev->props.brightness = gmux_get_brightness(bdev);
188 backlight_update_status(bdev);
191 * The backlight situation on Macs is complicated. If the gmux is
192 * present it's the best choice, because it always works for
193 * backlight control and supports more levels than other options.
194 * Disable the other backlight choices.
196 acpi_video_dmi_promote_vendor();
197 #ifdef CONFIG_ACPI_VIDEO
198 acpi_video_unregister();
200 apple_bl_unregister();
205 release_region(gmux_data->iostart, gmux_data->iolen);
211 static void __devexit gmux_remove(struct pnp_dev *pnp)
213 struct apple_gmux_data *gmux_data = pnp_get_drvdata(pnp);
215 backlight_device_unregister(gmux_data->bdev);
216 release_region(gmux_data->iostart, gmux_data->iolen);
219 acpi_video_dmi_demote_vendor();
220 #ifdef CONFIG_ACPI_VIDEO
221 acpi_video_register();
226 static const struct pnp_device_id gmux_device_ids[] = {
231 static struct pnp_driver gmux_pnp_driver = {
232 .name = "apple-gmux",
234 .remove = __devexit_p(gmux_remove),
235 .id_table = gmux_device_ids,
238 static int __init apple_gmux_init(void)
240 return pnp_register_driver(&gmux_pnp_driver);
243 static void __exit apple_gmux_exit(void)
245 pnp_unregister_driver(&gmux_pnp_driver);
248 module_init(apple_gmux_init);
249 module_exit(apple_gmux_exit);
251 MODULE_AUTHOR("Seth Forshee <seth.forshee@canonical.com>");
252 MODULE_DESCRIPTION("Apple Gmux Driver");
253 MODULE_LICENSE("GPL");
254 MODULE_DEVICE_TABLE(pnp, gmux_device_ids);