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
;
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.
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);
104 static const struct backlight_ops gmux_bl_ops
= {
105 .get_brightness
= gmux_get_brightness
,
106 .update_status
= gmux_update_status
,
109 static int __devinit
gmux_probe(struct pnp_dev
*pnp
,
110 const struct pnp_device_id
*id
)
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
;
119 gmux_data
= kzalloc(sizeof(*gmux_data
), GFP_KERNEL
);
122 pnp_set_drvdata(pnp
, gmux_data
);
124 res
= pnp_get_resource(pnp
, IORESOURCE_IO
, 0);
126 pr_err("Failed to find gmux I/O resource\n");
130 gmux_data
->iostart
= res
->start
;
131 gmux_data
->iolen
= res
->end
- res
->start
;
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
);
139 if (!request_region(gmux_data
->iostart
, gmux_data
->iolen
,
141 pr_err("gmux I/O already in use\n");
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
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");
159 pr_info("Found gmux version %d.%d.%d\n", ver_major
, ver_minor
,
162 memset(&props
, 0, sizeof(props
));
163 props
.type
= BACKLIGHT_PLATFORM
;
164 props
.max_brightness
= gmux_read32(gmux_data
, GMUX_PORT_MAX_BRIGHTNESS
);
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.
172 if (WARN_ON(props
.max_brightness
> GMUX_MAX_BRIGHTNESS
))
173 props
.max_brightness
= GMUX_MAX_BRIGHTNESS
;
175 bdev
= backlight_device_register("gmux_backlight", &pnp
->dev
,
176 gmux_data
, &gmux_bl_ops
, &props
);
182 gmux_data
->bdev
= bdev
;
183 bdev
->props
.brightness
= gmux_get_brightness(bdev
);
184 backlight_update_status(bdev
);
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.
192 acpi_video_unregister();
193 apple_bl_unregister();
198 release_region(gmux_data
->iostart
, gmux_data
->iolen
);
204 static void __devexit
gmux_remove(struct pnp_dev
*pnp
)
206 struct apple_gmux_data
*gmux_data
= pnp_get_drvdata(pnp
);
208 backlight_device_unregister(gmux_data
->bdev
);
209 release_region(gmux_data
->iostart
, gmux_data
->iolen
);
212 acpi_video_register();
216 static const struct pnp_device_id gmux_device_ids
[] = {
221 static struct pnp_driver gmux_pnp_driver
= {
222 .name
= "apple-gmux",
224 .remove
= __devexit_p(gmux_remove
),
225 .id_table
= gmux_device_ids
,
228 static int __init
apple_gmux_init(void)
230 return pnp_register_driver(&gmux_pnp_driver
);
233 static void __exit
apple_gmux_exit(void)
235 pnp_unregister_driver(&gmux_pnp_driver
);
238 module_init(apple_gmux_init
);
239 module_exit(apple_gmux_exit
);
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
);